U.S. Geological Survey Greater Everglades Science Program: 2002 Biennial Report

Cover graphic:
Project Implementation (Management Actions)
Science-Based Decision-Making
Public Input Monitoring and Evaluation
Integrated Science (Research and Studies)
Alternatives Evaluation (Modeling)

U.S. Geological Survey Greater Everglades Science Program: 2002 Biennial Report
Open-File Report 03-54
U.S. GEOLOGICAL SURVEY
*Science Conference hosted by: The Science Coordination Team a committee of the
SOUTH FLORIDA ECOSYSTEM RESTORATION TASK FORCE AND WORKING GROUP

Including USGS abstracts of presentations made at the Joint Science Conference* on Florida Bay and Greater Everglades Ecosystem Restoration (GEER) - "From  Kissimmee to the Keys"

April 13-18, 2003
Palm Harbor, Florida

Collaborators (Federal, State, Local and Tribal Agencies):
- Florida Department of Environmental Protection
- Florida Fish and Wildlife Conservation Commission, Eustis, FL
- Florida Marine Research Institute, St. Petersburg, FL
- National Marine Fisheries
- National Marine Sanctuary
- National Park Service
- National Resource Conservation Service
- National Oceanic and Atmospheric Administration
- National Water Research Institute, Environment Canada, Burlington, ONT, Canada
- Netherlands Institute of Ecology
- NOAA Fisheries, Southeast Fisheries Science Center, Miami, FL
- NOAA Fisheries, Estuarine Habitats and Coastal Fisheries Center, Lafayette, LA
- NOAA, NCCOS, Center for Coastal Fisheries and Habitat Research, Beaufort, NC
- Seminole Tribe of Florida
- South Florida Water Management District
- U.S. Army Corps of Engineers
- U.S.D.A. Forest Service, Southern Research Station, Pineville, LA
- U.S. Environmental Protection Agency
- U.S. Fish and Wildlife Service

Collaborators (Universities):
- Annis Water Resources Institute, Muskegon, MI
- Carleton University, Ottawa, Ontario, Canada
- Duke University, Durham, NC
- Florida Cooperative Fish and Wildlife Research Unit, University of Florida, Gainesville, FL
- Florida International University, Miami, FL
- Florida State University, Tallahassee, FL
- Nicholas School of the Environment Marine Laboratory, Beaufort, NC
- Michigan State University
- Rosenstiel School of Marine and Atmospheric Science, University of Miami
- Smith College, Northampton, MA
- Southern Illinois University, Carbondale IL
- Texas Tech University
- University of California, Department of Ecology, Evolution and Marine Biology
- University of Florida, Gainesville, FL
- University of Miami, Coral Gables, FL
- University of Guelph, Guelph
- University of Southern Illinois, Carbondale, IL
- University of Tennessee, Knoxville, TN
- University of Washington
- University of West Florida, Pensacola, FL
- Washington University, St. Louis, MO
- Wofford College, Spartanburg, SC
- Yale University, New Haven, CT

Photographs:
Photographs and images used in this report are from studies performed by the U.S. Geological Survey, Greater Everglades Science Program.

U.S. Geological Survey Greater Everglades
Science Program: 2002 Biennial Report
Including USGS abstracts of presentations made at the Joint Science Conference* on Florida Bay and Greater Everglades Ecosystem Restoration (GEER) - "From
Kissimmee to the Keys"
April 13-18, 2003,
Palm Harbor, Florida

Compiled by Arturo E. Torres, Aaron L. Higer, Heather S. Henkel, Patsy R. Mixson, Jane R. Eggleston, Teresa L. Embry, and Gail Clement
Under the direction of G. Ronnie Best, PhD, PWS, Coordinator U.S. Geological Survey, Greater Everglades Science Program

U.S. GEOLOGICAL SURVEY
Open-File Report 03-54
* Science Conference Hosted by: The Science Coordination Team a committee of the
SOUTH FLORIDA ECOSYSTEM RESTORATION TASK FORCE AND WORKING GROUP
Tallahassee, Florida 2003

U.S. DEPARTMENT OF THE INTERIOR
GALE A. NORTON, Secretary
U.S. GEOLOGICAL SURVEY
CHARLES G. GROAT, Director

The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey.
For additional information Copies of this report can be write to: purchased from: U.S. Geological Survey U.S. Geological Survey
2010 Levy Avenue Branch of Information Services
Tallahassee, FL 32310 Box 25286
Denver, CO 80225-0286
888-ASK-USGS

Additional information about water resources in Florida is available on the World Wide Web at http://sofia.usgs.gov.

CONTENTS
Introduction 
Summary of Greater Everglades
Restoration Workshop
Section I: Get the Water Quantity Right 
Section II: Get the Water Quality Right
Section III: Preserving Natural Habitats
and Species
Section IV: Information Systems
Section V: Facts and Flyers 
Section VI: Bibliography
Section VII: Author Index 

U.S. Geological Survey Greater Everglades
Science Program: 2002 Biennial Report
Introduction

The U.S. Geological Survey (USGS) conducts scientific investigations in south Florida to improve society's understanding of the environment and assist in the sustainable use, protection, and restoration of the Everglades and other ecosystems within the region. The investigations summarized in this document have been carried out under the Greater Everglades Science Program (previously known as the South Florida Ecosystem Program), which is part of the USGS Place-Based Studies initiative.

The USGS Placed-Based Studies initiative is a nationwide program that  oncentrates on areas with severe environmental problems. Through  interdisciplinary investigations the Program provides sound scientific information on which to base informed resource management decisions. Individuals from all the USGS programs (hydrology, geology, biology, mapping) work together with other scientists to cover the diverse scientific disciplines involved in this complex and challenging task. The Greater Everglades Science Program began in 1995 as one of the initial Place-Based Studies programs and serves as a model for similar future collaborative studies. Placed-Based Studies are also being conducted in the San Francisco Bay area, Chesapeake Bay, the Platte River, Greater Yellowstone, Salton Sea, and the Mojave Desert.

The South Florida Ecosystem Program is part of a coordinated federal effort, under the South Florida Ecosystem Restoration Task Force. The Task Force was started in 1993, through interagency agreement, to coordinate the efforts of the
agencies within six federal departments. In 1996, statutory authority formalized the Task Force and expanded it to include tribal, state, and local governments. The Task Force conducts its activities through the South Florida Ecosystem Working Group and teams, such as the Science Coordination Team. A Science Plan and Integrated Financial Plans are established to focus efforts and prevent duplicative efforts by the agencies.

Diagram of Greater Everglades Science Program
Place-Based Study Relations
South Florida
Ecosystem
Place-Based
Research
and Studies
Science
Coordination
Plan
DOI
Federal/State/
Tribal/Local
Task Force
South Florida
Working Group
Collaborators
Getting the Water
Right
Quantity
Getting the Water
Right
Quality
Preserving Natural
Habitats
and Species
Ecosystem Restoration Adaptive Management

Organization and Content of the Document
This document presents the results of over 60 studies and
200 investigators that are active in the USGS Greater Everglades
Science Program during the year 2003. The studies are categorized
according to the major focuses of the South Florida Ecosystem
Restoration Task Force.
Getting the Water Quantity Right - establishing the volume, quantity,
timing and distribution of surface and ground waters to approximate predevelopment conditions.
Getting the Water Quality Right  reducing or eliminating pollutants and other
undesirable substances from the water.
Preserving Natural Habitats and Species - providing the needs of the diverse
flora and fauna of this ecologically unique area 
Information Availability  exchanging information regarding programs,
projects, and activities to promote ecosystem restoration and maintenance - through South Florida Information Access (SOFIA)

This document also includes a bibliography of reports either published or in press, from the Greater Everglades Science Program Place-Based Study initiative.

Restoring the Nation's Greater Everglades Ecosystem

Restoring the Everglades is an enormous challenge, that involves returning essential functions to a large (over 11,000 square
miles) and diverse ecosystem that has had significant adverse impacts from man's activities over the past 50 years. America's Everglades
is a National treasure which must be restored to ensure that south Florida's unique and irreplaceable natural environment is
preserved, assure the quantity and quality of drinking water as well as agricultural and industrial water supplies, and in general improve
the quality of life for all south Florida's inhabitants.
The Comprehensive Everglades Restoration Plan (CERP) was developed over a period of six years by the U.S. Army Corps of
Engineers in partnership with the South Florida Water Management District and more than 30 tribal, federal, state and local agencies. It
is the primary planning vehicle for achieving the goal of improving the quantity, quality, timing and distribution of water that will return
health to this seriously degraded system. CERP proposes costs in excess of $7.8 billion and a time frame of about 30 years to complete
this massive and unprecedented restoration effort.
Both the U.S. Government and the State of Florida have made initial funding commitments for Greater Everglades ecosystem
restoration.
The complexity of this undertaking and the magnitude of the risks involved in an undertaking that includes some 68 interrelated
engineering projects and feasibility studies mandates a science-based approach to implementation of CERP. The USGS, through its
Greater Everglades Science Program Place Based Studies initiative, has committed to providing the highest level of scientific expertise
to support decision-making and ensure a successful restoration of the Greater Everglades and adjacent coastal ecosystems.
USGS Role in South Florida Ecosystem Restoration
In keeping with the mission of the USGS to provide the Nation with reliable, impartial information to describe and understand
the Earth, the USGS is involved in biologic, geologic, hydrologic, land use, mapping and topographic studies that contribute to the
safety, health, and well-being of Florida's citizens. The work conducted encompasses basic data collection, hydrological and ecological
modeling, and experimental research and monitoring. The USGS is capable of conducting multidisciplinary work due to the availability
of expertise in geologic, biologic, mapping, and water resources investigations. Expertise is available nationally and can be called upon
as needed for complex investigations, training of local personnel, and development of new approaches and technology to address the
complex science issues involved in ecosystem restoration.

As the Department of the Interior's science agency with a multi-disciplinary, non-regulatory, and non-advocacy focus, as well as
an established, long-term presence in south Florida, the USGS is well positioned to pursue baseline and monitoring activities such as
data collection from surface- and ground-water monitoring networks, cooperative studies with local and State agencies, and research
through extensive national programs such as Place-Based Studies, Global Change Research, National Water Quality Assessment
program (NAWQA), and other national research programs. In addition, about one half of the area to be restored is public land administered
by the National Park Service (NPS), Fish and Wildlife Service (FWS), state agencies, and the South Florida Water Management
District (SFWMD). The U.S. Geological Survey science leadership in the South Florida Ecosystem Restoration Task Force's Working
Group and Science Coordination Team, CERP, and other ecosystem restoration efforts in south Florida is closely linked to its mission
goal "to provide science for a changing world in response to present and anticipated needs; to expand our understanding of environmental
and natural resource issues on regional, national, and global scales; and to enhance predictive/forecast modeling capabilities." The
multidisciplinary approach applied by the USGS is necessary to provide a process level as well as holistic ecosystem-level evaluation of
system responses to proposed restoration alternatives and plans.
Historically, the USGS in Florida has operated basic data collection networks and conducted investigations that provide the
foundation for the wise stewardship of water and biological resources of the State. The hydrogeologic framework has been described in
many reports, aquifer characteristics have been determined through geophysical logging
and pumping tests, and ecological conditions have been monitored. The data that have
been collected for the advancement of general knowledge of our natural resources
provide the foundation for the understanding of the fate of contaminants in the environment.
The data also have been used in the development of hydrologic and ecological
models for predicting the effects of additional stresses on the natural resources and
provide the tools for evaluation of effects of land use changes and potential contaminant
releases in the environment. Real-time data networks, which include the application of
satellite or cellular telephone technology to existing data-collection sites across the State,
are providing needed information for advanced warning of floods and droughts.
Acknowledgements
The USGS's Greater Everglades Science Program Place-Based Studies initiative
is supported by several USGS national research programs including: biological research
and monitoring; earth surface dynamics; geographic research and application; groundwater
resources; hydrologic network and analysis; hydrologic research and development;
and toxic substances hydrology. Although most studies included in this 2002 biennial
report are supported through the Greater Everglades Place-Based Studies initiative, some
studies were supported by additional funding provided by the Department of Interior's
Critical Ecosystem Studies Initiative (CESI) administered by the National Park Service
through Everglades National Park, the U.S. Army Corps of Engineers, the South Florida
Water Management District, the Seminole Tribe, and others.
Building Scientific Knowledge
Develop new information - Identify the
pertinent issues, formulate critical scientific
questions related to the issues, and address the
questions through appropriate modeling,
monitoring and empirical studies.
Communicate - Promote improved
communication among restoration scientists and
managers through scientific conferences,
workshops and the mutual exchange of
information.
Synthesize Scientific Knowledge Relevant to
the Issues - Develop techniques for integrating
and synthesizing restoration data and distribute
the techniques to others involved in restoration
efforts.
Manage Integrated Data - Archive inventories
and other available databases in
multigovernmental database management
systems that are accessible through the internet
and updated regularly.
U.S. Department of the Interior
U.S. Geological Survey
Greater Everglades Science Program
The Workshops
During April and May 2002, the United
States Geological Surveys (USGS)
Greater Everglades Place Based Studies
(PBS) held fi ve information workshops
in south Florida to discuss status of
greater Everglades ecosystem research,
and to solicit suggestions for additional
studies from greater Everglades
restoration partners. These USGS
Workshops included: 1.Paleoecology
and Ecosystem History, April 29, 2002;
2. Hydrologic Modeling and Processes,
May 7-8, 2002; 3. Ecological Modeling
and Processes, May 9-10, 2002; 4.
Landscape Mapping and Topography,
May 23, 2002; and 5. Contaminants and
Biogeochemistry, May 29, 2002.
Background
The greater Everglades restoration program
is prescribing ecosystem-wide
changes to some of the physical, hydrological,
and chemical components of
this ecosystem. The ability to accurately
understand natural (prior to signifi cant
human alteration) conditions within the
greater Everglades ecosystem is crucial
for success of greater Everglades
ecosystem restoration and successful
implementation of the Comprehensive
Everglades Restoration Plan (CERP).
Information on the historical and current
natural system allows restoration planners
to establish realistic baseline conditions,
restoration goals, and performance
measures; create predictive models; and
monitor success of restoration efforts.
Understanding past conditions and
cycles of change also allows for betterinformed
planning, project implementation,
and land management decisions.
Many organizations and programs are
dependent on scientifi c knowledge and
more accurate models for restoring the
greater Everglades ecosystem. These
include federal, state, and local agencies,
Native American tribal governments, as
well as private organizations.
Research Needs
Research needs, including those directly
related to ecosystem history and those
relevant to other research topics, were
compiled during the workshop based on
discussions among the represented organizations
and individuals having interests
and roles within greater Everglades
restoration.
For Further Information
G. Ronnie Best, PhD, PWS Coordinator
Greater Everglades Science Program
Ronnie_Best@usgs.gov
Summary of Greater Everglades Ecosystem Restoration Workshop: Introduction
Map 1-2742
http://sofi a.usgs.gov
U.S. Department of the Interior
U.S. Geological Survey
Greater Everglades Science Program
July 2002 PBS Information Sheet IS 02-01
Paleoecology and Ecosystem
History Research Needs
Expand paleoecological sediment
analyses to include: Biscayne Bay;
Card Sound; transects that include
sawgrass ridges, sloughs, and tree
islands; southwest coast of Florida;
the eastern boundary of Everglades

National Park and adjacent agricultural
areas; and Estero Bay tributaries.
Compare current versus historical
ecologic aspects of: Biscayne Bay,
Barnes and Card Sounds, marl prairies,
location of ridge and slough
landscape; freshwater inputs to
Biscayne Bay; and Florida Bay nutrient
inputs.
Determine historic trophic conditions
within the Everglades.
Compare historical ecological conditions
north and south of Tamiami
Trail.
Determine impact on coral reefs due
to changes in natural hydrology of
the Everglades.
Determine the origin of long-term
salinity variation in Florida Bay
(e.g., climate, runoff, groundwater).
Present paleoecology data within the
context of the Natural System Model
(NSM) when applicable.
When presenting ecological models
and their components, and paleoecological
analyses of sediment cores,
include associated levels of certainty.
Determine rates of sea level rise
during the past several decades; use
these data to forecast future rates,
which can be incorporated into
CERP implementation.
Document historical events and
cyclic meteorological phenomena
(e.g., hurricanes, el nio, la nia) and
incorporate these within forecasting
models.
Summary of Greater Everglades Ecosystem Restoration Workshop:
1. Paleoecology and Ecosystem History, April 29, 2002











What can ecosystem history
studies tell us?
About the terrestrial Everglades . . .
Hydroperiod and water depth
 Pre-drainage conditions
 Natural spatial and temporal
variability
Tree Islands
 Geologic and hydrologic
requirements
 Historical patterns of change
 Longevity and stability
 Response to hydrologic
changes
Ridge and Slough systems
Fire History and Water Depth
Water Quality
About the estuaries. . .
Salinity
 Historical range of salinity
 Natural seasonal variation
 Timing and delivery of
freshwater
Water Quality
Seagrass
 Understanding the causes of
die-offs
 Historical patterns of change
Biodiversity
U.S. Department of the Interior
U.S. Geological Survey
Greater Everglades Science Program
July 2002 PBS Information Sheet IS 02-01
Research Needs Relevant to
Other Workshops Topics
Bathymetric data for southwest
Florida and Biscayne Bay.
Create a Florida Bay circulation
model/bathymetry for the year 2100
that considers sea level rise.
Model changes in precipitation that
could occur due to CERP implementation.
Expand current ecological modeling
efforts into southwest Florida.
Determine water levels and fl ows
that allow both tree islands and the
ridge and slough landscapes to exist.

Create estuarine/freshwater models
for southwest Florida.
Determine the role of nutrients recycling
versus introduced nutrients on
coastal ecosystems.
For Further Information
G. Ronnie Best, PhD, PWS
Coordinator
Greater Everglades Science Program

Ronnie_Best@usgs.gov
G. Lynn Wingard, PhD
Geologist, Earth Surface Processes
lwingard@usgs.gov
http://sofi a.usgs.gov
Academia
24 %
NGO
5 %
Private Org.
5 %
NPS
16 %
Miccosukee
9 % EPA
2 % USFWS
2 %
SFWMD
16 %
Miami-Dade
12 %
FDEP
5 %
Broward
2 %
Palm Beach
2 %
Participation by greater Everglades restoration partners during the 65-person Paleoecology and Ecosystem History Workshop (excluding USGS participants).
U.S. Department of the Interior
U.S. Geological Survey
Greater Everglades Science Program
July 2002 PBS Information Sheet IS 02-02
Hydrologic Modeling Research
Needs
Enhance connectivity between
SFWMM (South Florida Water
Management Model) and Southern
Inland and Coastal System (SICS)
and Tides and Infl ows in Mangroves
of the Everglades (TIME) models.
Develop internet-accessible SICS
and TIME model real-time animations.
Collect TIME equivalent data from
outside of TIME model domain.
Develop additional salinity simulation
capability to support Across
Trophic Level System Simulation
(ATLSS)
program for developing estuarine
species models.
Expand boundaries of SICS and
TIME models to the entire CERP
project area including areas east of
US 1.
Incorporate solute-transport and
simple settling algorithms in regional
models to assist in setting CERP
water quality performance measures.
Model CERP implementation
impacts on transport of nutrients
within the Everglades.
Incorporate seepage effects associated
with the eastern boundary of
the Everglades within all applicable
models.
Complete additional work to couple
water quality and hydrologic monitoring
data with SICS and TIME
models.
Increase spatial resolution of surface
water and groundwater elevation and
salinity monitoring.
Improve discharge and recharge
estimates associated with stormwater
treatment areas.
Increase spatial extent of monitoring
of fl ow structure in wetlands to
assess fl ow impacts on landscapes
and habitat, including tree islands.
Conduct additional studies on the

hydraulic properties of the surfi cial
aquifer system including the overlying
peat and marl unit.
Collect additional information on
Floridian Aquifer hydrogeology.
Develop additional models and
model inputs for the southwest coast
of Florida.
Develop stochastic methods for generating
rainfall input data needed for
applicable models.
Improve understanding of groundwater
solute transport and upwelling
(such as sulfates), and subsequent
surface water mixing in central
Everglades, particularly WCA-3A
south of Alligator Alley.
Create probabilistic/stochastic
approaches to better defi ne trends
and certainties within models.
Summary of Greater Everglades Ecosystem Restoration Workshop:
2. Hydrologic Modeling and Processes, May 7-8, 2002
Measuring flow velocity in Taylor Slough wetlands to develop a simulation model. {Photo by Eric Swain, 1997.}
U.S. Department of the Interior
U.S. Geological Survey
Greater Everglades Science Program
July 2002 PBS Information Sheet IS 02-02
Incorporate climate-change variables
into model simulations.
Research Needs Relevant to
Other Workshops Topics
Complete USGS Aerial Height
Finder (AHF) topographic survey
in Everglades National Park,
Loxahatchee, Big Cypress and Water
Conservation Areas.
Map and delineate unique landscape
features such as tree islands and
hammocks using AHF system.
Establish NAVD88 control along the
southwest Gulf coast in Everglades
National Park.
Conduct bathymetric surveys of tidal
rivers and creeks along the
southwest coast of Florida.
Create a centralized ecosystem data
repository system.
Gather reliable farm elevation/ topographic
information at appropriate
resolution.
Use multi-agency collaboration to
address data quality issues.
For Further Information
G. Ronnie Best, PhD, PWS
Coordinator
Greater Everglades Science Program
Ronnie_Best@usgs.gov
Raymond W. Schaffranek, PhD
Research Hydrologist
Water-National Research Program
rws@usgs.gov
http://sofi a.usgs.gov
Participation by greater Everglades restoration partners during the 85-person Hydrologic Modeling Workshop (excluding USGS participants).
Academia
14 %
NGO
6 %
Private Org.
5 %
Citizen
1%
USFWS
11 %
NPS
7 %
ACOE
5 %
Miccosukee
5 % NOAA
4 %
EPA
2 %
Other Federal
2 %
SFWMD
21 %
Miami-Dade
8 %
Broward
4 %
FDEP
2 %
FF&WCC
2 %
Palm Beach
1 %
U.S. Department of the Interior
U.S. Geological Survey
Greater Everglades Science Program
July 2002 PBS Information Sheet IS 02-03
Ecological Modeling and
Processes Research Needs
Develop spatially explicit species
index (SESI) models for southwest
Florida indicator species (i.e., wading
birds, manatees, seagrasses, oysters,
red cockaded woodpeckers, panthers,
amphibians, and/or others) to assist in
establishing restoration targets.
Incorporate fi re impacts into SESI
models.
Extend vegetation, landscape, and
mangrove models into southwest
Florida.
Develop an estuarine model that can
be integrated with a hydrologic model
that predicts seagrasses, oysters, fi sh

populations, and crab populations
based on surface-water management.
Create a fi sh migration/spawning
model for major tributaries, such as
the Caloosahatchee River and tributaries
in the Ten Thousand Islands.
Develop freshwater amphibian, reptile,

insect, and forage fi sh models to
predict success of restoration efforts
in short hydroperiod wetlands (i.e.,
seasonal marshes/pine fl atwoods
complexes, wet prairies, hydric pine
and mixed/pine/cypress systems).
Wet prairie communities appear to
be extremely important in providing
prey organisms for higher trophic
level animals. Research efforts
should closely examine hydrology,
fi re, nutrient loading, and effects of
exotic species on the dynamics of
wet prairies.
Model patterns of saltwater- versus
freshwater-wetlands use by wading
birds, with special emphasis on
wood storks and roseate spoonbills.
Create user-friendly predictive tools
for evaluating effects of fl oods and
droughts on availability of habitat for
wading birds, snail kites, and other
indicator species.
Integrate model results into tools that
match analyses with specifi c decision-
making objectives and tools that
guide confl ict resolution among multiple
objectives.
Ensure capability to run ATLSS
ecological models using the Natural
Systems Model (NSM). Plus, couple
ATLSS models with evolution of the
NSM and the South Florida Water
Management Model (SFWMM) to
ensure long-term compatibility.
Develop comparable/repeatable
protocols for monitoring status and

trends in amphibians and reptiles,
migratory birds, and wading birds
(i.e., link modeling and monitoring).
Draft additional documentation for
ecological models that includes:
parameter certainty, appropriate
model use, description of model
input sources, and model logic.
Evaluate historical water quality,
water quantity, and fi re on current
vegetation patterns with recommendations
for future water and fi re
management.
Create user-friendly predictive models
for evaluating effect of fl oods,

droughts and different control
strategies on exotic plant proliferation
(specifi cally, Lygodium and
Melaleuca).
Study changes in manatee behavior
and critical habitat based on surface
Summary of Greater Everglades Ecosystem Restoration Workshop:
3. Ecological Modeling and Processes, May 9-10, 2002
Across Trophic Level System Simulation (ATLSS) Structure






















 
 

 






  
U.S. Department of the Interior
U.S. Geological Survey
Greater Everglades Science Program
July 2002 PBS Information Sheet IS 02-03
water input through canals and natural
habitat restoration.
Determine conditions under which
(model variables) sawgrass out-competes
cattails.
Include species-specifi c pesticide
sensitivity within models.
Continue Florida panther monitoring
at historical levels (i.e., collaring all
captured cats).
Investigate and model Lygodium
control mechanisms.
Research Needs Relevant to
Other Workshops Topics
Develop a tool to establish estuarine
fl ow targets.
Extend existing coastal models (i.e.
SICS and TIME) east of Route 1 to
cooling canals at Turkey Point.
Collect additional topographic and
bathymetric data.
Collect topographic data with higher
spatial resolution for unique and/or
critical habitat.
Create updated land cover data using
classes predetermined to be compatible
with ecological modeling classifi
cation schemes.
For Further Information
G. Ronnie Best, PhD, PWS
Coordinator
Greater Everglades Science Program
Ronnie_Best@usgs.gov
Donald DeAngelis, PhD
Systems Ecologist
Don_DeAngelis@usgs.gov
http://sofi a.usgs.gov
Participation by greater Everglades restoration partners during the 91-person Ecological Modeling Workshop
(excluding USGS participants).

Academia
20 % NGO
6 %
Private Org.
3 %
Citizen
1 %
USFWS
15 %
NPS
9 % ACOE
4 %
Miccosukee
3 %
NOAA
2 % EPA
2 %
Other Federal
2 %
SFWMD
20 %
Miami-Dade
6 %
Broward
2 %
FDEP
2 %
FF&WCC
2 %
Palm Beach
1 %
U.S. Department of the Interior
U.S. Geological Survey
Greater Everglades Science Program
July 2002 PBS Information Sheet IS 02-04
Landscape Mapping Research
Needs
Expand the coverage of digital and
hard copy satellite image maps like
those created for the Southern
Everglades.
Develop techniques to detect relevant
land surface changes using remote
sensing.
Collect data required to detect landscape
change due to implementation of
CERP and Modifi ed Water Deliveries
(MWD) projects.
Collect data required to track vegetative
change from wet to dry season.
Create a process for mapping water
fl ow resistance due to vegetation.
Explore methods for estimating water
elevations using past and future
satellite data sources.
Develop mechanism for multi-agency
coordination of ground-truthing and
aerial/satellite data acquisition.
Topography Research Needs
Complete topographic maps for the
area encompassing the TIME (Tides
and Infl ows in the Mangrove Ecotone)
models.
Create high resolution/accuracy topographic
maps for WCA-1, WCA-2,
and northern WCA-3A.
Collect bathymetric data for near-shore
areas that have not been recently surveyed,
including the southwest coast.
Increase spatial resolution of topographic
data within selected landscape
types, including ecotones, tree islands,
ridge and slough, and rocky glades.
Map physical features including alligator
holes and tree islands.
Summary of Greater Everglades Ecosystem Restoration Workshop:
4. Landscape Mapping and Topography, May 23, 2002
Southern Everglades satellite image map
Southern Everglades topographic image
U.S. Department of the Interior
U.S. Geological Survey
Greater Everglades Science Program
July 2002 PBS Information Sheet IS 02-04
For Further Information
G. Ronnie Best, PhD, PWS
Coordinator
Greater Everglades Science Program
Ronnie_Best@usgs.gov
Landscape Mapping:
John W. Jones
Geographer
jwjones@usgs.gov
Topography:
Gregory B. Desmond
Physical Scientist
gdesmond@usgs.gov
http://sofi a.usgs.gov
Academia
16 %
NGO
3 %

Private Org.
4 %
Citizen
1 %
NPS
11 %
USFWS
11 %
ACOE
8 %
Miccosukee
5 % EPA
1 %
Other Federal
1 %
SFWMD
23 %
Miami-Dade
8 %
Broward
4 %
FF&WCC
3 %
Palm Beach
1 %
Participation by greater Everglades restoration partners during the 50-person Landscape Mapping and Topography Workshop (excluding USGS participants).
U.S. Department of the Interior
U.S. Geological Survey
Greater Everglades Science Program
July 2002 PBS Information Sheet IS 02-05
Contaminants Research Needs
Determine relative contribution of
local, regional and global sources
to mercury deposition within south
Florida.
Forecast mercury fate and toxicity
due to structural and hydrologic
changes during CERP implementation.
Determine mercury methylation
/demethylation rates and factors
affecting these rates.
A general predictive tool is needed
to determine mercury methylation
potential based on inputs of soil type,
mercury, sulfur, DOC concentrations,
hydroperiod, fi re and drought. A tool
is needed as a stopgap measure for
near-term activities using existing
research.
Determine if increased Everglades
fl ows will increase mercury delivered
to Florida Bay. Will increased
fl ows scavenge mercury or methyl
mercury associated with particles or
sediment, and/or increase loading of
dissolved mercury or mercury associated
with DOC/colloids?
Determine if lower salinities within
Florida Bay, which will result from
increased fl ow within the Everglades,
will enhance mercury methylation.
Determine possible impacts of aluminum,
iron, and chloride on mercury
methylation rates.
Determine if northern Everglades
methyl mercury generation and nutrient
mobilization after fi re/drought
also occurs within the more pristine
southern Everglades.
Derive data to support a sulfur
module for the Everglades Mercury
Cycling Model (E-MCM).
Wildlife Effects Research Needs
Expand current research on effect of
ambient levels of mercury and pharmaceuticals
on Everglades wildlife.
Suggested species include freshwater
mussels, largemouth bass, marine
fi sh, and alligators.
Further investigate effect of food
web structure and seasonal variation
in structure on mercury bioaccumulation.
Determine mercury dose-response
relations for wading bird, fi sh, and
other wildlife.
Archive biological samples as a
baseline for future investigations.
Summary of Greater Everglades Ecosystem Restoration Workshop:
5. Contaminants and Biogeochemistry, May 29, 2002
Theoretical mercury cycle within the Everglades


















 


U.S. Department of the Interior
U.S. Geological Survey
Greater Everglades Science Program
July 2002 PBS Information Sheet IS 02-05
Biogeochemistry Research Needs
Assess possible chemical reactions
that may occur within the subsurface
during Aquifer Storage and Recovery
(ASR). Mercury methylation rates,
and DOC-aquifer substrate interactions
were explicitly mentioned.
Determine potential effects on the
Everglades of reducing or eliminating
anthropogenic sources of sulfate.
Determine the effect of increased
fl ows and levee/canal degradation on
the areal extent of sulfur contamination.
Collect additional information on
sulfur/sulfi te within Big Cypress
Preserve.
Quantify sources of phosphorous in
Florida Bay.
For Further Information
G. Ronnie Best, PhD, PWS
Greater Everglades Science Program
Coordinator
Ronnie_Best@usgs.gov
David P. Krabbenhoft, PhD
Research Geochemist/Hydrologist
dpkrabbe@usgs.gov
http://sofi a.usgs.gov
Academia
16 %
NGO
9 % Private Org.
5 %
Citizen
1%
NPS
13%
USFWS
12 %
Miccosukee
5 %
EPA
4 %
NOAA
4 %
SFWMD
16 %
FDEP
6 %
Miami-Dade
4 %
Broward
3 %
FF&WCC
1%
Palm Beach
1%
Participation by greater Everglades restoration partners during the 50-person Contaminant and Biogeochemistry Workshop (excluding USGS participants).
18
Contents
Section I: Get the Water Quantity Right
Long-Term Data from the USGS/BRD Mangrove Hydrology Sampling Network in
Everglades National Park
By Gordon H. Anderson and Thomas J. Smith III . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Discharge from Caloosahatchee River that enters Estero Bay
By Michael J. Byrne . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Monitoring and Mapping Salinity Patterns in Estero Bay, Southwestern Florida
By Michael J. Byrne . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Do Surface and Groundwater Fluctuations Influence Sediment Surface Elevation in the Coastal
Everglades Wetlands?
By Donald R. Cahoon, James C. Lynch, Thomas J. Smith III, Kevin R.T. Whelan,
Gordon H. Anderson, and Christa Walker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Significance of Microtopography as a Control on Surface-water Flow in the Everglades
By Jungyill Choi, Judson W. Harvey, and Jessica T. Newlin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Measuring and Mapping the Topography of the Florida Everglades for Ecosystem Restoration
By Greg Desmond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Progress and Future Direction in Topographic Modeling for ATLSS Models
By Scott M. Duke-Sylvester and Louis J. Gross . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Evapotranspiration Rates from Two Different Sawgrass Communities in South Florida
during Drought Conditions
By Edward R. German and David M. Sumner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Characterization of Microtopography in the Everglades
By Judson W. Harvey, Jessica T. Newlin, and Jungyill Choi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Estuarine Creek Responses to Extreme Hydrologic Events in Northeastern Florida Bay
By Clinton D. Hittle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Continuous Hydrologic Data in Florida Bay Channels
By Clinton D. Hittle and Grant Poole. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Vegetative Habitats of Water Conservation Area-3A: Hydrologic Impacts of IOP
By Wiley M. Kitchens, Paul Wetzel and Erik Powers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
19
The Role of Seasonal Hydrology in the Dynamics of Fish Communities Inhabiting Karstic
Refuges of the Florida Everglades
By Robert M. Kobza and William F. Loftus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
The Effects of Hydroperiod on Life-History Parameters of two Species of Livebearing Fish
(Poeciliidae) in the Florida Everglades
By Timothy Konnert, Joel C. Trexler, and William F. Loftus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Recharge and Discharge Measurements in the Everglades using Short-lived Radium Isotopes
By James M. Krest and Judson W. Harvey. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Flows, Stages, and Salinities: How Accurate is the SICS Integrated Surface-Water/
Ground-Water Flow and Transport Model?
By Christian Langevin, Eric Swain, and Melinda Wolfert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Quantifying Internal Canal Flows in South Florida
By Mitch Murray, and Rick Solis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Hydrologic Information for Tidal Rivers along the Southwest Coast of Everglades National Park
By Eduardo Patino, Lars Soderqvist, Craig Thompson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Inventory and Review of Aquifer Storage and Recovery in Southern Florida
By Ronald S. Reese . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Impact of Water Management on Coastal Hydrology in Southeastern Florida
By Robert A. Renken, Joann Dixon, John Koehmstedt, Scott Ishman, A. C. Leitz,
Pamela Telis, Alyssa Dausman, Richard Marella, Jeff Rogers, and Steven Memberg. . . . . . . . 60
Sheet Flow in Vegetated Wetlands of the Everglades
By Raymond W. Schaffranek and Ami L. Riscassi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Applications of a Numerical Model for Simulation of Flow and Transport in Connected Freshwater-
Wetland and Coastal-Marine Ecosystems of the Southern Everglades
By Raymond W. Schaffranek, Harry L. Jenter, Ami L. Riscassi, Christian D. Langevin,
Eric D. Swain, and Melinda Wolfert. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Fire Effects on Flow in Vegetated Wetlands of the Everglades
By Raymond W. Schaffranek, Ami L. Riscassi, Nancy B. Rybicki, and Alfonso V. Lombana . . . . 66
Developing a Computational Technique for Modeling Flow and Transport in a Density-Dependent
Coastal Wetland/Aquifer System
By Eric Swain, Christian Langevin, and Melinda Wolfert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Everglades Tree-Island Response to Hydrologic Change
By Debra A. Willard, William H. Orem, Christopher Bernhardt, and Charles W. Holmes . . . . . . . 71
Using Hydrologic Correlation as a Tool to Estimate Flow at Non-Instrumented Estuarine Creeks
in Northeastern Florida Bay
By Mark Zucker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
20
Long-Term Data from the USGS/BRD Mangrove Hydrology Sampling Network in
Everglades National Park
By Gordon H. Anderson1, and Thomas J. Smith III2
1U.S. Geological Survey, Center for Water and Restoration Studies, Homestead, FL., USA
2U.S. Geological Survey, Center for Water and Restoration Studies, St. Petersburg, FL., USA
In 1992, under the
guidance and support of
the USGS Global
Change Research Program
(GCRP), The
"Groundwater-surface
water interactions and
sea-level rise in southern
Florida study" was initiated.
The principle focus
of the study was to
develop a systematic network
of shallow groundwater
well and surface
water monitoring sites to
evaluate the hydrodynamic
changes across the
transition zone or ecotone
between the freshwater
Everglades and
coastal mangrove estuaries.
Located on the
southwestern coast of
Florida, within Everglades
National Park,
transects were established
along the three
principal tidal rivers:
Shark, Lostman, and
Chatham River (fig. 1).
Shark River slough and
its estuary were selected
as the primary study
area, because of their significance
to the freshwater
Everglades system.
Each transect is ~30 km
in length (the mesoscale)
and has three permanent,
continuously
recording hydrologic monitoring stations. On the Shark River transect, Shark 1 (SH1) represents the upland nontidal
freshwater region; Shark 2 (SH2), the transitional ecotonal area between the two hydrologic systems; and Shark
3 (SH3) the coastal mangrove estuary region. Two additional hydrology stations (SH4 and SH5) were set up to mon-
Figure 1. Locations of hydrologic sampling sites within Everglades National Park.
21
itor hydrologic changes across the fringe mangrove/coastal marsh ectone which is approximately 300m in length
(the micro-scale). Shallow ground and surface water levels, temperature and specific conductance, and rainfall are
the principal parameters measured at each monitoring site.
Hydrologic data
from the Shark River
Transect has been compiled
for seven water
years: 1996-2002
(fig. 2). Daily surface
water from SH1 shows
the wet tropical summer
(June-October) weather
and drier cooler winter
(November-May) climate
patterns of south
Florida. The non-tidal,
freshwater marshes
respond quickly to local
rainfall and evaporation,
and surface-water discharge
from upstream.
Water levels in Shark
Slough were significantly
higher in 1995
and 1999. Hurricane
Irene in October 1999
was the largest single
event recorded at SH1
since 1995. SH2 is
located on the terminus
of the freshwater
slough, at the ecotone
with downstream tidal
systems. Principally,
SH2 showed a tidal signal
in the daily surface
water, however, it was
dampened by the overland
flow of surface
water during the summer
months, primarily
June and in September.
Tropical storm Harvey
in September 1999 was
the largest single event
recorded at SH2 since
1995. SH3 is located on a red mangrove delta island near the mouth of the Shark River estuary. It is overwhelmingly
a tidally influenced site, receiving a tidal influx twice daily. Tropical Storm Harvey in September 1995 was the single
largest event recorded at SH3 since 1995.
Figure 2. Period of record for surface water stage along the main Shark River transect.
22
The project is developing a common vertical reference for the southwest coast to provide greater comparative
analysis of hydrologic data (DeWitt et al., this volume). The Shark River hydrologic network is centrally positioned
to provide essential baseline empirical physical data needed for numerous research efforts and modeling involved
with Everglades restoration. Such projects include the Tides and Inflows in the Mangroves of the Everglades (TIME)
and a variety of interrelated USGS hydrological, ecological, geological, and mapping investigative studies. These
data provide valuable integration with south Florida National Parks resource management; the Comprehensive Everglades
Restoration Plan (CERP); and the Florida Coastal Long Term Ecological Research (LTER) project.
Contact: Gordon H. Anderson, U.S. Geological Survey, Everglades Field Station, c/o Beard Center, Everglades
National Park, 40001 State Road 9336, Homestead, FL 33034, Phone: 305-242-7891; FAX 305-242-7836; Email:
gordon_anderson@usgs.gov Poster, Hydrology & Hydrological Modeling
23
Discharge from Caloosahatchee River that enters Estero Bay
By Michael J. Byrne, U.S. Geological Survey, Center for Water and Restoration Studies, Fort Myers, FL., USA
Estero Bay is a State
aquatic preserve located about
3 miles south of the Caloosahatchee
River along the coast
of southwestern Florida. Five
major tributaries flow into this
long and shallow body of
water including Hendry
Creek, Mullock Creek, Estero
River, Spring Creek, and
Imperial River (fig. 1). Most
water exchange between
Estero Bay and the Gulf of
Mexico is through four inlets
through a chain of barrier
islands; Matanzas Pass, Big
Carlos Pass, New Pass, and
Big Hickory Pass. Lands surrounding
Estero Bay, including
the barrier islands, are
highly developed.
The hydrologic relation
between the Caloosahatchee
River and Estero Bay is poorly
understood. The quantity and
timing of freshwater flow into
the Caloosahatchee River
estuary has been altered due to
anthropogenic activities. Principal
discharge of water from
the Caloosahatchee River into
Estero Bay is through Matanzas Pass and Hurricane Pass. The discharge of the organic-rich water reduces water
clarity and salinity in the northern part of Estero Bay.
Research reveals that the altered flow pattern impacts the Caloosahatchee River estuary and Estero Bay. The
U.S. Geological Survey has undertaken a study to examine hydrology and salinity patterns in Estero Bay. Continuous
salinity and flow measurements are being taken at Mullock Creek, Estero River, Imperial River, Matanzas Pass,
Big Carlos Pass, and Big Hickory Pass (fig. 1). Surface-water salinity and temperature data also are being collected
near the mouth of the Caloosahatchee River; at points in Matlacha Pass, Pine Island Sound, and Sanibel Island; and
as far south as Wiggins Pass. These data, collected on a monthly basis, will be used to generate salinity maps. The
salinity, flow, and temperature data and additional discharge measurements may be collectively used to quantify the
volume of water from the Caloosahatchee River that enters Estero Bay.
The Caloosahatchee River receives water from Lake Okeechobee (to the northeast) and from numerous tributaries.
The tributaries north and south of the river drain a large basin consisting mainly of agricultural fields. The
South Florida Water Management District (SFWMD) regulates releases from Lake Okeechobee to the Caloosahatchee
River. Flow on the Caloosahatchee River is controlled by a series of gated structures, operated by the U.S.
Figure 1. The Estero Bay watershed.
24
Army Corps of Engineers (USACE). South Florida Water Management District permits discharge into the river in
regulated pulses. The low-level pulse release is designed to limit negative impacts to the estuary. However, the river
must also be maintained for navigation, water supply, and flood control. The USACE controls the locks on the river
to meet these water demands. During summer 2002, the flow-way gates of the westernmost lock (Franklin Lock,
S-79) were open almost continuously. Consequently, the Caloosahatchee River release occurred all summer, with
highest flows during the period of discharge from Lake Okeechobee.
Water from the Caloosahatchee River was detected in the near-shore waters of the Gulf of Mexico as far south
as Wiggins Pass, which is about 20 miles south of the mouth of the river. Salinity in the Gulf of Mexico substantially
decreased during periods of large water releases from the river and was significantly lower off of the northern barrier
islands than farther south where Caloosahatchee discharges had less effect. Freshwater entering the Gulf of Mexico
from the Caloosahatchee tends to color the oceanic water brown or black. Further research will be required to understand
the full extent of the freshwater discharge from the Caloosahatchee River.
Contact: Michael J. Byrne, U.S. Geological Survey, 3745 Broadway, Suite 301, Fort Myers, FL, 33901, Phone:
239-275-8448, Fax: 239-275-6820, mbyrne@usgs.gov, Hydrology and Hydrological Modeling
25
Monitoring and Mapping Salinity Patterns in Estero Bay, Southwestern Florida
By Michael J. Byrne, U.S. Geological Survey, Center for Water and Restoration Studies, Fort Myers, FL., USA
Estero Bay is a very long
and shallow estuary located about
3 miles south of the Caloosahatchee
River along the southwestern
coast of Florida.
Abundant and diverse flora and
fauna exist within the bay and its
watershed including threatened
and endangered species. Historically,
sheet flow from several
sloughs drained into Estero Bay.
Most flow now is concentrated at
several inflow points as a result of
rapid development within the
watershed. The principal inflows
come from Hendry Creek, Mullock
Creek, Estero River, Spring
Creek, and Imperial River (fig. 1).
Water exchange with the
Gulf of Mexico is restricted by a
series of barrier islands, with most
exchange through four passes;
Matanzas Pass, Big Carlos Pass,
New Pass, and Big Hickory Pass.
Monitoring and mapping salinity
in Estero Bay will help determine
the effects that altered flows have
had on the aquatic health of the
bay.
Baseline data for Estero
Bay and its tributaries are needed
to provide regional resource managers information to manage future development around the bay and its watershed.
The U.S. Geological Survey has undertaken a study to map salinity patterns and determine freshwater residence
times in Estero Bay. Salinity is the chemical tracer that will be used to map water movement through Estero Bay
and the information generated from this project will be used in the development of hydrodynamic models and statistical
analysis of salinity variance the bay.
The study began in April 2001 and will end in September 2004. Monthly surface-water salinity and temperature
data are presently being collected throughout Estero Bay. The methods of data collection involve attaching a
water-quality sensor to the stern of a boat just beneath the water surface and logging the precise location of data
points using a global positioning system (GPS) receiver. Two boats are used to collect about 6,000 individual data
points in the estuary over an 8-hour period. These data are used to generate the surface-water salinity maps and for
statistical analysis of salinity variability due to stormwater releases through the Caloosahatchee River.
Salinity results reveal a large volume of water from the Caloosahatchee River moves a short distance through
the Gulf of Mexico and then enters Estero Bay through Matanzas Pass. This organic-rich water may reduce light
penetration and salinity and increase sedimentation in the northwestern part of the bay. Water entering the north-
Figure 1. The Estero Bay watershed.
26
eastern part of the bay travels south and mixes with water from the Estero River before flowing through Big Carlos
Pass. In the south-central bay, hydrologic exchange is limited and salinities increase. Salinity data in southern Estero
Bay suggest the Imperial River discharges to the south and north in similar volumes. The Imperial River discharge
leaves Estero Bay through Big Hickory Pass and New Pass.
The salinity maps can be used to assess trends in saltwater movement within the estuary and improve an understanding
of manatee and fish migration. The information from these maps also can be used for hydrodynamic model
verification and to help map seagrass beds.
Contact: Michael J. Byrne, U.S. Geological Survey, 3745 Broadway, Suite 301, Fort Myers, FL, 33901, Phone:
239-275-8448, Fax: 239-275-6820, mbyrne@usgs.gov, Hydrology and Hydrological Modeling
27
Do Surface and Groundwater Fluctuations Influence Sediment Surface Elevation
in the Coastal Everglades Wetlands?
By Donald R. Cahoon1, James C. Lynch1, T. J. Smith III2, Kevin R.T. Whelan2, Gordon H. Anderson2, and
Christa Walker3
1U.S. Geological Survey, Patuxent Wildlife Research Center, Laurel, MD. USA
2U.S. Geological Survey, Center for Water and Restoration Studies, St. Petersburg and Miami, FL., USA
3DynCorp Systems and Solutions LLC, U.S. Geological Survey, Everglades Field Station, Homestead, FL., USA
The Greater Everglades ecosystem stretches over 360km, from Lake Kissimee in the north to Florida Bay in
the south. At its widest point it covers more than 100km from west to east. The vast flow way has been dissected
by a network of canals and levees over the recent past to control flooding, provide water storage for human consumption,
and protect croplands. Natural surface water flows into Everglades National Park have been seriously
disrupted, in terms of quantity, quality, and timing of flow. Presently federal, state, and local agencies have established
a $7.8 billion ecosystem restoration program for the Everglades, known as the Comprehensive Everglades
Restoration Plan (CERP). Many science questions remain unanswered as the restoration begins. Major questions
exist concerning rates of soil formation in the various wetland plant communities and about factors regulating surface
elevation in these wetlands.
This report provides data from a network of Surface Elevation Tables (SETs) in the southwest coastal wetlands
of Everglades National Park. At each of eight sites, three SETs were established. Three study locations were
along each of the Shark and Lostmans Rivers, the two major coastal drainages of the southwest Everglades. On
each river one site is in an upstream freshwater wetland, a second site is in the middle reach of the river in a brackish
marsh - mangrove forest community, and the third site is downstream near the river's mouth in a pure stand of mangrove
forest. The two freshwater sites are non-tidal and highly seasonal with respect to surface water flows and
depths (both highest in summer and negligible in the winter dry season). Tides are measurable, but small, at the
brackish waters sites and there is a noticeable variation in surface water. Tidal activity dominates the hydrological
signature at the saline, downstream, mangrove forest sites. The seventh and eighth sites are located at Big Sable
Creek, a marine dominated region on northwest Cape Sable. The cape was devastated by the 1935 Labor Day Hurricane
and again by Hurricane Donna in 1960. At this location three SETs are in mangrove forest and three are in
open, unvegetated, intertidal mudflat. Ground-water and surface-water sampling wells are present at all sites and
are instrumented to record elevation and conductivity at hourly intervals. SETs have been sampled at 3-6 month
intervals for more than three years (fig.1). For each of the eight sites we calculated the rate of change in relative
wetland surface elevation (only one site is currently surveyed to mean sea level) between sampling intervals. We
also calculated the rate of change in daily ground and surface water elevation for the same intervals. Average surface
and groundwater stage was determined for the day of SET sampling, and for the 15 and 30 days prior to sampling.
Simple linear regression was used to test for differences between surface elevation change and the water level
parameters and to calculate the slope of that relation for each site.
Sediment surface elevation at all sites showed apparent annual cycles that differed between sites. Surface elevation
appeared to be greatest during the dry season at upstream freshwater locations (fig.1) and lowest during the
dry season at downstream saline locations. The two brackish water, middle river, sites showed little variation in
sediment surface elevation. Surface-water stage, over the 15 days prior to sediment sampling, was strongly related
to the change in sediment elevation between samplings (fig. 2). Most importantly, this relation was the opposite
between sites. At freshwater sites, as average stage increased, sediment change decreased, whereas at saltwater
sites, increasing surface-water stages led to increasing sediment elevation between sampling periods. The pattern
at the two brackish sites was intermediate.
Why these two wetland systems behave in an opposite manner is unclear at this time. One hypothesis is that
in the freshwater systems, a sedimentation - re-suspension process is occurring whereby, as the dry season
progresses, flocculent material in the water column settles out, and as the wet season sets in and water levels (and
current velocities) go up, this material becomes re-suspended and lost from the site. This hypothesis will be tested
in coming months.
28
Contact: Smith III, Thomas J. USGS, Center for Water & Restoration Studies, 600 Fourth Street, South, St.
Petersburg, FL 33701. Voice: 727-803-8747, FAX: 727-803-2030; Email: Tom_J_Smith@usgs.gov
Shark River SH1
-40.00
-30.00
-20.00
-10.00
0.00
10.00
20.00
30.00
40.00
Sediment Elevation - mm
0
1
2
3
4
5
Stage
Sediment Elevation
Ground Water Stage
Surface Water Stage
2002 2001 2000 1999 1998
Figure 1. Representative data showing the time series of surface & groundwater stage and sediment surface elevation at the
upstream freshwater site on the Shark River (SH1).
Fresh (SH1) vs Salt (SH3) Water Wetland Comparison
y = -16.741x + 44.592
R2 = 0.3804
y = 20.041x - 25.43
R2 = 0.3703
-40.0
-20.0
0.0
20.0
40.0
1.00 1.50 2.00 2.50 3.00 3.50
Stage
Sediment Elevation
Change
Fresh-SH1 Salt-SH3 Linear (Fresh-SH1) Linear (Salt-SH3)
Figure 2. Sediment elevation change versus average surface water stage for a freshwater marsh
(SH1) and a salt water mangrove forest (SH3).
29
Significance of Microtopography as a Control on Surface-Water Flow in Wetlands
By Jungyill Choi1, Judson W. Harvey, and Jessica T. Newlin
U.S. Geological Survey, Reston, VA., USA
1Now at S.S. Papadopulos and Associates, Inc., Bethesda, MD., USA
Microtopography rarely has been considered in wetland surface-water flow models, even though the ground
surface often undulates significantly. We define microtopography as topographic variations in the wetland occurring
at a small spatial scale (1m or less) between hummocks and depressions, as well as an intermediate spatial scale
(tens or hundreds of meters) between the tops of ridges and the bottom of nearby sloughs. To our knowledge, no
previous model of surface-water flow in the Everglades has considered how microtopography (1) decreases the
cross-sectional area available for flow at low water levels, (2) increases surface-water exchange with sediment porewater,
and (3) increases flow resistance due to flow over and around microtopographic features.
The goal of the present project was to expand on the concepts and modeling of Hammer and Kadlec (1986)
and Kadlec (1990) by developing a governing equation that more explicitly isolates the effects of microtopography
on surface-water flow in wetlands,
, (1)
where fw is the fraction of free surface water normal to flow (a function of water level and microtopographic distribution),
Ss is the surface-water storage coefficient, h is the surface-water elevation, Sy is the specific yield of the
wetland sediments (i.e. subsurface-water storage coefficient), Kf is the flow conductance, d is the surface-water
depth,  is the exponent on depth, P is precipitation, ET is evapotranspiration, and GWi is ground-water inflow.
A schematic of
Everglades topography
(fig. 1) illustrates
how the cross-sectional
area available
for surface-water
flow is dependent on
the microtopographic
distribution as well as
on surface-water
stage. According to
Harvey and others
(this volume), the
ground-surface elevation
in Water Conservation
Area 2A
(WCA-2A) (fig. 2)
varies as much as 0.4

meters vertically over a horizontal distance of 100 meters, which is one third of the typical vertical fluctuation in
surface-water depth (1.2 m) in that part of the Everglades. Variability in topography and surface-water depth at
WCA-2A makes this an ideal location for testing a model of the effects of microtopography on surface-water flow.
Three different models were applied and compared by selectively combining three effects of microtopography
on surface-water flow. Model 1 was the base model simulation, which did not incorporate any of the effects of
microtopography. Model 2 included the effects of microtopography on cross-sectional area of surface flow, and
surface and porewater exchange. Model 3 included the depth-dependent influence of microtopography on flow
resistance in addition to those considered by model 2. All three models used daily water levels measured by South
( ) ) GW ET (P
x
h d K f
x t
h S f 1
t
h S f i
1 
f w y w s w + - + 






   

 =

   - +

   +
Figure 1. Schematic of wetland topography showing
change in cross-sectional area for surface-water flow
for "critical" surface-water stages.
Figure 2. Water Conservation Area 2A,
central Everglades, south Florida.
30
Florida Water Management District at sites F1, F4, and U3 in WCA-2A and field measurements of fw, d, Ss, Sy, P,
ET, and GWi. The two reaches that were modeled (F1-F4 and F4-U3) differed mainly in their vegetative characteristics
(fig. 2). The inverse modeling program, UCODE (http://www.usgs.gov/software/ ucode.html), was used to
objectively estimate the optimal values for Kf, and  for each model (table 1).
Surface-water flow simulations from model 2 showed a 15 percent improvement of the Root Mean Squared
Error (RMSE) over the model 1 results, demonstrating that consideration of the effect of microtopography on flow
cross-sectional area and storage-exchange improves the accuracy of the surface-water flow model (fig. 3). We
observed additional improvements in the model 3 simulation (40 percent decrease in RMSE from that of model
1) through incorporating stage-dependence in the flow parameters, Kf and . The stage-dependent parameters were
determined from separate inverse modeling runs of the low-stage period (first 45 days, fig. 3) and the high-stage
period (remaining 65 days, fig. 3). Flow parameters in model 3 are varied according to the critical stages defined by
field measurements of microtopography at sites F1 and U3 in WCA-2A (fig. 1).
Results of this study

indicate that microtopography
is a significant control
on surface-water flow
in the Everglades, especially
when the surfacewater
elevation declines to
depths that begin to expose
microtopographic highs.
Our current modeling
effort focuses on objectively
determining the critical
stages that affect
stage-dependence in flow
parameters through
inverse modeling.
REFERENCES
Hammer, D.E., and Kadlec, R.H, 1986, A model for wetland surface water dynamics: Water Resources Research,
vol. 22, no. 13, pp. 1951-1958.
Kadlec, Robert H., 1990, Overland flow in wetlands  vegetation resistance: Journal of Hydraulic Engineering,
vol. 116, no. 5, pp. 691-706.
Contact: Judson W. Harvey, U.S. Geological Survey, 430 National Center, Reston, VA 20192, Phone: 703-648-
5876, Fax: 703-648-5484, jwharvey@usgs.gov, Hydrology and Hydrologic Modeling
Table 1. Optimized flow parameters (Kf, ) for models 1, 2, and 3 as determined from inverse modeling.
Notes: Model 3 parameters vary with critical stage (see fig. 1), Parameters vary linearly for depth
ranges (c) to (d) and (a) to (b).
Reach 1 (F1 to F4) Reach 2 (F4 to U3)
Kf
(m/d/m -1)
b
Kf
(m/d/m -1)
b
Model 1 1.8 x 107 0.60 4.7 x 107 0.64
Model 2 3.4 x 107 0.41 8.9 x 107 0.16
Model 3
Stages greater than (d) 2.5 x 107 0.39 5.6 x 107 0.56
Stages (c) to (b) 8.2 x 106 0.46 5.6 x 107 0.56
Stages less than (a) 0.98 0.00 0.98 0.00
Figure 3. Comparison of simulation results from models 1, 2, and 3 at site F4 for the entire
modeling period (A) and the low-stage modeling period (B).
31
Measuring and Mapping the Topography of the Florida Everglades for
Ecosystem Restoration
By Greg Desmond
U.S. Geological Survey, Reston, VA., USA
One of the major issues facing ecosystem restoration and management of the Greater Everglades is the availability
and distribution of clean, fresh water. The south Florida ecosystem encompasses an area of approximately
28,000 square kilometers and supports a human population that exceeds 5 million and is continuing to grow. The
natural systems of the Kissimmee-Okeechobee-Everglades watershed compete for water resources primarily with
the region's human population and urbanization, and with the agricultural and tourism industries. Therefore, surface
water flow modeling and ecological modeling studies are important means of providing scientific information
needed for ecosystem restoration planning and modeling. Hydrologic and ecological models provide much-needed
predictive capabilities for evaluating management options for parks, refuges, and land acquisition and for understanding
the impacts of land management practices in surrounding areas. These models require various input data,
including elevation data that very accurately define the topography of the Florida Everglades.
Surface water levels and sheet flow in the Everglades are very sensitive to any differences in topography
because of the region's expansive and extremely flat terrain. Therefore, hydrologic models require very accurate
elevation data in order to simulate and predict water flow direction, depth, velocity, and hydroperiod. Water
resources, ecosystem restoration, and other land management decisions will rely, in part, on the results of these models,
so it is imperative to use the best elevation data available in order to achieve meaningful simulation results. Elevation
data points are being collected every 400 meters in a grid pattern to meet the requirements of various
hydrologic models. The vertical accuracy specification for these elevation data is 15 centimeters (6 inches) as referenced
to the North American Vertical Datum of 1988 (NAVD88).
Because traditional methods for collecting elevation data for the Everglades are impractical or too costly, the
U.S. Geological Survey (USGS) conducted a feasibility study to determine if state-of-the-art techniques using the
Global Positioning System (GPS) could meet the strict vertical accuracy specifications of the elevation data. The
feasibility study successfully demonstrated that differential GPS techniques, using airboats to navigate transects,
could in fact meet the vertical accuracy requirement. Also, the land surface being surveyed in the Everglades is typically
under water and obscured by vegetation. This precludes the use of other methods for collecting very accurate
elevation data, such as photogrammetry, Light Detection And Ranging (lidar), Interferometric Synthetic Aperture
Radar (insar), or other alternative remote sensing technologies. Therefore, topographic surveys over such a large
area of the Everglades with such a stringent accuracy specification can only be accomplished efficiently by using
GPS technology. This is especially the case in a harsh and inaccessible wilderness environment with unique landscape
characteristics.
Because the Everglades is so expansive and remote and includes environmentally sensitive areas, impenetrable
vegetation, or other areas unapproachable by airboat, access to many places is possible only by helicopter. To
solve this accessibility problem, the USGS developed a helicopter-based instrument, known as the Airborne Height
Finder (AHF), which is able to measure the terrain surface elevation in a noninvasive, nondestructive manner. Using
an airborne GPS platform and a high-tech version of the surveyor's plumb bob, the AHF system distinguishes itself
from remote sensing technologies in its ability to physically penetrate vegetation and murky water, providing reliable
measurement of the underlying topographic surface.
Accuracy tests have shown that the AHF system can consistently measure elevation points at the subdecimeter
level. An accuracy test of the AHF was conducted in May 2000 when 17 National Geodetic Survey (NGS) firstorder
benchmarks were measured at two different helicopter hover heights. The average difference between the
AHF measured elevations and the NGS published data sheet values was 3.3 cm. The largest difference was 8.6 cm,
and the smallest difference was 0.2 cm. The root mean square error was 4.1 cm. These accuracy test results provide
confidence that the elevation dataset being produced meets the 15 cm vertical accuracy specification.
32
Elevation data collected with the AHF have been applied in the USGS-developed Southern Inland and Coastal
System (SICS) numerical simulation model, which requires very accurate data for its hydrodynamic surface-water
computations. The SICS model was originally constructed with topographic estimates based on pre-existing contour
maps. Although these contour maps meet national map accuracy standards, the derived elevation data are not adequate
for hydrologic modeling purposes for the Florida Everglades. However, the distribution of surface-water flows
simulated by the SICS model was greatly improved when the AHF elevation data replaced the previously estimated
topography in the model. Flow and inundation estimates north of the West Lake area (southwest portion of the SICS
model domain) are most significantly affected by this elevation difference.
To date, tens of thousands of elevation data points covering significant parts of the Florida Everglades have
been collected and processed using differential GPS methods with airboats and the helicopter-based AHF system.
These data are organized by USGS 7.5-minute quadrangle maps and are available from the South Florida Information
Access Web Site at http://sofia.usgs.gov.
Contact: Gregory B. Desmond, U.S. Geological Survey, MS 521 National Center, 12201 Sunrise Valley Drive,
Reston, VA, 20192, Phone: 703-648-4728, Fax: 703-648-4165, e-mail: gdesmond@usgs.gov.
33
Progress and Future Direction in Topographic Modeling for ATLSS Models
By Scott M. Duke-Sylvester, and Louis J. Gross, University of Tennessee, Knoxville, TN., USA
Topographic variation in south Florida, though generally small, is very important for the flora and fauna of
the region. Recently the U.S. Geological Survey (USGS) started the High Accuracy Elevation Data (HAED) collection
project with the goal of obtaining an estimate of topography in south Florida at a high spatial resolution (nominally
400x400 meters) with high vertical accuracy (vertical estimates are accurate to within about 3 cm). The
project has now collected, processed, and made available topographic data for a large portion of the natural areas in
south Florida, including most of the Everglades National Park (ENP), portions of Big Cypress National Preserve
(BCNP) and Water Conservation Area 3.
Prior to the existence of the HAED project there were no topographic maps of south Florida with both the
spatial resolution and spatial extent needed to model the ecology of fauna and flora in south Florida. To fill this void,
the Across Trophic Level System Simulation (ATLSS) project developed the High Resolution Topography (HRT)
model. This model estimates elevation for 30x30 meter grid cells across the natural regions of south Florida. The
estimation is based on the types of vegetation and the patterns of hydrology at each location. The founding assumption
of the HRT model is that plants tend to be in places where local topography and hydrology combine to create
a suitable habitat. Knowledge of the vegetation and hydrology at a location can be used to estimate elevation by
choosing an elevation that results in hydrologic conditions suitable for local vegetation.
Three data sets form the basic inputs into the HRT model: a map of the distribution of vegetation in south
Florida, a map of the history of hydroperiod distributions, and a table of hydroperiod preferences for each of the
vegetation types in the vegetation map. The hydroperiod preferences are derived from a review of available literature.
The vegetation distribution map used is the Florida GAP (FGAP) map (version 2.1) created by Leonard Pearlstine
at the University of Florida. The FGAP map assigns one of 43 vegetation types to each 30x30 meter cell over
most of South Florida.
The hydroperiod data for the HRT model is created from the Calibration/Verification run of the South Florida
Water Management Model (SFWMM). The SFWMM is managed by the South Florida Water Management District
(SFWMD) and is the standard hydrologic model for South Florida. The Calibration/Verification run of this model
is considered to be the one that most accurately reflects the historical pattern of hydrology in South Florida from
1979 to 1995. The SFWMM partitions south Florida into a grid, where each grid cell is 2x2 miles. The model estimates
water depth in each 2x2 mile cell on a daily time step from January 1, 1979 to December 31, 1995.
Over the past two years there have been a number of advances in the ATLSS High Resolution Topography
(HRT) modeling project. An extensive literature review, Plant Community Parameter Estimates and Documentation
for the Across Trophic Level System Simulation (ATLSS) by Paul Wetzel has been completed and peer-reviewed.
This document describes the hydroperiod preferences of the natural vegetation types used in the 6.1 version of the
Florida GAP (FGAP) map.
The second major advance is the development of a new HRT map. This new version is based on FGAP 6.1,
hydrology data from the South Florida Water Management Model (SFWMM) version 3.7, and the hydroperiod estimates
that appear in Wetzel's report. We are currently waiting for a more current version of the SFWMM Calibration/
Verification output before completing a final version of the new HRT map.
Finally, we have begun an analysis that looks at the relation between HAED elevations, distribution of vegetation
as provided in the FGAP map, and hydrologic parameters as predicted by the SFWMM. This analysis uses a
multiple regression model with vegetation type and a number of yearly average hydrologic variables as predictors,
and elevation estimates from the HAED collection project as the response variable. There are two major purposes
in performing this analysis. The first is to test an assumption made by the HRT model that there is a relation between
the elevation of a location and the vegetation associated with that location by FGAP. The second is to determine if
a multiple regression model can be used to predict HAED elevation based on vegetation and hydrology. Both of
these results provide a basis for evaluating the output of the HRT model.
34
This analysis has been completed for the Big Boy Lake HAED sampling unit. The regression coefficients for
several of the vegetation types in this region are significantly non-zero. This indicates that vegetation provides some
information about variation in topography. However, the r2 and PRESS (Prediction Sum of Squares Statistics) values
for the regression model are not sensitive to the presence of vegetation as a descriptor variable. This indicates that in
the Big Boy Lake region the overall contribution of vegetation to explaining variation in elevation is small. The conclusion
we draw from this result is that for the Big Boy Lake HAED region we do not expect the HRT to perform
well when compared to the HAED data because the inputs to the HRT model have very little relation to the HAED
elevation data. The limited scope of this analysis leaves a number of unanswered questions. The relation between
vegetation and HAED elevation in other regions and at other spatial scales has not yet been explored. While working
with the HAED data we have noticed that elevations were not sampled in some tree islands. According to Greg Desmond,
HAED project leader at USGS, the methods used to collect elevation data for HAED result in the systematic
omission of tree islands. The effect of the sampling bias that arises from this omission is to compress the variance in
measured elevations relative to the actual variance.
The HAED data will become the primary basis for topography used by ATLSS models. However, the availability
of the HAED topography does not completely eliminate the need for the HRT model. In the short term, there
is still a need to use HRT estimates of topography for regions not yet covered by the HAED project. In the long term,
the methodologies used in the HRT model may be needed to augment the topography generated by the HAED. We
propose using the HRT map and the HRT methodologies to augment the HAED topography in areas where HAED
has omitted vegetation structures, or has compressed variation. Work has begun on identifying regions where the
HRT model can be useful for augmenting the HAED topography and the methods needed to incorporate HRT output
into a HAED-based topography.
Contact: Duke-Sylvester, Scott M., University of Tennessee, 569 Dabney Hall, Knoxville, TN, 37996-1610,
Phone: 865-974-0223, Fax: 865-974-3067, sylv@tiem.utk.edu
35
Evapotranspiration Rates from Two Different Sawgrass Communities in South
Florida During Drought Conditions
By Edward R. German, and David M. Sumner
U.S. Geological Survey, Center for Aquatic Resources Studies, Altamonte Springs, FL., USA
Evaporation and plant transpiration (ET)
are significant components of the water budget in
south Florida. Water loss through ET can exceed
rainfall during dry years. Recent advances in
instrumentation and measurement techniques
have made it possible to develop a better understanding
of ET processes and to quantify ET rates.
ET rates at two sites vegetated primarily by
sawgrass, one in Blue Cypress Marsh near Vero
Beach in the St. Johns River floodplain and the
other in the southern Everglades of Everglades
National Park (fig. 1), yield significantly different
ET rates during drought conditions that occurred
in January through June of 2000.
The Blue Cypress Marsh site (BCM) has
dense sawgrass in a thick peat soil. At this site, the
ET fraction (EF), which is the ratio of latent heat
(the energy equivalent of ET) to the sum of latent
heat and sensible heat (convective heat transport),
was affected little by the change in water level
even when nearly 3 feet below land surface. The
Everglades National Park site (ENP) has a relatively
sparse rush/sawgrass community in a thin
marl soil. At this site, the EF decreased markedly
as the water level dropped to about 2 feet below
land surface.
The monthly total ET was greater at BCM
than at ENP for each month except January (fig. 2). The largest differences in monthly ET rates (greater than 1 inch)
occurred from March through July, when water levels were below land surface at one or both sites. Annually, the
total ET was 55.7 inches at BCM and 43.5 inches at ENP. This difference in annual total ET is not explainable by
differences in available energy (138 watts/m2 at BCM and 132 watts/m2 at ENP for 2000), and is the result of the
differences in EF between the two sites.
The EF (and hence ET) apparently are related to water level at the ENP site but not at the BCM site. The reason
for this difference in behavior of EF is not understood, but probably is related to the differences in plant cover
and soil type between the two sites. The thick sawgrass cover at BCM apparently is able to transpire at maximum
efficiency even when the water level is more than 2.5 feet below land surface. The thick peat soil layer may play a
role in this high EF even during low-water conditions by providing a reservoir of soil moisture from which the
sawgrass can draw. Additionally, the sawgrass coverage at BCM is relatively uniform and thick, and the incident
solar radiation only penetrates the top of the sawgrass. At ENP the vegetative cover is thinner and less extensive.
Heating of the sawgrass probably is less than heating of the land surface in exposed locations, so that the utilization
of available energy for sensible heat transport likely is less at the BCM site than at the ENP. Less sensible heat transport
relative to latent heat transport would cause a relatively high EF.
Figure 1. Location of Blue Cypress Marsh site and Everglades
site.
36
Contact: Edward R. German, U.S. Geological Survey, 224 W. Central Parkway, Altamonte Springs, FL, 32714
Phone: 407-865-7575, Fax: 407-865-6733, egerman@usgs.gov
0
1
2
3
4
5
6
7
8
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Monthly total evapotranspiration, in inches
Blue Cypress marsh
Everglades
Figure 2. Monthly total evapotranspiration, January 2000 through December 2000.
37
Characterization of Microtopography in the Everglades
By Judson W. Harvey, Jessica T. Newlin, and Jungyill Choi1
U.S. Geological Survey, Reston, VA., USA
1Now at S.S. Papadopulos and Associates, Inc., Bethesda, MD., USA
As concerns over how to restore the Everglades intensify, the need to
improve capabilities of surface water flow models becomes increasingly important.
One of the physical factors not often considered in surface flow modeling
is the microtopography of the wetland surface. At the local scale (1-m horizontal),
the elevation of the wetland surface undulates between hummocks associated
with macrophytes and the depressions between them. At a larger spatial
scale (100 m), topography varies between the tops of ridges and the bottom of
nearby sloughs. We refer to all of these topographic variations as "microtopography."
Microtopography affects the cross-sectional area of a wetland that is available
for surface-water flow. As water levels decline seasonally, the tops of
ridges and hummocks become exposed, making flow paths more sinuous, and
therefore, increasing the resistance to surface flow. Microtopography also plays
a role in the water exchange between wetland surface water and porewater of
sediments.
To characterize microtopography, elevations of the top of the peat surface and the top of the layer of flocculent
organic material, or "floc," were estimated in Water Conservation Area 2A (WCA-2A) at sites F1 and U3 (fig. 1).
These two sites are located along a research transect where water generally flows toward the southwest.
Two types of measurement tools
were used to determine the microtopography
at different vertical
and horizontal scales. Schematic
diagrams of the measurement
tools are shown in figure 2. The
type I tool generally did not penetrate
the floc, and estimated the
elevation of the top of the floc
layer. Due to its more open footprint,
the type II tool penetrated
the floc and was used to measure
the elevation of the peat surface,
which is considerably firmer than
the floc. Field measurements of
microtopography were made in
different vegetative conditions
near sites F1 and U3 (fig. 3), and
the measurements were distributed
so that the variability of the wetland
surface could be characterized
for 100-meter and 1-meter
spatial scale. Measurements show
that the elevation of the peat surface
varies 3-4 times more at the 100-m scale compared with the 1-m scale
(table 1, and fig. 4).
Figure 1. Location of datacollection
sites in WCA-2A, central
Everglades, south Florida.
Figure 2. Top view schematics of type I
(A) and type II (B) measuring tools.
Figure 3. Location of microtopography
measurements at site F1 (A) and site U3
(B), WCA-2A, central Everglades, south
Florida.
38
Microtopography data for sites F1 and U3 are summarized in figure 5
by plotting an inverse distribution function, i.e. elevation of the peat or
floc surface versus the probability of occurrence when sampling at the
100-m scale. The x-axes in figure 5 can be interpreted as the fraction of
wetland cross-section that has an elevation equal to or less than a given
elevation. Using this function allows estimation of the average wetland
cross-section available for surface flow at a given surface-water level.
Our ongoing work focuses on using the microtopography distributions
in a surface-water flow model. In addition to using microtopography data to compute the cross-sectional area of
surface flow over a period of fluctuating water levels, these data are being used to quantify the water exchange fluxes
that occur between the surface water and the porewater of sediments that become exposed at low water levels. The
micro-topography measurements are also being used to identify critical surface-water levels below which the microtopography
becomes a dominant factor in flow resistance.
Contact: Judson W. Harvey, U.S. Geological Survey, 430 National Center, Reston, VA 20192, Phone: 703-648-
5876, Fax: 703-648-5484, jwharvey@usgs.gov, Hydrology and Hydrologic Modeling
Table 1. Microtopographic variability of
peat surface elevation (type II tool).
Horizontal
Scale of
Measurement
2 Standard Deviations
of the Peat Surface
Elevation
F1 U3
1-meter 0.20 ft 0.14 ft
100-meter 0.76 ft 0.48 ft
Figure 4. Variability of peat surface elevation (type II tool) at 1-meter and 100-meter
measurement scale. Site F1 (A) and site U3 (B), WCA-2A, central Everglades, south Florida.
Figure 5. Inverse cumulative distribution function of elevation measurements at site F1
(A) and site U3 (B), WCA-2A, central Everglades, south Florida.
39
Estuarine Creek Responses to Extreme Hydrologic Events
in Northeastern Florida Bay
By Clinton Hittle
U.S. Geological Survey, Center for Water and Restoration Studies, Miami, FL., USA
Understanding salinity and circulation dynamics along the boundary between the Everglades and Florida Bay
is an important component of Everglades restoration. Hydrodynamic models that simulate flows, water levels, and
salinity within Florida Bay and the interior wetlands are considered valuable tools for assessing proposed management
practices in the Comprehensive Everglades Restoration Plan (CERP) and for evaluating water control structural
modifications. Detailed information on how estuarine creeks respond to extreme hydrologic conditions along
the boundaries between estuaries and wetlands will improve model verification.
Data on water velocity,
water level, salinity, and
temperature are currently
being collected continuously
at 14 U.S. Geological
Survey (USGS) monitoring
stations in northeastern
Florida Bay (fig. 1). Data
from the monitoring stations
are available from
1996 to present.
These data allow a
detailed examination of
estuarine creek response to
extreme hydrologic events.
Two creeks (McCormick
and Trout) are presented
here for comparison. Daily
mean values of stage for
Trout Creek (fig. 2) identify
most of the major storms
that affected northeastern
Florida Bay since 1996,
including five hurricanes, two tropical storms, and an El Nio related winter storm.
Figure 1. Location of Florida Bay monitoring stations.
Figure 2. Daily mean
values of stage for
Trout Creek, 1996 -
2002.
40
A comparison
of storm surges
between McCormick
Creek and Trout
Creek for Tropical
Storm Harvey and
Hurricane Irene indicates
how storm
strength and path can
affect water levels and
salinities across central
and eastern Florida
Bay. Tropical
Storm Harvey made
landfall near Everglades
City on September 21, 1999 and moved east-northeast across Florida. Water levels between the two creeks
were similar in magnitude during Harvey (fig. 3).
Hurricane Irene made landfall near Cape Sable on October 15, 1999 and moved to the northeast across Florida.
Storm surge from Irene increased water levels at McCormick Creek about one foot more than at Trout Creek.
Increases in salinity
at McCormick Creek
and Trout Creek
were observed during
storm surges for
both Harvey and
Irene. During Harvey,
McCormick
Creek experienced
an increase in salinity
from about 20 to
30 parts per thousand
(ppt) in 20
hours, with a subsequent
decrease back
to 20 ppt in only four
hours (fig. 4).
At Trout Creek, salinity increased from about 7 ppt to 24 ppt in 24 hours, but took another 24 hours to drop
back to 7 ppt (pre-surge conditions). During Hurricane Irene, McCormick Creek salinity increased from about 5 ppt
to 17 ppt in 6 hours with a subsequent decrease to 5 ppt in 13 hours. Trout Creek salinity during Irene's passage
increased from about 1 ppt to 20 ppt in 10 hours, decreasing back to 5 ppt over the next 24 hours. After an additional
42 hours, salinity returned to the pre-storm level of about 1 ppt. Both creeks experienced a greater salinity increase
from Irene than Harvey. Residence time was also greater because more saline water associated with the surge was
pushed upstream.
A detailed evaluation of estuarine creek responses to extreme hydrologic conditions and subsequent comparison
to hydrodynamic model output will help verify model capabilities in simulating natural systems. The evaluation
also will support a science-based approach for CERP activities.
Contact: Clinton D. Hittle, U.S. Geological Survey, 9100 N.W. 36th Street, Suite 107, Miami, FL 33178.Phone:
305-717-5815, Fax: 305-717-5801, cdhittle@usgs.gov.
Figure 3. 15-minute interval stage values for McCormick and Trout Creek during Tropical Storm
Harvey and Hurricane Irene.
Figure 4. 15-minute interval salinity values for McCormick and Trout Creek during Tropical Storm
Harvey and Hurricane Irene.
41
Continuous Hydrologic Data in Florida Bay Channels
By Clinton Hittle and Grant Poole
U.S. Geological Survey, Center for Water and Restoration Studies, Miami, FL., USA
Hydrologic data
from six channels within
Florida Bay (fig. 1) are
being collected by the
U.S. Geological Survey
(USGS) to help understand
flow characteristics
and better define the
transport of post-larval
Pink Shrimp into and out
of the bay. The data will
improve hydrodynamic
and biological models
being developed for use
with the Comprehensive
Everglades Restoration
Plan (CERP), a goal of
which is to improve the
quantity, quality, timing,
and distribution of flows
within the Everglades
ecosystem. Continuous
water velocity, stage,
salinity, and temperature data have been collected at 15-minute intervals since January 2002. Monitoring stations
are co-located with post larval pink shrimp nets managed by the USGS, National Oceanographic and Atmospheric
Administration (NOAA), and the University of Miami Rosenstiel School of Marine and Atmospheric Science
(RSMAS).
All stations have salinity/temperature
probes installed at about mid depth in the
channel; probes are cleaned and calibrated
during routine site visits. Elevations
were established on each station in
2002 by the USGS and are referenced to
the North American Vertical Datum of
1988 (NAVD 88). Elevation data was
computed using a helicopter-based differential
global positioning system coupled
with a mechanical height finder (fig 2).
The elevation data established at each
monitoring station allows for comparisons
of water level between the sites.
Acoustic Doppler Velocity Meters
(ADVM) continuously monitor flow conditions
and water levels within the channels.
The ADVM measures an average
Figure 1. Location of Florida Bay monitoring stations.
Figure 2. Helicopter based survey method.
42
water velocity within a fixed sample volume. Continuous channel discharge is computed using velocity data collected
from the ADVM and a boat mounted Acoustic Doppler Current Profiler (ADCP). Regression analysis is used
to relate the ADVM velocity to mean measured velocity calculated during ADCP discharge measurements. The
resulting equation, known as an index velocity rating, converts all ADVM index velocities into approximate mean
channel velocities. These corrected velocities are multiplied by the channel area to produce continuous discharge
record. Acquiring ADCP discharge measurements over the entire range of flow conditions expected to occur at the
site improves this computation method. Figure 3 shows the relation between index velocities and ADCP mean measured
velocities at Whale Harbor Channel.
The continuous discharge data from these sites will benefit studies that require estimates of total hydraulic
transport into and out of the bay, while the continuous data for all parameters will be valuable for verifying future
simulations of Florida Bay hydrodynamics.
Contact: Clinton D. Hittle, U.S. Geological Survey, 9100 N.W. 36th Street, Suite 107, Miami, FL 33178. Phone:
305-717-5815, Fax: 305-717-5801, cdhittle@usgs.gov
Figure 3. Velocity relation for the Whale Harbor monitoring station
43
Vegetative Habitats of Water Conservation Area-3A: Hydrologic Impacts of IOP
By Wiley M. Kitchens1, and Paul Wetzel and Erik Powers2
1U.S .Geological Survey, Florida Cooperative Fish and Wildlife Research Unit, Gainesville, FL., USA
2University of Florida, Gainesville, FL., USA
A vegetation monitoring study has been initiated in Water Conservation Area-3A (WCA-3A) to document
impacts of a new hydrologic regulation schedule implemented 1 July 2002 under the Interim Operation Plan for the
Protection of the Cape Sable Seaside Sparrow, Everglades Park - Alternative 7R (IOP-Alt.7R). This study was
implemented to address the concern that IOP-Alt.7R could adversely affect the endangered snail kite (Rostrhamus
sociabilis) and their habitat in WCA-3A, the largest and most consistently utilized of designated critical habitats.
Much of the area is already currently seriously degraded. Various studies have documented the conversion of wet
prairies (preferred foraging habitat) to aquatic sloughs in that area along with losses of interspersed herbaceous and
woody species essential for nesting habitat. The concern is carrying capacity (habitat quality) will be further
impaired from elevated water depths and increased hydroperiods indicated by hydrological predictions.
The principal objective is to separate plant community responses due to typical seasonal and year-to-year variances
from effects due to new and (or) predicted hydrologic regimes. The vegetative community structure of these
sites is an expression of both recent past and current hydrological conditions. It is critically important to determine
how the species associations within these communities respond differentially to changes in hydrology through time
and over space. Given the immense area of WCA 3A, this study focuses on areas represented by two Indicator
Regions (IR's 14 and 17). The areas include major gaging stations (GS 63, 64, and 65) and traditional foraging and
nesting regions used by kites.
A multi-tiered approach was required to determine community change through time and space while differentiating
seasonal responses from projected hydrologic changes.
1) Spatial Patterns and Change Detection at the Broad Vegetation Class Level- (example, sawgrass strands,
tree islands, cattail patches, and wet prairie/slough). Aerial or satellite imagery will be used to remotely sense spatial
distributions, extent, and patterning of broad major vegetation classes. Change detection will conducted on at
least three sets of imagery, 4-5 years pre-project, at project onset, and 3-4 years post-project.
2) Development of "modeled-topographic" database and hydrologic characterization of Indicator Regions.
Stage information generated by SFWMM model for the units comprising each Indicator Region is gridded 2 mi. on
a side. Stage duration curves generated from this data are determined from estimated ground surface elevations generalized
from a weighted mean over the 4 sq. mi. area of each grid. This level of detail is far too generalized for
assessment impacts to habitat suitability of wetland vegetation for subtle changes in hydroperiods and inundation
depth regimes. To resolve this issue, we have located 10 sample complexes (1 kilometer on a side) within each of
the indicator regions (14 and 17) (Fig. 1) using a stratified random approach (peat depths, general elevation, and
snail kite nest density). Water levels will be continuously monitored in each complex. Each complex is subdivided
into a grid 100-m on a side. Replicate ground surface elevations will be measured (survey-grade GPS) in each
major plant community types (as per vegetation maps as per above) near the intersection points in the grid. Elevations
will be surveyed for each of the plant types separately in each grid by confining kreiging routines for the elevations
for that plant type only within polygons labeled for that type. This is repeated for each plant type and each
cell. Polygons are re-composited and merged in a GIS providing a topographic database driven by plant community
types. Stage data for the sample complex will be related to elevation data specific to each plant community type
creating stage duration curves for each vegetation type in the individual cells. Long term and predicted hydroperiod
and depth duration data for each vegetation type in each cell will be generated by statistical regression with the nearest
permanent gaging station.
44
3) Establishment of permanent
transects plots across elevation gradient in
each Indicator Region. Permanent monitoring
plots (combinations of quadrats and
transects) have been established in the sample
complexes across the local elevation gradient
in each complex. Regularly placed
multiple or replicate quadrats arrayed as continuous
belts along a transect perpendicular
to the elevation gradient within each sample
complex. Each site is sampled seasonally (3
times/yr) for species numbers, stem counts,
and biomass (both living and standing dead).
Water depths are monitored continuously
within each sample complex for determinations
of hydroperiods and depth duration
curves. Each complex consists of three belt
transect complexes, five plots of the principal
habitat types (sawgrass, wet prairie,
sloughs), and five permanent tree island/
shrub heads plots sites typical of kite nest
habitat. Multivariate techniques (NMS and
multivariate regression tree, and structural
equation models) will be used to resolve
relation between plant community structure
and hydrology. Structural equation modeling
(SEM) will define statistical correlations
among species and associated hydrologic
and other environmental parameters and provide
probabilistic measures for environmental
mechanisms involved in plant community
succession.
Contact: Kitchens, Wiley, Florida Cooperative Fish and Wildlife Research Unit, Bldg. 810, University of Florida,
Gainesville, FL 326211- Phone: 352-836-0536, Fax: 352-846-0841, kitchensw@wec.ufl.edu, Ecology
Figure 1. Image of WCA-3A indicating IR and sample complex
locations.
45
The Role of Seasonal Hydrology in the Dynamics of Fish Communities Inhabiting
Karstic Refuges of the Florida Everglades
By Robert M. Kobza and William F. Loftus
U.S. Geological Survey, Center for Water and Restoration Studies, Homestead, FL., USA
Our goal is to understand the
influence of altered surface
flooding on access to groundwater
refuges for surfacedwelling
aquatic animals, primarily
fishes, in the karstic
wetlands east of Shark River
Slough, Everglades National
Park, Florida, USA. The current
management proposal for
these wetlands call for water
levels to not fall more than 46
cm (1.5 ft) below ground level
for greater than 90 days per
year at an average periodicity
of no more than once in three
years. This study includes four
areas in the extreme southeastern
Everglades (fig. 1) and is in
its fifth year. We will present

the results of data collected in 1999-2000 in addition to those from 2001-2002. We suggest that the impact of
groundwater management on dry-season refuges should be considered when establishing criteria for species management.
The solution hole environment became
more lethal to fishes as water levels receded.
From analysis of a number of factors, temperature,
pH, dissolved oxygen, and chlorophyll
a were most significant in structuring
dry-season fish communities in 1999 and
2000. These factors changed on a seasonal
basis, with nutrient concentrations increasing
(fig. 2) and dissolved oxygen decreasing in
holes during the dry season. In our four study
regions, 84 percent of solution holes were
less than 46 cm deep, and those deeper than
1 m were rare (< 3 km-2) (fig. 3).
The capture of fishes in solution holes
increased as water levels fell until mid-dry
season. This was followed by a significant decline in the late dry season, and a subsequent increase in early wet
season (fig. 4). This pattern indicates that fishes are surviving in solution holes until conditions become critical.
Mortalities then occur, but holes are repopulated by subsequent re-invasions of foraging and nesting species upon
Figure 1. Map of sampling locations in Everglades N.P.
= no data
Figure 2. The concentration of nutrients in solution holes by
month.
46
PA-HAY-OKEE
30
34
38
42
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82
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102
FREQUENCY
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40
Main Road
30
34
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90
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FREQUENCY
0
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Context Road
DEPTH (cm)
30
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FREQUENCY
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Wilderness Road
DEPTH (cm)
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FREQUENCY
0
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Longest-hydroperiod region
Total holes surveyed: 17
1.71.16 holes/transect
Mean depth: 33.03.0 cm
Short-hydroperiod region
Total holes surveyed: 197
19.72.66 holes/transect
Mean depth: 37.07.0 cm
Short-hydroperiod region
Total holes surveyed: 163
16.35.39 holes/transect
Mean depth: 41.011.0 cm
Short-hydroperiod region
Total holes surveyed: 70
7.02.94 holes/transect
Mean depth: 40.012.0 cm
Figure 3. Depth frequency of solution holes by region.
Figure 4. Average catch-per-unit-effort (CPUE) of fishes and average water depth across all regions in
1999 and 2000.
47
inundation. Native cyprinodontiforms were abundant in shallow solution holes that dry annually under current
management, while predatory species (often non-native) tended to dominate deeper holes. The percentage of nonnative
fishes captured varied by season and across regions, with a maximum of 63 percent occurring at the Wilderness
Road region, and an average of 23 percent non-native fishes across all regions and seasons (fig. 5).
Our work suggests that solution holes serve as necessary dry-season habitat and that an immense loss of fish
biomass occurs when water levels fall 46 cm below ground surface within our study regions. We recommend that
the effect of groundwater management on dry-season and drought refuges should be included while developing criteria
for minimum flows and levels for the management of the Everglades and other aquatic ecosystems.
This research was funded through the Critical Ecosystem Studies Initiative by agreement between the U. S.
Geological Survey (USGS) and the U. S. National Park Service.
Contact: Kobza, Robert, U. S. Geological Survey, 40001 State Road 9336, Homestead, FL, 33034-6733, Phone:
305-242-7800, Fax: 305-242-7836, Robert_kobza@usgs.gov, Ecology and Ecological Monitoring
Figure 5. Percentage of non-natives in total fishes captured in holes by "early" (January-March) and
"late" (March-July) dry-seasons for 1999 and 2000.
48
The Effects of Hydroperiod on Life-History Parameters of two Species of
Livebearing Fish (Poeciliidae) in the Florida Everglades
By Timothy Konnert1, Joel C. Trexler1, and William F. Loftus2
1Florida International University, Miami, FL., USA
2U.S. Geological Survey, Center for Water and Restoration Studies, Homestead, FL., USA
Ecologists often make assumptions about the "stressfulness" of habitats
based on fluctuation in the physical environment and its presumed
effects on organismal vital rates such as age-specific survivorship or fertility.
In aquatic habitats, fluctuations in water level leading to dry-down events are
often considered "stressful" for fishes because it is assumed that reduced
habitat area and crowding have adverse effects on survivorship and fertility.
However, the degree of drying, as demonstrated by variations in minimum
surface-water depths, is rarely constant among years in the Everglades. That
variation may produce dramatically different effects on the fish community,
depending on factors such as availability and quality of refuges that remain
wetted. Furthermore, organisms typically have physiological and behavioral
adaptations to compensate for environmental variability, including synchronization
of reproductive and migratory patterns with environmental fluctuation,
and phenotypic plasticity. Consequently, the matching of recurrent
"stress" with measures of survivorship and reproduction are critical to produce
predictive demographic models. While comparative statements about
the relative stressfulness of habitats are common in the literature on life histories,
we question the ability to make such comparisons without age-specific
survival and fertility data. To improve the utility of management models such as ATLSS, we sought to estimate
explicitly the effects of hydroperiod on demographic rates of two of the most common species in the Everglades, the
sailfin molly and the least killifish (Poeciliidae) (fig. 1).
We used estimates of age-length relation to
estimate age-specific survival and fertility for
sailfin mollies and least killifish from six sites in
the Everglades that experience a gradient of
hydrological conditions (fig. 2). These six sites
are the focus of long-term monitoring of fish communities,
and we used samples collected from
1997 to 1999 to estimate age-specific survivorship
curves and fertility schedules. From those
data, we constructed life tables to compare patterns
in vital rates of each species with hydroperiod.
Also, we compared the idealized estimate of
population growth rate from the life table to real
population dynamics over the same time period.
Otoliths were used (fig. 3) to determine the relation
between size and age for male, female, and
juvenile sailfin mollies from the six study sites
(fig. 4).
Calibrations indicated that this method was
very accurate for juvenile fish, but tended to
under-estimate age in older, mature specimens.
Figure 1. Top: sailfin molly
(Poecilia latipinna); bottom: least
killifish (Heterandria formosa).
Figure 2. Map showing six
study sites.
49
We also dissected female fish from the long-term field collections to estimate size-specific fertility for females of
each species. We used the otolith data to estimate the age of females based on size in order to transform these data
into age-specific fertility tables for each study site.
The analyses indicated that growth rate and age-specific fertility
differed among locations, and that some patterns could be
explained by hydroperiod. However, many of the patterns were
not consistent with the expectation that short-hydroperiod sites are
more stressful for these two species. For example, the longest life
expectation and highest lifetime fertility were noted at the short
hydroperiod sites for both taxa. These results yielded greater estimates
of population growth rate [r] for the two short-hydroperiod
sites. Either both species have adaptations that permit them to circumvent
the conditions that make these sites appear stressful to
ecologists, or immigration is subsidizing populations in shorthydroperiod
sites yielding a more favorable demographic profile
than is actually realized by residents of the site. Ongoing research
on dispersal by similar species before and after droughts suggests
a complex pattern that may include dispersal from long-hydroperiod
sites to the short-hydroperiod sites, and persistence in local
refuges. The exact role of dispersal in re-establishing short-hydroperiod fish populations appears to depend on local
topography and ambient rainfall. On the other hand, our data are consistent with the long-held hypothesis that small
fish species experience less predation from piscivorous fish in short-hydroperiod than in long-hydroperiod habitats.
This hypothesis predicts that these fishes should experience longer life spans in short-hydroperiod sites, as we
observed. More research is needed on the relative role of immigration as a mechanism to sustain small fish populations
in short-hydroperiod marshes of the Everglades. This study suggests that management models of fishes must
incorporate rapid recovery from drought events. Some species may experience greater population growth rates in
short-hydroperiod habitats, although ultimate population sizes may be limited by periodic dry down, site productivity,
and other factors.
This research was funded
through a cooperative agreement
between the USGS and FIU under
the Place-Based Studies initiative
of the USGS (CA 1445-CA09-95-
0112, Sub-agreement No. 12).
Contact: Timothy, Konnert,
Dept. of Biological Sciences,
Florida International University,
University Park, Miami, FL
33199 Phone: 305-348-4032,
Konnertt@fiu.edu
Figure 3. Cross-section of a sailfin molly
otolith. The number of rings indicates the
fish's age in days.
Sta
nda
rd
Le
ngt
h
(m
m)
Age (days)
WCA SRS Hydroperiod
Long
Short
Site 5
0
10
20
30
40
50
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Site 8
0
10
20
30
40
50
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Site 11
0
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20
30
40
50
0 50 100 150 200 250 300
Site 7
0
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30
40
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0 50 100 150 200 250 300
Site 37
0
10
20
30
40
50
0 50 100 150 200 250 300
Site 50
0
10
20
30
40
50
0 50 100 150 200 250 300
Age (days)
0.161 mm/day
0.105 mm/day
0.174 mm/day
0.204 mm/day
0.146 mm/day
0.128 mm/day
Figure 4. Size-age relationships for female sailfin mollies from our six study
sites. The slopes of each line are indicative of growth rate.
50
Recharge and Discharge Measurements in the Everglades using Short-lived
Radium Isotopes
By James M. Krest and Judson W. Harvey
U.S. Geological Survey, Reston, VA., USA
The Everglades peat layer acts as an interface
between groundwater and surface water, a zone
where the interactions between physical, chemical
and biological processes are enhanced, influencing
the cycling of elements between water and sediments.
Common methods for measuring exchange
across the peat layer are prone to complications.
For example, hydrologic approaches yield results
with high variances when small hydraulic gradients
are encountered, especially over short distances.
Likewise, direct seepage-meter measurements tend
to be imprecise at low seepage rates. Furthermore,
some geochemical approaches (e.g. radon and
chloride) rely on the measurement of fine scale gradients
that are frequently affected by processes
independent of recharge or discharge (e.g. methane
ebullition or mechanical disturbance of the surface
sediments). We present here a new method to quantify
these slow vertical fluxes through the peat layer
by modeling the pore-water profiles of 223Ra and
224Ra.
223Ra (t1/2 = 11.4 d) and 224Ra (t1/2 = 3.7 d) are naturally occurring isotopes of radium which are useful tracers for
quantifying rates of groundwater recharge and discharge in wetlands, particularly for time scales of a few days to
weeks. Near the interface between peat sediments and the underlying aquifer, or near the interface between the peat
and overlying water, pore-water radium activities are commonly different than the amount expected from the radium
production rate (fig. 1). This disequilibrium results from vertical transport of radium by pore water. In situations
where groundwater recharge or discharge is significant, the rate of vertical water flow can be determined from this
disequilibrium using a combined model of radium transport, production, decay, and exchange with solid phases:
where C is the number of dissolved radium atoms per volume of water, C* is the number of adsorbed radium atoms
per mass of dry sediment, t is time, Z is depth below the peat surface, D is the hydrodynamic dispersion coefficient,
v is the pore-water advective velocity, f is the mass of dry sediment per mass of bulk sediment, KD is the ratio of
adsorbed to dissolved radium, is the production rate exchangeable radium (adsorbed plus dissolved), is the
radium decay constant, and is the pore water density.
Figure 1. Idealized profiles showing the expected radium
activities in surface water and peat pore-water for the cases
of groundwater recharge (top) and groundwater discharge
(bottom). Mixing due to dispersion could look similar to
either of these profiles.
transport production decay exchange
( ) D D K t
C C
f K f
P
Z
C v
Z
C D
t
C  

 + -
- +
+

 -

 =

 *
2
2

1

P
51
We have developed and tested this technique at three sites in the freshwater portion of the Everglades by quantifying
vertical advective velocities in areas with persistent groundwater recharge or discharge, and estimating a
coefficient of dispersion at a site that is subject to reversals between recharge and discharge (Krest and Harvey
2003). Groundwater velocities (v) were determined to be between 0 and -0.5 cm d-1 for a recharge site, and 1.5 
0.4 cm d-1 for a discharge site near Levee 39 in the Everglades (fig. 2). Our approach has a distinct advantage in the
Everglades because strong gradients in 223Ra and 224Ra usually occurred at the base of the peat layer, which avoided
the problems of other tracers (e.g. chloride) for which greatest sensitivity occurs near the peat surface - a zone in
which gradients are readily disturbed by processes unrelated to groundwater flow.
This technique should be readily applicable to any wetland system that has different production rates of these
isotopes in distinct sedimentary layers or surface water. The approach is most straightforward in freshwater systems
because constant pore-water ionic strength can usually be assumed, which simplifies the modeling of radium
exchange with solid phases. In estuarine or marine systems, changing ionic strength could be addressed with additional
data and an extended model.
REFERENCES
Krest, J. M. and J. W. Harvey (2003). "Using natural distributions of short-lived radium isotopes to quantify groundwater
discharge and recharge." Limnology and Oceanography 48(1): 290-298.
Contact: Krest, James M., U.S. Geological Survey, 12201 Sunrise Valley Drive, Mail Stop 430, Reston, VA
20192; Phone: (703) 648-5472; Fax: (703) 648-5484; jmkrest@usgs.gov; Hydrology and Hydrological Modeling
Figure 2. Pore-water radium activities as a function
of depth. a) 224Ra, and b) 223Ra activities at site
S10C-S are highest at the base of the peat and
decrease upwards as the excess radium in
discharging groundwater decays to a level
supported by its equilibrium production and
exchange with the adsorbed fraction. c) 224Ra and
d) 223Ra activities at S10C-N are elevated only in
the upper portion of the peat, suggesting that
recharge occurs at this site.
0 20 40 60
Depth Below Peat Surface (m)
0.00
0.25
0.50
0.75
1.00
c
0 2 4 6
0.00
0.25
0.50
0.75
1.00
d
223Ra (dpm 100L-1)
0 2 4 6 8
0.00
0.25
0.50
0.75
1.00
b
224Ra (dpm 100L-1)
0 20 40 60
Depth Below Peat Surface (m)
0.00
0.25
0.50
0.75
1.00
a
S10C-N
Advection
0.0 > v > -0.9 cm d-1
S10C-N
Advection
0.0 > v > -0.43 cm d-1
S10C-S
Advection
v = 2.4  0.6 cm d-1
S10C-S
Advection
v = 0.50  0.25 cm d-1
Recharge Discharge
52
Flows, Stages, and Salinities: How Accurate is the SICS Integrated Surface-
Water/Ground-Water Flow and Transport Model?
By Christian Langevin, Eric Swain, and Melinda Wolfert
U.S. Geological Survey, Center for Water and Restoration Studies, Miami, FL., USA
The Southern
Inland and Coastal
Systems (SICS)
model was developed
by the U.S. Geological
Survey to simulate
flows, stages, and
salinities within the
area surrounding Taylor
Slough and northeastern

Florida Bay.
The SICS model consists
of a two-dimensional
hydrodynamic
surface-water flow
and transport model
coupled to a threedimensional
variabledensity
ground-water
flow and transport
model. A description
of the computer code
used for the simulations
is described in a
companion abstract
included in these proceedings. The current version of the model represents a 5-year period from January 1995 to
December 1999. Comparisons between observed and simulated values of flow, stage, and salinity suggest that the
model provides a good representation of the physical system; and that, with some additional effort, the model could
be used to evaluate the hydrologic effects of the Comprehensive Everglades Restoration Project (CERP) on the
coastal wetlands and northeastern Florida Bay.
Water-level hydrographs are useful ecological indicators because they can be used to calculate hydroperiod,
which is the number of days per year with standing water. Within the Taylor Slough area, the SICS model seems to
provide an accurate description of water-level fluctuations. Figure 1 compares measured and simulated stage for
monitoring station TSH in central Taylor Slough. The mean absolute error in simulated water level for the 5-year
period is 0.06 meters. The average hydroperiod at TSH calculated by the model (259 days) compares to within 2
percent of the hydroperiod calculated using measured data (255 days).
Trout Creek is the major outlet for freshwater flow from the coastal wetlands into northeastern Florida Bay.
An advantage of using a fully hydrodynamic surface-water model instead of a simplified model that neglects the
effect of wind, for example, is that volumetric discharge (and thus salinity) in complex coastal environments can be
represented. For example, figure 2 shows the comparison between measured and simulated discharges for Trout
Creek. Flow is positive for most of the simulation period, indicating discharge into Florida Bay. During periods of
southerly winds, however, brackish water from Florida Bay is forced inland into the coastal wetlands. Although the
current version of the SICS model simulates total discharge at Trout Creek that is slightly higher than measured dis-
Figure 1. Measured and simulated stage at the TSH monitoring site, located in central Taylor
Slough.
53
charge, figure 2 suggest the model is capable of representing overall discharge trends. The ability to represent transport,
and thus salinity patterns, is another advantage to using a fully hydrodynamic surface-water model. Figure 3
shows the comparison between measured and simulated surface-water salinities at the mouth of Trout Creek. The
mean absolute difference in salinity is 4.6 parts per thousand.
The SICS model has
the potential for providing
the important link between
the managed hydrologic system
of southeastern Florida
and the Florida Bay estuary.
One of the current plans is to
complete the coupling of the
SICS model with the South
Florida Water Management
Model (2x2). The linked
SICS model could then be
used to determine the effect
of alternative water management
scenarios on coastal
wetland salinities and freshwater
flows to Florida Bay.
Contact: Christian Langevin, U.S. Geological Survey, 9100 NW 36th Street, Ste. 107, Miami, FL, 33178, Phone:
305-717-5817, Fax: 305-717-5801, langevin@usgs.gov
Figure 2. Measured and simulated discharge values for Trout Creek.
Figure 3. Measured and simulated salinity values for Trout Creek.
54
Quantifying Internal Canal Flows in South Florida
By Mitch Murray, and Rick Solis
U.S. Geological Survey, Center for Water and Restoration Studies, Miami, FL., USA
The need to determine future surfacewater
flow requirements in the interior canal
system of south Florida is being met with the
successful implementation of strategic
placed stream-flow and water-quality gaging
sites in the interior of southern Florida.
The multi-agency effort involves four entities
that collect, analyze, and distribute
information for water managers. In 1995 the
U.S. Geological Survey (USGS) established
three monitoring sites south of Lake
Okeechobee in an effort to accurately gage
flows in canals entering and exiting Tribal
lands, the Big Cypress National Preserve,
and Water Conservation Area 3A in southern
Florida. These flows are also being monitored
to calculate nutrient loads in the
canals that cross or border Tribal lands. Two
of the gaging sites, L-28U and L-28IN, are
located on the southern border of the Seminole
Tribal lands along the L-28 canal and

the L-28 Interceptor canal, respectively,
west of Water Conservation Area 3A in Hendry
County (fig. 1). The third gaging site, L-
28IS, is located along the L-28 Interceptor
canal where flows enter the western lands of
the Miccosukee Indian Tribe from the Big
Cypress National Preserve in Collier County
and has been discontinued.
Acoustic instrumentation, in lieu of
standard methods for field data collection
and flow computations, is used to quantify
flows in the canals. Using the acoustic
velocity meter (AVM), Acoustic Doppler
Velocity meter (ADV), and the Acoustic
Doppler Current Profiler (ADCP), it is possible
to more accurately gage flows in this
type of environment because of new capabilities
to quickly measure low or rapidly
changing water velocities. Construction,
instrumentation, and calibration of the flow
gaging sites were completed by the USGS
during 1996 and 1997. The South Florida
Water Management District (SFWMD)
55
installed flow-weighted samplers at the gaging sites for nutrient analysis in conjunction with the stream flow monitoring;
the Seminole and Miccosukee Indian Tribes have serviced the flow-weighted samplers. Real-time telemetry
instrumentation and programming assistance along with phosphorus and nitrogen load calculations have been provided
by the SFWMD. ADCP calibration of the installed acoustic velocity meter indexes is ongoing and development
of the "sum of least squares regression" has been provided for data processing at all sites and continues to be
refined. Velocity data collected during the dry season has displayed a phenomenon known as acoustic refraction or
ray bending produced by thermal stratification in the water column during extended periods of very slow vertical
flow. Various installed electromagnetic and new Doppler mean velocity-indexing techniques have been tested and
proven largely successful.
The L-28U site along the L-28 canal is used to monitor freshwater flows from the lands of the Seminole Tribe
and to provide nutrient data load summaries. Average annual runoff of 63,930 acre-feet for the period from 1997 to
2001, represents about twice the inflow amount determined by the SFWMD at their upstream U.S. Sugar Outflow
(USSO) site located on the northwestern border of the Seminole Tribal lands. The L-28IN site along the L-28 Interceptor
canal is used to monitor flows from the lands of the Seminole Indian Tribe to the Big Cypress National Preserve
and ultimately to Miccosukee Tribal lands as well as providing nutrient data for water-resources planning and
management. Annual runoff averaged 53,140 acre-feet from 1997 through 2001. The L-28IS site along the L-28
Interceptor canal, discontinued September 1999, was used to monitor flows from the lands of the Seminole Indian
Tribe and the Big Cypress National Preserve to the lands of the Miccosukee Indian Tribe. For the three years of
operation this site also provided flows and associated nutrient load data for water managers, and was instrumental
in bracketing and quality assuring the flow calibration conditions for the upstream L-28IN site. Average annual runoff
at the site for the 1997-1999 periods was calculated to be 49,070 acre-feet.
Measuring flow-weighted nutrient loads requires extremely accurate flow-data collection combined with a
highly coordinated nutrient collection and analysis procedure. A collaborative product that meets this need is provided
as part of current efforts and has been documented in seven semi-annual progress reports presented to the
SFWMD/Seminole Working Group. An ancillary report was produced from funding sources outside of the USGS
Placed Based Studies (PBS) program budget during the 2002 water year (Lietz, 2002). The report examines the feasibility
of estimating concentrations and loads based both on USGS acoustic backscatter data and Seminole Tribe
nutrient water quality data.
REFERENCES
Lietz, A.C., 2002 (in press), Feasibility of estimating constituent concentrations and loads based on data recorded
by acoustic instrumentation: U.S. Geological Survey Open File Report 02-285, 10 p.
Contact: Mitch Murray, mmurray@usgs.gov, Rick Solis, rsolis@usgs.gov, U.S. Geological Survey, 9100 NW
36 St., Ste. 107, Miami, FL, 33178. Phone: (305) 717-5827, Fax: (305) 717-5801. Question 1.
56
Hydrologic Information for Tidal Rivers along the Southwest Coast of Everglades
National Park
By Eduardo Patino, Lars Soderqvist, and Craig Thompson
U.S. Geological Survey, Center for Water and Restoration Studies, Ft. Myers, FL., USA
The health of estuaries and bays along
the mangrove zone of southwest coast of Everglades
National Park (ENP) is dependent on
the amount and quality of fresh water the area
receives. For decades this area has been
affected by management practices that control
freshwater flows across Tamiami Trail and
determine water budgets of ENP. Until recent
years however, limited hydrologic information
has been collected in the area, making it difficult
to understand and describe the magnitude
of the effects along the mangrove zone.
From 1960 to 1969, the U.S. Geological
Survey (USGS) conducted a study of tides and
flow in coastal rivers (fig. 1) along the Shark
River Slough system to aid in the calculation of
water budgets for ENP. In 1996, the USGS initiated
a second hydrologic study to determine
Figure 1. Photograph of the Harney River monitoring station in
1960.
Figure 2. Location of monitoring stations for coastal rivers along the southwest coast of
Everglades National Park.
the flow and nutrient characteristics
of some of the
same tidal rivers of the
Shark River Slough system,
and in 2001 the study was
expanded to cover the area
from Whitewater Bay to
Everglades City (fig. 2).
USGS hydrologic data from
these stations and others in
nearby coastal marshes,
along with hydrologic data
from the Marine Monitoring
Network of ENP, can now
be used to describe the flow
and water-quality characteristics
of estuaries along the
southwest coast of ENP.
The primary goals of
the current study are to
describe the salinity patterns
along the southwest coast of
ENP in relation to freshwater
inflows to the estuaries
57
and tidal exchange with the Gulf of Mexico, provide support to the USGS Tides and Inflows in the Mangroves of
the Everglades model (TIME), and to aid programs such as Everglades Long Term Ecological Research (LTER).
Continuous salinity data from
the main rivers and along transects
from freshwater wetlands to the Gulf of
Mexico (fig. 3) will be useful for
describing both spatial and seasonal
variation of salinity throughout the
study area. The data also will help scientists
and managers determine how
salinity patterns may change in
response to restoration efforts affecting
freshwater deliveries to ENP and Big
Cypress National Preserve.
Contact: Patino, Eduardo, epatino@
usgs.gov, Soderqvist, Lars,
lsoderq@usgs.gov, Thompson, Craig,
cthompso@usgs.gov, U.S. Geological
Survey, 3745 Broadway, Suite 301,
Fort Myers, FL, 33901, Phone: 239-
275-8448, Fax 239-275-6820, primary
conference topic: hydrology and
hydrologic modeling.
Figure 3. (A and B) Daily salinity values for rivers along the southwest
coast of Everglades National Park, and (C) for a transect along the Shark
River System.
58
Inventory and Review of Aquifer Storage and Recovery in Southern Florida
By Ronald S. Reese
U.S. Geological Survey, Center for Water and Restoration Studies, Miami, FL., USA
Aquifer storage and
recovery (ASR) in southern
Florida has been proposed
on an unprecedented scale as
part of the Comprehensive
Everglades Restoration Plan
(CERP). ASR wells were
constructed or are under construction
at 27 sites in southern
Florida, mostly by local
municipalities or counties in
coastal areas. The Upper
Floridan aquifer, the principal
storage zone of interest to
the Restoration Plan, is the
aquifer being used at 22 of
the sites. The aquifer is
brackish to saline in southern
Florida, which can greatly
affect the recovery of the
freshwater recharged and
stored.
The purpose of this
study is to inventory and
compile data for existing
ASR sites in southern Florida
and identify various hydrogeologic, design, and management factors that control the recovery of freshwater
injected (recharged) into ASR wells. Data for all wells at most of the 27 sites were compiled into four main categories:
(1) well identification, location, and construction data; (2) hydraulic test data; (3) ambient formation water-quality
data; and (4) cycle testing data. Each cycle during testing or operation includes periods of recharge of freshwater,
storage, and recovery that each last days or months. Cycle testing data include calculations of recovery efficiency,
which is the percentage of potable recharged water recovered for each cycle.
Potable water recovery efficiencies for 16 of the 27 sites were calculated and, generally, recovery efficiency
improves with the number of cycles. Except for two sites, the highest number of cycles was five. Only nine sites had
a recovery efficiency above 10 percent for the first cycle or two. However, at two out of the other seven sites, low
recharge volumes per cycle of less than 10 million gallons (Mgal) could explain the poor recovery. Ten sites achieved
a recovery efficiency above 30 percent during at least one cycle. The highest recovery efficiency achieved per cycle
was 84 percent for cycle 16 at the Boynton Beach site (fig. 1). Recharge volume per cycle averaged 95 Mgal, ranging
from 0.6 to 714 Mgal, for 55 cycles at 14 Upper Floridan aquifer sites. Recharge volume for cycle 3 at the West Well
Field site in Miami-Dade County was 714 Mgal and included simultaneous recharge into 3 ASR wells. All cycles
were conducted in a single well, except for two cycles at the West Well Field site.
Factors that could affect recovery of freshwater varied widely among sites. The thickness of the open storage
zone at all sites ranged from 45 to 452 feet. For Upper Floridan aquifer sites, transmissivity based on tests of the
storage zones ranged from 800 to 108,000 ft2/d (feet squared per day), chloride concentration of ambient water
Figure 1. Operational cycles at the Boynton Beach East Water Treatment Plant site in Palm Beach
County and relations of volumes recharged and recovered, time, and percent recovery for each cycle.
Recovery for cycle 15 was 34 percent for and ending chloride concentration of 146 milligrams per
liter.
59
ranged from 500 to 11,000 mg/L (milligrams per liter), and leakance values indicated that confinement between the
storage zone and lower zones may be limited in some areas. High transmissivity can adversely affect recovery,
because it may equate to high dispersive mixing in a limestone aquifer. Additionally, depending on the ambient
salinity of the storage zone, the probability of buoyancy stratification increases as transmissivity increases. At three
sites that have transmissivities above 70,000 ft2/d with 3 to 5 cycles at each, recovery efficiencies over 10 percent
per cycle were not obtained.
Based on review of four case studies and data from other sites, several hydrogeologic and design factors
appear to be important to the performance of ASR in the Floridan aquifer system. Performance is maximized when
the storage zone is thin and located at the top of the Upper Floridan aquifer (fig. 2), and transmissivity and ambient
salinity of the storage zone are moderate (less than 30,000 ft2/d and 3,000 mg/L of chloride concentration, respectively).
The structural setting at a site could also be important because of the potential for updip migration of a
recharged freshwater bubble due to density contrast or loss of overlying confinement due to deformation.
This five-year
study is divided into
two phases, the first of
which lasted two years.
The first phase laid the
groundwork for data
inventory, review, and
analysis. The second
phase will allow for collection
of additional
data as it becomes available,
expand the hydrogeologic
framework,
and perform a more
complete comparative
analysis of ASR sites.
Results from the first
phase are provided in
Reese (2001); results
from the current phase
also will be published.
REFERENCES
Reese, R.S., 2001, Inventory and review of aquifer storage and recovery in southern Florida: U.S. Geological Survey
Water Resources Investigation Report 02-4036, 56 p.
Contact: Ronald S. Reese, U.S. Geological Survey, Center for Water and Restoration Studies, 9100 NW 36
Street, Suite 107, Miami, FL, 33178, Phone: (305) 717-5821, Fax: (305) 717-5801, rsreese@usgs.gov
Figure 2. Location of storage zone in relation to geophysical logs, lithology, flow zones, and
geologic and hydrogeologic units for the aquifer storage and recovery well at the Boynton Beach
East Water Treatment Plant site in Palm Beach County.
60
Impact of Water Management on Coastal Hydrology in Southeastern Florida
By Robert A. Renken1, Joann Dixon1, A. C. Lietz1, Pamela Telis1, Alyssa Dausman,1 Jeff Rogers1, Steven
Memberg1, John Koehmstedt2, Scott Ishman3, and Richard Marella4
1U.S. Geological Survey, Center for Water and Restoration Studies, Miami, FL., USA
2U.S. Geological Survey, Reston, VA, USA
3University of Southern Illinois, Carbondale, IL, USA
4U.S. Geological Survey, Tallahassee, FL, USA
Surface and ground water hydrology and natural
ecosystems of southeastern Florida have been subjected
to conflicting anthropogenic stresses, which
are attributed to the development of a highly controlled
water-management system designed to
reclaim land for urban and agricultural development.
During the first half of the 20th century, Everglades
wetlands and coastal estuaries were viewed as a
wasteland suitable only for drainage and development.
Predevelopment surface- and ground-water
systems were intensely transformed by construction
of a complex system of canals, impoundments, control
structures, levee systems, and many large well
fields. These features were collectively designed to
manage the competing needs of agriculture, urban
users, and natural ecosystem areas. Water-management
systems were used to control floods, sustain
ecosystems, prevent overland flow from moving eastward
and flooding urban and agricultural areas, maintain
water levels to prevent saltwater intrusion, and
provide an adequate water supply.
Miami-Dade, Broward, and Palm Beach Counties
have experienced explosive population growth,
increasing from less than 4,000 inhabitants in 1900 to
more than 3.8 million in 2000. The use of ground
water, the principal source of municipal supply, has
increased considerably, from 3 well fields producing
65 Mgal/d (million gallons per day) in 1930 to more
than 770 Mgal/d from 79 operating well fields in
1995. Agricultural water use increased from 505
Mgal/d in 1953 to almost 1,150 Mgal/d in 1988, but has since declined to 764 Mgal/d in 1995. This decline is partly
due to the displacement of agriculture by urban growth. Present-day agricultural supplies are obtained largely from
surface-water sources in Palm Beach County and ground-water sources in Miami-Dade County, whereas agricultural
growers in Broward County have been largely displaced.
Before 1948, surface-water conveyance canals provided unregulated flow and were incapable of effectively
transporting floodwaters. A lack of canal control structures exacerbated overdrainage of the aquifer during periods
of low rainfall and drought. The Central and Southern Florida Flood Control project restructured the existing conveyance
system through canal expansion, construction of protective levees and control structures, and greater management
of ground-water levels within the surficial aquifer. Currently, gated canal control structures discharge
excess surface water during the wet season and remain closed during the dry season to induce recharge.
CANAL
-3.0
-2.0
-1.0
0
1.0
2.0
3.0
4.0
5.0
0
0
AVERAGE DIFFERENCES
IN WATER LEVELS
(FEET)
EXPLANATION
Miami
Fort
Lauderdale
Lake
Okeechobee
West
Palm
Beach
8045 8030 8015 8000
2700
2645
2630
2615
2600
2545
2530
2515
West Palm Beach Canal
HENDRY COUNTY
Hillsboro Canal
North N
ew River Canal
COLLIER COUNTY
Miami Canal
MONROE COUNTY
Biscayne Bay
Atlantic Ocean
PALM BEACH COUNTY
PALM BEACH COUNTY
BROWARD COUNTY
BROWARD COUNTY
MIAMI-DADE COUNTY
Average difference in water levels between
October 1940-44 and October 1990-94
61
Managed surface-water conveyance has been used successfully to increase ground-water levels near the coast
to impede saltwater intrusion, minimize urban and agricultural flooding, and maintain lower inland ground-water
levels. Measured canal stage at the coastal reaches increased during the latter half of the 20th century, whereas surface-
water discharge to coastal bays and the Atlantic Ocean declined. Stage increase is presumably the result of
efforts to prevent saltwater intrusion into major canals and aquifers. The decline in coastal surface-water discharge
is attributed to municipal ground-water withdrawals that induce recharge from the canal to the aquifer. The rerouting
of surface water in major canals to secondary canals to elevate coastal ground-water levels also may have contributed
to these declines. In contrast to coastal areas, long-term canal flow near the western margin of the urban area
has remained relatively consistent (without a general increase or decrease in flow). Consistent long-term surface
water flow along the western edge of urban areas and a decline in flow near the coast further supports municipal
well withdrawals as a causative agent of declining coastal discharge.
Ground-water levels within the surficial aquifer respond quickly to rainfall; annual wet- to dry-season fluctuations
within the aquifer can range from 2 to 8 ft. Wide seasonal variability in water levels can tend to obfuscate
longer-term patterns. To better illustrate the effect of canal drainage on the water table, long-term "average condition"
analyses were used to dampen storm and drought climatic events. During 1990-94, wet-season (October) and
dry-season (April) inland water levels within the surficial aquifer averaged 1 to 4 ft lower than the "average" water
levels experienced during 1940-44. However, coastal ground-water levels averaged 1 to 2 ft higher, thus reflecting
efforts to minimize coastal saltwater intrusion as previously described.
A broad zone of diffusion defines the saltwater interface, and its position is largely a function of lateral movement
of seawater from the ocean, seepage from tidal canals, and upconing of relict seawater. The predevelopment
balance between freshwater and saltwater was altered considerably following construction of conveyance and drainage
canals and municipal supply wells. Saltwater intrusion has been an issue of concern in southeastern Florida
since the early 1930s; its effects were most prominent in Miami-Dade and Broward Counties during the 1940s and
1950s, respectively. Canal drainage seems to have had the most widespread impact on saltwater intrusion, lowering
water levels within the surficial aquifer and contributing to landward movement of the interface
The pre-1900 Biscayne Bay coastal ecosystem and salinity was different than it is today as recorded in sediment
cores. Salinity increased in the early 1900s, remained stable until the early 1940s, and then increased above
levels recorded in the early 1900s. The marine fossil record shows that coastal vegetation changes that have
occurred. Sea grass became more abundant during the past century in the central bay and in the coastal Manatee Bay
region. Increasing epiphytal and macro-algal habitat dwelling organisms indicate a change in substrate conditions.
From the late 1980's to present time, salinity has decreased slightly in Manatee Bay, and field observations in this
region suggest the health of sea grasses is deteriorating.
Contact: Robert A. Renken, U.S. Geological Survey, 9100 N.W. 36th Street, Suite 107, Miami, Florida, 33157,
Phone: 305-717-5822, Fax 305-717-5801, rarenken@usgs.gov, Hydrology and Hydrological Modeling
62
Sheet Flow in Vegetated Wetlands of the Everglades
By Raymond W. Schaffranek and Ami L. Riscassi
U.S. Geological Survey, National Center, Reston, VA., USA
Little is known about the behavior
of shallow surface-water (sheet) flows in
and through the vegetated wetlands of the
Everglades, including the nature and
extent of the effects of water-management
controls. This project focuses on quantifying
flow velocities and investigating local
and regional forces both internal and
external that affect sheet flows in varied
vegetative communities of the southern
Everglades. The purpose of the project is
to determine the magnitude, direction, and
nature of flows in the wetlands of Everglades
National Park (ENP). Insight into
sheet flow behavior in wetlands is essential
to the development and use of models
to evaluate and compare restoration scenarios
for the Greater Everglades ecosystem.
Three stations were established in
1999 and 2000 to monitor flows and
related hydrologic conditions in differing
vegetative communities within Shark
River Slough (fig. 1). Monitoring station
SH1 was established in medium dense spikerush (Eleocharis) on the edge of a dense sawgrass (Cladium jamaicense)
stand; GS-203 was located in medium dense sawgrass at the edge of dense sawgrass; and GS-33 was established in
an area of patchy, medium dense spikerush with significant concentrations of submerged aquatic vegetation and periphyton.
All three stations were co-located with hydrologic stations to provide water level and rainfall data for flow
analyses. Additionally, GS-33 was located near a gage that provided meteorological data for use in flow analyses.
Flow velocities, water and air temperatures, and specific conductances were monitored continuously, typically
bi-hourly, at all sites. Flow velocities were measured at a fixed point in the water column using autonomous-recording,
acoustic Doppler velocity (ADV) meters. The ADV meter yields 3-D velocity components to a resolution of
0.1 mm/s with an accuracy of 1 percent of measured velocity (Sontek, 2001). Water and air temperatures were monitored
using thermistors spaced at 5-cm or 10-cm depth intervals above the plant litter layer. Specific conductances
were sampled at a fixed point in the water column near the plant litter layer. All data were collected, edited, and
filtered according to methods established and documented in Riscassi and Schaffranek (2002).
Vectors showing flow speeds and directions, in the horizontal plane relative to magnetic north, during the
2000-2001 wet season at GS-203 are shown in figure 2. Flow velocities were measured 10 cm above the plant litter
layer throughout the wet season. Water depths at the ADV probe (fig. 2) were fairly constant at approximately 40 cm
in late October through early November, but fell steadily in late November through mid-January (31 to 16 cm) except
for one 4-cm increase on December 9th due to a rain event. Early in the wet season when water levels were relatively
high, flow speed and direction averaged 0.62 cm/s and 235 degrees, respectively, with standard deviations of 0.06
cm/s and 7 degrees. As water levels declined in the later part of the wet season, the average flow velocity was slightly
lower at 0.53 cm/s with an identical average direction. However, there was more than a threefold increase in the
Figure 1. South Florida image showing stations GS-203, GS-33, and SH1.
63
range of measured flow speeds and directions with standard deviations increasing to 0.19 cm/s and 22 degrees,
respectively. Perturbations on the flow are considerably damped with increased flow depth as is clearly evidenced
by both the quality and range of measured flow velocities. Implications are that during times of higher water levels
more stable regional factors appear to drive flows more uniformly, however, as water levels fall, flow velocities at
the sample depth decrease and become more susceptible to dynamic forces imposed by wind and rainfall at the water
surface. Changes in the relation between the water depth and vegetation composition as water levels fall also appear
to alter the influences that vegetation has on vertical flow structure and, therefore, local sheet flow behavior.
Data sets similar to that for GS-203 illustrated in figure 2, collected at the other sites, have yielded additional
insight into the typical range of flow velocities found in particular vegetative communities and the dynamics of
velocities and sheet flow conditions within and between sites. Findings from all data collected and analyzed to date
at all sites indicate that dynamics in the magnitude, direction, and nature of sheet flows are attributed in varying
degrees to both internal and external effects, both locally- and regionally-driven. Local conditions include the type,
density, and physical attributes of vegetation in the area, as well as the presence and composition of submerged
aquatic vegetation and (or) periphyton. Upstream vegetation, water levels, water-surface slopes, landscape gradients,
proximity of airboat trails, presence of tree islands, and vegetative heterogeneity are regional factors that affect
sheet flow conditions. Dynamic forces such as storm and rainfall events also have variable effects on sheet flow
behavior.
REFERENCES
Riscassi, A.L., and Schaffranek, R.W., 2002, Flow velocity, water temperature and conductivity in Shark River
Slough, Everglades National Park, Florida: July 1999-August 2001, U.S. Geological Survey Open File Report
OFR-02-159, 32 p.
SonTek, 2001, SonTek ADV acoustic Doppler velocimeter technical documentation, SonTek, Inc., San Diego, CA,
202 p.
Contact: Schaffranek, Raymond W., U.S. Geological Survey, National Center MS 430, Reston, VA 20192, (703)
648-5891, FAX: (703) 648-5484, rws@usgs.gov
Figure 2. Water depths and flow velocities at station GS-203.
64
Applications of a Numerical Model for Simulation of Flow and Transport in
Connected Freshwater-Wetland and Coastal-Marine Ecosystems of the
Southern Everglades
By Raymond W. Schaffranek1, Harry L. Jenter1, Ami L. Riscassi1, Christian D. Langevin2, Eric D. Swain2, and
Melinda Wolfert2
1U.S. Geological Survey, National Center, Reston, VA., USA
2U.S. Geological Survey, Center for Water and Restoration Studies, Miami, FL., USA
Water-management agencies responsible for implementing the Comprehensive Everglades Restoration Plan
(CERP) need to ensure that hydrologic conditions are maintained in land-margin ecosystems of Everglades National
Park (ENP) that satisfy habitat requirements of endangered freshwater and estuarine species. The U.S. Geological
Survey has developed a hydrodynamic/transport model uniquely suited to simulate flow and salt flux through these
coupled surface- and ground-water ecosystems. A numerical algorithm was developed to synchronize surface-water
tidal-compatible time steps with ground-water stress periods and to assure mass conservation of simulated flux
quantities across the surface-/ground-water interface and land-surface boundary in the model (Swain and others,
2002). Hydraulic expressions, derived from hydrologic process studies in the Everglades, have been formulated to
link flow resistance (Lee and others, 2002), wind stress (Jenter and Duff, 1999), and evapotranspiration processes
(German, 2000) to vegetation properties and shallow flows typical of these low-gradient wetlands.
Two applications of the coupled model
have been made that are largely within the confines
of ENP (fig. 1). The Southern Inland and
Coastal Systems (SICS) model encompasses the
Taylor Slough wetlands, part of the C-111 drainage
basin, and sub-tidal embayments along the
northern coastline of Florida Bay. The Tides and
Inflows in the Mangrove Ecotone (TIME) model
encompasses the SICS model domain, Shark
River Slough, other western sloughs, and subtidal
embayments and tidal creeks along the
southwest Gulf coast. Measured surface-water
flow discharges, water levels, and salt concentrations
at tidal creeks (fig. 1) (Hittle and others,
2001); wetland water levels and flow velocities
(Tillis, 2001; Riscassi and Schaffranek, 2002);
and ground-water heads and salinities (Price,
2001) supplemented by sub-surface salinity maps
(Fitterman and Deszcz-Pan, 1998) and peat thickness
and hydraulic gradients (Harvey and others,
2000) were used for model calibration and verification.
Tide levels and salt concentrations along
the coast and discharges and water levels at
hydraulic structures (fig. 1) and road culverts constitute
the data used to drive the SICS and TIME simulations.
Flow exchanges between the surface- and ground-water systems simulated by the SICS model are presented
in figure 2 to demonstrate its capability and illustrate typical model output. Positive exchanges, expressed as averages
in cm/day for the 5-year simulation, indicate areas of recharge to the aquifer and negative values indicate areas
of discharge to the wetlands. Similar output is available that identifies salt fluxes between the surface- and groundwater
systems. Model output such as this is needed to fully evaluate the potential impact of restoration decisions
for the Greater Everglades on coastal land-margin ecosystems of ENP.
Figure 1. South Florida satellite image showing SICS and TIME
model domains.
65
REFERENCES
Fitterman, D.V., and Deszcz-Pan, M., 1998, Helicopter EM mapping of saltwater intrusion in ENP, Florida: Exploration
Geophysics, v. 29, p. 240-243.
German, E.R., 2000, Regional evaluation of evapotranspiration in the Everglades, USGS WRI 00-4217, 48 p.
Harvey, J.W., Jackson, J.M., Mooney, R.H., and Choi, J., 2000, Interaction between ground water and surface water
in Taylor Slough and vicinity, ENP, South Florida: Study methods and appendixes, USGS OFR 00-483, 67 p.
Hittle, C., Patino, E., and Zucker, M., 2001, Freshwater flow from estuarine creeks into northeastern Florida Bay.
USGS WRI 01-4164, 37 p.
Jenter, H.L., and Duff, M.P., 1999, Locally-forced wind effects on waters with emergent vegetation. Third International
Symposium on Ecohydraulics, 9 p.
Langevin, C.D., Swain, E.D., and Wolfert, M.A., 2002, Numerical simulation of integrated surface-water/groundwater
flow and solute transport in the southern Everglades, Florida. Second Federal Interagency Hydrologic
Modeling Conference, 12 p.
Lee, J.K., Roig, L.C., Jenter, H.L. and Visser, H.M., 2002, Vertically averaged flow resistance in free surface flow
through emergent vegetation at low Reynolds numbers. Submitted to Ecological Engineering.
Price, R.M., 2001. Geochemical determinations of groundwater flow in ENP. Ph.D. Dissertation, University of
Miami, Coral Gables, FL, 235 p.
Riscassi, A.L., and Schaffranek, R.W., 2002, Flow velocity, water temperature, and conductivity in Shark River
Slough, Everglades National Park, Florida: July 1999-August 2001. USGS OFR 02-159, 32 p.
Schaffranek, R.W., Jenter, H.L., and Riscassi, A.L., 2002, Overview of the "Tides and Inflows in the Mangroves of
the Everglades" (TIME) project of the U.S. Geological Survey's South Florida Ecosystem Program. Second
Federal Interagency Hydrologic Modeling Conference, 12 p.
Swain, E., Langevin, C., and Wolfert, M., 2002, Cooperative linkage of numerical models for coastal wetlands planning".
AWRA Spring Specialty Conference, May 13-15, 2002, pp. 375-380.
Tillis, G.M., 2001, Measuring Taylor Slough boundaries and internal flows, Everglades National Park, Florida.
USGS OFR 01-225, 16 p.
Contact: Schaffranek, Raymond W., U.S. Geological Survey, National Center MS 430, Reston, VA 20192, (703)
648-5891, FAX: (703) 648-5484, rws@usgs.gov
Figure 2. SICS model
output showing surface-/
ground-water exchange.
66
Fire Effects on Flow in Vegetated Wetlands of the Everglades
By Raymond W. Schaffranek, Ami L. Riscassi, Nancy B. Rybicki, and Alfonso V. Lombana
U.S. Geological Survey, National Center, Reston, VA., USA
Fires are a critical, but not well-understood, dynamic occurrence that randomly and variously affect the Everglades
ecosystem. However, fire impacts on subsequent surface-water (sheet) flow conditions have never been investigated.
The nature of sheet flow in burned areas has not been documented and compared to adjacent unburned areas
and any residual effects of fire on sheet flow behavior during vegetation recovery have not been assessed. The potential
impacts of fire disturbances on vegetation and sheet flow behavior should be recognized and considered in the
analyses of restoration scenarios being evaluated for the Greater Everglades ecosystem.
In the late afternoon of June 2, 2001, lightning ignited a fire about 10 km west of Pa-hay-okee Lookout Tower
in Everglades National Park (ENP). The fire was centered in a dense stand of sawgrass (Cladium jamaicense) at the
headwaters of Squawk Creek, a narrow tributary of Tarpon Bay, approximately 5 km south of the ENP P35 waterlevel
gage (fig. 1). On the afternoon of June 3, a rainstorm extinguished the fire but not before it burned approximately
202 hectares. Residual sawgrass plant stems, about 10 to 15 cm in length, remained above the top of the root
zone. The location of the burn area afforded the opportunity to quantify the effects of fire on sheet flow conditions
and to investigate flow behavior during vegetation recovery.
In August
2001, two flowmonitoring
stations
were established at
the southern extent
of the Squawk Creek
burn area (fig.1).
Located in burned
and unburned vegetation
approximately
280 m apart, each
station consisted of a
self-recording,
point-sampling,

acoustic Doppler
velocity (ADV)
meter. The ADV
meters were set to
record mean flow
velocities simultaneously
over two-minute sample intervals every 15 minutes. Analyses of initial continuous ADV data revealed periods
during which flow velocities in the burn area were on the order of two times faster than in the unburned
vegetation. During intermittent site visits, vertical velocity profiling was conducted at 3-cm depth intervals to document
the water-column flow structure (fig. 2a) in conjunction with 10-cm incremental determination of vegetation
volume (fig. 2b). Data from eight sets of vertical velocity profiles covering a depth range of 22 to 42 cm revealed
similar two-fold velocity magnitude differences between the sites, particularly in the upper part of the water column
(fig. 2a).
During site visits, vegetation types and densities immediately upstream and within the flow paths to the ADV
meters were assessed by measuring vegetation properties in selected areas of similar composition in the local vicinity
of, but removed from interference with, the ADV probes. Initial vegetation differences, observed in August 2001,
included lower plant heights and less biomass in the burn area as implied by the smaller number of leaves per
Figure 1. Satellite image of Squawk Creek burn area.
67
sawgrass culm than in the unburned vegetation. During June and October 2002, emergent stem densities and vegetation
volumes (expressed as a percentage of the water column volume) were measured at 10-cm depth intervals
in three 0.04 m2 quadrats at each site. Additionally, the diameters of all plant stems in the top 10 cm of the water
column were measured to calculate stem spacing near the water surface. Plant heights were measured and qualitative
observations of vegetation type and density also were recorded. In June 2002, the dominant plant species was
sawgrass at both sites with lower plant heights measured in the quadrats and observed throughout the burn area.
Vegetation volume within the 41-cm water column was less at the burn site (0.54 vs. 0.69 percent) (fig. 2b) and stem
spacing near the water surface was greater (3.4 vs. 2.5 cm). In October 2002, sawgrass remained the dominant plant
species at both sites with lower plant heights again measured in the quadrats and observed throughout the burn area.
However, significant quantities of periphyton and muskgrass (Chara sp.) also were found in the burn area. Both
vegetation volume within the 32-cm water column, which included the periphyton and chara, (1.28 vs. 1.14 percent)
and stem spacing near the water surface (5.9 vs. 3.6 cm) were greater at the burn site.
Implications from measured, vertical velocity profiles (fig. 2a) are that remnant dead plant stems continue to
impart equivalent, pre-fire shear-resistance effects on flow in the lower part of the water column. Although flow
depths at the two monitoring stations were similar during all site visits, unit mass flux through the upper part of the
water column at the burn site was computed to be equivalently greater than at the unburned site due to the greater
flow velocities near the water surface. Reduced plant heights above the water surface as well as greater stem spacing
just below the water surface appear to yield diminished sheltering effects from wind and reduced shear-resistance
effects from vegetation thus contributing to the greater flow velocities in the upper part of the water column at the
burn site.
Contact: Schaffranek, Raymond W., U.S. Geological Survey, National Center MS 430, Reston, VA 20192, (703)
648-5891, FAX: (703) 648-5484,rws@usgs.gov
Figure 2. Velocity (a) and vegetation volume (b) measured at the burned (light gray) and unburned
(dark gray) sites in June 2002.
68
Developing a Computational Technique for Modeling Flow and Transport in a
Density-Dependent Coastal Wetland/Aquifer System
By Eric Swain, Christian Langevin, and Melinda Wolfert
U.S. Geological Survey Center for Water and Restoration Studies, Miami, FL., USA
The USGS Center for Water and Restorations Studies has continued its numerical modeling in the coastal
regions of the southern Everglades. A combined model referred to as Flow and Transport in a Linked Overland-Aquifer
Density Dependent System (FTLOADDS) is the latest step in an ongoing effort to develop and refine the numerical
representation of flow and transport in this area. FTLOADDS is a numerical framework that includes and
coordinates execution of the SWIFT2D hydrodynamic surface-water model and the SEAWAT ground-water model.
The SWIFT2D and SEAWAT models are designed to account for salinity transport in each regime, surface-water and
ground-water flow, and the associated affects of density variations on flow. The FTLOADDS coupling passes the
necessary information between the two models. This involves passing aquifer heads and ground-water salinity from
SEAWAT to SWIFT2D and computed leakage volumes and salt fluxes from SWIFT2D to SEAWAT.
The original modeling application is referred to as the Southern Inland and Coastal Systems (SICS) model. As
part of this application, the SWIFT2D model was used to represent the surface-water regime and modified to account
for the effects of rainfall, evapotranspiration, and other factors. Model setup utilized numerous field studies to define
the input parameters for frictional resistance, evapotranspiration, land elevation, and flow calibration. Approximate
ground-water boundaries were defined, but a more accurate scheme was needed. Previous coupled models represent
the water-level/flow relation in both the surface-water and ground-water regimes to various degrees of complexity.
However, to represent the hydrologic conditions in a coastal area, such as the northeastern shoreline of Florida Bay,
salinity transport must be considered, because the induced density variations affect ground-water flow, surface-water
flow, and the leakage rate between the two regimes. Consequently, transport must also be represented in these flow
computations. The ideal candidate for simulating the ground-water regime is the SEAWAT model, which links the
well-known MODFLOW three-dimensional ground-water flow model with the MT3DMS transport code. The
FTLOADDS coupling allows SWIFT2D and SEAWAT to retain as much of their original form as possible, because
only relevant information is exchanged.
A primary requirement of any simulation is to conserve mass. In FTLOADDS, the amount of water and salt
passed from one model must equal the amount received by the other, and be computed by the most valid technique
known. To conserve mass between the models, their timesteps must be reconciled. Given the hydrodynamic nature
of the surface-water computation, the surface-water timesteps are almost always much shorter than the ground-water
timesteps. As in other models, the most logical place for the computation of leakage is in the shorter timestep surface-
water model, SWIFT2D. A subroutine was created for SWIFT2D that computes a leakage volume for each
timestep based on ground-water and surface-water head using the equation:
Qleak = Cleak Acell (Hgw - Heq + D),
where
Qleak =leakage flow (L3/T),
Cleak =leakage coefficient (1/T),
Acell =surface area of model cell (L2),
Hgw =freshwater equivalent aquifer head (L),
Hsw =freshwater equivalent surface-water head (L),
D =(Zcell-Zelev) (ave-f) / f,
Zcell =elevation of center of aquifer cell (L),
69
Zelev =land elevation (L),
ave =average density of ground water and surface water (M/L3), and
f =density of fresh water (M/L3).
Within this equation, effects of density variation on head gradient are accounted for in the subroutine when
calculating leakage. The leakage flow is multiplied by the timestep length to obtain a leakage volume, which is
added or subtracted from the surface-water cell. The leakage volumes for each surface-water timestep are summed,
and sent back to the ground-water model to be added or subtracted from the corresponding aquifer cell.
The net salt flux between surface water and ground water must also be taken into account. When the leakage
volume is computed for a surface-water timestep, salt flux is computed based on flow direction. If the flow is upward
from ground to surface water, the salt mass flux is calculated by multiplying leakage volume and ground-water salinity.
The calculated salt mass is added to the surface-water salt mass in the SWIFT2D transport subroutine. If flow
is downward from surface to ground water, the salt mass flux is calculated as the product of leakage volume and
surface-water salinity. The total salt mass flux is summed for the surface-water timesteps and divided by the total
leakage volume. This gives an equivalent salinity concentration for the total leakage over the ground-water timestep.
Whichever direction the leakage is moving, the computed equivalent salinity is used in SEAWAT as the concentration
of the water added or removed from the aquifer as leakage. This concentration only reflects the proper salt mass
exchanged; If there are multiple reversals in leakage direction during the surface-water timesteps, and the salinity
of the ground water and surface water are very different, the equivalent concentration can be very large. If the direction
of the net leakage water volume is opposite than the direction of net salt flux, the equivalent concentration computed
can be negative.
The flowchart of FTLOADDS is shown in
figure 1. For each ground-water timestep,
SWIFT2D is called first, using the final groundwater
head from the previous timestep to compute
leakage. Computed leakage and salinity is passed to
SEAWAT for the ground-water timestep. A comparison
of measured salinity values at McCormick
Creek, a coastal creek in the SICS study area, with
values computed in SWIFT2D alone (no ground
water), and in FTLOADDS (with ground water) is
shown in figure 2. The coupling to the SEAWAT
model within FTLOADDS has resulted in a marked
improvement in the ability to represent salinity.
The FTLOADDS coupled SWIFT2D/SEAWAT
model has greatly improved the ability to
model coastal wetland scenarios for restoration science.
Using this continuously improving tool, water
resource managers will be able to answer the critical
restoration questions for the Everglades and
Florida Bay.
Figure 1. FTLOADDS flowchart.
70
Contact: Eric Swain, U.S. Geological Survey, 9100 NW 36th St. Ste. 107, Miami Fl, 33178, Phone: 305-717-
5825, Fax: 305-717-5801, edswain@usgs.gov,
Date
Salinity,
parts
per
thousand
Figure 2. Salinity at McCormick Creek.
71
Everglades Tree-Island Response
to Hydrologic Change
By Debra A. Willard1, William H. Orem1,
Christopher Bernhardt1, and Charles W.
Holmes2
1U.S. Geological Survey, Reston, VA., USA
2USGS, Center for Coastal and Watershed
Studies, St. Petersburg, FL., USA
The stability of Everglades tree islands is
influenced strongly by hydrologic parameters,
including water depth, hydroperiod, and seasonality
of flow. Based on analysis of pollen from
sediment cores, we have reconstructed changes
in vegetation and tree island size in response to
hydrologic changes of the last century.
Transects of sediment cores were collected
on 29 tree islands throughout the Everglades:
five in Arthur R. Marshall Loxahatchee
National Wildlife Refuge, two in Water Conservation
(WCA) 2A, eleven in WCA 3A, two in
WCA 3B, four in Shark River Slough, and five
in Taylor Slough, Florida (fig. 1). The tree
islands are geologically old features, with
mature tree-islands present in the northern and
southern Everglades for at least 2,000 and 1,000
years, respectively. Even before classical treeisland
formation, sites now occupied by treeisland
heads were drier than surrounding
marshes and sloughs; this finding is consistent
with the hypothesis that topographic highs in the
underlying limestone were favorable sites for
tree-island development.
The response of tree-island vegetation to
20th century hydrologic changes varied with
location within the Greater Everglades ecosystem.
On strand islands in Loxahatchee NWR,
slight increases in abundance of shrubby taxa
(holly, wax myrtle) and weedy species occurred
in the early 20th century. After 1960, pollen of
trees and shrubs increased at least fivefold,
resulting in the dominance of holly and bays
now seen on these islands. On a "drowned" tree
island in WCA 2A, the abundance of tree-island taxa decreased greatly whereas water lily pollen increased during
the 1960's; this finding is consistent with sustained flooding after construction of the Central & South Florida
(C&SF) Project. The subsequent replacement of waterlily by sawgrass in the 1970's reflects altered water management
practices, which incorporated periodic drawdowns into the management scheme. Overall, the vegetational
pattern indicates the loss of tree-island vegetation after sustained high water for 10-15 years.
72
Sites in WCA 3A and 3B have insufficient sedimentation rates to resolve 20th century changes; however,
assemblages from sediments deposited during the last 500 years show little change.
On and around tree islands in Shark River Slough in Everglades National Park, pollen of marsh taxa disappeared
almost entirely around 1930, when initial canal and road construction was completed. After 1960, replacement
of taxa characteristic of relatively wet conditions with tree-island taxa suggests that the tree island head
expanded southward as fresh-water flow was reduced to Shark River Slough.
Our results indicate that tree-island response to future hydrologic changes will not be uniform within the
Greater Everglades ecosystem. Restoration pre-20th century hydroperiods and water depths to Shark River Slough
is likely to result in a decrease in size of tree-island heads, whereas drowned tree islands in WCA 2A may see a gradual
increase in size and restoration of previous tree-island plant communities. The distinctive composition of Loxahatchee
strand islands also is a recent vegetational feature, and changes in biodiversity at those sites are likely as
hydrology is altered. Our results highlight the variability of tree-island composition within the Everglades and indicate
that no single performance measure should be devised to evaluate the success of tree-island restoration throughout
the Everglades.
Contact: Debra A. Willard, U.S. Geological Survey, 926A National Center, Reston, VA 20192, Phone: 703-648-
5320, Fax: 703-648-6953, dwillard@usgs.gov, Oral, Hydrology and Hydrological Modeling
73
Using Hydrologic Correlation as a Tool to Estimate Flow at Non-Instrumented
Estuarine Creeks in Northeastern Florida Bay
By Mark Zucker
U.S. Geological Survey, Center for Water and Restoration Studies, Miami, FL., USA
Understanding the quantity, timing, and distribution of freshwater flow to northeastern Florida Bay and other
coastal environments is critical for restoring south Florida estuaries. A coastal monitoring network was established
in 1996 by the U.S. Geological Survey to provide flow at five estuarine creeks in northeastern Florida Bay. Four
additional estuarine creeks were not instrumented and discharge was estimated using hydrologic correlation. This
technique assumes that flow from streams near each other correlate because of similarities in geomorphology, rainfall,
and distance from source waters. To verify this technique, East Highway Creek, Oregon Creek, and three creeks
in Joe Bay were instrumented in July 2001 to quantify the accuracy of the estimated discharge at non-instrumented
sites. A test case is presented here for East Highway Creek comparing computed and estimated discharge.
Initially, discharge was estimated at East Highway Creek using hydrologic correlation. Diascharge measured
using Acoustic Doppler Current Profiler (ADCP) at East Highway Creek was related to the instantaneous discharge
computed using the calibrated velocity meter at West Highway Creek. The equation generated from regression analysis
provided the means to estimate discharge over time using computed discharge from West Highway Creek as
the explanatory variable. To compute discharge at East Highway Creek, continuous velocity and stage data were
collected using an Acoustic Doppler Velocity Meter (ADVM) with an upward acoustic stage sensor. The ADVM
velocities were calibrated to the mean channel velocity over a range of velocity conditions using an ADCP. A more
detailed discussion of acoustic methods and discharge estimation techniques is provided in Hittle and others (2001).
Differences in discharge volume, wet season discharge volume, and dry season discharge volume were evaluated
for the period of record. From February 10, 2002 to September 30, 2002, computed and estimated discharge
volume equaled 17,277 acre-feet (mean = 37.5 ft3/s) and 14,788 acre-feet (mean = 32.1 ft3/s), respectively. During
the 233-day comparison, the estimated discharge volume was 14.4 percent lower than the computed discharge volume.
An evaluation of seasonal discharge volume indicated that dry season estimates were less accurate than wetseason
estimates. Computed and estimated dry season flows equaled 4,316 acre-feet (mean = 19.6 ft3/s) and 853
acre-feet (mean = 3.9 ft3/s), respectively. During the 111-day dry season comparison, the estimated discharge volume
was 80 percent lower than the computed discharge volume. Computed and estimated wet season discharge volume
equaled 12,961 acre-feet (mean = 53.7 ft3/s) and 13,935 acre-feet (mean = 57.7 ft3/s), respectively. During the
122-day wet season comparison, the estimated discharge volume was 7.5 percent greater than the computed discharge
volume. Since the regression equation used to estimate discharge at East Highway Creek from 1996 to 2001 was similar
to the regression equation used in this analysis, it is probable that these findings apply to prior estimates (fig. 1).
Figure 1. Scatterplot
of computed
and estimated daily
mean discharge at
East Highway
Creek including the
line of equality.
74
Although wet season discharges were slightly overestimated at East Highway Creek, the discharge trend was
reproduced (fig. 2). Dry season discharges were underestimated at East Highway Creek and primarily represent
saline exchanges between northeastern Florida Bay and the estuarine creeks, rather than freshwater runoff. However,
the exchange of saline water towards upstream wetlands, to ground-water systems, and the impact on local ecology
may be important. Concerns over the accuracy of the computed East Highway discharge record is considered critical
because only five flow conditions have been measured. Improvements to the computed discharge record are possible
with additional ADCP measurements at low flow conditions.
REFERENCES
Hittle, C.D., Patino, Eduardo., and Zucker, Mark, 2001, Freshwater Flow from Estuarine Creeks into Northeastern
Florida Bay: U.S. Geological Survey Water Resources Investigation Report 01-4164, 32 p.
Contact: Mark Zucker, U.S. Geological Survey, 9100 NW 36 St., Ste. 107 Miami, FL, 33178, Phone: 305-717-
5852, Fax: 305-717-5801, mzucker@usgs.gov
Figure 2. Time-series graph of computed and estimated daily mean discharge at East Highway
Creek.
76
Contents
Section II: Get the Water Quality Right
Interactions of Dissolved Organic Matter with Mercury in the Florida Everglades
By George Aiken . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Using Nitrogen and Carbon Isotopes to Explain Mercury Variability in Largemouth Bass
By Bryan E. Bemis, and Carol Kendall, Ted Lange, and Linda Campbell . . . . . . . . . . . . . . . . . . . 80
Isotopic Evidence for Spatial and Temporal Changes in Everglades Food Web Structure
By Bryan E. Bemis, Carol Kendall, and Scott D. Wankel, Ted Lange, and
David P. Krabbenhoft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Origins and Isotopic Characteristics of Dissolved Nitrogen Species in Ground Water,
Imported Domestic Water, and Wastewater in the Florida Keys
By John Karl Bhlke, Eugene Shinn, Christopher Reich, and Ann Tihansky . . . . . . . . . . . . . . . . . . . . . . 84
Salinity History of Florida Bay: An Evaluation of Methods, Trends, and Causes
By T. M. Cronin, L. Wingard, J. H. Murray, G. Dwyer, and Mike Robblee. . . . . . . . . . . . . . . . . . . 85
Estimating Water Quality Along the Southwest Florida Coast for Hydrologic Models Using
Helicopter Electromagnetic Surveys
By David V. Fitterman and Maria Deszcz-Pan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Atrazine Exposure and the Occurrence of Reproductive Abnormalities in Field Caught
Bufo marinus From South Florida
By Timothy S. Gross, Marisol Sepulveda, J.A. Carr, J.P. Giesy,
A.J. Hosmer, R.J. Kendall, K, Solomon, E.E. Smith, and G. Van Der Kraak. . . . . . . . . . . . . 90
Characterization of Solute and Fine-Particle Transport in Shark Slough, Everglades National
Park by a Tracer Release in the Florida International University (FIU) In Situ Flumes
By Judson W. Harvey, James E. Saiers, James M. Krest, Steven Mylon, Jessica T. Newlin,
Christine Taylor, and Evelyn E. Gaiser. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Thermally-Driven Vertical Mixing in the Everglades
By Harry L. Jenter, Raymond W. Schaffranek, and Thomas J. Smith, III . . . . . . . . . . . . . . . . . . . . 93
Is Food Web Structure a Main Control on Mercury Concentrations in Fish in the Everglades?
By Carol Kendall, Bryan E. Bemis, Joel Trexler, Ted Lange, Q. Jerry Stober. . . . . . . . . . . . . . . . . 96
Biogeochemical and Hydrologic Controls on Food Web Structure in the Everglades
By Carol Kendall, Bryan E. Bemis, and Scott D. Wankel, Ted Lange, and
David P. Krabbenhoft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
77
Unraveling the Complexities of Mercury Methylation in the Everglades: The Use of Mesocosms
to Test the Effects of "New" Mercury, Sulfate, Phosphate, and Dissolved Organic Carbon
By David P. Krabbenhoft, William H. Orem, George Aiken, and Cynthia Gilmour . . . . . . . . . . . . 100
Water Quality in Big Cypress National Preserve and Everglades National Park ---Trends and
Spatial Characteristics of Selected Constituents
By Benjamin F. McPherson, Ronald L. Miller, Robert Sobczak, and Christine Bates. . . . . . . . . . . 102
Whole-Ecosystem Phosphorus Budgets for Freshwater Everglades Wetlands
By Gregory B. Noe and Daniel L. Childers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Sulfur Contamination and Geochemistry of the Everglades
By William Orem, Harry Lerch, Anne Bates, Margo Corum, and Marisa Beck . . . . . . . . . . . . . . . 106
Source Identification of Florida Bay's Methylmercury Problem: Mainland Runoff versus
Atmospheric Deposition and In Situ Production.
By Darren Rumbold, Larry Fink, Nicole Niemeyer, Angela Drummond, David Evans,
David Krabbenhoft, and Mark Olson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Effects of Microhabitats on Stable Isotopic Composition of Biota in the Florida Everglades
By Scott D. Wankel, and Carol Kendall, Paul McCormick, and Robert Shuford . . . . . . . . . . . . . . 111
Spatial and Temporal Patterns in Isotopic Composition of Aquatic Organisms at Everglades
Nutrient Removal Project Sites
By Scott D. Wankel, and Carol Kendall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
An Evaluation of Contaminant Exposures and Potential Effects on Health and Endocrine Status
for Alligators in the Greater Everglades Ecosystem
By Jon J. Wiebe, Ken Rice, Carla M. Wieser, and Timothy S. Gross . . . . . . . . . . . . . . . . . . . . . . . 115
An Evaluation of Contaminant Exposures and Potential Effects on Health and Endocrine Status for
Largemouth Bass in the Greater Everglades Ecosystem
By Carla M. Wieser, Jon J. Wiebe, D. Shane Ruessler, Timothy S. Gross, and Ted Lange . . . . . . 117
Long-Term Water-Quality and Streamflow Monitoring in the Lake Okeechobee Watershed
By Molly S. Wood and Pamela A. Telis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Surface Water Geochemical Surveys in Florida Bay
By Kimberly Yates, Iuri Herzfeld, Nathan Smiley, and Chris Dufore . . . . . . . . . . . . . . . . . . . . . . . 121
78
Interactions of Dissolved Organic Matter with Mercury in the Florida Everglades
By George Aiken
U.S. Geological Survey, Boulder, CO., USA
Interactions of mercury (Hg) with dissolved organic matter (DOM) are hypothesized to play important roles
in controlling the reactivity, bioavailability, and transport of Hg in the Everglades. Little is known, however, about
how Hg interacts with DOM or how strong these interactions are. The questions being addressed by this research
are: 1) By what mechanisms and how strongly does Hg interact with DOM, and 2) What role do these mechanisms
play in controlling the effects that Hg has on organisms. This research is driven by the hypothesis that the chemistry
and structural characteristics of the DOM in the Everglades strongly influence the processes that control Hg cycling
and bioavailability in the environment. A combined field/laboratory approach designed to characterize DOM in the
Everglades and to relate the structural characteristics of the DOM to its reactivity with Hg is being used to test this
hypothesis.
Most of the DOM in the Everglades originates from the degradation and leaching of organic detritus derived
from the algae, bacteria, and macrophytes living within the wetland environment. In addition, organic matter is
transported to the Water Conservation Areas of the Everglades in the canals that drain the Everglades Agricultural
Area. Areas strongly influenced by the Everglades Agricultural Area had higher dissolved organic carbon (DOC)
concentrations, had a greater amount of hydrophobic acids and hydrophobic neutrals, and the DOM was more aromatic
than samples collected from less impacted areas. Pore waters were found to contain greater DOC concentrations
than overlying surface waters, with the highest DOC concentrations in pore waters from the more eutrophic
study areas. DOC concentrations and the contributions of aromatic organic molecules to the pool of molecules comprising
the DOM were lower in those areas with higher concentrations of methylmercury. The amount and nature
of DOM in the Everglades was found to be dependent on the dominant vegetation types, hydroperiod, interactions
of surface water with peat pore waters, and interactions with canal water.
To better define the nature and strength of interactions between DOM and Hg, the hydrophobic acid fraction
(HPOA), hydrophilic acid fraction (HPIA), hydrophobic neutral fraction (HPON), fulvic acid, and humic acid were
isolated from various surface waters in the Florida Everglades. Using these isolates, Hg-DOM binding constants
were determined over a wide range of Hg(II) to DOM concentration ratios by means of a modified equilibrium dialysis
ligand exchange method. Very strong interactions (KDOM' = 1023.20.5 L kg-1 at pH = 7.0 and I = 0.1), indicative
of Hg-thiol bonds, were observed at Hg(II)/DOM ratios below approximately 1 g Hg(II) per mg DOM. Hg(II)/
DOM ratios above approximately 10 g Hg(II) per mg DOM gave much lower KDOM' values (1010.70.5 L kg-1 at
pH = 4.9 to 5.6 and I = 0.1), consistent with Hg(II) binding mainly to oxygen functional groups. These results suggest
that the binding of Hg(II) to DOM under natural conditions [very low Hg(II)/DOM ratios ranging from 0.01 to 10
ng of Hg/mg of DOM] is controlled by a small fraction of DOM molecules containing reactive thiol functional
groups. Similar strong Hg-DOM binding constants were obtained in studies of the partitioning of Hg(II) between
DOM and particulate organic matter (POM). In this work, the HPOA isolate from F1, a northern, eutrophic site, was
more effective at competing with POM for Hg(II) than the sample from 2BS, a more pristine site.
Under most environmental conditions, therefore, it can be expected that only the strongest DOM sites will
interact with Hg(II). In the case of fully oxygenated Everglades water (sulfide-free), the binding of Hg(II) by DOM
should dominate Everglades dissolved inorganic mercury speciation. However, even for the case of strong binding
sites (KDOM' = 1023.20.5), Hg-sulfide complexes are predicted to dominate dissolved inorganic Hg solution speciation
in the presence of small concentrations (nanomolar) of sulfide because of the strong sulfide affinity for Hg.
Where measurable total sulfide concentrations are present in the surface water and pore water of the Everglades,
therefore, Hg-sulfide complexes likely predominate.
A chemical equilibrium approach does not completely explain the behavior of Hg(II) in the presence of DOM,
however. For instance, chemical speciation models indicate that pore waters in the Everglades, especially in the
eutrophic areas, are supersaturated with respect to cinnabar (mercuric sulfide, HgS); however, no cinnabar has been
found in the peat soils of the Everglades. Therefore, to better define the geochemical interactions between DOC,
79
Hg(II) and sulfide, experiments were designed using the organic matter isolates and whole water samples to study
interactions of DOC with Hg in cinnabar dissolution and precipitation experiments. Cinnabar is a relatively insoluble
solid (log Ksp = -52.4) under most environmental conditions, but, in the presence of DOM, particularly the humic
fractions (HPOA, humic acid, and fulvic acid), a significant amount of Hg (up to 1.7 M/mg C) was released from
cinnabar over a period of seven days at pH 6.0. The amount of Hg dissolved by various fractions of organic matter
followed the order: humic acid > HPOA  fulvic acid >> HPIA. The hydrophobic and hydrophilic neutral fractions
dissolved insignificant quantities of Hg from cinnabar. Model compounds such as cysteine and thioglycolic acid dissolved
small amounts of Hg from the cinnabar surface, while other model compounds such as acetate, citrate, and
EDTA dissolved no detectable Hg. There was a positive correlation (R2 = 0.84) between the amount of Hg released
and the aromatic carbon content of the DOM.
Precipitation and aggregation of metacinnabar (black HgS) was inhibited in the presence of low concentrations
of humic fractions of DOM isolated from the Florida Everglades. At low Hg concentrations [5x10-8 molar
(M)], DOM prevented the precipitation of metacinnabar. At moderate Hg concentrations (5x10-5 M), DOM inhibited
the aggregation of colloidal metacinnabar (Hg passed through a 0.1 m filter, but was removed by centrifugation).
At Hg concentrations greater than 5x10-4 M, mercury formed solid metacinnabar particles that were removed
from solution by a 0.1 m filter. Organic matter rich in aromatic moieties was preferentially removed with the solid.
HPOA, humic and fulvic acids inhibited aggregation better than HPIA. Inhibition of metacinnabar precipitation
appears to be the result of strong DOM-Hg binding. Prevention of aggregation of colloidal particles appears to be
caused by adsorption of DOM and electrostatic repulsion.
A general observation that can be drawn from all of our studies of Hg(II)-DOM interactions is that the amount
of dissolved Hg(II) present in a given system is greater in the presence of reactive DOM. This is significant because
many of the processes (both abiotic and biotic) involved in Hg cycling in the Everglades are hypothesized to be
strongly dependent on the concentration of total dissolved Hg. Preliminary results of ongoing wetland enclosure
(mesocosm) experiments in the Everglades are consistent with this hypothesis. In these experiments, mesocosms
amended with the most reactive organic matter from the Everglades, the HPOA fraction of the DOM obtained from
site F1, contained higher concentrations of total dissolved Hg than control enclosures containing less reactive, native
DOM. The DOM amended enclosures also were found to have enhanced methylation (both biotic and abiotic pathways)
of Hg(II) and enhanced photo-oxidation of methylmercury relative to the controls. Future research will
address the mechanisms by which DOM influences these important reactions.
Contact: Aiken, George, U.S. Geological Survey, 3215 Marine Street, Boulder, CO, 80303, Phone: 303-541-
3036, FAX: 303-447-2505, graiken@usgs.gov
80
Using Nitrogen and Carbon Isotopes to Explain Mercury Variability in
Largemouth Bass
By Bryan E. Bemis1, Carol Kendall1, Ted Lange2, and Linda Campbell3
1U.S. Geological Survey, Menlo Park, CA., USA
2Florida Fish and Wildlife Conservation Commission, Eustis, FL., USA
3National Water Research Institute, Environment Canada, Burlington, ONT, Canada
We are investigating whether variations in the nitrogen (15N) and carbon (13C) isotopic composition of
largemouth bass (Micropterus salmoides) tissue can explain a significant amount of the variation in mercury concentrations
in this top predator fish. The 15N and 13C values of tissues are integrated measures of diet assimilated
over time, with consumers enriched in the heavier isotope relative to their diet. This stepwise isotopic increase
toward higher trophic positions has been used for decades to reconstruct relative food web structure in a variety of
ecosystems, with a focus on intercomparison of northern temperate lakes. Relatively few studies have applied this
technique to wetlands.
One of the goals of restoration efforts in the Everglades is to better understand the sources and distribution of
mercury in the food web, in order to develop management strategies to minimize mercury contamination of the ecosystem.
Because bioavailable methyl mercury is retained in tissues of Everglades biota, successive trophic levels
within the food web accumulate higher mercury levels. Mercury concentrations in top predators such as the sport
fish largemouth bass typically exceed EPA safety limits. Isotopic estimates of diet and energy flow within the food
web are expected to provide potential information about the sources and pathways of mercury bioaccumulation in
Everglades marshes.
Stepwise multiple regression is used to identify parameters that explain a significant amount of variance in
largemouth bass total mercury (THg) at 12 marsh and canal sites throughout the Everglades representing a variety
of hydropatterns (extremely short to long). The five predictor variables include: latitude of collection site (i.e., spatial
influence), collection year (1996-1998; i.e., temporal influence), total fish length (a size estimate), 15N, and
13C. In addition, we repeat the regressions for individual sites to identify locally important influences.
Of the twelve marsh and canal sites we are investigating, seven have
complete data for the years 1996-1998. When data for these seven sites
are combined, spatial differences (i.e., latitude) explain the most THg
variance in largemouth bass tissue (approximately 38 percent), which is
consistent with locally differing influences (Kendall et al., 2001). Fish
length explains approximately an additional 15 percent of THg variance,
with relatively minor contributions by 15N (approximately 5 percent)
and interannual differences (approximately 3 percent). 13C is not a significant
influence at this landscape scale. The spatial differences may
reflect differences in hydropattern, available methyl mercury concentrations
(Gilmour et al., 1998), or other environmental variables such as dissolved
organic carbon (DOC) concentration or water pH. Future addition
of these data to the regression models may help identify the sources of the
intersite differences.
When the data are analyzed separately for the twelve collection
sites, fish length explains the most THg variance (approximately 34-77
percent) for ten of the twelve sites (fig. 1). Length is the second most
important predictor at another site, explaining ~11% of THg variations.
The importance of fish size on THg found here is consistent with the
results of the site-grouped analysis in this study, as well as previous studies
(Lange et al., 1999); larger fish are typically older and have had more time to accumulate mercury in their tissues.
Figure 1. Correlation of the log10 of total
mercury concentration (THg as g/g ww)
with the square root of total fish length (TL
in mm) for largemouth bass at
Loxahatchee. Symbols represent
individual fish.
81
In contrast with the findings for the site-grouped analysis, the
site-specific analyses indicate that 15N, 13C, and temporal variations
can be locally important predictors of THg in largemouth bass (fig. 2).
15N is a significant predictor of THg variation at four sites (approximately
16-27 percent variance explained), and explains the most variance
in two of these (likely an indicator of relative trophic level
differences among largemouth bass within a site). 13C is a significant
predictor of THg at three sites. At one of these sites, 13C is the best
predictor of THg variation (approximately 23 percent), whereas at the
other two it explains only about 2-6 percent of THg variation. The
small expected consumer-diet enrichment of 13C (compared to 15N)
and large 13C spatial variations (Kendall et al., 2001) suggest that
13C is tracking something other than trophic position (perhaps microenvironmental
variations). Interannual variations are a significant
influence at ten of the twelve sites, where they explain approximately
5-31percent of variation in THg. The importance of these predictor
variables in explaining largemouth bass mercury does not appear to
correlate with marsh versus canal sites.
In summary, 15N and 13C can provide locally important information
about mercury variations in largemouth bass tissue in the Everglades.
However, fish size and temporal changes in the ecosystem are typically much more important influences
that may mask information that could contribute to better understanding the transfer of mercury within food webs.
REFERENCES
Gilmour, C.C. et al., 1998. Methylmercury concentrations and production rates across a trophic gradient in the
northern Everglades. Biogeochemistry, 40: 327-345.
Kendall, C. et al., 2001. Use of Stable Isotopes for Determining Foodwebs and Explaining Spatial Variability in Hg
in the Everglades, Proceedings of the Workshop on the Fate, Transport, and Transformation of Mercury in
Aquatic and Terrestrial Environments, West Palm Beach, Florida.
Lange, T.R., Richard, D.A. and Royals, H.E., 1999. Trophic Relationships of Mercury Bioaccumulation in Fish
from the Florida Everglades, Florida Department of Environmental Protection, Florida Game and Fresh Water
Fish Commission, Fisheries Research Laboratory.
Contact: Bryan, Bemis, U.S. Geological Survey, 345 Middlefield Road, MS 434, Menlo Park, CA, 94025,
Phone: 650-329-5603, Fax: 650-329-5590, bebemis@usgs.gov
Figure 2. Correlation of the log10 of
total mercury concentration (THg as g/g
ww) with the log10 of 15N () for
largemouth bass at Loxahatchee.
Symbols represent individual fish.
82
Isotopic Evidence for Spatial and Temporal Changes in
Everglades Food Web Structure
By Bryan E. Bemis1, Carol Kendall1, Scott D. Wankel1, Ted Lange2, and David P. Krabbenhoft3
1U.S. Geological Survey, Menlo Park, CA., USA
2Florida Fish and Wildlife Conservation Commission, Eustis, FL., USA
3U.S. Geological Survey, Madison, WI., USA
Trophic structure within a food web is often implicated as a control on how mercury is distributed and transferred
throughout an aquatic ecosystem. Methyl mercury bioaccumulates in the food web, with higher concentrations
typically found in tissues of organisms that occupy higher trophic positions. Reducing mercury contamination
in the ecosystem is a major focus of restoration efforts in the Everglades. Therefore, knowledge about Everglades
trophic structure is critical for making management decisions about how to effectively minimize mercury concentrations
in biota.
The nitrogen (15N) and carbon (13C) isotopic composition of tissues is a tracer of diet that can be used in
many aquatic ecosystems to distinguish the relative trophic positions of organisms. We use measured 15N and 13C
values of Everglades biota to investigate spatial and temporal variability in food web structure. Plants, invertebrates,
and fish were collected from 16 well-studied ACME (Aquatic Cycling of Mercury in the Everglades) sites during
1995-1999 as part of a collaboration between the USGS and the Florida Fish and Wildlife Conservation Commission
(FFWCC). These collections provided more than 350 site-date sampling groups.
Within this massive data set, we focus on several sites with multiple collection periods during 1996-1998 that
have a sufficient number of organisms to investigate spatial and temporal differences in food web structure. The
organisms analyzed for tissue 15N and 13C represent a broad range of trophic positions within the food web, from
primary producers to top-tier predator fish. 15N and 13C values of primary producers reflect those of the water
chemistry, modified by isotopic fractionations associated with nutrient uptake and growth. The isotopic compositions
of invertebrates and fish are integrated measures of diet, with an expected relative enrichment of the heavier
isotope (i.e., higher 15N/14N and 13C/12C) at each trophic level.
We use 15N versus 13C plots to identify relative trophic
positions of biota within the food web for each site and collection
date. Based on laboratory and field studies, the expected pattern of
trophic enrichment is increasing 15N and 13C toward higher
trophic positions (for example, site U3, September 1997) (fig. 1).
The magnitude of 15N and 13C ranges varies among sites and collection
dates. This is not entirely surprising, given the large range
of consumer-diet isotopic fractionations reported for different species
(for example, McCutchan, 1999). However, the statistically
significant, yet different, 15N:13C slopes for the biota analyzed in

each site-date group suggest that processes influencing consumerdiet
isotopic fractionations within a food web are spatially and temporally
unique. The 15N:13C slope differences likely indicate
spatial and temporal differences in the food web base and/or complexity
of trophic interactions.
Figure 1. 15N versus 13C at site U3 during
September 1997. The 15N:13C slope for
invertebrates and fish is +1.3 (n = 12; p = 0.02;
R2adj = 0.37). Symbols are median values.
83
15N:13C slopes are typically positive, as expected
(fig. 1). However, rare negative slopes (for example, site F1,
September 1997) suggest the unlikely possibility that consumers
are relatively depleted in the heavier isotope of carbon than
their diets (fig. 2). Figure 3 shows location of sampling sites
U3 and F1, in Water Conservation Area 2. Although this pattern
has been observed for individual species in controlled
growth experiments (for example, DeNiro and Epstein, 1978),
an alternative explanation for the multiple-species pattern plotted
here is that the biota isotopes reflect the presence of multiple
food web bases with distinct 13C and 15N values. For
example, if mosquitofish, bluefin killifish, least killifish, and
shrimp are components of one food chain at site F1 and golden
topminnow and gator flea utilize another food web base (fig.
2), then this could explain the appearance of a single,
"reversed" trophic hierarchy in carbon isotope space.
REFERENCES
DeNiro, M.J. and Epstein, S., 1978. Influence of diet on the
distribution of carbon isotopes in animals. Geochimica et
Cosmochimica Acta, 42: 495-506.
McCutchan, J.H., Jr., 1999. Carbon Sources for Macroinvertebrates
in St. Vrain Creek, Colorado. Ph.D. Thesis, University
of Colorado, Boulder, 300 pp.
Contact: Bryan, Bemis, U.S. Geological Survey, 345 Middlefield
Road, MS 434, Menlo Park, CA, 94025, Phone: 650-
329-5603, Fax: 650-329-5590, bebemis@usgs.gov
Figure 2. 15N versus 13C at site F1 during
September 1997. The 15N:13C slope for
invertebrates and fish is -1.5 (n = 6; p = 0.03;
R2adj = 0.66). Symbols are median values.
Figure 3. Location of sampling sites U3 and F1, in
Water Conservation Area 2.
84
Origins and Isotopic Characteristics of Dissolved Nitrogen Species in Ground
Water, Imported Domestic Water, and Wastewater in the Florida Keys
By John Karl Bhlke1, Eugene Shinn, Christopher Reich2, and Ann Tihansky3
1U.S. Geological Survey, Reston, VA., USA
2U.S. Geological Survey, Center for Coastal and Watershed Studies, St. Petersburg, FL., USA
3U.S. Geological Survey, Center for Coastal and Watershed Studies, Tampa, FL., USA
Marine and estuarine ecosystems in the region surrounding the Florida Keys may be sensitive to minor
changes in the abundance of nitrogen in surface water and discharging ground water. Because there are many potential
natural and anthropogenic sources of nitrogen, the origins and isotopic characteristics of nitrogen species were
investigated in various water sources in the region including the Florida Keys, Florida Bay, and the offshore reef
tract. The 15N values of ammonium in saline ground waters in karst aquifers underlying most of the region ranged
from about +2 to +7  and were correlated spatially with the 15N values of organic matter in overlying sub-aqueous
carbonate sediments. Those data are consistent with the hypothesis that much of the ground-water ammonium was
derived naturally from diagenesis of organic matter in the overlying sediments and transported downward in hypersaline
bay water and offshore seawater. In contrast, wastewater from small-scale sewage treatment plants and wastewater
injection sites in the Keys generally had large concentrations of waste-derived nitrogen (mainly nitrate,
generally less ammonium) with 15N  7 . Tap water imported to the Florida Keys from the south Florida mainland
also contained substantial amounts of nitrate and ammonium, representing as much as 5 to 10 % of the anthropogenic
load of fixed nitrogen to the Keys. Chemical and isotopic analyses indicate that the tap-water nitrate (15N
= 16 to 22 ) was derived from nitrate-bearing ground water that was pumped and processed for distribution,
whereas the tap-water ammonium (15N = 0 to 5 ) was largely the result of the water treatment. Fresh ground
water at the water-supply well field on the mainland, and brackish ground water beneath the Keys and near-shore
areas, commonly had excess non-atmospheric nitrogen gas (15N = -0.7 to +5.0 ) that is attributed to denitrification,
which also increased the 15N values of nitrate after it was recharged on land or injected with wastewater.
These results indicate that some of the anthropogenic sources of nitrogen in the Keys that are abundant locally
in shallow fresh and brackish ground waters (largely nitrate and derivative nitrogen gas) may be distinguished chemically
and isotopically from major natural sources of fixed nitrogen that are widely distributed in saline and hypersaline
ground waters underlying the region (mainly ammonium). Overall, the data do not indicate direct
anthropogenic contributions to nitrogen in ground water beneath the reef tract or most offshore areas including Florida
Bay, but they do indicate localized anthropogenic contributions to nitrogen in shallow ground waters near onshore
development. Denitrification reduced substantially the concentration of nitrate in the Keys water supply before
it was pumped from the source, and it reduced the concentration of nitrate in treated wastewater after it was injected
beneath the Keys. Nevertheless, nitrogen was moving through both ends of the anthropogenic water cycle, some
being introduced with the drinking water supply and some ultimately discharging to near-shore surface waters after
use and disposal.
Contact: John Karl Bhlke, U.S. Geological Survey, 431 National Center, Reston, VA 20192, Phone: 703-648-
6325, Fax: 703-648-5274, jkbohlke@usgs.gov, Question 2
85
Salinity History of Florida Bay: An Evaluation of Methods, Trends, and Causes
By T. M. Cronin1, L. Wingard1, J. H. Murray1, G. Dwyer2, Michael Robblee3
1U.S. Geological Survey, Reston, VA., USA
2Duke University, Durham, NC., USA
,3U.S. Geological Survey Center for Water and Restoration Studies, Miami, FL., USA
Concern exists over hypersalinity - salinity exceeding marine salinity of approximately 35 ppt - in Florida
Bay and its negative impact on the ecosystem. High salinity is one of several factors that may cause changes in
seagrass distribution, abundance, and density (Fourqurean and Robblee, 1999). To determine the causes of historical
changes in seagrass communities, as well as other ecosystem disturbances, and to improve model ability to simulate
ecosystem response to future restoration, the patterns and causes of salinity variability in Florida Bay must be
determined.
We describe progress towards distinguishing natural salinity variability due to climate variability from
changes caused by water diversion in the Everglades during the 20th century. Variability in salinity in Florida Bay
reflects the bay's geometry, which features the Gulf of Mexico to the southwest, the Florida Keys to the southeast,
and the Everglades to the North, and its shallow bathymetry and circulation resulting from the complex of mudbanks
in the bay. Florida Bay salinity varies over seasonal, interannual, and decadal timescales but the instrumental record
prior to the 1990s is insufficient to attribute cause to decadal trends. Here we specifically address the application
of quantitative "retrodictive" estimates of past salinity patterns derived from geochemical studies of ostracodes from
sediment cores from the central part of Florida Bay. Parallel studies of molluscan shell chemistry and seasonal salinity
variability using the same sediment cores will be given in a separate presentation at the meeting.
The ratio of magnesium to calcium (Mg/Ca) ions in the calcium carbonate shells of the crustacean group
ostracodes is strongly influenced by the salinity and temperature in which the organism secretes its shell (see Dwyer
et al., 2002). The variability in Mg/Ca ratios of Florida Bay water is "captured" in the Mg/Ca ratios of the ostracode
shell when it secretes its adult shell. It is conventional to express the relationship between shell and water chemistry
as follows:
(Mg/Ca) ostracode calcite = (K D-me) (Mg/Cawater)
where
Mg/Ca represents the atomic ratio of Mg to Ca and K D-me is the partition coefficient for magnesium (Dwyer
and Cronin 2001). Mg/Ca ratios in fossil ostracodes from sediment cores were used to construct a paleosalinity
curve for central Florida Bay. The results showed that 20th century decadal oscillations in salinity were related
mainly to regional rainfall variability, which in turn was influenced by climate processes associated with interannual
El Nio-Southern Oscillation and decadal Pacific North American patterns (Cronin et al., 2002).
In this study, the accuracy of the Mg/Ca salinity curve was "groundtruthed" against instrumental records of
salinity from Florida Bay (Nuttle et al., 2000). Figure 1 shows the Mg/Ca paleosalinity curve plotted against the
instrumental record of salinity for the last 50 years. The instrumental record was constructed from mean monthly
salinity values for Whipray, Rankin, and Bob Allen Basins pooled to yield a grand mean for the central region.
Table 1 summarizes the paleosalinity-instrumental salinity comparison for Russell Bank.
Table 1. Comparison between Mg/Ca paleosalinity and instrumental record salinity minima
Salinity
Maxima
Mg/Ca
Salinity
Instrumental
Salinity
Salinity Max.
Difference
Salinity Minima
Mg/Ca
Salinity
Instrumental
Salinity
Salinity Min.
Difference
1990-1993 40.63 41.70 -1.08 1993-1995 36.15 36.45 -0.30
late 1970s 45.03 44.08 0.95 1980s 24.91 28.53 -3.61
mid 1960s 51.37 48.41 2.96 late 60s-early 70s 28.35 30.22 -1.87
1950s 57.02 47.32 9.70 ~1960 27.05 27.89 -0.84
86
Both records exhibit large decadal swings in salinity in central Florida Bay ranging from > 50 ppt to the low
20s. For salinity maxima during the early 1990s, late 1970s and mid-1960s the difference between paleo and instrumental
salinity was approximately -1.1., 0.9, and 3 ppt, respectively. The paleosalinity method overestimated the
maxima for the 1950s by 9.7 ppt, however the instrumental record stops in 1957 and it is unlikely the two records
had a similar period of record for this high salinity event. The differences for four periods of Florida Bay salinity
mimima approximately 1993-1995, the 1980s, the late 1960s-early 1970s and around 1960 were 0.3, 3.6, 1.9 and 0.8
ppt, respectively. Given the temporal gaps in the instrumental record, the error bar on the sediment core age estimates,
and the spatial and temporal averaging used for both records, these comparisons provide a remarkable confirmation
that the Mg/Ca-based shell chemistry method yields accurate estimates of past salinity to within < 1 to 4
parts per thousand.
Figure 1 also compares paleosalinity with hydrological instrumental records from south Florida: mean
monthly water height at USGS well 196a, Homestead, Florida, annual discharge at Taylor Slough since 1961, and
NOAA monthly regional rainfall anomalies. The results reveal decadal patterns in rainfall and water well height
since the 1930s and an inverse correlation between salinity and well height, rainfall and discharge. For example, wet
periods (i.e., approximately 1960, late 1960s, early 1980s) were characterized by positive precipitation and well
height anomalies and relatively low Florida Bay salinity. Periods of low salinity recorded in the Mg/Ca paleosalinity
curve during the early 1950s and the early 1940s are also evident in the precipitation and well height curves. Decadal
salinity oscillations over the past century are also evident from Mg/Ca analyses from Park and Bob Allen Keys, and
Little Madeira Bay (Dwyer and Cronin 2001).
Regional precip. anomaly Homestead well hgt. anom.
0 20000 40000 60000
Taylor Slough Disch. (cfs)
Florida Bay salinity (ppt)
Mg/Ca
paleosalinity
measured
Taylor Disch
year
Homestead
Well height
Figure 1. Comparison between paleosalinity and measured salinity (left), Homestead well level and Taylor
discharge (center), and NOAA regional rainfall (right).
-2 -1 0 1 2 3 4
1920
1930
1940
1950
1960
1970
1980
1990
2000
10 20 30 40 50 60
1920
1930
1940
1950
1960
1970
1980
1990
2000
-3 -2 -1 0 1 2
87
These results demonstrate that the Mg/Ca method reconstructs salinity patterns that faithfully record salinity
extremes to within a few parts per thousand and that the Mg/Ca method could be applied to new core sites to build
a network of long-term salinity records in Florida Bay and adjacent bays.
REFERENCES
Cronin, T. M., et al. 2002. Climate Research 19: 233-245.
Dwyer, G. S. and Cronin, T. M. 2001. Bull. of Amer. Paleont. 361: 249-276.
Dwyer, G. S., et al. 2002. AGU Monograph 131: 205-225.
Fourqurean, J. W. and Robblee, M. B. 1999. Estuaries 22: 345-357.
Nuttle, W. K. et al. 2000. Water Resources Research 36: 1805-1822.
Robblee, M. et al. 1991. Marine Ecology Progress Ser. 71: 297-299.
Contact: Cronin, Thomas M. 926A US Geological Survey, Reston, V 20192, Phone: 703-648-6363, Fax: 703-
648-6953, tcronin@usgs.gov
88
Estimating Water Quality Along the Southwest Florida Coast for Hydrologic
Models Using Helicopter Electromagnetic Surveys
By David V. Fitterman and Maria Deszcz-Pan
U.S. Geological Survey, Denver, CO., USA
Modern, three-dimensional hydrologic models are valuable tools for understanding and managing groundwater
resources. Great quantities of data in the form of hydrologic properties are needed to build these models; adding
solute transport to the model requires thousands of estimates of water quality. Traditional approaches relying
upon water quality measured in wells and then interpolated or extrapolated across the model can be woefully inadequate,
especially when well data are sparse. Combining well information with the results of helicopter electromagnetic
(HEM) surveys produces a better hydrologic model.
HEM surveys measure the electrical conductivity of the ground at multiple frequencies using an instrument
pod slung beneath a helicopter. A measurement is made about every 5-10 meters along flight lines. Flight-line spacing
is typically 400 meters. The depth of exploration varies from 20 to 50 meters depending upon the formation resistivity.
(Electrical resistivity is the reciprocal of electrical conductivity.) In more conductive zones, such as those
saturated with seawater, the exploration depth is diminished, while in freshwater saturated zones deeper exploration
is possible. The HEM data are used to estimate a layered-earth electrical resistivity model at every measurement
point. The data can then be used to create a three-dimensional grid of electrical properties.
Electrical resistivity of geologic materials is controlled by the amount of pore space, the electrical resistivity
of the pore fluid, the degree of saturation, and the presence of clay minerals. The relationship between specific conductance
(SC) of the pore water and the formation resistivity can be determined by correlation of data from wells.
Using this correlation, the HEM-determined electrical resistivity model can be turned into estimated water quality.
This approach was used on a previous HEM survey (see fig. 1) in Everglades National Park (Fitterman and
Deszcz-Pan, 2001, 2002). We are using the same approach with a survey flown in October 2001 over parts of Big
Cypress National Preserve (BCNP) and Everglades National Park (ENP). The survey has 2,692 line-km of flight
lines covering an area of approximately 1,020 sq-km (see fig. 1).
Figure 1. Location of south Florida HEM surveys.
89
The primary products of this survey are apparent resistivity maps, one for each of the five measurement frequencies.
Lowering the frequency probes deeper into the subsurface. The data are converted into resistivity-depth
functions, which are then used to produce formation-resistivity, depth-slice maps. The depth-slice maps are used to
create a formation resistivity volume that can be interactively displayed. The cell size of this volume is 200 m horizontally
and 5-10 meters vertically, dimensions that are commensurate with the Tides and Inflows in the Mangrove
Ecotone (TIME) hydrologic model being developed by Schaffranek et al., 2003.
The depth-slice maps show a general decrease in formation resistivity (0.5-10 ohm-m) moving towards the
coast with resistivities inland that are in the range of 20-100 ohm-m. (Images of the depth slices can been seen at
the South Florida Information Exchange web site: http://sofia.usgs.gov/projects/geophys_map/.) The transition
between the conductive and resistive zones deepens in the landward direction starting near the surface and reaching
a depth of 50 meters over a distance of 2 to 5 km. This feature is interpreted as being the freshwater/saltwater interface.
There do not appear to be any influences on this transition that can be related to natural drainages or manmade
features as are seen in ENP (Fitterman and Deszcz-Pan, 2001).
Weedman et al. (1997, 1999) developed relation between the formation water SC and the bulk formation resistivity
in the northern part of the BCNP survey that we use in creating a three-dimensional water quality estimate. In
turn this information is used in the TIME model as data to compare against the calculated salinity variations (Schaffranek
et al., 2003).
The use of HEM data combined with water quality information from selected wells is a new approach for
meeting the data demands of three-dimensional hydrologic models. The relatively flat lying geology in south Florida
justifies the use of one-dimensional interpretation of the HEM data. The sparsity of clay minerals in the aquifer
makes establishing the relation between water quality and formation resistivity relatively straightforward. The combined
use of well and HEM data could be used to meet the data requirements of modern hydrologic models in other
study areas.
REFERENCES
Fitterman, D.V., and Deszcz-Pan, M., 2001, Using airborne and ground electromagnetic data to map hydrologic features
in Everglades National Park, in Proceedings of the Symposium on the Application of Geophysics to Engineering
and Environmental Problems SAGEEP 2001, Denver, Colorado, Environmental and Engineering
Geophysical Society, p. 17 p..
Fitterman, D.V., and Deszcz-Pan, M., 2002, Helicopter electromagnetic data from Everglades National Park and
surrounding areas: Collected 9-14 December 1994: U.S. Geological Survey Open-File Report 02-101, 38 p.
Schaffranek, R.W., Jenter, H.L., Riscassi, A.L., Langevin, C.D., Swain, E.D. and Wolfert, M., 2003, Applications
of a numerical model for simulation of flow and transport in connected freshwater-wetland and coastal-marine
ecosystems of the southern Everglades (abstract): Proceedings of Joint Conference on the Science and Restoration
of the Greater Everglades and Florida Bay Ecosystem, this publication.
Weedman, S.D., Paillet, F.L., Means, G.H., and Scott, T.M., 1997, Lithology and geophysics of the
surficial aquifer system in western Collier County, Florida: U.S. Geological Survey Open-File
Report 97-436, 167 p.
Weedman, S.D., Paillet, F.L., Edwards, L.E., Simmons, K.R., Scott, T.M., Wardlaw, B.R., Reese, R.S.,
and Blair, J.L., 1999, Lithostratigraphy, geophysics, biostratigraphy, and strontium-isotope
stratigraphy of the surficial aquifer system of Easter Collier County and Northern Monroe County,
Florida: U.S. Geological Survey Open-File Report 99-432, 125 p.
Contact: David V. Fitterman, U.S. Geological Survey, Box 25046 MS 964, Denver, CO 80225 Phone: 303-236-
1382, Fax: 303-236-1425, fitter@usgs.gov
90
Atrazine Exposure and the Occurrence of Reproductive Abnormalities in Field
Caught Bufo marinus From South Florida
By Timothy S. Gross1, Marisol Sepulveda1, Carr JA2, Giesy JP3, Hosmer AJ4, Kendall RJ2,
Solomon K5, Smith EE2, and G. Van Der Kraak5
1U.S. Geological Survey Florida Integrated Science Cemter and University of Florida, Gainesville, 2Texas Tech
University, Lubbock, 3Michigan State University, East Lansing, 4Syngenta, Greensboro, SC, 5University of Guelph,
Guelph
Many chemicals in our environment are suspected or known to influence endocrine system function. Endocrine
disrupting chemicals (EDCs) have been broadly defined as exogenous agents that interfere with the production,
release, transport, metabolism, binding, action, or elimination of natural hormones responsible for maintenance of
homeostasis and regulation of developmental processes. Since hormones are important modulators of tissue differentiation,
developing organisms are thought to be especially sensitive to EDCs. Indeed, many agricultural contaminants
such as herbicides, fungicides, and insecticides have been shown to induce developmental toxicity through
alterations in hormonal activity. For example, the insecticide DDT and its metabolite p,p'DDE are known to affect
development through an anti-androgenic mechanism.
Atrazine is the most commonly used herbicide in
the United States. Recent reports have suggested that
environmentally relevant levels of atrazine can alter sexual
development in laboratory exposed African Clawed
frogs (Xenopus laevis), however, similar experiments
have been unable to replicate these findings. The goal of
the current study was to document whether similar reproductive
system anomalies were common in anurans from
Florida sugarcane agricultural areas, which have the highest
per acre atrazine use in the U.S. The giant toad or cane
toad (Bufo marinus) was chosen as the focal species
because they posses a nonfunctional rudimentary ovary
(Bidder's organ), which potentially makes them sensitive
to EDCs that influence gonad development. They are an
invasive species, so destructive sampling is not expected
to cause negative impacts on local diversity, and they are
found in large numbers in sugar cane fields were atrazine
is extensively applied. The goal of the current study was
to document whether exposure of frogs to sugarcane agricultural
areas in south Florida would result in a higher
incidence of intersex and/or developmental anomalies.
Sugarcane agriculture has the highest per acre atrazine
use in the U.S., which could represent the highest potential
risk for exposure of native anuran species to atrazine.
To determine the distribution and concentration of
atrazine at south Florida sites, multiple water samples
were colleted from several canals/ditches at each of two
agricultural sites every two weeks from February through June, 2002 (fig. 1). Adult toads were collected from two
sugarcane agricultural areas Canal Point (CP), and Belle Glade (BG) as well as from a University of Miami pond/
canal (reference site with little to no atrazine use or agricultural input) during April-June 2002. Adult Bufo marinus
were collected from these three sites: Canal Point (N=55), Belle Glade (N=50), and University of Miami (N=24).
Body weight, length, and coloration were recorded, blood was collected, and gonads were removed and weighed.
Figure 1. Atrazine concentrations in water for both
sugarcane agricultural sites. Line indicates mean
concentrations across each site.
91
This species is sexually dimorphic, with females having a mottled appearance and males having a solid coloration.
Sex was identified as follows: the presence of ovarian tissue and absence of testicular tissue = female; presence of
testes and absence of developing eggs, oviduct, and ovarian tissue = normal male; and presence of testes with developing
eggs or oviduct or ovarian tissue = intersex . Macroscopic identification of additional testicular anomalies
included: segmented testes, abnormal shaped testis, twisted or curled testes, and multiple testes. Gonads from each
individual that had testicular tissue were both macroscopically and histologically examined. Blood plasma was analyzed
for phospho-lipoprotein (an indirect measure of vitellogenin) and estradiol and testosterone concentrations
were analyzed using RIA procedures.
Atrazine levels were highest at Canal Point during March, but were highest at Belle Glade in February. B.
marinus tadpoles were potentially exposed to atrazine concentrations as high as 20ppb during development at Canal
Point and 26ppb at Belle Glade during 2002. Toads collected from the nonagricultural /reference, University of
Miami, site exhibited the characteristic gender-specific pattern which correlated to subsequent gonadal morphology
and histology. However, all toads collected from both agricultural sites, Belle Glade and Canal Point, exhibited the
distinctive female pattern, although subsequent gonadal morphology and histology demonstrated male, intersexed,
and female toads. The frequency of males exhibiting "testis abnormalities" was not significantly different among
sites. The frequency of intersexed animals was significantly different among sites: 39 percent and 29 percent of the
individuals at the agricultural sites, Canal Point and Belle Glade. No individuals from the non-agricultural/reference
site were intersexed. The types of abnormal female tissue found in association with testicular tissue varied between
CP and BG. Plasma sex steroids did not differ between intersexed and normal males. However, plamsa phospholipoprotein
(an indirect indicator of vitellogenin was increased in intersexed males to levels which were similar to

those for vitellogenic females.
The purpose of this preliminary study was to determine if animals found in sugarcane exhibit reproductive
abnormalities similar to those seen in African Clawed Frogs exposed to atrazine in the laboratory. The incidence
of testicular anomalies, other than intersex were similar across sites. However, the incidence of intersex was
increased for both agricultural sites as compared to the non-agricultural/reference site. Nonetheless, Bufo marinus
adults were active and breeding at all sites. Data suggests that agricultural exposure, including exposure to atrazine,
may explain the differences in the percent of intersexed individuals and length of oocytes between Canal Point and
Belle Glade sites. However, we can not conclude that atrazine is responsible for these abnormalities, since other
agricultural chemcials are likely present at both sites. In addition, water quality analyses were not conducted for
the non-agricultural/reference site (University of Miami) and exposure to atrazine at this site is unknown. The University
of Miami site is expected to have low levels of atrazine, but is probably not atrazine free. Further research
should be conducted to determine whether atrazine is capable of causing the effects we have documented in B. marinus
under controlled laboratory conditions as well as expanded field studies of these and other sites. Nonetheless,
these results indicate an increased incidence of intersex in toads exposed to agricultural contaminants. The implications
of these data to future and ongoing restoration is unknown, however, a redistribution of water resources in
the greater everglades ecosystem could result in additional exposures for amphibian populations in this sensitive
ecosystem.
Contact: Timothy S. Gross, USGS-FISC, 7920 NW 71st St., Gainesville, FL 32653., Phone: 352-378-8181
Ext 323, FAX: 352-378-4956, Tim_s_gross@usgs.gov
92
Characterization of Solute and Fine-Particle Transport in Shark Slough,
Everglades National Park by a Tracer Release in the Florida International
University (FIU) In Situ Flumes
By Judson W. Harvey1, James E. Saiers2, James M. Krest1, Steven Mylon2, Jessica T. Newlin1, Christine Taylor3,
and Evelyn E. Gaiser3
1 U.S. Geological Survey, Reston, VA, 2 Yale University, New Haven, CT, 3 Florida International University,
Miami, FL., USA
Experiments that introduce dissolved or particulate tracers into flowing water are useful to characterize rates
of material movement and mixing. Parameters determined from tracer experiments, such as advection and dispersion,
are especially needed in models that simulate the effects of flow and mass transport on biogeochemical reactions
and water quality. Presently, there are few data or guidelines available to understand mechanisms that control
transport of materials with flowing water in the Everglades. Recently, a group of USGS and university researchers
conducted a tracer experiment in central Shark Slough at one of the Florida International University (FIU) phosphorus
dosing flume facilities. Each flume consists of 4 side-by-side channels, each enclosing a 3-m wide by 100-m long
flow-way oriented with the natural direction of surface-water flow. More about flume design and results of the lowlevel
phosphorus dosing can be found at several FIU websites (http://www.fiu.edu/~ecosyst/index.htm).
This abstract provides a brief description of a tracer experiment conducted from November 20-22, 2002 in
flume A. The purpose of the experiment was to characterize transport of both solutes and fine-particles in Shark
Slough, including surface-water exchange with subsurface water in the floc and underlying peat. The experiment was
conducted in the westernmost channel of flume A. That channel receives the 'middle' level of phosphorus dosing
being applied to determine the effects of added phosphorus on the Everglades ecosystem. At the time of the experiment,
visible differences in macrophyte density were not apparent in the experimental channel when compared with
areas immediately outside the flume. The depth of surface water was approximately 60 cm at the time of the tracer
test and the location of the injection was 0.75-m upgradient of the 0-m reference point in the channel, which is the
location where the 'mixing' reach for phosphorus dosing ends and the front edge of vegetation begins. The experiment
consisted of a constant-rate injection for 22 hours of a sodium bromide (NaBr) solution made up in 0.2 um
filtered Everglades water. The injection was accomplished using two metering pumps to deliver the tracer; dividing
the flow between four soaker hoses (2.65-m long) stationed horizontally across the channels at evenly spaced depths.
After termination of the NaBr injection, fine particles composed of titanium dioxide (TiO2) were injected into the
flume for a period of six hours. The TiO2, which has a density of 3.9 g/cm3, was suspended in filtered Everglades
surface water by stirring and delivered by metered injection through a single slotted tube, oriented horizontally and
positioned at a depth of 30 cm. Sampling for the tracers began before the start of the NaBr injection and lasted for
48 hours. Concentrations of both dissolved and particulate tracers were monitored at four stations at distances of
6.8, 26, 43, and 86m down the channel from the injection site. At each monitoring station, small-volume (20-ml)
water samples were repeatedly collected by suction at seven discrete points, which characterized horizontal and vertical
variability in tracer distribution across the channel. In addition to sampling surface water, porewater was sampled
at two locations at a distance of 6.3 m downstream from the injection site. Analysis of bromide concentration
in each sample is being conducted by ion chromatography, while concentrations of TiO2 particles are being determined
by inductively coupled plasma-atomic emission spectrometry following acid digestion of the particles.
Results from the experiment are not available at this time, due to the limited number of analyses completed.
A full presentation of findings will be prepared upon completion of the sample processing and simulation modeling.
In addition to providing fundamental information about transport processes in the Everglades, the expectation is that
results can be combined with complementary data to better characterize rates of biogeochemical reactions in the
Everglades. Parameters describing solute and particle transport will also be available as inputs for the water-quality
and landscape-process models that are currently guiding restoration planning in the Everglades.
Contact: Harvey, Judson W., U.S. Geological Survey, 12201 Sunrise Valley Drive, Mail Stop 430, Reston, VA
20192; Phone: (703) 648-5876; Fax: (703) 648-5484; jwharvey@usgs.gov; Water Quality and Water Treatment
Technologies
93
Thermally-Driven Vertical Mixing in the Everglades
By Harry L. Jenter1, Raymond W. Schaffranek1 and Thomas J. Smith, III2
1U.S. Geological Survey, Reston, Virginia, USA
2USGS, Center for Water and Restoration Studies, St. Petersburg, FL., USA
Vertical mixing in most natural freshwater bodies is driven predominantly by boundary shear stresses such as
wind stress on the free surface of a lake or bed friction on the channel bottom and banks of a rapidly flowing river.
However, in the slowly flowing wetlands of the Everglades, thermally-driven convection is the dominant mixing
mechanism. This diel mixing has potential implications for mercury methylation, evapotranspiration, oxidation,
nutrient and contaminant transport and cycling, and other processes of concern in the Everglades wetlands.
Flow-velocity measurements and temperature profiles collected within an area of medium-dense spike rush
on the edge of a large area of dense sawgrass in lower Shark River Slough within Everglades National Park reveal
the behavior, timing, and extent of thermal mixing. Flow velocities were sampled using an acoustic Doppler velocity
meter capable of resolving very low velocities to an accuracy of 1 mm/s over a range of a few cm/s. Two 600-sample
measurement bursts are depicted in Figure 1. Each burst was collected at 10 Hz and, therefore, represents a oneminute
sample. There are two plots for each burst. The first shows the three components of flow velocity: eastwest,
north-south and up-down. The second shows a signal quality statistic, correlation, which can be considered
an indicator of small-scale turbulence in the acoustic pathway. Lower correlations indicate higher turbulent mixing.
Velocity data in the first pair of plots, collected during the daytime, fluctuate minimally about their median
values and have very high correlations. In strong contrast, velocity data in the second pair of plots, collected at midnight,
fluctuate wildly and have substantially more variable and lower correlations. This phenomenon is typical and
constitutes a pattern observed nearly every day.
Figure 1. Typical flow velocity and signal correlation at SH1.
94
Highly variable flow velocities in the hours after sunset can be linked to thermal convection by considering
temperature data obtained from a set of thermistors, having an accuracy of 0.1 C, cabled vertically 10 cm apart in
a string deployed near the velocity meter. Thermistor data show the heavily vegetated water column to be isothermal
at the beginning of each day (fig. 2). Initial heating of the water surface at sunrise is followed by progressive heating
of the water column with depth throughout the day, resulting in increasing stratification throughout the late morning
and early afternoon. Maximum stratification occurs at mid-afternoon and averages approximately 3C through
60 cm of the water column (5C/m). Typically, the water column reaches its maximum temperature around midafternoon.
The water column cools through the remaining daylight hours, but remains stratified until approximately
sunset when the air temperature begins to fall sharply and eventually drops below the water temperature at the surface.
Diel coincidence of the thermal destratification and pronounced velocity fluctuations indicates the onset of
mixing in the water column driven by thermal convection. The mixing process begins abruptly within approximately
the upper 40 cm of the water column. Temperatures within this layer coincide through the remainder of the night.
This mixed layer continues to cool and deepen throughout the night, not warming until just after sunrise the next day.
A thin layer at the water surface remains slightly cooler than the mixed layer through the night, providing a constant
source of negatively buoyant water that drives the mixing process. The mixing process continues until the air temperature
rises above the temperature of the water at the surface.
The thermally-driven mixing process also affects the temperature structure within the upper portion of the
plant-litter layer at the bottom of the water column. The slow exchange of mass and heat across the water-column/
litter-layer boundary causes temperatures in the plant-litter layer to lag temperatures in the water column. Decreased
heat exchange causes the peak temperature in the litter layer to occur after midnight and the minimum temperature
to occur around noon. There is a brief time just before sunrise when the temperature in the litter layer is greater than
in the water column. The daily range of temperatures in the litter layer (approximately 0.5C) is much smaller than
the range of temperatures at any particular point in the water column (approximately 3-5C).
Figure 2. Typical temperature at SH1 (curve 1 = plant litter, 2-7 = water, 8-11 = air).
95
Individual daily temperature profiles in the Everglades wetlands are observed to vary only slightly with meteorological
conditions and indicate that daytime destratification rarely occurs. Thermally-driven mixing appears to
dominate at SH1 during more than 90 percent of the days. Only in the case of persistently strong winds, heavy rainfall,
or dramatic drops in air temperature is the water column in the Everglades wetlands thermally well-mixed during
the daytime. The presence of vegetation appears to be the primary factor increasing the consistency with which
thermally-driven convection dominates the vertical mixing process in the Everglades. The ubiquitous nature of this
mixing implies a likely role in a number of important processes in the ecologically stressed Everglades wetlands.
Contact: Harry L. Jenter, USGS, 12201 Sunrise Valley Drive, MS 430, Reston, VA 20192, Phone: (703) 648-
5916, Fax: (703) 648-5484, hjenter@usgs.gov, Hydrology and Hydrological Modeling.
96
Is Food Web Structure a Main Control on Mercury Concentrations in Fish in the
Everglades?
By Carol Kendall1, Bryan E. Bemis1, Joel Trexler2, Ted Lange3, and Q. Jerry Stober4
1U. S. Geological Survey, Menlo Park, CA., USA
2Florida International University, Miami, FL., USA
3Florida Fish and Wildlife Conservation Commission, Eustis, FL., USA
4U. S. Environmental Protection Agency, Athens, GA., USA
Many lake studies have found good correlations between the mercury (Hg) concentrations in fish and the relative
trophic positions of fish as determined by analyses of gut contents and (or) stable isotopes. But is this true in
dynamic marsh ecosystems such as the Everglades? Based on the extensive REMAP (Regional Environmental Monitoring
and Assessment Program) assessment of the Everglades ecosystem, Stober et al. (2001) concluded that spatial
(especially N-S) differences in "food web structure" are a likely cause of spatial differences in Hg concentrations in
mosquitofish. Food web structure is a general term that encompasses differences in food chain length, food web
complexity, and food web base. The extensive isotope and gut contents datasets assembled by several agencies can
be used to evaluate this hypothesis.
Over 5000 algae, macrophyte, invertebrate, and fish samples were collected at 15 sites studied by the USGS
ACME (Aquatic Cycling of Mercury in the Environment) team during multiple trips 1995-1999. These samples
were analyzed for 13C and 15N to determine temporal and spatial differences in food web structure; a smaller subset
was also analyzed for 34S. Samples consisted of both composites and individuals. Most samples were analyzed
in bulk; however, muscle tissue was analyzed for most large fish. This large dataset was used to calculate the differences
in 15N and 13C between all possible consumer-diet pairs. The difference in 15N between consumer and
diet (ƥ15N) is a proxy for the length of the food chain between the species at a particular site and date, and the
difference in 13C (ƥ13C) reflects differences in the base of the food webs of the species. An evaluation was then
made of how often the ƥ15N and ƥ13C values differed between types of sites. There were no statistically significant
differences in ƥ15N values between high and low nutrient sites, suggesting that there was no evidence for
shorter food chains at high nutrient sites, as found by Stober et al. (2001). However, there are statistically significant
differences in ƥ13C values between low and high nutrient sites. One likely explanation for the ƥ13C differences
is a difference in the dominant base of the food webs at such sites. Food webs at low nutrient sites appear to be more
algal dominated while macrophyte debris appears to be a significant contribution to the base of the food webs at high
nutrient sites.
Samples of periphyton, mosquitofish, and
sediment samples collected during September
1996 at about 100 REMAP marsh sites were
analyzed for 13C, 15N, and 34S. The ƥ15N
calculated for periphyton and mosquitofish
pairs (n = 68) showed no significant correlation
with region (Above Alligator Alley, Between
Alligator Alley and Tamiami Trail, Below
Tamiami Trail) (p = 0.67) or latitude (p = 0.20),
and no correlation with mosquitofish Hg levels
(p = 0.55), suggesting a lack of evidence for spatial
differences in food chain length. However,
the ƥ13C values showed strong spatial patterns,
including statistically significant differences
between data from different regions (p =
0.04) and latitudes (p < 0.01) (fig. 1). Figure 1. Graph showing significant correlation of
ƥ13C with latitude (n = 68; p < 0.01; R2adj = 0.13).
97
One likely explanation for the patterns is that they reflect spatial differences in the relative importance of algae
versus macrophyte debris to the mosquitofish food web. In general, the spatial patterns of ƥ13C values are very
similar to spatial patterns interpreted by Stober et al. (2001) as differences in food web structure. Hence, two very
different sets of samples and data from the same regional assessment agree that there are similar spatial differences
in some aspect of the food web structure, but disagree about whether this difference is mostly due to trophic variations
or food base differences. An evaluation of the gut contents of mosquitofish collected in 1996 and 1999 at the
same REMAP sites, indicated that these data did not support the hypothesis that trophic position could be used to
explain spatial differences in Hg concentrations (Stober et al., 2001). We are currently re-evaluating the isotope data
in conjunction with the gut contents data to see if this will provide new insights into causes of spatial variations in
food web characteristics.
This work was made possible by contracts from and collaborations with the US Geological Survey, US Environmental
Protection Agency, and Florida Fish and Wildlife Conservation Commission.
REFERENCES
Stober, Q.J., Thornton, K., Jones, R., Richards, J., Ivey, C., Welch, R., Madden, M., Trexler, J., Gaiser, E., Scheit,
D., and Rathbun, S., 2001, South Florida Ecosystem Assessment: EPA Report 904-R-01-003.
Contact: Carol, Kendall, U.S. Geological Survey, 345 Middlefield Road, MS 434, Menlo Park, CA, 94025,
Phone: 650-329-4576, Fax: 650-329-5590, ckendall@usgs.gov,
98
Biogeochemical and Hydrologic Controls on Food Web Structure in the
Everglades
By Carol Kendall1, Bryan E. Bemis1, Scott D. Wankel1, Ted Lange2, and David P. Krabbenhoft3
1U. S. Geological Survey, Menlo Park, CA., USA
2Florida Fish and Wildlife Conservation Commission, Eustis, FL., USA
3U. S. Geological Survey, Middleton, WI., USA
A clear understanding of the aquatic food web -- the relative trophic positions of different fish, birds, and other
aquatic life -- is essential for determining the entry points and subsequent biomagnification pathways of contaminants
such as methyl-mercury (MeHg) in the Everglades. Anthropogenic changes in nutrients and sulfur can significantly
affect the entry points of MeHg by changing food web structure from one dominated by algal productivity to one dominated
by macrophytes and associated microbial activity. These changes in the base of the food web also influence the
distribution of animals within the ecosystem, and subsequently the bioaccumulation of MeHg up the food chain. We
are attempting to use the 15N, 13C, and 34S of biota in marshes and canals in the Everglades as (1) indicators of local
environmental conditions that may impact water quality and biota, and (2) indicators of food web structure.
The isotopic compositions of several thousand sediment, plant, invertebrate, and fish samples collected in collaboration
with several agencies from several hundred sites in the Everglades show strong spatial patterns on a landscape
scale. The spatial variability of 15N, 13C, and 34S values reflects spatial variability of reducing conditions in
the marshes that promote methane production, sulfate reduction, and denitrification. The isotopic compositions of
aquatic plants integrate the variability in water column isotopic compositions, and the resulting spatial patterns are
incorporated throughout the food web. Therefore, organisms that live in sites where geochemical conditions are dominated
by particular redox reactions have distinctive isotopic compositions. The temporal and spatial variability in
the isotopic compositions of aquatic plants at the base of the food webs complicates the use of isotopic techniques
for determining food web structure in the Everglades. In particular, the isotopic effect of these biogeochemical reactions
must be removed from the isotopic compositions of biota before it is possible to evaluate temporal and spatial
changes in food webs.
The temporal and spatial variability of biota isotopic compositions provide very useful insight into seasonal
and spatial changes in biogeochemical and hydrological processes across the Everglades. For example, aquatic vegetation
and detritus samples collected in September 1998 and March 1999 from various sites along two parallel
transects in WCA (Water Conservation Area) 2A show that 15N values of vegetation tend to decrease (from around
+5 to around 0) with distance from the canal, while 13C values show an increase with distance from the canal
(from -30 to -26). Shrimp and other invertebrate samples collected at the same times also show approximately
a 2 decrease in 15N and ~5 increase in 13C along the same gradient. Also, we find that plants and macroinvertebrates
collected from microhabitats (such as open-water sloughs, cattail marsh, sawgrass marsh, and
spikerush stands) within 100 m of site U3 in WCA2A have 0.5 to 1 variation in 13C and a 1 to 2 variation in
15N between marsh types. The differences in isotopic composition of biota within microhabitats at each site suggest
that local influences, such as differences in the relative rates of photosynthesis and respiration, and differences in
nitrification and denitrification, strongly affect the 13C and 15N (respectively) of local biota. Temporal changes
in these same processes, as well as changes in species composition, cause algae samples collected weekly from three
slightly different microhabitats near U3 to have 13C values that range from -32 to -27, and 15N values that
range from +2 to +6 during the fall of 1997.
The  values of organisms collected at the same site usually show an inverse relation between 13C and 15N
over time. Seasonal shifts in water level can cause shifts in biogeochemical reactions and nutrient levels, with corresponding
variations in the  values of biota. For example, small changes in water level may change the balance of
photosynthesis, respiration, and atmospheric exchange reactions that control the 13C of dissolved inorganic C
(DIC). Such changes probably also will affect the 15N of dissolved inorganic N (DIN) because of corresponding
changes in N uptake and redox conditions. During the dry season, the marshes probably become more anoxic due to
shallower water levels, less photosynthesis, and increased quantities of decaying vegetation. At some sites, the 13C
99
and 15N of algae show strong positive correlations with water level fluctuations. These oscillations are substantially
damped up the food chain, probably because of the longer C and N integration times of animals vs. plants.

Our large dataset of 13C and 15N analyses of samples collected at 15 sites studied by the USGS ACME
(Aquatic Cycling of Mercury in the Environment) team during multiple trips in 1995-1999 was used to calculate the
differences in 15N and 13C between all possible consumer-diet pairs. The difference in 15N between consumer
and diet (ƥ15N) is a proxy for the length of the food chain between the species at a particular site and date, and the
difference in 13C (ƥ13C) reflects differences in the base of the food webs of the species. An evaluation was then
made of how often the ƥ15N and ƥ13C values differed between types of sites. There were no statistically significant
differences in ƥ15N values between high and low nutrient sites, suggesting that there was no evidence for
shorter food chains at high nutrient sites. However, there are statistically significant differences in ƥ13C values
between low and high nutrient sites.
We find that 13C values provide a powerful tool for distinguishing between sites where algae is the dominant
base of the food web vs. sites where macrophyte debris (and the bacteria living on it) is also a significant food
source. The 13C values of organisms from relatively pristine marsh sites sampled by the USGS are consistent with
algae being the dominant food web base most of the time (perhaps depending on water levels). At the more nutrientimpacted
sites, the 13C and 15N values of scavengers such as shrimp and crayfish are consistent with macrophyte
debris being an important food source most of the time. The 13C values of samples collected by the EPA REMAP
program in September 1996 also show spatial differences in the importance of algae as a base of the food web. Macrophyte
debris appears to also be important to the mosquitofish food web at about half of these sites.
The ƥ15N calculated for periphyton and mosquitofish pairs at the REMAP sites showed no correlation with
region or latitude, and no significant correlation with mosquitofish Hg levels, suggesting a lack of evidence for spatial
differences in food chain length. However, the ƥ13C values showed strong spatial patterns, including statistically significant
differences between data from different regions (p = 0.04) and latitudes (p < 0.01). One likely explanation for
the patterns is that they reflect spatial differences in the relative importance of algae vs. macrophyte debris to the mosquitofish
food web. In general, the spatial patterns of ƥ13C values are very similar to spatial patterns interpreted by
Stober et al. (2001) as differences in food web structure. Hence, two very different sets of samples and data from the
same regional assessment agree that there are similar spatial differences in some aspect of the food web structure, but
disagree about whether this difference is mostly due to trophic variations or food base differences.
Several chemical parameters measured at the sites by the REMAP program show significant differences
between sites where the food webs are predominantly algal versus ones with appreciable contributions from macrophyte
debris. These data are consistent with macrophyte-impacted sites generally having more anoxic conditions
than sites where algae is the dominant base of the food web. The general agreement of the REMAP data with the
conceptual model developed to explain temporal and spatial variability in food webs at USGS sites provides moderate
evidence that spatial differences in the dominant food web base across the Everglades are related to environmental
conditions such as nutrient availability, redox conditions, and hydroperiod.
Applications of our isotopic investigations to the Everglades Restoration include: (1) Biota isotopes provide
a map of the current spatial distributions of the extent of several biogeochemical reactions (especially sulfate reduction)
affecting nutrient and Hg uptake. (2) By comparing the spatial patterns in the biota with those in the shallow
sediments, recent anthropogenic changes in biogeochemical processes at the landscape scale can be demonstrated
and dated. (3) Isotopes provide detailed information about temporal and spatial changes in trophic relations that
complements traditional gut-contents analyses used by the Florida Fish and Wildlife Conservation Commission
(and others) for understanding food webs and the bioaccumulation of contaminants. (4) The preliminary synthesis
of the biota isotopes at USGS and 1996 REMAP sites provides a mechanism for extrapolating the detailed food
webs developed at the intensive USGS sites to the entire marsh system sampled by REMAP. (5) Biota isotopes provide
a simple means for monitoring how future ecosystem changes affect the role of periphyton (vs. macrophytedominated
detritus) in the mosquitofish food chain, and for predictive models for MeHg bioaccumulation under different
proposed land-management changes.
Contact: Carol Kendall, U.S. Geological Survey, 345 Middlefield Road, MS 434, Menlo Park, CA, 94025,
Phone: 650-329-4576, Fax: 650-329-5590, ckendall@usgs.gov
100
Unraveling the Complexities of Mercury Methylation in the Everglades: The Use of
Mesocosms to Test the Effects of "New" Mercury, Sulfate, Phosphate, and
Dissolved Organic Carbon
By David P. Krabbenhoft1, William H. Orem2, George Aiken3, and Cynthia Gilmour4
1U.S. Geological Survey, Middleton, WI., USA
2U.S. Geological Survey, Reston, Virginia, USA
3U.S. Geological Survey, Boulder, Colorado, USA
4Academy of Natural Sciences, St. Leonard, Maryland, USA
Mercury (Hg) contamination of the Everglades ecosystem is one of the most severe cases in the published literature.
Currently, no human consumption of any Everglades sport fish is recommended. Although it is widely recognized
that mercury contamination of aquatic ecosystems is largely the result of atmospheric mercury emissions,
long-range transport and subsequent deposition, providing a scientific understanding of this problem with the necessary
detail to prescribe appropriate corrective measures has remained unclear. From 1995 to 1999, the Aquatic
Cycling of Mercury in the Everglades (ACME) project studied the biogeochemical cycling of Hg in detail at a series
of sites spanning most of the north-to-south extent of the Everglades, and many of the major sub-ecosystem types.
The ACME project revealed that mercury and methylmercury (MeHg) distributions in water, sediment and biota
show complex seasonal and spatial trends, and that the cycling rates of Hg and MeHg are so rapid that many measurements
must be conducted on a diel basis in order to provide an adequate understanding of the controlling factors.
These studies revealed relations between biogeochemical factors and the production rate of MeHg, which is the most
bioaccumulative and toxic form of mercury, and thus is central to understanding the mercury problem in the Everglades
and elsewhere. Specifically, through field experiments and laboratory studies, we established links between
MeHg production and several key ecosystem factors, including: hydroperiod, atmospheric Hg loading, sulfate loading
from Everglades Agricultural Area (EAA) runoff, and dissolved organic carbon (DOC) levels in surface water.
However, because all these driving factors of MeHg production co-vary spatially across our study sites, definitive
quantitative assessments of which parameters are most important for limiting future methylmercury production
remained unclear. In addition, because all of these factors are likely to be altered by the Everglades Restoration
Project, a more "controlled" experimental approach was developed to estimate how this ambitious project might
affect mercury toxicity for the Everglades in the future.
One approach for sorting out the complex responses of MeHg formation to alterations in critical water quality
constituents (Hg, sulfate, phosphate and DOC) is through the use of in situ mesocosms (or wetland enclosures), in
which dosing studies can be conducted. Such an approach has the advantage of maintaining many of the qualities
of natural ecosystems that are very difficult to replicate in a laboratory setting, such as soil structure, redox, rainfall
inputs, diel temperature and light cycles, as well as indigenous flora and fauna. On the other hand, mesocosms do
potentially suffer from so called "wall" effects, and thus strict monitoring of the enclosed and native environment
must be maintained to validate results. Starting in May 2000, the ACME Phase II project initiated mesocosm experiments
at four of our long-term study sites (F1, U3, 2BS, and 3A15) located in Water Conservation Areas (WCA)
2A, 2B and 3A. Initial experiments were limited only to mercury dosing to quantify the ecosystem response to
changes in mercury loading. At each site, we added mercury to mesocosms at 0.5, 1.0, and 2.0 times the current
ambient loading rate (about 22 g/m2/y), and dedicated two mesocosms as experimental controls. At each site we
also constructed clear plastic "roofs" for two mesocosms, which excluded mercury deposition from contemporary
rainfall, but allowed for exchange of air and light to promote algal and plant productivity.
To distinguish between "new" and "old" (previously existing) mercury, mesocosm dosing was conducted
using stable isotopes of mercury (e.g., 201Hg, 202Hg), which can be distinguished from ambient, mercury using a
mass spectrometer. The examination of new versus old mercury was also tested by adding multiple Hg doses in the
same mesocosms but, at different times, and using different isotopes for each addition. It had been hypothesized that
101
the mercury contamination problem may continue for very long periods of time if existing mercury pollution in soils
and sediment sustained the mercury cycle. Results of these types of experiments, therefore, are significant for
assessing the potential effectiveness of mercury emissions reductions on mercury cycling in the Everglades.
Results from the mercury dosing experiment revealed several important findings. First, there is a positive and
linear relation between mercury added and the production of MeHg in the Everglades. Second, there is an exceptionally
close tie between mercury added and bioaccumulation of the added mercury in fish (Gambusia); the relation
has a coefficient of determination greater than 0.9. Last, there is an "aging effect" for new mercury added to the
ecosystem, such that more recent doses of mercury isotopes are more likely to be bioaccumulated than older mercury.
All these results support the conclusion that recent mercury additions are proportionally more responsible for
sustaining mercury exposure to wildlife and humans in south Florida, and any attempts to reduce current loading
rates would likely have rapid and positive effects.
In 2001 we expanded the experimental design of our mesocosm experiments to examine the effects of sulfate,
phosphate, and DOC dosing on mercury cycling. In addition, a new experimental site in Loxahatchee National
Wildlife Refuge (WCA1) was added. Because DOC and sulfate levels in WCA2 and WCA2B are elevated due to
runoff from the EAA, sulfate and DOC dosing could only be performed at our sites in WCA 1 and 3, where more
pristine conditions exist. Also, because ecosystems can require extended periods of time to achieve a new equilibrium
after the addition of phosphate, phosphate-dosing mesocosms previously established by researchers from the
South Florida Water Management District were accessed and sampled. Lastly, in some mesocosms, we conducted
mixed addition experiments (mercury and sulfate, and mercury and DOC) to test for possible synergistic or antagonist
effects of co-dosing.
The mercury, sulfate, DOC, and phosphate addition experiments revealed several novel observations. Surprisingly,
the addition of DOC alone stimulated the production of additional MeHg from "old" mercury in sediments.
In the mixed DOC plus mercury addition experiments we observed greatly elevated methylation of the added
mercury isotope, about 4 to 8 times greater than when mercury alone was added. These results suggest DOC is
directly involved in the methylation process, rather than the common assumption that DOC is simply an attractive
ligand for mercury in aqueous solution. Finally, when compared against the mercury-only dosed mesocosms, the
mixed sulfate plus mercury mesocosms, yielded significant additional isotopically-labeled MeHg. However, high
sulfate dosing levels gave rise to lower overall MeHg formation, which is consistent with our previous field observations
in WCA2 where very high levels of sulfate contamination exist and these high levels reduce mercury methylation
rates by sulfide inhibition. Lastly, no clear trend could be observed between phosphate dosing level and
MeHg formation and accumulation.
Contact: David P. Krabbenhoft, U.S. Geological Survey, 8505 Research Way, Middleton, WI 53562 Phone: 608-
821-3843, FAX: 608-821-3843, dpkrabbe@usgs.gov
102
Water Quality in Big Cypress National Preserve and Everglades National Park ---
Trends and Spatial Characteristics of Selected Constituents
By Benjamin F. McPherson1, Ronald L. Miller1, and Robert Sobczak2, Christine Bates2
1U.S. Geological Survey, Center for Coastal and Watershed Studies, Tampa, FL., USA
2National Park Service, Ochopee, FL., USA
The National Park Service (NPS)
maintains hydrologic monitoring stations for
measuring water level (stage) and water quality
in Big Cypress National Preserve and
Everglades National Park (fig 1). The data
collected at these stations provide a historical
baseline for assessing hydrologic conditions
and making a wide range of management
decisions. We have assessed selected waterquality
data at these stations and at nearby
canal sites for the period of record, 1959-
2000, to define baseline conditions and to
evaluate whether long-term trends have
occurred.
Seasonal changes in water levels and
flows in Big Cypress National Preserve and
Everglades National Park affect water quality.
As water levels and flows decline during
the dry season, physical, geochemical, and
biological processes increase the breakdown
of organic materials and the build-up of
organic waste, nutrients, and other constituents
in the remaining surface water. For
example, during much of the year, concentrations
of total phosphorus in the marsh usually
are less than 0.01 milligrams per liter (mg/L),
but during the dry season, concentrations
sometimes rise briefly above this value and,
occasionally under drought conditions,
exceed 0.1 mg/L.
Long-term changes in water levels,
flows, water management, and upstream land
use also affect water quality in Big Cypress National Preserve and Everglades National Park, based on analysis of
available data (1959-2000). Specific conductance and concentrations of chloride increased in the Taylor Slough and
Shark River Slough in the 1980s and early 1990s; for example, chloride concentrations more than doubled from 1960
to the 1990, primarily due to greater canal transport of high-dissolved solids into the sloughs. Some of the long-term
trends in sulfate and total phosphorus were likely attributable to the high percentage of values reported as "less-than"
and "zero", and to changes in reporting levels over the period of record. High spikes in nutrient concentrations were
evident during dry periods of the 1980s and attributable to (1) increased canal inflows of water that is nutrient-rich
relative to marsh inflows, (2) increased nutrient releases from breakdown of organic bottom sediment, or
(3) increased build-up of nutrient waste from concentrations of aquatic biota and wildlife in remaining ponds. Long-
P36
Everglades
National
Park
Mexico
Florida
Bay
0 5 MILES
Everglades
Agricultural Area
Miami
Canal
L28N
Canal
L28
North
Feeder
West
Feeder
A12
S190
S140 A2
A1
A3
A13
A14
A4
P37
TSB
P35
P34
P33
A9
AB
A B D
A5
S344
S343
S12s
S333
S332
Taylor
Slough
Shark River
Slough
EP
L67
Ext
L28
L67
A
B
arron
River
Canal
L67
C
75
C-111
A5
S332
L28
STATION
Location
and number
CONTROL
STRUCTURE
Location and
number
LEVY Location
and number
-
-
-
EXPLANATION
Alligator
Alley
Whitewater
Bay
40 Mile
Bend
Tamiami
Trail
BR105
(A6)
Monroe
Turner
River
NE1 NP201
S177
S18C
Big Cypress
National Preserve
L31
Water
Conservation
Area 3A
C
River
New
US41
Bay
de Leon
InterceptorCanal
Ponce
Gulf of
Location
of Study
Area
Florida
41
Figure 1. Hydrologic monitoring stations in Big Cypress National
Preserve and Everglades National Park
103
term changes in water quality over the period of record are less pronounced in the western Everglades and the Big
Cypress Swamp, however, seasonal and drought-related changes are evident.
Water quality varies spatially across the region due to natural variations in geology, hydrology, and vegetation
and because of differences in water management and land use. Nutrient concentrations are relatively low in Big
Cypress National Preserve and Everglades National Park compared with concentrations in parts of the northern
Everglades that are near agricultural and urban lands. Concentrations of total phosphorus generally are higher in Big
Cypress National Preserve (median values, 1991-2000, were mostly above 0.015 mg/L) than in Everglades National
Park (median values, 1991-2000, below 0.01 mg/L), probably because of higher phosphorus in natural sources such
as shallow soils, rocks, and ground water in the Big Cypress region than in the Everglades region. Concentrations
of chloride and sulfate, however, are higher in Everglades National Park (median values in Shark River Slough,
1991-2000, mostly above 2 mg/L sulfate and 50 mg/L chloride) than in Big Cypress National Preserve (median values,
1991-2000, less than 1 mg/L sulfate and at most sites less than 20 mg/L chloride) probably due to the canal
transport system that conveys more water from an agricultural source into Everglades National Park than into Big
Cypress National Preserve.
Trace elements and contaminants such as pesticides and other toxic organics are in relatively low concentrations
in Big Cypress National Preserve and Everglades National Park compared with concentrations in parts of the
northern Everglades, which are near agricultural and urban sources. Concentrations rarely exceeded aquatic life criteria
in Big Cypress National Preserve and Everglades National Park. Atrazine was the only pesticide that exceeded
the criteria (in 2 out of 304 samples). The pesticides p, p-DDE, lindane, and heptachlor expoxide exceeded criteria
in canal bed sediments in 16, 2, and 1 percent of the samples, respectively.
Contact: McPherson, Benjamin F. 10500 University Center Dr., Suite 215, Tampa, FL, 33612, Phone: 813-975-
8620, ext 126, Fax 813-975-0839, bmcphers@usgs.gov
104
Whole-ecosystem phosphorus budgets for freshwater Everglades wetlands
By Gregory B. Noe1, and Daniel L. Childers2
1U.S. Geological Survey, Reston, VA., USA
2Florida International University, Miami, FL., USA
We are currently developing synthetic, whole-ecosystem phosphorus (P) budgets for freshwater Everglades
wetlands. The development of P budgets will aid attempts to understand the impact of P enrichment on oligotrophic
Everglades wetland ecosystems and prioritize future research by identifying knowledge gaps. Preliminary P budgets
were developed for oligotrophic wet prairie (slough; fig. 1), oligotrophic Cladium, mixed Cladium/Typha, and Typha
marsh ecosystem types. Mean P standing stocks (g P m-2) for each component were quantified by reviewing published
and unpublished literature on biomass and P concentrations in the Everglades. Fluxes (g P m-2 yr-1) were
determined by a variety of methods, including estimates of C turnover (assuming fixed C:P), water velocity, 32P
cycling, and long-term soil accretion rates. No reasonable estimate could be independently derived for many flux
rates, in which case flux was determined by mass balance. As a first approximation, the P budgets assume steadystate
conditions, 12-month hydroperiod, no mega-consumers, and no consumption of macrophyte detritus by consumers.
In addition, nutrient turnover rates of periphyton, floc, and consumers in Cladium marsh were assumed to
be equivalent to wet prairie marsh.
Mean total ecosystem P standing stocks ranged from 3.46 in wet prairie, 3.65 in Cladium, 7.29 in Cladium/
Typha, to 10.44 g P m-2 in Typha marsh. In wet prairie, soils (0-10 cm) held the most P in the ecosystem (72 percent),
followed by floc (22 percent), live macrophyte rhizomes and roots (2.3 percent), aquatic consumers (1.5 percent),
periphyton (1.2 percent), live aboveground macrophytes (1.1 percent), dead aboveground macrophytes (0.4%), and
the water column (0.2 percent). Phosphorus partitioning, the percentage of total ecosystem standing stock, differed
Figure 1. The P budget for oligotrophic wet-prairie marsh. Boxes represent the P standing stock
(both organic and inorganic) of the different ecosystem components (g P m-2) and arrows indicate
net annual P fluxes between components (g P m-2 yr-1). Underlined fluxes have high uncertainty.
105
in oligotrophic Cladium and P-enriched Cladium/Typha and Typha marshes. In Cladium marsh, P partitioning is 4x
and 6x greater in live and dead aboveground macrophytes, respectively, and 5x less in periphyton compared to the
same components in wet prairie. As Everglades wetlands receive additional P loading and shifts in macrophyte species
occur, live and dead aboveground macrophytes store increasingly larger proportions of whole-ecosystem P
standing stock. Live aboveground macrophyte tissues store 3x and 9x larger proportions of ecosystem P in Cladium/
Typha and Typha marsh, respectively, than in oligotrophic wet prairie. Similarly, dead aboveground macrophyte tissues
increase P partitioning 11x in Cladium/Typha and 7x in Typha marsh. Periphyton partitioning increases slightly
in the P-enriched ecosystems. Finally, floc stores 2x smaller proportions of P in the ecosystem as it enriches with P.
Long-term, steady state P dynamics in oligotrophic Everglades marshes are limited by average inputs (atmospheric
deposition, 0.03 g P m-2 yr-1) and outputs (soil burial, 0.09 g P m-2 yr-1). Very large quantities of P flow in
and out of a given area of oligotrophic marsh (~ 800 g P m-2 yr-1), but net ecosystem uptake from the water column
(0.06 g P m-2 yr-1) is constrained by atmospheric input and soil burial. In wet prairie marsh, slow turnover of macrophyte
stems and low P standing stocks result in relatively low net annual P flux from macrophytes compared to
periphyton, floc, and consumers. For example, periphyton net annual through-flux is estimated to be 1.33 g P m-2
yr-1, while live aboveground macrophyte tissues cycle 0.04 g P m-2 yr-1. The smaller periphyton and greater macrophyte
biomass in Cladium marsh relative to wet prairie are paralleled in less periphyton (0.27 g P m-2 yr-1) and
more macrophyte (0.23 g P m-2 yr-1) throughput. Phosphorus enrichment, and the invasion of Typha, greatly
increases the importance of macrophytes (both P standing stocks and throughput) to the ecosystem P budget. Macrophyte
senescence results in the annual net movement of 1.59 g P m-2 yr-1 in Typha marsh.
Although data on biomass and P concentrations, and hence P standing stocks, are plentiful, few measurements
of P fluxes exist. Relative to fluxes involving soils and macrophytes, fluxes between the water column, floc, periphyton,
and consumers are less well quantified. In addition, most P flux rates have been measured in wet prairie
and few rate measurements exist for Cladium or Typha marsh. Furthermore, most P cycling occurs in the water column
between water, periphyton, floc, and consumers, while soil stores the largest amount of P in the ecosystem.
Finally, P enrichment in the Everglades results in an increased importance of macrophytes to P cycling.
As part of the Florida Coastal Everglades LTER, these nutrient budgets will be expanded in the future to
include site-specific data and nitrogen and carbon dynamics. In addition, nutrient budgets can serve as an integrative
and synthetic tool for comparing freshwater marsh, mangrove, and seagrass ecosystems, and the impacts of nutrient
enrichment on ecosystems.
Contact: Gregory B. Noe, U.S. Geological Survey, 430 National Center, Reston, VA, 20192, Phone: 703-648-
5826, Fax: 703-648-5484, gnoe@usgs.gov, Water Quality
106
Sulfur Contamination and Geochemistry of the Everglades
By William Orem, Harry Lerch, Anne Bates, Margo Corum, and Marisa Beck
U.S. Geological Survey, Reston, VA, USA
Sulfur is an important water quality issue in the Everglades because of its role in microbial sulfate reduction
and the methylation of mercury. Microbial sulfate reduction produces toxic hydrogen sulfide (H2S) as an endproduct,
and accumulation of H2S in sediment porewater may change sediment redox chemistry and the ability of aquatic
macrophytes and other marsh plants to maintain necessary oxygen levels in root systems. Microbial sulfate reduction

also produces methylmercury (MeHg), a neurotoxin that is bioaccumulated. MeHg has been found in high concentrations
in freshwater fish from the Everglades, and poses a potential threat to fish-eating wildlife and to human
health (especially pregnant women) through fish consumption. Based on USGS results, sulfur appears to play a key
role in regulating both the magnitude and distribution of MeHg within the ecosystem.
Freshwater wetlands typically have low sulfur concentrations, but we discovered high concentrations of sulfate
sulfur in surface water of the northern Everglades. Independent studies conducted by the U.S. EPA and the South
Florida Water Management District have also documented high concentrations of sulfate in large parts of the northern
Everglades. Marshes in portions of the Water Conservation Areas (WCA's) have surface water sulfate concentrations
that average nearly 60 mg/l, compared to concentrations of 1 mg/l in pristine areas of the Everglades. Areas
with high surface water sulfate concentrations are concentrated in the northern WCA's, and especially near sites of
canal discharge and along canal levees. Even higher concentrations of sulfate (average >70 mg/l and sometimes
approaching 200 mg/l) were found in canal water draining from the Everglades Agricultural Area (EAA). This canal
water appears to be the major source of excess sulfate entering the Everglades. The high loads of sulfate entering the
ecosystem stimulate microbial sulfate reduction, and areas with high concentrations of sulfate in surface water also
have very high levels of toxic H2S in sediment porewaters. Porewater sulfide concentrations range from 5,000 ppb
at marsh sites near canal discharge, to <0.05 ppb at pristine sites. Porewater sulfide concentrations were highly correlated
with surface water sulfate concentrations.
We used sulfate concentration data and the sulfur (d34S) and oxygen (d18O) isotopic composition of sulfate
in marsh surface water, canal water, rainwater, and groundwater to trace the source(s) of the excess sulfate entering
the Everglades. Although the canals originate in Lake Okeechobee, the lake on average contributes only about 20
percent of the sulfate observed in the canals. Rainwater has too little sulfate to account for the high sulfate concentrations
observed in the canals and in large portions of the Everglades. Groundwater beneath the Everglades has
either too low a sulfate concentration or a d34S signature that is inconsistent with that of surface water in the Everglades.
Both sulfate concentration data and the d34S values of sulfate in surface water from the Everglades and canal
water confirm that canals in the EAA are the major source of excess sulfate entering the ecosystem. Furthermore,
results showed that canal water with the highest sulfate concentrations had d34S values of +16 per mil, which is consistent
with the d34S signature of agricultural sulfur (a soil amendment used in the EAA). Sulfate extracted from the
upper 10 cm of soil in a sugarcane field in the EAA also had a d34S value of about +16 per mil. These data suggest
that agricultural sulfur is the principal source (but not the only source) of excess sulfate entering the canals and Everglades
wetlands.
The high levels of sulfate entering the Everglades from canal discharge have had important effects on the ecosystem.
The H2S buildup in sediment porewater at sites in the northern Everglades has significantly lowered redox
potentials in the sediments. The lower redox conditions and high levels of H2S in the sediments may have an impact
on vascular plant growth in the Everglades by limiting oxygen penetration to roots. It is noteworthy that cattails have
replaced sawgrass as the dominant macrophyte at sites heavily impacted by sulfur, although factors other than sulfur
(e.g. eutrophication and high water levels) may also be influencing this change. Similarly, tree islands have disappeared
mostly from the northern Everglades, in areas heavily impacted by sulfur.
The effect of excess sulfur load on MeHg production in the Everglades is complex. Sulfur appears to stimulate
MeHg production through increased microbial sulfate reduction, but buildup of sulfide in sediment porewater inhibits
MeHg production. The balance between these two effects of sulfur influences both the magnitude and location of
107
MeHg production in the Everglades, and produces the interesting effect that the zone of maximum MeHg production
occurs in areas with sulfur loads only moderately higher than natural. This MeHg "Goldilocks" zone (where sulfur
levels are just right) occurs in the central portion of WCA 3A, at the front end of the northern Everglades sulfur
contamination plume. The complex relationship between sulfur geochemistry and MeHg production in the Everglades
was first hypothesized from field studies at various sites in the ecosystem. This hypothesis has been further
solidified from experimental studies in the Everglades using mesocosms. These mesocosm studies show that
increasing sulfate concentrations increases MeHg production up to sulfate concentrations of about 10 mg/l. At sulfate
concentrations >10 mg/l buildup of sulfide from microbial sulfate reduction inhibits the methylation of Hg.
The principal sink for sulfur entering the Everglades ecosystem is long-term storage in sediments. Sequestration
of sulfur in sediments typically results from microbial reduction of sulfate to sulfide, and subsequent reaction
of sulfide with either organic matter, to form organic sulfur compounds; or metals, to form insoluble metal mono-
and disulfides. The dominant sulfur species in Everglades sediments is organic sulfur. Sulfur accumulation rates
(gm-2 day-1) in Everglades sediments ranges from 9.0 x 10 -3 to 0.38 x 10-3, a difference of more than 20 fold. The
highest sulfur accumulation rates occur in brackish water mangrove (average of 6.0 x 10-3), and sulfur-contaminated
freshwater marsh areas (average of 4.5 x 10-3). Sulfur accumulation rates average about 1.6 x 10-3 at pristine sites.
Sulfur in sediments represents a reservoir of reduced sulfur that may be reoxidized and remobilized during
drought/fire and subsequent rewetting. Because drought and fire are frequent occurrences in the Everglades ecosystem,
the remobilization of sulfur from sediments is an important factor influencing sulfur and mercury geochemistry.
Studies of sulfur remobilization were conducted in northern WCA 3A following a burn and subsequent
rewetting in that area during 1999. The average sulfate concentration in surface water at 14 sites was 58.6 mg/l
immediately after the burn and rewetting of this area, compared to an average sulfate concentration of 5.10 mg/l
before and over a year after the burn. The sulfate remobilized after the burn and rewet stimulated sulfate reduction
and extreme levels of MeHg production (see abstract by Krabbenhoft et al., this volume). Cores from burned and
control (e.g. unburned) sites in northern WCA 3A showed that burned sites had significantly lower total sulfur contents
in sediments. A simulated laboratory experiment was conducted in which mini-cores were dried under simulated
natural sunlight in controlled laboratory conditions for a specified period of time and then rewetted to further
examine the effects of fire/drought on S geochemistry and MeHg production. Results verified the remobilization of
sulfate and stimulation of MeHg production following fire/drought events. Ecosystem and water managers must
consider the effect of drying and rewetting portions of the Everglades in order to avoid exacerbating the already
extensive MeHg problem in the Everglades.
Contact: William Orem, U.S. Geological Survey, 956 National Center, Reston, VA 20192, 703-648-6273
(office); 703-648-6419 (fax); borem@usgs.gov
108
Source Identification of Florida Bay's Methylmercury Problem: Mainland Runoff
versus Atmospheric Deposition and In Situ Production.
By Darren Rumbold1, Larry Fink1, Nicole Niemeyer1, Angela Drummond1, David Evans2, David Krabbenhoft3, and
Mark Olson3
1South Florida Water Management District, West Palm Beach, Fl., USA
2National Oceanic and Atmospheric Administration, Beaufort, NC., USA
3US Geological Survey, Middleton, WI., USA
Mercury is a contaminant of concern in many areas of the world, including the Florida Everglades and Florida
Bay, where fish consumption advisories have been issued for select species. Although atmospheric loading is often
the dominant proximate source of inorganic mercury to many water bodies, the complication lies in the relation
between influx of inorganic mercury and the amount that is methylated post deposition by sulfate reducing bacteria.
The latter process is of fundamental concern because methylmercury (MeHg) is the more toxic and bioaccumulative
form that can build up in the food chain to levels harmful to humans and other fish-eating animals. While much has
been learned recently about mercury cycling in the Everglades, less is known about Florida Bay's mercury problem.
Most importantly, there remains an incomplete understanding of the factors that govern production, transport and
fate of MeHg in the bay.
Accordingly, in 2000, we integrated two on-going studies into a single multi-agency study, the objectives of
which were to: 1) determine the source of MeHg driving bioaccumulation in eastern Florida Bay and, 2) assess the
potential for modifications in freshwater delivery stemming from the Comprehensive Everglades Restoration Plan
(CERP) to affect the bay's mercury problem. As a first step, we began collecting surface water, sediment and fishes
along two transects into the bay. The first transect begins in the C-111 Canal and extends south through Joe Bay out
to Nest Key. The second transect follows the flow path of Taylor Slough out through Little Madeira into the bay. In
addition, a single reference site was sampled in the center of Whipray Basin, which receives little direct runoff.
Finally, to assess the potential for in situ production of MeHg in Florida Bay sediments, we conducted a series of net
methylation rate assays using intact sediment cores and stable mercury isotopes.
Sampling was completed in September 2002. Preliminary results describe significant spatial distributions and,
in some instances, seasonal differences. Most importantly, levels of mercury in certain gamefish exceeded 0.5 mg/
kg and sometimes exceeded 1.5 mg/kg (for further details on mercury in bay fishes, see Evans et al. this volume).
Concentrations of total mercury (THg) in unfiltered surface water collected quarterly along the transects ranged from
0.38 ng/l to 5.98 ng/l (median was 1.55 ng THg/l; n = 115); whereas MeHg concentrations ranged from <0.02 ng/l
to 1.79 ng/l (median was 0.08 ng MeHg/l; n = 115). Both THg and MeHg concentration increased substantially in
the mangrove transition zone following late summer rains, with concentration maxima occurring in Taylor River
(fig. 1).
On average, non-filterable or dissolved forms (<0.45 m) accounted for 80 percent and 73 percent of the THg
and MeHg, respectively. MeHg constituted 8 percent of the non-filterable THg, but ranged up to 36 percent in the
transition zone of Taylor River. Interestingly, concentrations of THg and MeHg in the surface water collected from
the reference site in Whipray Basin (medians of 1.29 ng/L and 0.15 ng/L, respectively; n = 10) were not significantly
different than concentrations observed along the two flowpaths.
THg and MeHg in sediments collected semi-annually from the bay and upstream canals ranged from 5.8 to
145.6 ng/g dry weight (median was 19.9 ng THg/g) and from 0.05 to 5.4 ng/g dry weight (median was 0.26 ng MeHg/
g), respectively. Although the highest median THg concentration occurred in sediment from the C111 Canal (115
ng/g), sediments from the mangrove transition zone along both flowpaths also contained relatively high levels of
THg. The highest median sediment-MeHg (1.76 ng/g) occurred at the mouth of Taylor River. While these data must
be normalized based on total organic carbon (measured in later cores) before any definitive conclusions can be
reached, it was clear that sediments both from upstream marshes and from the bay often contained elevated concen-
109
trations of MeHg. Sediments collected from near Nest Key, for example, contained up to 1.8 ng MeHg/g, which
constituted almost 8 percent of the THg present. These results came as a surprise because, except for one or two
recent studies, inhibition of mercury methylation had been reported for marine environments due to sulfidic porewaters
and salinities. For these reasons, net methylation rates were measured in intact cores using stable isotope tracers
of 202Hg (and more recently, to measure demethylation, CH3
199Hg). Results from the first set of cores showed
methylation rates in the 0-4 cm horizon to range from <1 percent to 11.2 percent conversion during the 24-h incubation
period, with sediments from several sites in the bay having higher methylation rates than sediments from the
mangrove transition zone. Although these data must be viewed in the context of a completed loading assessment,
they indicate that mercury bioaccumulation in the bay is, at least in part, driven by in situ production. These data
2/00 6/00 10/00 2/01 6/01 10/01 2/02 6/02 10/02
MeHg (ng/L)
0.0
0.3
0.6
0.9
1.2
1.5
1.8
M M
M
M
M A
A
A
A A
A
A
A
A
A
T
T
T T
T
T
T
T
T
T
L
L
L
L L
L
L L L
L
B
B
B
B
B B B B B
B
R
R
R R
R
R R
R R R
2/00 6/00 10/00 2/01 6/01 10/01 2/02 6/02 10/02
C1 C1
C1
C1
C1
C1
C1 C1
C1
C1
C2 C2 C2
C2
C2 C2
C2
C2
C2
C2
M
M M
M
M
J
J J
J
J
J
J J
J
J W
W
W
W
W
T
T
T
T
T T
T T
T
T
S
S S S
S S
S
S
S S
N
N
N
N
N
N
N
N
N
N
C111 at S178 C1
C111 at S18C C2
FW Marsh M
Joe Bay NE creek J
Joe Bay west W
Trout Creek T
Stump Pass S
Nest Key N
2/00 6/00 10/00 2/01 6/01 10/01 2/02 6/02 10/02
C1 C1 C1
C1
C1 C1 C1
C1 C1
C1
C2 C2 C2 C2 C2 C2 C2
C2
C2
C2
M
M
M
M
M
J
J
J J
J
J J
J
J
J
W W W
W
W
T T
T T T T
T T T
T
S S S S S S S S S
S
N
N
N N N N N N N
N
2/00 6/00 10/00 2/01 6/01 10/01 2/02 6/02 10/02
THg (ng/L)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
M
M
M
M
M
A
A
A
A
A
A
A
A
A
A
T
T
T T
T
T
T
T
T
T
L
L L
L
L
L
L
L
L
L
B
B
B
B
B
B
B
B
B
B
R R R R
R
R R
R
R
R
FW Marsh M
Argyle Henry pond A
Taylor River mouth T
Little Madiera L
Outer Bay B
Whipray Basin ref. site R
2/00 6/00 10/00 2/01 6/01 10/01 2/02 6/02 10/02
Monthly mean flows (CFS)
0
200
400
600
800
1000
Taylor River flows
2/00 6/00 10/00 2/01 6/01 10/01 2/02 6/02 10/02
Monthly rainfall totals (in)
0
2
4
6
8
10
12
14
16
Trout Creek flows
Date
Figure 1. Time series of total mercury (THg), methylmercury (MeHg), flows and rainfall (bars)
measured along two transects into northeastern Florida Bay. Note, rainfall was recorded in Joe Bay
and flows after 6/2002 not yet available.
110
also indicate that understanding the MeHg problem in the bay will require a more complete understanding of the
fluxes and bioavailability of inorganic mercury for methylation.
When completed, results of this study should improve our understanding of mercury cycling in Florida Bay,
and our ability to make informed decisions about the management of Everglades inflows for the restoration of the
sport fishery and the protection of fish-eating wildlife in Florida Bay.
Contact: Rumbold, Darren, SFWMD, Mail code 4720, 2301 McGregor Blvd, Ft. Myers, Fl 33901, 941-338-
2929, Fax 941-338-2936, drumbol@sfwmd.gov
111
Effects of Microhabitats on Stable Isotopic Composition of Biota in the Florida
Everglades
By Scott D. Wankel1, Carol Kendall1, Paul McCormick2, and Robert Shuford2
1U. S. Geological Survey, Menlo Park, CA., USA
2South Florida Water Management District, West Palm Beach, FL., USA
Attached algae (periphyton) serve an extremely important role in the Everglades ecosystem as a source of
organic carbon to foodwebs. As important primary producers within the wetland ecosystem, they establish the isotopic
composition of the base of the foodweb. However, this initial algal composition is established by the composition
of the inorganic nutrients (DIC and DIN) in the water column, the compositions of which can vary
significantly. Subsequently, the detrital foodweb begins with the decomposition of this plant material (composed
of both emergent macrophytes and periphyton). The bacteria decomposing the detritus may have a lower 13C value
than the original plant material - imparting a lower 13C signature to organisms consuming the detritus and assimilating
the lighter bacterial carbon. Thus, foodwebs capitalizing on detrital components will exhibit isotopic variability
due both to the variations in the original plant material and the processes decomposing the detrital material
itself. An understanding of how these processes and linkages operate is critical to any interpretation of stable isotope
data from the Everglades and to evaluating the success of the restoration process.
Aquatic vegetation and detritus samples were collected from various sites along two parallel transects in
WCA 2A (Sites E1, E4, E5, F1, F4, F5, and U3). Sampling was carried out during the wet season (September 1998)
and the dry season (March 1999) in order to discern any seasonal variations in isotopic composition. While the data
indicate very little difference in 13C and 15N between seasons, there was a strong spatial trend moving from the
canal into the marsh center. 15N values of vegetation (living and dead) tend to decrease (from around +5 to
around 0) with distance from the canal, while 13C values show an increase with distance from the canal (from -
30 to -26). Shrimp and other invertebrate samples collected at the same times also show approximately a 2
decrease in 15N and approximately a 5 increase in 13C along the same gradient.
In addition to the sampling
of the primary vegetation and
detrital matter at each site,
benthic macroinvertebrates were
collected within several microhabitats
at each site. Microhabitats
sampled at each site varied
but included open-water sloughs,
cattail marsh, sawgrass marsh
and spikerush stands. The microhabitats
were not farther than
100m apart within each site. At
each site, there were differences
between the 13C and 15N of
invertebrates from different habitats.
At U3, for example, there
was a 0.5 to 1 variation in 13C
and a 1 to 2 variation in 15N
between marsh types (fig. 1).
However, the only generalization
that can be made for the microhabitat
variations between sites
was that invertebrates had lower
Figure 1. Differences in the 13C and 15N of selected invertebrates collected during
the dry season (March 1999) at 3 different types of microhabitats (spikerush marsh,
sawgrass marsh, open slough) near site U3 in WCA2A.
112
13C values in sloughs than in cattail or sawgrass marshes. The differences in isotopic composition of benthic macroinvertebrates
within microhabitats at each site suggest localized influences, perhaps due to the relative rates of photosynthesis
and respiration.
Additionally, in October 1997, algal growth experiments were conducted at site U3, a pristine marsh site
within WCA 2A. Plexiglass plates were submerged within three slough-wet prairie habitats and allowed to colonize
with algae for 8 weeks. Site U3-1 was a slough with abundant water lilies whereas the other two sites were spikerush
marshes. Weekly samples collected from each site were analyzed for 13C and 15N, as well as diatom species composition
(fig. 2). 13C of the algae ranged from -32 to -27, while the 15N ranged from +2 to +6. Isotopic
compositions showed discrete temporal trends over the 8-week experiment that correlated well with changes in the
dominant diatom species. These data are consistent with spatial variation in local microhabitat biogeochemistry and
species composition controlling bulk algal isotopic composition.
Contact: Scott Wankel, U.S. Geological Survey, 345 Middlefield Road, MS 434, Menlo Park, CA, 94025, Phone:
650-329-4303, Fax: 650-329-5590, sdwankel@usgs.gov
Figure 2. Changes in 13C and 15N of algae growing on plates at 3 locations near site U3 in
WCA2A.
113
Spatial and Temporal Patterns in Isotopic Composition of Aquatic Organisms at
Everglades Nutrient Removal Project Sites
By Scott D. Wankel, and Carol Kendall
U. S. Geological Survey, Menlo Park, CA., USA
The Everglades Nutrient Removal Project (ENR) began in 1994 with the goal of reducing the phosphorus (P)
load downstream of the Everglades Agricultural Area. The effects of different vegetative habitats in treatment cells
on P loads were evaluated. Cell 3 is dominated by emergent macrophytes such as cattails and water hyacinths, while
cell 4 is dominated by an assemblage of submerged macrophytes and periphyton. During some sampling periods,
there appeared to be significant differences in the mercury (Hg) concentrations of some aquatic organisms from the
different cells, perhaps as a consequence of differences in food web structure (Hurley et al., 1999). We have analyzed
sets of biota collected in 1997-98 from several locations in the four different cells of the ENR for 15N and
13C to (1) better understand the biogeochemical controls on the isotopic composition of Everglades foodwebs, and
(2) assess whether there is any evidence for differences in food webs at the different sites that might explain differences
in Hg concentrations.
Statistically significant differences in the isotopic composition (both 13C and 15N) of muscle tissue from
mosquitofish, least killifish, bluefin killifish, sailfin molly, and grass shrimp in Cell 3 between June 1997 and June
1998 suggest a shift in the isotopic composition of the diets of these fish. Samples collected in June 1997, January
1998, and June 1998 show increasing 15N values and decreasing 13C values. For example, the 15N of least killifish
increase from +11.3 to +13.2 while the 13C values decrease from -25 to -29. This swing in the isotopic
composition of these fish can be explained either by a change in diet or by a shift in the isotopic composition of their
food source. The close tracking of the isotopic compositions of omnivorous fish (mosquitofish, killifish) with herbivorous
fish (sailfin molly) over time suggests changes in the isotopic compositions of the algae. Since the isotopic
composition of algal material is controlled largely by the composition of the inorganic nutrients within the water
column, the isotopic composition of the fish reflects changes in the biogeochemistry operating in the water column
at the time of algal growth.
The 15N and 13C values for mosquitofish, sailfin molly, and shrimp collected in June 1998 from Cell 3 and
Cell 4 show significantly different averages and distributions (fig. 1). The data from Cell 3 plot in distinct clusters
whereas data from Cell 4 show a striking alignment along a negative slope. It is not clear whether these differences
reflect differences in diet or just differences in the isotopic composition of plants at the base of the food webs. At
Figure 1. 13C and 15N values of selected biota collected from Cell 3 and Cell 4 in June 1998.
114
both sites, sailfin mollys have the lowest 15N and highest 13C values, shrimp have intermediate values, and mosquitofish
have the highest 15N and lowest 13C values. Hence, there appears to be no major differences in their
relative trophic positions in June 1998. Therefore, it is likely that the differences in 13C and 15N of organisms
between Cell 3 and Cell 4 reflect differences in the isotopic composition of the diets between cells. Aquatic plants
from Cell 4 show a much greater range of 13C values than plants from Cell 3, but a similar range of 15N values.
The larger range of 13C values in Cell 4 may be related to the higher amounts of open water and periphyton growth
in Cell 4 compared to Cell 3. Increased light penetration may cause larger changes in the 13C of dissolved inorganic
carbon (DIC) in the water column by allowing more light penetration and therefore more benthic photosynthesis.
Higher rates of benthic photosynthesis would lead to higher 13C values as seen in the organisms sampled in Cell 4.
The variations in isotopic composition over both time and space within the ENR emphasize the importance of
localized biogeochemistry for interpretation of stable isotope data. Fluctuations in water depth (hydroperiod) and
plant cover over time in the ENR may explain a significant portion of the variability of 13C and 15N of primary
consumers (mosquitofish, killifish, sailfin mollies). Understanding the mechanisms for the foodweb base shift,
whether it is a shift in diet or isotopic composition of the diet (or both?), is critical to tracing contaminant bioaccumulation
within these Everglades foodwebs.
REFERENCES
Hurley, J.P., Cleckner, L.B., and Gorski, P., 1999. Everglades Nutrient Removal Project small fish bioaccumulation
study - final report to the SFWMD (contract PC C-8691-0300).
Contact: Scott Wankel, U.S. Geological Survey, 345 Middlefield Road, MS 434, Menlo Park, CA, 94025, Phone:
650-329-4303, Fax: 650-329-5590, sdwankel@usgs.gov
115
An Evaluation of Contaminant Exposures and Potential Effects on Health and
Endocrine Status for Alligators in the Greater Everglades Ecosystem
By Jon J. Wiebe, Ken Rice, Carla M. Wieser, and Timothy S. Gross
USGS, Center for Aquatic Studies and the University of Florida, Gainesville, FL., USA
Alterations in sexual differentiation, endocrine function and health have been documented among alligators
in Central Florida as a potential response to environmental contaminants. These data suggest that exposure to sitespecific
sources, primarily agricultural sites and pesticides, may be responsible for these toxicities. The assessment
of exposures for alligators within the Greater Everglades Ecosystem is an essential component of current and future
assessments of risks and potential effects of proposed and ongoing restoration. To enable an assessment of contaminant
risks for the Greater Everglades Ecosystems it is critical that an initial, complete food-chain, characterization
of contaminants be conducted. These results would form the critical basis of any initial risk assessment and are
necessary for any evaluation and/or assessment of risk that may be related to restoration of the Greater Everglades
Ecosystem. In addition, these results would form the basis of any future evaluations of adverse effects, paired field
and laboratory studies, and the critical assessments or evaluations of restoration success or resultant adverse effects.
The current study evaluated contaminant exposures and potential physiological effects on alligators in the
Greater Everglades Ecosystem. Alligators (approximately 5 ft in length; n=10 animals per site during Fall 1999 and
2000) were collected and sacrificed from several specific sites involved in future restoration efforts: Everglades
National Park, Loxahatchee National Wildlife Refuge, Big Cypress National Preserve, and Water Conservation
Areas 2A, 3A-N and 3A-S. Several tissues were collected for contaminant analysis: blood, scute, liver, muscle, bile,
and fat. Contaminant analyses will include an assessment of chlorinated hydrocarbons (i.e. pesticides, PCB's,
PAH's), water-soluble herbicides, organophosphates, carbamates, and metals (i.e. mercury, lead, selenium etc).
Blood was utilized for blood chemistry assessments of health status and endocrine status (sex steroids and thyroid
function). Gonadal and liver tissues were examined histologically for an evaluation of reproductive status and liver
toxicity. Selected samples from several alligators were composited to assess the appropriate tissues for each contaminant
analysis. Samples collected during 1999 (approx. 3 animals per site) were also composited and analyzed
for selected contaminants (persistent pesticides and several current use pesticides). Plasma was analyzed for biomarkers
of reproductive status (estradiol and testosterone) and metabolism/thryroid function (T3 and T4).
Results for the preliminary
phase of this project indicated a differential
tissue distribution for each class
of contaminant. Lipid soluble pesticides
(i.e. chlorinated hydrocarbons)
were detectable in all tissues examined
except blood and scute. Blood
and scute concentrations of the chlorinated
hydrocarbon pesticides were, in
general, below detection limits. In
contrast, analyses of water-soluble
pesticides (i.e. current use pesticides),
organophosphates and carbamates
were routinely detected in blood.
Muscle tissue (i.e. fillets) were chosen
for the focus of these preliminary
analyses for the organochlorine pesticides,
while blood plasma was utilized
for the other pesticide contaminants.
Initial analyses were conducted on a composite of three alligators from each site and preliminary results are summarized
in figures 1 and 2.
Figure 1. Preliminary analysis of total organochlorine hydrocarbon pesticides for
several tissues from alligators across several broad regions of the Greater
Everglades ecosystem. Results are as ppb for wet weight of tissue. Lipid
concentrations did not differ between sites for each tissue. Note the differential
distribution of pesticides across tissues.
0
50
100
150
200
250
300
350
400
Loxahat chee Big Cypress WCA- 2A WCA- 3AN WCA-3AS ENP
Blood
Muscle
Scute
Liver
116
Results indicate site-specific patterns of contaminant exposure for alligators in the Greater Everglades Ecosystem,
and the potential for endocrine system and reproductive effects. These data demonstrate the need for a thorough
assessment of exposures for wildlife within the Greater Everglades ecosystem as an essential component of
current and future assessments of risks and the potential effects of proposed and ongoing restoration.
Contact: Timothy, Gross, USGS-BRD Florida Caribbean Science Center, 7920 NW 71st St., Gainesville, FL
32653, Phone: 352-378-8181 ext 323, Fax: 352-378-4956 Tim_s_gross@usgs.gov,
Figure 2. Preliminary analysis of organochlorine pesticides in muscle tissue for
alligators across several regions within the Greater Everglades ecosystem. Data is
listed as ppb. Note the increased exposures at the WCA;'s as compared to the
other sites.
0
50
100
150
200
250
300
350
Loxahat chee Big Cypress WCA- 2A WCA- 3AN WCA-3AS ENP
DDE
Methoxychlor
Chlordane
Dieldrin
Toxaphene
Atrazine
Diazinon
117
An Evaluation of Contaminant Exposures and Potential Effects on Health and
Endocrine Status for Largemouth Bass in the Greater Everglades Ecosystem
By Carla M. Wieser1, Jon J. Wiebe,1, D. Shane Ruessler1, Timothy S. Gross1, and Ted Lange2
1U.S. Geological Survey, Florida Integrated Science Center and the University of Florida, Gainesville, FL.
2Florida Fish and Wildlife Conservation Commission
Alterations in endocrine function and reproductive success have been documented among largemouth bass in
Central Florida as a potential response to environmental contaminants. These data suggest that exposure to site-specific
sources, primarily agricultural sites and pesticides, may be responsible for these toxicities. The assessment of exposures
for largemouth bass within the Greater Everglades ecosystem is an essential component of current and future
assessments of risks and potential effects of proposed and ongoing restoration. To enable an assessment of contaminant
risks for the Greater Everglades Ecosystems it is critical that an initial, complete food-chain, characterization of contaminants
be conducted. These results would form the critical basis of any initial risk assessment and are necessary
for any evaluation and (or) assessment of risk that may be related to restoration of the Greater Everglades Ecosystem.
In addition, these results would form the basis of any future evaluations of adverse effects, paired field and laboratory
studies, and the critical assessments or evaluations of restoration success or resultant adverse effects.
The current study evaluated contaminant exposures and potential physiological effects for largemouth bass in
the Greater Everglades ecosystem. Largemouth bass were collected and sacrificed from several specific sites
involved in future restoration efforts (32 sites, n=20 per site, over 750 samples): Everglades NP, Loxahatchee NWR,
Big Cypress NP, Canals including C111, L39, L5, U3, S5A, G3, Holyland; STA's 1, 2, 3, 4, 5 and 6; Water Conservation
Areas 2A, 3A-N, and 3A-S. Several tissues were collected for contaminant analysis: blood, liver, muscle, and
gonad. Contaminant analyses will include an assessment of chlorinated hydrocarbons (i.e. pesticides, PCB's,
PAH's), water-soluble herbicides, organophosphates, carbamates, and metals (i.e. mercury, lead, selenium, etc.).
Blood was utilized for blood chemistry assessments of health status and endocrine status (sex steroids and thyroid
function). Gonadal and liver tissues were examined histologically for an evaluation of reproductive status and liver

toxicity. Sex was identified as follows: the presence of ovarian tissue and absence of testicular tissue = female; presence
of testes and absence of ovarian tissue = normal male; and presence of testes with ovarian tissue = intersex .
Selected samples from several fish were composited to assess the appropriate tissues for each contaminant analysis.
Samples collected during 1999 (approx. 5 animals per site) were also composited and analyzed for selected contaminants
(persistent pesticides and several current use pesticides). Plasma was analyzed for biomarkers of reproductive
status (estradiol and testosterone) and metabolism/thryroid function (T3 and T4).
Results of the preliminary phase of this
project indicated a differential tissue distribution
for each class of contaminant. Lipid soluble
pesticides (i.e. chlorinated
hydrocarbons) were detectable in all tissues
examined except blood. Blood concentrations
of the chlorinated hydrocarbon pesticides
were, in general, below detection limits.
In contrast, analyses of water-soluble pesticides
(i.e. current use pesticides), organophosphates
and carbamates were routinely
detected in blood and tissues at similar levels.
Muscle tissue (i.e. fillets) was chosen for the
focus of these preliminary analyses for the
organochlorine pesticides, while blood
plasma was utilized for the other pesticide
contaminants. Initial analyses were conducted
on a composite of five fish from each
site and preliminary results are summarized
in figures 1 and 2.
Figure 1. Preliminary analysis of chlorinated hydrocarbon pesticides for
muscle tissue from largemouth bass across several broad regions of the
Greater Everglades ecosystem. Results are as ppb for wet weight of
tissue. Lipid concentrations did not differ between sites.
0
50
100
150
200
250
300
350
400
450
500
DDE
Methoxychlor
Chlordane
Dieldrin
Toxaphene
Diazinon
118
Results indicate site-specific patterns of contaminant exposure for fish in the Greater Everglades ecosystem,
and the potential for endocrine system and reproductive effects. These data demonstrate the need for a thorough
assessment of exposures for wildlife within the Greater Everglades ecosystem as an essential component of current
and future assessments of risks and the potential effects of proposed and ongoing restoration.
Contact: Timothy, Gross, USGS-BRD Florida Caribbean Science Center, 7920 NW 71st St., Gainesville, FL
32653, Phone: 352-378-8181 ext 323, Fax: 352-378-4956 Tim_s_gross@usgs.gov,
0
10
20
30
40
50

60
70
80
90
100
Atrazine
Figure 2. Preliminary analysis of plasma atrazine and incidence of intersex for sites
throughout the Greater Everglades ecosystem. Atrazine data is listed as ppb. Note low
background level of intersex for all sites and increased incidence of STA's 2, 4, 5 and 6.
0
10
20
30
40
50
60
70
80
90
100
Loxahatchee
Big Cypress
WCA-2A
WCA-3AN
WCA-3AS
ENP
C111
L69
L5
G3
Holyland
U3
STA-1
STA-2
STA-3
STA-4
STA-5
STA-6
% Intersex
119
Long-Term Water-Quality and Streamflow Monitoring in the Lake Okeechobee
Watershed
By Molly S. Wood1, and Pamela A. Telis2
1U.S. Geological Survey, Center for Aquatic Resources Studies, Altamonte Springs, FL, USA
2Center for Water and Restoration Studies, Jacksonville, FL, USA
Lake Okeechobee is a large, shallow lake located in south-central Florida. With a surface area of 730 square
miles, it is the second largest lake within the contiguous United States and has an average depth of 9 feet. The lake
is the heart of south Florida's water supply and flood control system and is a major source of water for the Everglades.
Agricultural development in the drainage area and construction of the Central and Southern Florida (C&SF)
project during the last century has resulted in excess nutrient inputs and more efficient delivery of stormwater to the
lake. As a result, in-lake phosphorus concentrations have doubled since 1970. This increase in phosphorus has
shifted the natural balance of nutrients in the lake, led to conditions that are favorable for blue-green algal blooms,
and contributed to the accumulation of phosphorus-rich bed sediments over an extensive area of the lake. The C&SF
project canals that discharge waters from Lake Okeechobee to the St. Lucie and Caloosahatchee estuaries and to the
Everglades have severely impacted these ecosystems.
Many agricultural sources of phosphorus pollution in the Lake Okeechobee watershed have been regulated
under the Taylor Creek-Nubbin Slough Rural Clean Waters Program, the Dairy Rule, and South Florida Water Management
District (SFWMD) Works of the District Program through installation of farm-level best management practices.
Some reductions in phosphorus loads to the lake were observed in the mid-1980s to early 1990s, perhaps due
to these activities. However, phosphorus loads into the lake have since been rising, and in-lake concentrations are
well above the level needed to restore the lake to more natural conditions (fig. 1). Additional programs have been
established under the Surface Water Improvement and Management (SWIM) Act and the Lake Okeechobee Protection
Bill to help improve water quality, but these activities alone will not accomplish restoration of the lake and
downstream waters.
In the 1990s, the
U.S. Army Corps of Engineers
re-evaluated the
C&SF project and developed
the Comprehensive
Everglades Restoration
Plan (CERP) for the restoration,
protection, and
preservation of water
resources of central and
southern Florida. This
plan was signed into law
by President Clinton in
December 2000. To help
fill the gap in Lake
Okeechobee restoration
and further understand
watershed processes, the
Lake Okeechobee Watershed
Project (LOWP) was
developed, incorporating 4 of the 68 major components of CERP. The LOWP has two major objectives; to improve
water quality and to attenuate flood flows to Lake Okeechobee. LOWP activities will include the construction of
stormwater treatment areas, restoration of wetlands, and dredging of sediment from canals.
Figure 1. Five-year rolling average loads and annual mean concentrations of phosphorus in
Lake Okeechobee. Source: Surface Water Improvement and Management (SWIM) Plan,
Update for Lake Okeechobee, SFWMD, 2002.
120
As part of the LOWP, the U.S.
Geological Survey (USGS) will
conduct a 10-year water-quality
and streamflow monitoring program
at the sub-basin scale in the
LOWP area. Previous water-quality
monitoring in the watershed
has been focused on concentrations,
not loads, or has been limited
in scale and frequency. The
objectives of the monitoring program
are to compute loads, examine
spatial and temporal trends in
loads, and compare pre- and postrestoration
activity conditions.
The monitoring network will be
composed of 16 water-quality and

streamflow monitoring sites and 1
streamflow-only monitoring site
(fig. 2). Data collection is anticipated
to begin in mid-2003. Load
monitoring is currently conducted
by the SFWMD at inflow points to
the lake, and additional monitoring sites will be established at individual stormwater treatment areas and wetlands
to evaluate the effectiveness of those restoration activities.
Two types of water-quality samples will be collected weekly by the USGS; flow-weighted composite samples
collected using an autosampler and equal-width-increment samples collected manually. The samples will be analyzed
for three forms of phosphorus, three forms of nitrogen, and total suspended solids. In addition, weekly field
measurements of water temperature, specific conductance, dissolved-oxygen concentration, and pH will be made.
Streamflow will be determined through continuous monitoring of stream stage and index velocity, using hydroacoustic
Doppler instruments. This monitoring network poses unique challenges to the collection of high quality data.
The LOWP area is a low-gradient watershed that has numerous flow-control structures, and streams are subject to
bidirectional flow and backwater conditions. These challenges present an opportunity to apply and test national datacollection
protocols and cutting-edge instrumentation.
The establishment and operation of this monitoring network by the USGS provides a foundation for other
research opportunities that are not part of CERP, thus adding value to the network. Integrated, multidisciplinary
research will be possible, such as the co-location of biological research sites with water-quality monitoring sites and
the subsequent sharing of data and observations. Additional water-quality parameters may be added relatively inexpensively
because the primary cost of data collection is already covered within the monitoring network, thus leading
to additional scientific research that may improve the understanding of the complex south Florida ecosystem and the
effects of the Everglades restoration.
Contact: Molly S. Wood, U.S. Geological Survey, Center for Aquatic Resources Studies, 224 W. Central Parkway,
Suite 1006, Altamonte Springs, FL 32708. Phone: (407) 865-7575, Fax: (407) 865-6733, E-mail:
mswood@usgs.gov
Figure 2. Existing and proposed monitoring sites in the LOWP area.
121
Surface Water Geochemical Surveys in Florida Bay
By Kimberly Yates, Iuri Herzfeld, Nathan Smiley, and Chris Dufore
U.S. Geological Survey, Center for Coastal and Watershed Studies, St. Petersburg, FL., USA
Monitoring changes in surface water geochemistry is critical for identifying and predicting ecological
response to restoration in Florida Bay. Many basic estuarine processes directly impact water quality and vice versa.
For example, calcification, photosynthesis, and respiration directly affect dissolved oxygen, pH, dissolved inorganic
carbon, and a number of other chemical characteristics of the water column. Alternatively, changes in salinity, carbon
speciation in the water column, and other water quality parameters affect rates of metabolism and growth of
estuarine species and rates of carbonate sedimentation. These processes are sensitive to changes in water quality that
result from flow modifications in the Everglades. Bay-wide geochemical surveys were conducted bimonthly
throughout the year to establish baseline data from which to gauge restoration impacts.
Geochemical survey tracts target the perimeter of each of the smaller basins within Florida Bay, transect larger
basins, and include sampling sites near canal and slough discharge areas. Salinity, conductivity, temperature, pH,
and dissolved oxygen were measured using a flow-through analytical system towed at a speed of less than 15 knots.
Data from each parameter was logged once every 4 to 8 seconds of travel resulting in collection of approximately
20,000 data points for each parameter through the entire bay within three to four days. Water samples were collected
from each of 24 sites distributed throughout the Bay and analyzed for total alkalinity and total carbon via rapid scan
linear array spectrophotometry and carbon coulometry, respectively. Air:sea CO2 gas fluxes were directly measured
at each of the 24 sampling sites using a floating bell and a LiCor 6252 infrared CO2 gas analyzer. Each carbon dioxide
exchange rate reflects the linear slope with a best Pearson product moment correlation coefficient (r2) calculated
from a curve of approximately 900 data points.
Results from bimonthly geochemical surveys show the persistence of elevated salinity events in central Florida
Bay during spring and early summer months. Air:sea CO2 gas flux data show a persistent trend of CO2 uptake
into surface waters in the central region, and CO2 out gassing in the eastern region throughout the year (fig. 1). Carbon
dioxide gas flux data were superimposed over bottom-type data to identify potential correlations between
Figure 1. Example of Florida Bay air:sea carbon dioxide exchange data from April 2001. Boxes with and "x" indicate
transfer of CO2 from the air to surface waters. Boxes with a "" indicate transfer of CO2 from surface water to the air.
Similar maps have been generated for salinity, temperature, pH, dissolved oxygen, total alkalinity, and total carbon.
122
benthic processes and gas exchange trends. No apparent correlation exists between bottom type and gas exchange
rate. Other processes that may affect gas flux rates include plankton and macro-algal blooms, transport and degradation
of dissolved and particulate organic carbon, and changes in other physicochemical parameters. Potential correlations
among these parameters remain to be determined. Preliminary analysis of pH and dissolved oxygen data
show no consistent spatial trends in variation. Total alkalinity and total carbon data are currently being analyzed.
Statistical correlations will be made between surface water geochemical parameters to gain insight into the interdependencies
of water quality parameters, the processes affecting them, and the potential impact of freshwater flow
modifications resulting from restoration.
Contact: Kimberly Yates, U.S. Geological Survey, 600 Fourth Street South, St. Petersburg, FL, 33701, Phone:
727-803-8747, Fax: 727-803-2031, Email: kyates@usgs.gov, Poster, Question 4
124
Contents
Section III: Preserving Natural Habitats
and Species
Development and Stability of the Everglades Ridge and Slough Landscape
By Christopher E. Bernhardt, Debra A. Willard, and Charles W. Holmes. . . . . . . . . . . . . . . . . . . . 128
Functional Response of Three Wading Bird Species to Prey Density
By Erynn Call and Dale E. Gawlik. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Northern Everglades Canals: Alligator Population Sources or Sinks?
By Matthew D. Chopp, H. Franklin Percival, and Kenneth G. Rice . . . . . . . . . . . . . . . . . . . . . . . . 132
Postlarval Transport of Pink Shrimp into Florida Bay
By Maria M. Criales, John Wang, Joan A. Browder Thomas Jackson, Mike Robblee, and
Clinton Hittle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
The Effect of Plant Community Structure on Apple Snail Abundance in the Everglades
By Phil Darby, Laksiri Karunaratne, Robert E. Bennetts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Overview of the Across Trophic Level System Simulation (ATLSS) Program: Model Development,
Field Study Support, Validation, Documentation, and Application
By D.L. DeAngelis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
SELVA-MANGRO: Integrated Landscape and Stand-level Model of Mangrove Forest Response
to Sea-level Rise and Hydrologic Restoration of the Everglades
By Thomas W. Doyle, Kenneth W. Krauss, Marcus Melder and Jason Sullivan . . . . . . . . . . . . . . . 140
ATLSS Vegetation Succession Model Project.
By Scott M. Duke-Sylvester, Louis J. Gross, and Paul R. Wetzel . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Using Strip-Transect Aerial Surveys to Estimate Manatee Abundance and Population Trend
in the Ten Thousand Islands Region of Southwest Florida
By Dean E. Easton, Lynn W. Lefebvre, and Terry J.Doyle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Shifts in the Position of the Marsh/Mangrove Ecotone in the Western Florida Everglades.
By Ann M. Foster and Thomas J. Smith III . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
ATLSS PanTrack Telemetry Visualization Tool
By Louis J. Gross and E. Jane Comiskey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Evaluation and Calibration of ATLSS SESI Models
By Louis Gross, Jane Comiskey, Mark Palmer, Donald DeAngelis. . . . . . . . . . . . . . . . . . . . . . . . . 151
125
Pulley Ridge - the United States' Deepest Coral Reef?
By Robert B. Halley, Virginia E. Garrison, Katherine T. Ciembronowicz, Randy Edwards,
Walter C. Jaap, Gail Mead, Sylvia Earle, Albert C. Hine, Bret Jarret, Stan D. Locker,
David F. Naar, Brian Donahue, George D. Dennis, and David C. Twichell. . . . . . . . . . . . . . . . 153
Distribution, Abundance, and Population Structure of a Broadly Distributed Indicator Species,
the Diamondback terrapin (Malaclemys terrapin), in the Mangrove-dominated Big Sable
Creek Complex of Southwest FL, Everglades National Park
By Kristen M. Hart, Carole C. McIvor, and Gary L. Hill. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Environmental Fluctuation and Population Dynamics of Two Species of Freshwater Crayfish
(Procambarus spp.) in the Florida Everglades
By A. Noble Hendrix , Joel Trexler, and William F. Loftus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
Southern Biscayne Bay Nearshore Fish and Invertebrate Community Structure
By David Kieckbusch, Michael Robblee, AndrZ Daniels, and Joan Browder, and Jeremy Hall. . . 159
Landscape Analysis of Gramminoid Habitats to Water Quality and Hydrology in Arthur R.
Marshall Loxahatchee National Wildlife Refuge
By Wiley M. Kitchens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Woody Debris in South Florida Mangrove Wetlands
By Kenneth W. Krauss, Thomas W. Doyle, Kevin R.T. Whelan, and Robert R. Twilley . . . . . . . . 162
Recent Fish Introductions into Southern Florida Freshwaters, with Implications for the Greater
Everglades Region
By William F. Loftus, Leo G. Nico, Jeffrey Kline, Sue A. Perry, Joel C. Trexler . . . . . . . . . . . . . . 163
Fish Community Colonization Patterns in the Rocky Glades Wetlands of Southern Florida
By William F. Loftus, Robert M. Kobza, Delissa Padilla, and Joel C. Trexler . . . . . . . . . . . . . . . . 165
Population Dynamics of the Snail Kite in Florida
By Julien Martin, Wiley M. Kitchens, and W.M. Mooij . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
The Relationship of Seagrass-Associated Fish and Crustacean Communities to Habitat
Gradients in Florida Bay
By R.E. Matheson, David Camp, Mike Robblee, Gordon Thayer, Dave Meyer,
and Lawrence Rozas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
Status of the American Alligator (Alligator mississippiensis) in Southern Florida and its Role in
Measuring Restoration Success in the Everglades
By Frank J. Mazzotti, Michael S. Cherkiss, Mark W. Parry, Kenneth G. Rice,
and Laura A. Brandt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
Fish Assemblages of Tidally Flooded Mangrove Forested Habitat along a Salinity Gradient in
Shark River
By Carole C. McIvor, Noah Silverman, Gary L. Hill, and Katie Kuss . . . . . . . . . . . . . . . . . . . . . . 173
126
Assessing the Consequence of Hurricane-Induced Conversion of Mangroves to Mudflats on
Fish and Decapod Crustacean Assemblages in the Big Sable Creek Complex of
Southwest Florida
By Carole C. McIvor and Noah Silverman. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Projecting Future Population Dynamics of the Florida Snail Kite in Relation to Hydrology by
Means of a Suite of Models
By W.M. Mooij, D. L. DeAngelis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
Habitat Selection and Home Range of American Alligators in the Greater Everglades
By Michael L. Phillips, Kenneth G. Rice, Cory R. Morea, H. Franklin Percival, and
Stanley R. Howarter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Movements and Habitat Requirements of Radio Tagged Manatees in Southwest Florida;
Implications for Restoration Assessment
By James P. Reid, Susan M. Butler, Dean E. Easton, and Brad Stith . . . . . . . . . . . . . . . . . . . . . . . . 180
Inventory and Monitoring of the Amphibians and Reptiles of Biscayne National Park
By Kenneth G. Rice, Amber D. Dove, Marquette E. Crockett, and J. Hardin Waddle. . . . . . . . . . . 182
The Effects of the Cuban Treefrog (Osteopilus septentrionalis) on Native Treefrog Populations
within Everglades National Park
By Kenneth G. Rice, Marquette E. Crockett , J. Hardin Waddle, and Amber D. Dove . . . . . . . . . . 184
Impacts of Off-Road Vehicle Use on Wildlife in the Prairie Ecosystem of Big Cypress National
Preserve
By Kenneth G. Rice, Hardin Waddle, and Frank J. Mazzotti . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
Using Proportion of Area Occupied to Estimate Abundance of Amphibians in Everglades
National Park and Big Cypress National Preserve
By Kenneth G. Rice, J. Hardin Waddle, and H. Franklin Percival . . . . . . . . . . . . . . . . . . . . . . . . . . 188
Evaluating the Effect of Salinity on a Simulated American Crocodile (Crocodylus acutus)
Population
By Paul M. Richards, Wolf M. Mooij, and Donald L. DeAngelis . . . . . . . . . . . . . . . . . . . . . . . . . . 190
Fish and Shrimp in Relation to Seagrass Habitat Change in Johnson Key Basin, Western
Florida Bay (1985 - 1995)
By Michael B. Robblee and AndrZ Daniels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
The ATLSS American Alligator Population Model: Results from Restoration Alternatives
By Daniel H. Slone, Kenneth G. Rice, Jon C. Allen, and H. Franklin Percival . . . . . . . . . . . . . . . . 194
Mangrove Die-Off in Florida Bay: A Recurring Natural Event?
By Thomas J. Smith III, Lenore Fahrig, Paul W. Carlson, Thomas V. Armentano, and
Gina M. Peery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
127
A Decade of Mangrove Forest Change Following Hurricane Andrew
By Thomas J. Smith III, Kevin R.T. Whelan & Gordon H. Anderson, Christa L. Walker,
Jeffrey S. Dismukes, and Thomas W. Doyle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
Invasive Exotic Plant Management at the Arthur R. Marshall Loxahatchee National Wildlife
Refuge, an Integrated Approach
By Allison G. Snow, William Thomas, Jr. and Laura A. Brandt . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
Clipping as a Substitute for Fire to Study Seasonal Fire Effects on Muhly Grass (Muhlenbergia
capillaris var. filipes)
By James R. Snyder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
Modeling Manatee Response to Restoration in the Everglades and Ten Thousand Islands
By Bradley M. Stith, Jim Reid, Dean Easton, and Susan Butler . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
Abundance and Diet of Rana grylio across South Florida Wetlands
By Cristina A. Ugarte and Kenneth G. Rice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Short-Term Dynamics of Vegetation Change Across a Mangrove - Marsh Ecotone in the
Southwest Coastal Everglades: Storms, Sea-Level, Fire, and Freeze
By Christa L. Walker, Thomas J. Smith III, and Kevin R.T. Whelan. . . . . . . . . . . . . . . . . . . . . . . . 209
Characteristics of Lightning Gaps in the Mangrove Forests of Everglades National Park
By Kevin R. T. Whelan and Thomas J. Smith III . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Ecosystem History of Central Biscayne Bay Based on Sediment Core Analyses
By G.L. Wingard, T.C. Cronin, D.A. Willard, G.S. Dwyer, S.E. Ishman, C.W. Holmes,
J.B. Murray, R. Stamm, and C. Williams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
Evidence of Freshwater Influx into Rankin Basin, Central Florida Bay, Everglades National Park,
Prior to 1900
By G. Lynn Wingard, Thomas M. Cronin, Gary S. Dwyer, William Orem, Charles W. Holmes,
and Eugene Shinn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
Molluscan Shells as Recorders of Environmental Change in South Florida
By G.L. Wingard, R. Stamm, and J.B. Murray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
Patterns of Movement of Florida Gar (Lepisosteus platyrhincus) in the Everglades Revealed
by Radio Telemetry
By Lawrence F. Wolski, Joel C. Trexler , Jason Knouft, Carl Ruetz III, William F. Loftus. . . . . . . 218
Body Condition Analysis for the American Alligator for Use in Everglades Restoration
By Christa L. Zweig, Frank J. Mazzotti, Kenneth G. Rice, Laura A. Brandt, and
Clarence L. Abercrombie . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
128
Development and Stability of the Everglades Ridge and Slough Landscape
By Christopher E. Bernhardt1, Debra A. Willard1, and Charles W. Holmes2
1U.S. Geological Survey, Reston, VA., USA
2U.S. Geological Survey, Center for Coastal and Watershed Studies, St. Petersburg, FL., USA
The Ridge and Slough landscape is a widespread habitat type in the Everglades, consisting of a system of
dense sawgrass ridges separated by relatively open waterlily sloughs. The ridges run approximately parallel to each
other, oriented in the direction of flow. Using pollen and chronological analyses of sediment cores, we tested the
hypotheses that 20th century compartmentalization and water-management practices have altered the ridge and
slough landscape and that ridges are expanding at the expense of sloughs.
A suite of surface samples collected in different subenvironments of the landscape were analyzed to determine
which vegetation types were distinguishable in the pollen record. These include: dense Cladium (sawgrass) with
scattered Cephalanthus (buttonbush) in the central ridge; less dense, shorter Cladium, with abundant Cephalanthus
and occasional Crinum and Sagittaria in the ridge-slough transition zone; and Nymphaea, Utricularia, Panicum,
Pontederia, and Eleocharis in the slough. Using Mann-Whitney tests and cluster analyses, it was shown that ridge
and slough assemblages differ significantly, primarily in abundance of Cladium pollen. Incorporation of these data
into the existing database of 170 sites and eight vegetation types provides a tool reconstruct past vegetation and its
response to hydrologic changes based on pollen analysis of sediment cores.
Transects of sediment cores were collected across ridges and sloughs in Water Conservation Area (WCA) 3A
and 3B (fig. 1); these transects include cores collected in the central part of the dense sawgrass ridge, the ridge-slough
transition zone, and central slough. Analysis of the slough core indicates that slough vegetation occupied the site for
>2,000 years; however, increased abundance of sawgrass pollen during the 20th century indicates the onset of drier
conditions. Likewise, the central ridge site was occupied by sawgrass for approximately 2,000 years. The central
ridges and sloughs appear to have been stable over long time scales. At the ridge-slough transition site, however,
slough vegetation was present for >2,000 years before expansion of sawgrass ridge sometime in the last 200 years.
Completion of geochronological analyses will document the timing of the expansion more precisely.
These preliminary data provide evidence that sawgrass ridges have expanded laterally into sloughs. Future
coring strategies will address the issue of north-south stability of ridges and sloughs and will expand into WCA 2A
to determine whether the ridge and slough landscape previously occupied more northerly sites and, if so, when it
shifted to predominantly sawgrass vegetation.
Contact: Debra A. Willard, U.S. Geological Survey, 926A National Center, Reston, VA 20192, Phone: 703-648-
5320, Fax: 703-648-6953, dwillard@usgs.gov, Oral, Hydrology and Hydrological Modeling
129
130
Functional Response of Three Wading Bird Species to Prey Density
By Erynn Call1, and Dale E. Gawlik2
1South Florida Water Management District, West Palm Beach, FL., USA
2South Florida Water Management District, West Palm Beach, FL., USA
Declining wading bird populations in the last century have been considered one of the most prominent signs
of the degradation of the Everglades ecosystem. Consequently, recovery of these populations will be a key indicator
of successful restoration efforts. It has been hypothesized that the specific mechanism by which Everglades degradation
has led to declining bird populations is related to changes in hydropatterns. These changes have most likely
altered the availability of prey to wading birds.
Prey availability is determined by both the abundance of prey and the vulnerability of prey to capture. Prey
abundance is affected by factors such as nutrient levels and hydroperiod whereas vulnerability to capture is affected
by such things as behavior of the prey species, water depth, vegetation density, and body size.
Each component of prey availability is affected differently under various water management scenarios. For
example, management for long periods without severe drydowns changes the species composition of the fish community.
Different species of fishes exhibit different behavioral response to predators, thus changing their availability
to capture. Moreover, these behavioral differences of the prey may be dependent on water depths. When the water
column is deep, social species like the golden shiner (Notemigonus crysoleucas) may occur in schools and present
wading birds with a very different capture probability than more solitary fishes like the bluegill (Lepomis macrochirus).
However, as the water level recedes, capture probabilities of the two species may converge.
Ongoing modeling efforts in south Florida, such as the U.S. Geological Survey Across Trophic Level System
Simulation (ATLSS) program, integrate information on hydrology and wading bird food availability to provide predictive
power for future water management decisions. Currently, the biggest information gap limiting the wading
bird component of ATLSS is foraging success as a function of prey availability and water depths. We conducted a
series of experiments aimed at determining the effects of water management (manifested through changes in prey
availability) on the use of foraging sites by wading birds. Here we present the preliminary analysis and results of
the experiment addressing the effect of fish species, fish density, and water depth on wading bird foraging behavior.
The study was conducted in the Everglades Nutrient
Removal Project adjacent to the northwest boarder of
A.R.M. Loxahatchee National Wildlife Refuge, Palm Beach
County, Florida (fig. 1). The experiment was initiated on 10
March 1997 when ponds were stocked with golden shiners
(Notemigonus crysoleucas) and bluegill (Lepomis macrochirus),
and was completed on 15 March 1997 when bird use
nearly ceased. Treatments were assigned randomly among
12 ponds using a 2x2x2 (water depth 10 cm, 28 cm; fish density
low and high; fish species golden shiner and bluegill)
factorial arrangement with two replicates.
A video camera was used to monitor foraging flocks.
Following the video monitoring, time-activity budgets of
focal birds were constructed using information from videotapes.
Three bird species were observed during this experiment:
Great Egret (Ardea alba; visual feeder), White Ibis
(Eudocimus albus; tactile feeder), and Wood Stork (Mycteria
americana; tactile feeder). Two measures of prey consumption
were calculated, mean prey capture per minute and the mean time interval between prey captures.
The relation between these two measure of prey consumption and predicted fish density (fish/m2) was investigated.
We wanted to determine if capture rates were affected by low versus high fish density treatments.
Figure 1. Location and arrangement of experimental
ponds.
131
Capture rate (fish/min) and the mean time interval between prey captures were plotted against predicted fish
density for visual (figs. 2, 3) and tactile (figs. 4, 5) feeding wading birds. After visually inspecting the data, it
appeared that prey density did not influence capture rates for visually feeding birds. In other words, wading birds
had similar capture rates at low and high predicted fish densities. Sample sizes were too small to draw conclusions
about the tactile feeding species.
Several of our experiments showed a strong numerical response to prey density by wading birds, in contrast
to the apparent lack of functional response shown here. In other words, once these birds were at the ponds, capture
rates were similar. One possible explanation for constant capture rates is that wading birds will leave a patch before
intake rates decrease substantially. As a result, no decreasing intake rates can be detected. The fish density at which
an individual wading bird will leave a pond in search of a new foraging locale is termed the giving up density
(GUD). Further investigation of the relationship between prey density and wading bird foraging behavior will be
conducted. The GUD will be calculated for this experiment and offer useful insight into the linkage among drydowns,
fish populations, and wading birds.
Contact: Call, Erynn M. and Dale E. Gawlik, South Florida Water Management District, 3301 Gun Club Road,
West Palm Beach, FL 33406, Phone: 561-686-8800, Fax: 561-681-6310, ecall@sfwmd.gov
Fig. 2 - Predicted fish density vs. capture rate for visual
feeding wading birds at 10 and 28 cm water depths.
Predicted fish density (fish/m2)
0 2 4 6 8 10
Capture rate (fish/min)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Water depth 10 cm, Bluegill
Water depth 28 cm, Shiner
Fig. 3 - Predicted fish density vs. mean interval between captures
for visual feeding wading birds at 10 and 28 cm water depths.
Predicted fish density (fish/m2)
0 2 4 6 8 10
Mean time interval (min) between prey captures
0
2
4
6
8
10
12
Water depth 10, Bluegill
Water depth 28, Shiner
Fig. 4 - Predicted fish density vs. capture rate for tactile
feeding wading birds at 10 and 28 cm water depths.
Predicted fish density (fish/m2)
0 2 4 6 8 10
Capture rate (fish/min)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Water depth 10 cm, Bluegill
Water depth 28 cm, Shiner
Fig. 5 - Predicted fish density vs. mean inteval between captures
for tactile feeding wading birds at 10 and 28 cm water depths.
Predicted fish density (fish/m2)
0 1 2 3 4 5
Mean time inteval (min) between prey captures
0.0
0.5
1.0
1.5
2.0
2.5
Water depth 10 cm, Bluegill
Water depth 28 cm, Shiner
132
Northern Everglades Canals: Alligator Population Sources or Sinks?

By Matthew D. Chopp1, H. Franklin Percival2, and Kenneth G. Rice3
1Florida Cooperative Fish and Wildlife Research Unit, Department of Wildlife Ecology and Conservation,
University of Florida, Gainesville, FL., USA
2U.S. Geological Survey, Florida Cooperative Fish and Wildlife Research Unit, Gainesville, FL., USA
3U.S. Geological Survey, Center for Water and Restoration Studies, Ft. Lauderdale, FL., USA
The Comprehensive Everglades Restoration Plan (CERP) includes the proposed removal of canals that fragment
the Everglades wetland landscape. Dense populations of American alligators (Alligator mississippiensis) exist
in canals throughout the system. Clutch and hatchling survival in canal and interior habitats at A.R.M. Loxahatchee
National Wildlife Refuge (LNWR) were calculated during 2000 and 2001 to investigate the effects of canal habitats
on alligator production. Data were collected from 112 nests and 779 hatchling alligators. Individuals from 57
hatchling pods were recaptured during this study.

No sampled clutches in the interior
experienced flooding during 2000 and
2001 (fig. 1). However, most clutches in
canal habitats were flooded or partially
flooded (fig. 1). Nests were depredated by
raccoons (Procyon lotor) at a higher rate
during 2001 than 2000 (fig. 2). The number
of clutches successfully producing at
least one hatchling was greater during
2000 than 2001, and greater in interior
than canal habitats (fig. 3). Survival probability
estimates for 2000-cohort
hatchlings for the first 6 and 13 months of
life were 44 percent and 20 percent,
respectively. Mean production per nest
after 13 months was 2.4 + 0.5 in interior
and 0.8 + 0.8 in canal habitats.
Compared to nests in interior habitats,
canal nests were subjected to a larger
range of water levels during clutch incubation
and were more susceptible to flooding.
Flooding was found to be the greatest
risk to canal nests at LNWR. The majority
of nests in LNWR interior habitats were
on tree islands. High clutch mortality,
small pod size, and overall low mean
hatchling survival at LNWR, resulted in
negligible production in canal habitats
during 2000 and 2001. Comparatively
high adult densities in canals at LNWR,
and likely other areas of the Everglades,
are sustained by immigration and high
adult survival rates. Everglades canals
appear to be population sinks for alligators
and canal removal will probably not affect
the overall population.
77
100
0 0
0
20
40
60
80
100
Habitat by Year
Clutch Flooding (%)
Canal 2000
Canal 2001
Interior 2000
Interior 2001
Figure 1. Percentage of American alligator clutches that experienced
flooding during incubation in canal (n = 13 and 30) and interior (n = 35
and 24) habitats at A.R.M. Loxahatchee National Wildlife Refuge during
2000 and 2001, respectively.
3
12
58
0
0
20
40
60
80
100
Habitat by Year
Nest Depredation (%) Canal 2000
Canal 2001
Interior 2000
Interior 2001
Figure 2. Percentage of American alligator nests that experienced
depredation during incubation in canal (n = 13 and 29) and interior (n = 33
and 24) habitats at A.R.M. Loxahatchee National Wildlife Refuge during
2000 and 2001, respectively.
133
Contact: Matthew D. Chopp, Florida Cooperative Fish and Wildlife Research Unit, PO, Box 110430, University
of Florida, Gainesville, FL 32611; Phone: 353-392-2861, email: chopp@ufl.edu
38
10
92
57
0
20
40
60
80
100
Habitat by Year
Nests Producing at Least 1
Hatchling (%)
Canal 2000
Canal 2001
Interior 2000
Interior 2001
Figure 3. Percentage of American alligator nests that successfully
produced at least one hatchling during the hatch event in
canal (n = 13 and 30) and interior (n = 36 and 35) habitats at
A.R.M. Loxahatchee National Wildlife Refuge during 2000 and
2001, respectively.
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Postlarval Transport of Pink Shrimp into Florida Bay
By Maria M. Criales1, John Wang1, Joan A. Browder2, Thomas Jackson2, Mike Robblee3, and Clinton Hittle3
1Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL., USA
2NOAA Fisheries, Southeast Fisheries Science Center, Miami, FL., USA
3U.S. Geological Survey, Center for Water and Restoration Studies, Miami, FL., USA
The life cycle of the ecologically and commercially important pink shrimp (Farfantepenaeus duorarum) of
the Dry Tortugas involves complex migrations between spawning and nursery grounds. To effectively manage population
dynamics of this species, it is necessary to have accurate knowledge of the number of postlarvae that enter
the nursery grounds and the processes linking nursery and spawning ground populations. Spawning and early larval
development stages occur in the vicinity of the offshore Tortugas fishing grounds, while late stage postlarvae and
juveniles occur in south Florida coastal waters and Florida Bay, approximately 120 km to the northeast. Population
dynamics of this species are thus affected by factors occurring in Florida Bay, the Atlantic coastal zone, the Florida
Shelf, and the Gulf of Mexico. Physical oceanographic processes may affect transport and supply of postlarvae. Until
recently, transport across channels in the Lower and Middle Keys has been the most widely recognized larval transport
pathway of pink shrimp to Florida Bay. Larvae drifting downstream with the Florida Current may enter Florida
Bay by onshore Ekman surface transport when southeast winds blow along the east-west aligned coastline. Eddies
that propagate downstream with the Florida Current from the Dry Tortugas also may serve as a transport mechanism

of postlarvae in the Middle Florida Keys. In contrast, larval transport across the broad, shallow southwest Florida
Shelf has not been considered an important pathway because the main surface current at the Tortugas grounds is
toward the southwest and subtidal currents nearshore are of small amplitude and mainly in the alongshore (northsouth)
direction as a direct response to the wind events.
With the support of the South Florida Ecosystem Restoration Prediction and Modeling (SFERPM) program
and as part of the development of a simulation model of the pink shrimp in south Florida, efforts have been focused
on determining the most common migration route of pink shrimp postlarvae entering Florida Bay and physical processes
affecting transport along this route. A multidisciplinary study of postlarval influx entering the Bay was initiated
in January 2000. Pink shrimp postlarvae have been collected in western Florida Bay (Sandy Key, Middle
Grounds) in wide channels that connect the Bay with the southwestern Shelf of the Gulf of Mexico, and in tidal channels
in the Middle Florida Keys (Whale Harbor, Indian Key) that connect the southeastern margin of the Bay with
the Atlantic Ocean. In July 2001 two interior bay stations were added, Conchie Channel in western Florida Bay and
Panhandle Key in south central Florida Bay. Sampling has been conducted during two nights around the new moon
using two moored subsurface channel nets (0.75 m2 opening, 1-mm mesh net, 500- mesh in the cod end) per channel.
Cod ends are placed on the nets before dusk and removed shortly after dawn each day. Acoustic Doppler Velocity
Meters (ADVM's) that measure continuous velocity, and associated CTD instruments that measure conductivity,
temperature, and depth (tide/stage) were installed in each channel in January 2002. A boat-mounted Acoustic Doppler
Current Profiler (ADCP) is used to calculate total discharge along a transect of the channels during monthly
samplings. Surface current, temperature and salinity data from ADCP's, and sensors moored at two stations on the
inner shelf of the Gulf of Mexico, about 25 and 35 km north from Cape Sable, have been provided by the Florida
Bay Circulation and Exchange Study team (T. Lee, E. Williams, RSMAS and L. Johns, NOAA).
Our monthly catches of postlarvae indicate that the greatest influx occurs at the western border of the Bay,
with a strong seasonal pattern from July through September over three years (2000-2002). The influx of postlarvae
is approximately ten times higher in magnitude and less variable at the western stations than at the Florida Keys stations
(fig.1). This difference may indicate that onshore mechanisms across the southwestern shelf are more effective
in transporting pink shrimp postlarvae. Based on this result, recent efforts have focused on defining transport mechanisms
of postlarvae to western Florida Bay across the shelf. Our working hypothesis is that postlarvae may be transported
by a selective tidal stream mechanism, which assumes that postlarvae control their movements in the water
column by sitting on the bottom during the ebbing tide and rising into the water column on the flood tide. A harmonic
analysis was conducted on 3-yr ADCP data from two inner-shelf stations to define tidal components and current
135
magnitude. Results show a dominance of the semidiurnal tidal constituent M2, with an east-west velocity of
0.3 m/sec, and north-south velocity of 0.07 m/sec. For the analysis period, astronomical semi-diurnal and diurnal
tidal components accounted for 97 and 71 percent of the total variance in the east-west and north-south current data
respectively in the onshore station and 97 percent and 30 percent of the total variance in the east-west and northsouth
current data respectively in the offshore station. Interestingly, this east-west tidal velocity is much stronger
than the averaged subtidal current of the east-west component at both stations (0.01 m/sec). Assuming that postlarvae
use the eastward flow only during the night flood, they may be transported from the spawning grounds to the
western border of Florida Bay in 26.9 days. This estimated time agrees well with the duration of larval development
of this species, which is approximately 25 days to become late stage postlarvae ready for settlement. Experiments
were conducted in summer 2002 at one of the western stations to determine the response of postlarvae to tidal currents.
Consecutive pairs of dark-flood and dark-ebb plankton samples were taken in two new moon and one full
moon periods at Sandy Key. Overall catches showed clearly that dark-ebb catches were negligible (< 10%) by comparison
with dark-flood catches (> 90%). This result may suggest that pink shrimp postlarvae respond to tidal
cycles, migrating into the water column during the dark-flood cycle. However, environmental factors that trigger
migration, the age at which postlarvae recognize the tidal signal, and the behavior of postlarvae during ebb flow
need to be defined. A simulation model that uses current meter and salinity observations to simulate transport on
tides at night and the influence of salinity gradients is under development. These simulations will help to explore
cause-and-effect relationships and the effect of seasonally varying subtidal transport.
The influx of postlarvae through Middle Keys passes is smaller but more continuous through the year than
that entering Florida Bay through western passes. Influxes through the Middle Keys passes occurred in May, July,
August and October in 2000; in January, April, July and October in 2001; and in January, March and June in 2002
(not complete year yet). The high temporal variability of postlarval influx observed at the Middle Florida Keys may
be related to the arrival of coastal eddies that propagate downstream from the Tortugas area; however alternative
mechanisms should be investigated.
Contact: Maria M. Criales, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami,
FL 33149, mcriales@rsmas.miami.edu, Ph: 305-361-4073; FAX: 305-4600.
J F M A M JJ/JJ A S O N D J F M A M J J A S O N D J F M A M J J A S
0
400
800
1200
1600
2000
2400
MG1
MG2
SK1
SK2
CH1
CH2
J F M A M J J/J J A S O N D J F M A M J J A S O N D J F M A M J J
0
20
40
60
80
100
PH1
PH2
WH1
WH2
IK1
IK2
Postlarvae 1000 m-3
2000 2001 2002
Western Florida Bay Florida Keys
2000 2001 2002
Figure 1. Densities of pink shrimp postlarvae at the two sampling sites.
136
The Effect of Plant Community Structure on Apple Snail Abundance
in the Everglades
By Phil Darby1, Laksiri Karunaratne1, and Robert E. Bennetts2
1University of West Florida, Pensacola, FL., USA
2U.S. Geological Survey, Center for Aquatic Resources Studies, Gainesville, FL., USA
As the exclusive food of the endangered snail kite and prey to a variety of other wetland fauna, apple snails
are generally recognized as a critical resource warranting monitoring in the context of the Greater Everglades ecosystem
restoration. Snail kite abandonment of wetlands in dry down conditions have led to unsubstantiated conclusions
that drying events (presumably of any timing and duration) devastate snail populations, thus forcing kites to
leave. Researchers and natural resource managers have subsequently recommended nearly continuous inundation
of wetlands deemed critical habitat to kites. However, suppressing drying events would be contrary to critical aspects
of snail autecology that have been documented: 1) longer hydroperiods decrease the abundance of emergent wet
prairie macrophytes needed for snail oviposition and aerial respiration and 2) snails do tolerate dry down conditions
(the majority surviving up to 4 months once they reach a threshold size) and that this species has a life history well
adapted to periodic dry downs. Not only are snails adapted to dry downs, we believe that drying events are essential
to supporting suitable snail habitat. Elucidating the relationship between apple snail abundance and habitat structure
also relates directly to habitat management for snail kites. As visual hunters, snail kites cannot forage in densely
vegetated habitats such as sawgrass and cattail, but selection among more structurally 'open' habitats (slough or prairie)
have not been documented. If they have a preference, it could be because some habitats support more snails than
others, or because the structure of some habitats may render snails more available to foraging kites. This study tests
the hypothesis that snail abundance is greater in prairie versus slough habitats, and contributes to an understanding
of habitat selection by foraging kites.
Two concurrently funded projects were initiated in Spring 2002 in two different Everglades wetland units:
WCA-1 (funded by U.S. Fish and Wildlife Service) and WCA-3A (funded by U.S. Geological Survey), which taken
together will function as a single more comprehensive study. A total of six sites were selected to test hypotheses
about snail abundance and habitat structure. Each site consisted of prairie habitat (dominated by emergent species
of Eleocharis, Rhynchospora or Panicum) juxtaposed and/or interspersed with slough habitat (dominated by Nymphaea
odorata). In most sites, the prairie (especially) or slough was not contiguous; i.e., the prairie habitat sampled
within a site may have been partitioned into three or more patches. Patches of habitat judged as transitional or intermediate
between prairie and slough (i.e., patches with both Nymphaea and emergent macrophytes) were avoided.
Snail density was determined using 1-m2 throw traps (n50-70 throw traps in a 50 x 50 m area) extracted with
a dip net, with explicit estimation of capture probabilities to assess sampling efficiency across different habitat types.
The 1-m2 throw trap method has also proven effective in estimating crayfish (Procambarus alleni) and freshwater
prawn (Palaemonetes paludosus) densities; therefore, we recorded numbers of these important prey items found during
our snail sampling effort. Throw trap sampling was conducted from approximately February through early May

in order to avoid the annual post-reproductive die-off. Egg cluster production was monitored in transects established
in each sampling site in order to document that throw trapping was completed prior to the die-off.
At this point we have not completed our analyses; thus, any conclusions should be considered preliminary.
Data were analyzed within a generalized linear modeling framework. Preliminary results indicate consistently
higher snail densities in the prairie habitat relative to the Nymphaea-dominated slough. A similar trend was found
for crayfish. Habitat effect on freshwater prawn density varied among sites, but no overall habitat effect was indicated.
The data appear to support the hypothesis that snail abundance in prairie exceeds that in slough habitats.
137
Qualitative assessment of the data thus far suggests that within the wet prairie communities, there may be specific
associations among snails and some plant species. Such associations will be a primary focus of this study over
the next two years, and we expect to refine the hypothesis regarding apple snail-plant community-snail kite interactions
accordingly. Given the inextricable link between hydrology, vegetation and apple snails, this research effort
will support the development of ecologically significant performance measures that respond to the Greater Everglades
restoration activity.
Contact: Phil Darby, University of West Florida, Biology Department, 11000 University Parkway, Pensacola,
FL, 32514, Phone: 850-474-2647, Fax: 850-474-2749, pdarby@uwf.edu.
138
Overview of the Across Trophic Level System Simulation (ATLSS) Program:
Model Development, Field Study Support, Validation, Documentation, and
Application
By D.L. DeAngelis
U.S. Geological Survey, Center for Water and Restoration Studies, University of Miami, Coral Gables, FL., USA
An overview of the ATLSS Program is presented. The program has produced a set of models of spatially
explicit species index, population demography, and ecosystem process models that are available for applications. In
addition, the program has supported field studies designed to produce data for model construction and validation.
This report describes the following aspects of the program.
The Spatially Explicit Species Index (SESI) models quantify relative effects of hydrologic conditions on the
habitat suitability of species. There are several currently available ATLSS SESI models:
 Cape sable seaside sparrow breeding potential index (Version 1.1)
 Snail kite breeding potential index (Version 1.1)
 Long-legged wading bird foraging condition index (Version 1.1)
 Short-legged wading bird foraging condition index (Version 1.1)
 Empirically-based fish biomass index (Version 1.1)
 White-tailed deer breeding potential index (Version 1.1)
 American alligator breeding potential index (Version 1.1)
 Everglades and slough crayfish (Version 1.1)
 Apple snail SESI model (Version 1.1)
The ATLSS SESI models accomplish the following. They produce values for habitat suitability ranging from
0.0 to 1.0 for all 111,000 cells of the 500 x 500 m array. These can be calculated for every individual year in the
multi-year sequence (1965-1995 for the Restudy scenarios), or averages can be taken over any set of years (e.g., wet
years, dry years, all 31 years). The SESI models are intended to be used to make relative comparisons between scenarios,
not to produce absolute evaluations of habitat quality. The output can be viewed using the ATLSS Data
Viewer, which allows viewing at any scale and performing of statistics. The ATLSS Data Viewer is available to all
agencies that are interested. Training sessions can be scheduled when requested.
There are currently three available ATLSS Demographic Models. The ATLSS demographic models are spatially
explicit individual-based (SEIB) models of the dynamics of the populations:
 Cape sable seaside sparrow demographic model (SIMSPAR - Version 1.3)
 Snail kite demographic model (EVERKITE - Version 3.1)
 American alligator (Version 1.1)
The ATLSS Structured Functional Group models simulate the size-structured and biomass dynamics of the
population. There is currently one available ATLSS Structured Functional Group model:
 Freshwater fish dynamics (ALFISH - Version 3.1.17)
 There are background models that provide landscape information for other ATLSS models:
 High Resolution Topography (HRT - Version 1.4.8)
 Vegetation productivity (HTDAM -Version 1.1)
 High Resolution Hydrology (HRH - Version 1.4.8)
ATLSS model runs for scenario evaluations can be made in the following ways for particular models. The
Snail kite demographic model (EVERKITE) is available in PC form for use (can be downloaded from Web) and user
support for those wanting to use this model. Alternatively, this model will be run at the University of Miami and
results posted. Currently, the remaining ATLSS models can be run at the University of Tennessee, which is funded
to carry out several such runs. Results will be posted. Also, these models can be installed at agencies that have Unix
workstations. A NSF-funded project at the University of Tennessee is currently underway to allow dispersed
139
resource managers to access remotely the capabilities of the SInRG (Scalable Intracampus Research Grid) at the
University of Tennessee. This will allow users at resource agencies in south Florida, with relatively little computer
expertise, to initiate ATLSS simulations on the computers at the University of Tennessee.
Technical documentation of ATLSS models is available on the ATLSS web site (ATLSS.ORG) and listed in
ATLSS Program Publications (available) - and will be further improved. Open literature publications exist for the
available ATLSS models. Nearly all models have appeared in open-literature, peer-reviewed papers (see ATLSS
Publications). An internal USGS panel reviewed the ATLSS Program in May 2002. Additional review by the
Model Refinement Team of CERP is planned.
Validation of models is an important issue. Some degree of model validation has been performed on some

models (SIMSPAR, ALFISH). Model validation on other models depends on the availability of data sets. Now data
sets are becoming available for several species, and new data for others. A "validation tool", which can be applied
along with the ATLSS Data Viewer, allows empirical data (e.g., nest success rate, fish biomass) to be compared spatially
with SESI index values at any spatial scale. Statistical testing can be done using spreadsheets programs. Validation
is being done, or will be done soon on Cape Sable seaside sparrow, snail kite, and American alligator SESI
models.
User interfaces for running models and analyses have been developed. For running SESI models, only a
UNIX platform is currently available, but extension to PC is planned. The snail kite model (EVERKITE) runs on
a PC.
Output of the SESI models can be displayed on the ATLSS Data Viewer. This will be extended to the demographic
models.
ATLSS models nearly completed or under development include:
 Vegetation succession model
 Alligator structured population model
 Apple snail structured population model
 Crayfish structured population model
 Roseate spoonbill SESI model
 Estuarine fish dynamics
Contact: D.L. DeAngelis, U.S. Geological Survey, Biological Resources Division, Department of Biology,
University of Miami, P.O. Box 249118, Coral Gables, FL 33124; Phone: 305-284-1690, Fax: 305-284-3030,
don_deangelis@usgs.gov
140
SELVA-MANGRO-Integrated Landscape and Stand-Level Model of Mangrove
Forest Response to Sea-Level Rise and Hydrologic Restoration of the Everglades
By Thomas W. Doyle1, Kenneth W. Krauss1, Marcus Melder2, and Jason Sullivan2
1U.S. Geological Survey, National Wetlands Research Center, Lafayette, LA., USA
2Johnson Control World Services Inc., USGS-NWRC, Lafayette, LA., USA
The near sea-level elevation and flat slope of the protected Everglades ecosystem accounts for one of the largest
contiguous tracts of mangrove forests found anywhere in the world and punctuates their potential vulnerability
to rising sea level and changes in freshwater runoff. These forests are subject to coastal and inland processes of
hydrology largely controlled by regional climate, disturbance regimes, and water management decisions. Mangroves
are highly productive ecosystems and provide valued habitat for fisheries and shorebirds. Mangrove forests
are universally composed of relatively few tree species and a single overstory strata. Three species of true mangroves
are common to intertidal zones of the coastal margin of the Everglades, namely black mangrove, Avicennia germinans
(L.) Stearn, white mangrove, Laguncularia racemosa (L.) Gaertn.f., and red mangrove, Rhizophora mangle L.
Mangroves are halophytes and can, therefore, tolerate the added stress of waterlogging and salinity conditions
that prevail in low-lying coastal environments influenced by tides. Global warming has been projected to increase
sea water temperatures and expansion that may accelerate sea level rise and further compound ecosystem stress in
mangrove dominated systems. While early researchers attributed zonation patterns to salinity gradients, more recent
field and experimental studies indicate that mangroves have wide tolerances to salinity and other soil factors and may
be influenced to a greater degree by local hydrology and episodic disturbance events. Increases in relative sea level
will eventually raise saturation and salinity conditions at ecotonal boundaries where mangroves are likely to advance
or encroach upslope into freshwater marsh/swamp habitats. Changes in freshwater runoff as a result of climatic variability
and water management controls may alter the health and migration of mangrove communities in conjunction
with potential sea-level rise.
A landscape simulation model, SELVA-MANGRO, was developed for mangrove forests of south Florida to
investigate the potential impacts of climate change and freshwater flow on the quality and distribution of future mangrove
habitat. The SELVA-MANGRO model represents a hierarchically integrated landscape model that manages
the exchange of system parameters up, down, and across scale between linked simulation models SELVA and MANGRO.
SELVA is a Spatially Explicit Landscape Vegetation Analysis model that tracks predicted changes in the biotic
and abiotic conditions of each land unit (1 sq ha) on an annual basis for the entire simulated landscape. The SELVA
model administrates the spatial articulation of the landscape composed of land units composed of habitat classifications
(forest, marsh, aquatic) and any forcing functions that predict changes in hydrology and disturbance. Intertidal
forest units are then simulated using the MANGRO model based on unique sets of environmental factors and forest
history. MANGRO is a spatially explicit stand simulation model constructed for mangrove forests of the neotropics.
MANGRO is an individual-based model composed of a set of species-based functions predicting the growth, establishment,
and death of individual trees. MANGRO predicts the tree and gap replacement process of natural forest
succession as influenced by stand structure and environmental conditions.
Model applications were conducted to forecast mangrove migration under projected climate change scenarios
of sea-level rise and saltwater intrusion for the Everglades coastal margin without hydrologic restoration. A high
resolution model of surface topography was needed to predict the rate and fate of coastal inundation from sea-level
rise over the next century. Tidal inundation and circulation are key factors controlling mangrove distribution in this
coastal environment. The ability to predict landward transgression of mangrove caused by sea-level rise depends on
the relation between landward slope and elevation in relation to tide range and extent plus an understanding of relative
sea-level rise. A historic topographic and drainage map circa 1940-50 with 1 ft contour intervals across the south
Florida Everglades was rectified and digitized into a geographic information systems application. Boundary zones
of major habitat classes were also digitized from the natural vegetation map of Florida produced by Davis (1943) to
delineate the lower and upper elevations of the intertidal zone as defined by mangrove extent. The coastline was
assigned an elevation of mean sea level while the upper transition zone of mangrove extent was approximated at
141
mean high water for available tide datums along the southwest coast of Florida. These combined data sources and
proxy contours served as baseline elevation values for constructing a detailed digital elevation model of south Florida
for SELVA-MANGRO application.
Sea-level rise was modeled as a function of historic sea-level conditions at Key West, Florida based on mean
annual tide records (1940 to present) projected into the 21st century with the addition of curvilinear rates of eustatic
sea level expected from climate change. The data record was extended into the next 100 years for sea-level rise scenarios
of 15 cm to 1.1 m by year 2100 based on low, mid, and high projections obtained from global climate change
models. Model results show that species and forest cover will change over space and time with increasing tidal inundation
across the simulated landscape for all sea-level rise scenarios. The greater the rate of sea-level rise the faster
or more extensive the encroachment of mangroves onto the Everglades slope. The model shows that freshwater
marsh/swamp habitats will be displaced as the tidal prism increases over time as it moves upslope without Everglades
hydrologic restoration. Under these modeling assumptions, mangrove habitat will increase over the next century
under climate change and conversely, freshwater marsh/swamp is expected to decrease.
Modeling upgrades are under development for the SELVA-MANGRO model to assess the impact of increased
freshwater runoff under various Everglades restoration alternatives. Empirical data of riverine and basin mangrove
forests show that precipitation and runoff events effect short-term hydrology and salinity conditions that are relatively
minor in relation to coastal influences of daily and seasonal tidal forcing. Everglades restoration alternatives
will increase runoff conditions above current normal patterns and may abate any influence of sea-level rise in the
near future. Model trials indicate that proposed freshwater flow rates may need to exceed current engineering design
to affect stage and salinity at the coastal margin to affect potential mangrove migration and expansion into freshwater
habitats.
Contact: Contact: Thomas W. Doyle, U.S. Geological Survey, National Wetlands Research Center, 700 Cajundome
Blvd., Lafayette, LA, 70506, Phone: 337-266-8647, Fax: 337-266-8592, Email: tom_doyle@usgs.gov, Oral,
Ecology and Ecological Modeling
142
ATLSS Vegetation Succession Model Project
By Scott M. Duke-Sylvester1, Louis J. Gross1, and Paul R. Wetzel2
1University of Tennessee, Knoxville, TN., USA
2Smith College, Northampton, MA., USA
The U.S. Geological Survey Across Trophic Level System Simulation (ATLSS) models in their current form
all assume that vegetation will remain unchanged over the period of the model simulations. This is not likely to be
true, as changes in hydrology are almost certain to result in changes in vegetation patterns in many parts of the Everglades
over periods of decades. There is already some evidence of changes in vegetation types in some areas of the
Everglades over the last 10 years.
The development of a set of succession models for the major vegetative types in the Everglades region is generally
regarded as being essential, if scientists and managers are to be able to project the possible effects of changes
in the hydrology of the region. Vegetation response is also sensitive to changes in nutrient concentrations and fire.
Furthermore, important animal species, such as wading birds, the snail kite, and the Cape Sable seaside sparrow, have
specific habitat needs that are tied to particular types of vegetation. The basic goal of this ATLSS project is to develop
succession models that estimate future patterns of vegetation for targeted habitats and to describe how these habitats
are affected by changes in hydrology, available nutrients, fires and the interaction of these processes. Three basic
community types, pine/scrub/flatwood, cypress forest, and herbaceous plant communities will be included in the
modeling. Within these types, a more detailed structure using Florida GAP vegetation alliances has been developed,
allowing for explicit alliance responses to patterns of hydrology, nutrients, and fire.
The vegetation succession model will cover approximately 48 percent of the total area in south Florida (urban,
agricultural, and mining areas excluded), uses all 22 of the Florida GAP alliances present in the ATLSS study area
and will provide yearly estimates of vegetation alliance distribution at a 100x100 meter resolution. Model parameters
have been determined from an intensive literature review followed by an extensive compilation and synthesis of the
available data [available in two documents: Plant Community Parameter Estimates and Documentation for the
Across Trophic Level System Simulation (ATLSS), and Nutrient and Fire Disturbance and Model Evaluation Documentation
for the Across Trophic Level System Simulation (ATLSS)]. The information from the literature review
was structured around the Florida GAP vegetation alliances, which provided a basis for the model parameters and
succession models of the three basic community types.
Review of the data suggests that, at the spatial scale of the ATLSS succession model, the effects of hydrology,
phosphorous, and fire are very important, while the effects of nitrogen enrichment are of lesser importance and will
not substantially affect model dynamics. Two different fire types will be included in the model; those that damage
the soil, commonly referred to as muck fires, and surface fires that destroy vegetation but do not burn the soil. Making
a distinction between muck and non-muck fires is important for succession modeling because burning soil
changes local topography, which in turn changes the hydrology of local habitats. The interactions between fire and
hydrology, and fire and nutrients also have been estimated in the succession documentation, based upon the limited
available information on interaction effects for the vegetation alliances in south Florida.
The model uses a two-part approach to simulating the process of succession. First, a static look up table was
constructed for each basic community type. Each look up table describes the potential future states of a plant community
as a function of the history of hydrology, fire, nutrients and the interaction between these processes. The table
also provides parameters for the expected time for a change to take place for each of the different processes affecting
succession. The look up table is based on the literature review and synthesis.
Secondly, once local environmental changes indicate that succession to a new vegetation alliance is possible,
the succession pathway is treated as a Markovian stochastic process. The change to the new vegetative state is random
with the probability distribution for the various new states and the expected time for transformation given by
the look up table.
143
Presenting the output of the vegetation succession model will follow the relative assessment approach using
three panel maps applied in the analysis of other ATLSS models. This synthesis will present two maps representing
the distribution of FGAP vegetation alliances produced by two different hydrology scenarios with the third map
indicating locations and type of differences between the two distributions. The classification of differences is still
an open question and depends largely on what information is most useful to the various scientific, managerial and
policy making entities operating in south Florida.
ATLSS model evaluation will begin in the earliest stages of model development. The evaluation effort is necessary
to determine the usefulness and accuracy of plant community succession in ATLSS. Peer review, Turing tests,
gradient response and extreme condition tests, and tracing the behavior of specific variables or vegetation types
through a model run are all possible model evaluation procedures suitable for the plant community succession module
of ATLSS.
There are several goals for the succession model: it will provide an estimate of relative changes in vegetation
distribution in response to changes in the abiotic environment and it will provide additional information about the
potential effects of restoration. Model results also will be useful as input to other ATLSS and non-ATLSS models,
including SIMSPAR and the ATLSS SESI models, that simulate processes sensitive to changes in the distribution
of vegetation in south Florida.
Contact: Duke-Sylvester, Scott M., University of Tennessee, 569 Dabney Hall, Knoxville, TN, 37996-1610,
Phone: 865-974-0223, Fax: 865-974-3067, sylv@tiem.utk.edu
144
Using Strip-Transect Aerial Surveys to Estimate Manatee Abundance and
Population Trend in the Ten Thousand Islands Region of Southwest Florida
By Dean E. Easton1, Lynn W. Lefebvre1, and Terry J. Doyle2
1U.S. Geological Survey, Center for Aquatic Resources Studies, Gainesville, FL., USA
2U.S. Fish and Wildlife Service, Ten Thousand Islands NWR, Naples, FL., USA
Strip-transect aerial surveys have been used extensively in Australia to estimate trends in offshore dugong populations
(Marsh and Sinclair, 1989). The use of strip-transect methods in estimating manatee population size and
trend, however, has been limited (Miller et al. 1998). Manatee surveys have typically not been designed to sample
quantified survey areas, or to produce estimates of abundance. While useful in obtaining minimum manatee counts
and distribution information, the latter surveys do not permit statistical comparison of survey results over time (Lefebvre
et al., 1995). Our objective in this study is to determine if manatee density and distribution in the nearshore
waters of the Ten Thousand Islands and the Everglades National Park change in response to restoration of natural
hydrologic patterns in southwestern Florida. The Ten Thousand Islands region is of particular interest because of proposed
changes to the Southern Golden Gate Estates and Faka Union Canal drainage. We want to statistically compare
pre- and post-restoration indices of manatee abundance. We also believe that strip-transect methods are likely to be
successful in the Ten Thousand Islands region, unlike many other regions of Florida, in which manatees may be highly
aggregated at winter sites, or their density may be too low and distribution too linear to permit this approach.
Six surveys were conducted between 25 July and 22 October 2000, eight were conducted between 15 July and
30 August 2001, and eight were conducted between 20 June and 17 September 2002. We established parallel
transects, 1 km apart, with a survey strip width of approximately 250 m. Transects flown during July-October 2000
were oriented perpendicular to shore, between Palm Bay and the Ferguson River (fig. 1A). Based on results from
these surveys, we omitted 5 transects (26-30; fig.1A) and established 5 new transects (31-35; fig.1B) near Cape
Romano for the 2001 and 2002 surveys. Transect lengths ranged from 6.6 to 8.4 km in 2000 and 3.4 to 8.4 km in
2001 and 2002, respectively; water area surveyed ranged from 0.79 to 1.53 km2 per transect in 2000 and 0.83 to
1.53 km2 per transect in 2001-2002. Manatee locations were plotted on topographic maps, and flight paths were
recorded on a Trimble Basic Plus GPS. Surveys were conducted from a Cessna 172 at an altitude of 153 m, traveling
at approximately 120-140 km per hour. Perception bias, which occurs when some of the manatees visible within a
strip transect are missed by an observer, was estimated by applying a Petersen mark-recapture model to counts made
by two observers (Pollock and Kendall 1987; Marsh and Sinclair 1989). We did not attempt to develop a correction
factor for manatees that were not visible within the transects (availability bias), thus our results are underestimates
of actual manatee numbers and densities.
The corrected number of manatee groups (a group = 1 or more individuals in the same location) sighted on
transects ranged from 7.0 to 25.7, 12.9 to 27 and 15.0 to 20.4 per survey during 2000, 2001, and 2002, respectively.
The corrected number of individuals counted ranged from 10.0 to 39.8 in 2000, 15.1 to 61.7 in 2001, and 24.6 to
61.2 per survey in 2002. Mean group size per survey ranged from 1.0 to 2.0, 1.1 to 2.3, and 1.4 to 3.0 during 2000,
2001, and 2002 respectively. Survey-specific population estimates in this study were 1.09 to 4.57 per km2 in 2000,
1.62 to 6.64 per km2 in 2001, and 2.65 to 6.58 per km2 in 2002. Excluding the Cape Romano transects, the overall
distribution of sightings was somewhat bimodal, with average (mean = 0.44 groups per transect) or higher than average
number of groups sighted on transects 1-9 and 17-21 during 2000. Transect 6 starts near the mouth of the Barron
River, and Transects 19 and 20 start near the mouth of the Faka Union Canal. Virtually no manatee sightings were
made on transects 25-30, at the western end of the study area during 2000. The replacement of these five transects
with five transects near Cape Romano (31-35) in 2001 produced a somewhat higher estimate of manatee abundance
in the region. The Faka Union Canal is known to attract large numbers of manatees, particularly in the winter, presumably
because of the availability of freshwater at its head and thermal buffering provided by its depth. In this
study, we considered the canal to be a separate, high-density stratum, analogous to the "hot spots" described by
Miller et al. (1998). When manatee counts from this stratum were added to the transect-based estimates, estimates
for the whole study area on all dates ranged from 39 to 187 in 2000, 59 to 247 in 2001, and 95 to 235 in 2002.
145
Population estimates and densities in this study were similar to those for the Banana River, an important area
for manatees on the Atlantic coast in the warm season. The latter estimates ranged from 112 to 209, or approximately
0.67 to 1.26 per km2 (Miller et al. 1998). Mean group size per survey in Ten Thousand Islands (1.62) was
lower than in Banana River surveys (2.19). Group size was 2.00 in 18 of the 22 Ten Thousand Island surveys and
2.00 in 13 of 15 Banana River surveys (Miller et al. 1998). These findings suggest that poorer water clarity in the
Ten Thousand Islands than in the Banana River, where the bottom can be seen in most of the survey area, may contribute
to greater variability and smaller observed group size in our surveys.
To assess the potential for detecting statistically significant trends in the Ten Thousand Islands population,
we used the TRENDS software (Gerrodette, 1993) with estimated CVs of 0.30 and 0.15, based on observed survey
results. We determined that we would need a minimum of eight surveys per year for a minimum of 4 years to detect
an annual rate of change of 10 percent per year. Variation in group size and population estimates is a reflection of
the challenging survey conditions presented by the Ten Thousand Islands, as well as additional variability caused
by weather. Nevertheless, the strip-transect approach shows promise for monitoring the manatee population using
this region during the warm season, if weather-related variability can be minimized.
A
B
Figure 1. Spatial arrangement of 30 manatee aerial
survey strip-transect polygons in the Ten Thousand
Islands during flights July-October 2000 (A) and July
2001-September 2002 (B).
146
REFERENCES
Gerrodette, T. 1993, TRENDS: software for a power analysis of linear regression. Wildlife Society Bulletin 21:515-
516.
Lefebvre, L.W., B.B. Ackerman, K.M. Porter, and K.H. Pollock, 1995, Aerial survey as a technique for estimating
trends in manatee population size-problems and prospects. Pages 63-74 in T.J. O'Shea, B.B. Ackerman, and
H.F. Percival, editors. Population biology of the Florida manatee: U.S. Department of the Interior, National Biological
Service Information and Technology Report 1.
Marsh, H., and D.F. Sinclair, 1989, Correcting for visibility bias in strip transect aerial surveys of aquatic fauna:
Journal of Wildlife Management 53:1017-1024.
Miller, K.E., B.B. Ackerman, L.W. Lefebvre, and K.B. Clifton, 1998, An evaluation of strip-transect aerial survey
methods for monitoring manatee populations in Florida: Wildlife Society Bulletin 26(3):561-570.
Pollock, K.H., and W.L. Kendall, 1987, Visibility bias in aerial surveys: a review of estimation procedures: Journal
of Wildlife Management 51:502-510.
Contact: Easton, Dean. U.S. Geological Survey, Center for Aquatic Resources Studies, Sirenia Project; 412 NE
16th Ave., Rm. 250; Gainesville, FL. Phone:(352)372-2571 FAX:(352)374-8080 Dean_Easton@usgs.gov
147
Shifts in the Position of the Marsh/Mangrove Ecotone in the Western Florida
Everglades
By Ann M. Foster1, and Thomas J. Smith III2
1U.S. Geological Survey, Center for Aquatic Studies, Gainesville, FL., USA
2U.S. Geological Survey, Center for Water and Restoration Studies, St. Petersburg, FL., USA
The Everglades of southern and central Florida are a unique
system that has been recognized as a valuable global resource. Up
until the 1940's it had remained relatively undisturbed, with only
minor incursions along the coastal fringe. This results in a situation
in which to study the impacts of both global climate change and land
use change on coastal ecosystems. In 1900, a broad freshwater system
stretched from Lake Okeechobee southward for more than 160
km before draining into the estuaries along the southern tip of the
Florida mainland. Today, over 600,000 ha of marsh have been converted
to the Everglades Agricultural Area for production of sugarcane,
sod and winter vegetables.
It has been hypothesized that shifts in the position of the
mangrove/marsh ecotone are pulsed events, possibly initiated by
large-scale disturbance and (or) influenced by sea level rise. As the
flow of freshwater to the estuaries decreases, this results in an emulation
in the rise in sea level. This reduction in freshwater flow, in
conjunction with events such as hurricanes, fire, sea-level rise, and
decreased precipitation may be influential in the migration of the
mangrove forest into the freshwater marsh.
Select areas along the western coast of Everglades National
Park (fig.1) are examined using a time series of aerial photographs
from the park archives (Briere et al, this volume; Coffin et al, this
volume).
In some of the areas we examined, the decreases in the freshwater
marsh occur closest to the coastline. In these areas the marsh
has persisted further inland and has even shown signs of returning
along the edges of some rivers and bays (fig. 2). Historical aerial
photos have shown in some areas that the migration of the mangrove
forest into the freshwater marsh is evident. In other regions
no change is apparent.
Figure 1. Western coast of Everglades National
Park. The area in the vicinity of the Lopez River
is enclosed in a box in the upper left corner.
Figure 2. Location of the marsh in the vicinity of the Lopez River in 1927, 1940, and 1990. The shaded areas
indicate the extent of the marsh for a specific year.
1927 1940 1990
148
Determining which factor or combination of factors contributes to this migration remains to be answered. However,
it would appear given the diversity of patterns we see along the marsh/mangrove ecotone, it is a complex process.
Contact: Ann M. Foster, U.S. Geological Survey, 412 NE 16th Ave. Rm 250, Gainesville, FL 32601, 352-372-
2571 x25, ann_foster@usgs.gov
149
ATLSS PanTrack Telemetry Visualization Tool
By Louis J. Gross and E. Jane Comiskey
University of Tennessee, Knoxville, TN., USA
ATLSS PanTrack is a visualization tool designed to display and analyze spatial movement data of panthers
over georeferenced landscape maps. It has been customized for the display of radiotelemetry observations collected
for the Florida panther endangered species recovery project. PanTrack was developed to help define panther behavior
rules for the spatially explicit, individual-based ATLSS Deer/Panther model. The effectiveness of individualbased
models depends upon the availability of detailed observations about individuals on the landscape, and on the
ability to find patterns in these observations that provide insight into key animal behaviors. The availability of Pan-
Track, a programmable tool customized for the Florida panther data set, has facilitated the evaluation of telemetry
data, and has also proved invaluable in facilitating interaction and exchange of information between the modeler and
field biologists, allowing on-the-spot confirmation of field observations in the context of the full set of monitoring
data and rapid visual identification of patterns in landscape/panther associations. Having a readily customizable display
and analysis tool has also enabled researchers to study published panther analyses closely, evaluating whether
trends reported in spatial and temporal subsets of panther data are reflected in the entire data set.
South Florida is home to the last remaining population of endangered Florida panthers (Puma concolor
coryi). Panther survival is threatened by habitat loss and degradation, geographical isolation, disease, and problems
associated with small population size, including inbreeding and sensitivity to stochastic events. The current verified
population size is 80 adult and subadult panthers. Because the few remaining panthers have been intensively studied,
a fairly detailed database is available for individuals in the population. Monitoring of Florida panthers by radiotelemetry,
initiated in 1981 with the radio-collaring of two individuals, has now expanded to include 39 panthers.
Over 60,000 telemetry locations are available over the monitoring period. Four Global Positioning System (GPS)
collars were deployed for the first time in 2002, providing as many as eight locations around the clock compared to
the current collection schedule of three daytime locations per week.
Recent demographic trends in the panther population are in sharp contrast to earlier observations, necessitating
a thorough reevaluation of rules and parameters in light of changes in the population. A genetic restoration
project was initiated in 1995 because of low genetic variation and health and reproductive problems likely caused
by inbreeding. Eight reproductive females from a closely related subspecies of Puma concolor were translocated
from Texas and introduced into the south Florida population. Five of those females have mated with Florida panthers,
producing a total of 17 F1 offspring over a 7-year period. F1 panthers and their offspring have been vigorous
and healthy thus far, showing none of the heart and reproductive problems seen in Florida panthers. The success of
genetic restoration in increasing genetic variation and producing healthy intercrossed panthers has changed the
course of panther recovery, and has confounded published theories and opinions about panther ecology in south
Florida.
The panther population has more than doubled since 1995, including a 5-fold increase in formerly sparsely
populated areas of BCNP and ENP, thought by some researchers to be unsuitable habitat for panthers. Earlier observations
and theories about habitat use, home range establishment, dispersal patterns, and rates of reproduction and
kitten survival must now be reevaluated in light of new data. Pre-introgression panther habitat selection studies that
focused narrowly on forest were based on the unsupported assumption that habitats associated with daytime telemetry
locations are representative of total habitat use. Panther distribution patterns previously attributed to habitat
suitability now appear to have resulted from dynamics associated with limited dispersal potential in a small, inbred
population with low reproductive rates living in a barrier-rich environment.
Panther recovery and Everglades restoration efforts, and the modeling projects that support and guide them,
depend on accurate characterizations of panther habitat use and requirements, based on all available information.
With these changes in mind, the set of panther location observations (1981-1995) on which preliminary panther
behavior rules for the ATLSS Deer/Panther model were originally based has been expanded to include post-intro-
150
gression observations so that recent trends can be reflected in revised rules for behavior and habitat use. The Pan-
Track Tool is being used to display and analyze the full set of available panther telemetry data for the purpose of
redefining behavior rules. The predictive capabilities of an individual-based model are closely tied to the realism of
the decision rules that determine how individual animals move across the landscape, interact with one another and
respond to their environment. The definition of these rules is in turn tied to the availability and interpretation of
empirical observations about these behaviors and movement patterns. In this context, PanTrack has been used to
study abundance and distribution; movement and dispersal patterns; seasonal effects; home range characteristics;
patterns of reproduction, recruitment, and mortality; effects of gender, age, and genetic group, and patterns of habitat
use.
ATLSS panther researchers have reported results of their analyses in an extensive article in the online journal
Conservation Ecology. Using programming extensions to PanTrack, innovative telemetry mapping and fractal analysis
techniques were used to explore panther habitat use and home range characteristics. Wildlife biologists contributed
field observations indicating that habitat selection is considerably broader during active nighttime hours than
during daytime. The paper provides a critical evaluation of the assumptions and limitations of the dominant forestcentered
view of panther ecology, concluding that percent forest cover is a poor predictor of home range size and
that forest cannot be considered a surrogate for useful panther habitat. Factors other than habitat have contributed
substantially to habitat suitability, population density, and distribution.
The authors conclude that Puma concolor in Florida, as elsewhere in their range, are habitat generalists,
exploiting the broad spectrum of available habitats for hunting, resting, mating, travel, denning, and dispersal. While
panthers readily utilize forested habitat with understory and prey, we found no support for the view that only forested
land within a habitat mosaic is potential panther habitat, or for the contention that only forested habitats are used by
panthers within existing home ranges. This work suggests a more ecologically-consistent management and recovery
paradigm based on maintaining the integrity of the system of overlapping home ranges that characterizes panther
social structure and satisfies breeding requirements. Such a paradigm focuses on the requirements for reproductive
success of a small population in a changing environment.
PanTrack currently operates on Sun workstations or on PC's with a LINUX operating system installed. Installation
of PV-WAVE Version 7.50 (Visual Data Analysis Software by Visual Numerics) is required. PanTrack data

and program installation require 15MB of disk space. The run-time PanTrack screen consists of a Landscape Map
Window and a menu board user-interface. Zoom and animation windows may be created and dismissed during the
session. Data may be subset for display by time period (day, month, year) and (or) by group (e.g., individuals, age,
gender, genetic lineage, cause of death).
Contact: Comiskey, E. Jane, University of Tennessee, 569 Dabney Hall, Knoxville, TN, 37996-1610;
Phone: 865-974-0224, Fax: 865-974-3067, ecomiske@tiem.utk.edu
151
Evaluation and Calibration of ATLSS SESI Models
By Louis Gross1, Jane Comiskey1, Mark Palmer1, and Donald DeAngelis2
1University of Tennessee, Knoxville, TN., USA
2U.S. Geological Survey, Center for Water and Restoration Studies, University of Miami, Coral Gables, FL., USA
A primary product of the U.S. Geological Survey Across Trophic Level System Simulation (ATLSS) Program
is the set of Spatially Explicit Species Index (SESI) models developed for the Greater Everglades area. These models
(eight as of 2002) produce values for habitat suitability ranging from 0.0 to 1.0 for all 111,000 cells of the 500
x 500 m array. These habitat suitability values are typically calculated for every individual year in a 31-year
sequence, simulated using inputs from the South Florida Water Management Model (SFWMM) as processed by the
ATLSS High Resolution Hydrology Model. Averages can also be computed over any set of years (e.g., wet years,
dry years, all 31 years), and over a variety of sub-regions within the total region included. The SESI models are used
for relative comparisons between alternative future scenarios, not for producing absolute evaluations of habitat quality.
The current versions of ATLSS SESI models were evaluated and calibrated with historical demographic
observations to the maximum extent possible, given data availability and time constraints. Abundance data for many
Everglades species are scarce/sporadic, and methods of collection and reporting are often inconsistent over time and
space. The degree to which SESI model evaluation was possible has also been limited by delays in availability of
calibration water data for the model for recent years, when more complete and consistent species abundance data
have been collected. The lack of high-spatial-resolution water data continues to limit evaluation efforts.
As an example of using the best available data in SESI calibration, spatial abundance data were extracted for
each group of wading birds from Systematic Reconnaissance Flight (SRF) records as they became available. The
3-level estimates of water depth recorded along with SRF observations (dry, transitional, wet) were used to approximate
historical water depths. Abundance counts were summed and demographic trends were graphed over each
sub-region. These trend graphs were compared to SESI output, graphed over model sub-regions, for year-to-year
trends, and trends in wet, average, and dry periods. These evaluations were all made based upon the SFWMM Calibration/
Verification data available through 1995.
There was no opportunity during the rapid cycle of model development to formalize and document these
efforts to compare SESI model output to empirical observations and adjust model parameters to reflect historical
biological responses to hydrologic parameters such as hydroperiod and water depth. This process is being formalized
and improved as additional monitoring data become available and as restoration modifications proceed. The
SESI model code is in an object-oriented structure that readily allows for model modification as data collection proceeds.
As with the SESI models, availability of new data has required testing and revisions of the SFWMD Hydrology
Model, which produces hydrology data sets used to drive ATLSS scenario evaluations. An expanded set of
hydrologic calibration data, providing daily water depths over the model area during the period 1979 to 2000, will
become available from the SFWMD. Generation of this data set has required hydrology model modifications and
revisions that will result in output that differs from the original calibration hydrology data. Together with recent
data documenting species abundances over the model area, this extended and modified set of hydrologic inputs will
enable further testing, evaluation, and revision of SESI models. This activity is essential in order to increase the
reliability of the relative predictions made by SESI models.
Some approaches to be used in current and further SESI model development, evaluation, and refinement
include the following activities.
(1) Extensive model runs have already been performed to evaluate the sensitivity of the models to wet, dry,
and typical hydrological patterns as represented in both the F2050 base and the AltD13R scenario. These model
runs were accomplished by creating new water data sets by extracting wet, dry, and typical years of water data from
the existing water files and recombining them to create multiple water files representing scenarios which were
152
wetter, drier, and more average for each of the F2050 and the AltD13R scenarios than the original F2050 and
AltD13R scenarios. The model output for these resultant water files was then summarized for both the entire model
region and selected sub-regions and compared to the summarized output for the original water file. Analysis of these
results has indicated that the models do indicate the appropriate response to water level differences (index values
increase on average across the region for the American Alligator under wetter conditions). These results also indicate
a fairly consistent relative pattern of differences for the models (e.g., if the average index value from a model
for AltD13R is higher than its value for F2050, this ranking usually holds true for scenarios comprised of wet, dry,
and typical water years). An expansion of this methodology is planned to evaluate the sensitivity of scenario rankings
to variation of model parameters.
(2) A web-based interface to the SESI models as an extension of the ATLSS Data Viewer will be made available
that allows authorized users to make modifications to selected model parameters and execute models on an
ATLSS computational server. The resultant output file(s) could then be downloaded to the user's computer and the
ATLSS Data Viewer used to compare different model runs and compare abundance data. The ATLSS Data Viewer
tool would be invaluable in comparing model output with empirical data, as this tool incorporates many of the spatial
summary routines required for such analysis.
The original restoration science concept for south Florida included continuing feedback between modeling,
monitoring, and management programs. This must incorporate open lines of communication among modelers, biologists,
and managers. Long-range stable funding must be secured for model evaluation, updating, and analysis as
new monitoring and calibration data become available. Planned, periodic version updates of SESI models should
incorporate information from trends reflected in current monitoring data.
In order for modeling to play an effective role in the restoration process, the following tasks necessary for
model development, updating, and effective use over the period of adaptive restoration management in south Florida
should be explicitly planned and funded:
Accumulation and timely distribution of monitoring data.
Maintenance of links and dialogues with experts, ensuring that models continue to reflect what is known about
modeled species as the knowledge base grows.
Liaison with users of model output, explaining caveats and restrictions, what output represents and how it
should be interpreted.
Contact: Louis J. Gross, University of Tennessee, 569 Dabney Hall, Knoxville, TN, 37996-1610; Phone: 865-
974-4295, Fax: 865-974-3067, gross@tiem.utk.edu
153
Pulley Ridge-The United States' Deepest Coral Reef?
By Robert B. Halley1, Virginia E. Garrison1, Katherine T. Ciembronowicz1, Randy Edwards1, Walter C. Jaap2, Gail
Mead3, Sylvia Earle3, Albert C. Hine4, Bret Jarret4, Stan D. Locker4, David F. Naar4, Brian Donahue4, George D.
Dennis5, and David C. Twichell6
1U.S. Geological Survey, Center for Coastal and Watershed Studies, St. Petersburg, FL., USA
2Florida Marine Research Institute, St. Petersburg, FL., USA
3Sustainable Seas Expedition
4Center for Coastal Ocean Mapping, College of Marine Science, University of South Florida, St. Petersburg, FL., USA
5U.S. Geological Survey, Center for Aquatic Resources Studies, Gainesville, FL., USA
6U.S. Geological Survey, Woods Hole, MA., USA
Pulley Ridge is a 100+
km-long series of N-S trending,
drowned, barrier islands
on the southwest Florida
Shelf approximately 250 km
west of Cape Sable, Florida
(Fig. 1). The ridge has been
mapped using multibeam
bathymetry, submarines and
remotely operated vehicles,
and a variety of geophysical
tools. The ridge is a subtle
feature about 5 km across
with less than 10 m of relief.
The shallowest parts of the
ridge are about 60 m deep.
Surprisingly at this depth, the
southern portion of the ridge
hosts an unusual variety of
zooxanthellate scleractinian
corals, green, red and brown
macro algae, and typically
shallow-water tropical fishes.
The corals Agaricia sp.
and Leptoceris cucullata are
most abundant, and are deeply pigmented in shades of tan-brown and blue-purple, respectively. These corals form
plates up to 50 cm in diameter and account for up to 60 percent live coral cover at some localities. Less common
species include Montastrea cavernosa, Madracis formosa, M. decactis, Porities divaricata, and Oculina tellena.
Sponges, calcareous and fleshy algae, octocorals, and sediment occupy surfaces between the corals. Coralline algae
appear to be producing as much or more sediment than corals, and coralline algal nodule and cobble zones surround
much of the ridge in deeper water (greater than 80 m).
In addition to coralline algae other abundant macro algae include Halimeda tuna, Lobophora variegata, Ventricaria
ventricosa, Verdigelas peltata, Dictyota sp., Kallymenia sp., and particularly striking fields of Andaymonene
menzeii. The latter algae covers many hectares at densities of tens of individuals per square meter,
constructing regions that appear like lettuce fields growing in the dusk at this depth on the sea floor.
Figure 1. Location of Pulley ridge study area and divesites.
154
The fishes of Pulley ridge comprise a mixture of shallow water and deep species sharing this unusual habitat.
More than 60 species have been identified. Commercial species include Epinephelus morio (red grouper) and
Mycteroperca phenax (scamp). Typical shallow-water tropical species include Thalassoma bifasciatum (bluehead),
Stegastes partitus (bicolor damselfish), Cephalopholis fulva (coney), Lachnolaimus maximus (hogfish), Pomacanthus
paru (French angelfish), and Holacanthus tricolor (rock beauty). The deepwater fauna is represented by Chaetodon
aya (bank butterflyfish), Sargocentron bullisi (deepwater squirrelfish), Bodianus pulchellus (spotfin hogfish),
Pronotogrammus martinicensis (roughtongue bass), and Liopropoma eukrines (wrasse bass). Malacanthus plumieri
(sand tilefish) and several other species construct large burrows and mounds that serve as refuge for multiple species.
Mounds and pits larger than 1m2 are apparent on side-scan sonar images and have been counted in excess of 200/km2
in parts of the ridge.
The extent of algal cover and abundance of herbivores suggest benthic productivity is moderate to high on
parts of the ridge. Such productivity is unusual, if not unique at this depth in the Gulf of Mexico and Caribbean.
Several factors help to account for the existence of this community. First, the underlying drowned barrier islands
provided both elevated topography and lithified substrate for the hard bottom community that now occupies the
southern ridge. Second, the region is dominated by the western edge of the Loop Current that brings relatively clear
and warm water to the southern ridge. Third, the ridge is within the thermocline, a water mass that is known to provide
nutrients during upwelling to shallow reefs in Florida.
Notwithstanding the positive factors for reef growth listed above, this largely photosynthetic community
appears to be thriving on 1-2 percent (5-30 microEinsteins/m2/sec) of the available surface light (PAR) and about 5
percent of the light typically available to shallow-water reefs (500 - 1000 microEinsteins/m2/sec). The corals generally
appear to be healthy, with no obvious evidence of coral bleaching or disease. Although the community is
clearly one adapted to low light conditions, the variety and extent of photosynthetic organisms between 60 and 70
meters depth is impressive.
Is southern Pulley Ridge the deepest coral reef in the United States? That depends, of course, on one's preferred
definition of a coral reef. There are deeper, ahermatypic coral buildups both in the Gulf of Mexico and Atlantic
off Florida coasts. Classically, a coral reef is a wave resistant structure built by hermatypic corals and hazardous to
shipping. From a geologist's point of view, Pulley Ridge corals appear to have built a biostrome, an accumulation
at least a few meters thick, although corals may not account for the bulk of the topography. From that of a biologist,
the most abundant corals in the ridge are hermatypic corals but they are lying, mostly unattached, on the surface.
Clearly a ship's captain could not run his vessel aground on this reef, so mariners would not consider this a reef.
Nevertheless, from the scientific perspective of a structure built from hermatypic corals, southern Pulley Ridge may
well be the deepest coral reef in the United States.
Contact: Robert B. Halley, Center for Coastal and Watershed Studies, 600 4th St. South, St. Petersburg, Florida
33701, Phone:(727) 803-8747 ex. 3020, FAX (727) 803-2032, rhalley@usgs.gov
155
Distribution, Abundance, and Population Structure of a Broadly Distributed
Indicator Species, the Diamondback Terrapin (Malaclemys terrapin), in the
Mangrove-Dominated Big Sable Creek Complex of Southwest Florida,
Everglades National Park
By Kristen M. Hart1, Carole C. McIvor2, and Gary L. Hill3
1U.S. Geological Survey Center for Coastal and Watershed Studies, and Duke University, Nicholas School of the
Environment Marine Laboratory, Beaufort, NC., USA
2U.S. Geological Survey, Center for Coastal and Watershed Studies, St Petersburg, FL ., USA
3U.S. Geological Survey, Center for Coastal and Watershed Studies, St Petersburg, FL., USA
Diamondback terrapins (Malaclemys terrapin) are long-lived turtles that exist as continuously distributed
geographic populations along North America's Atlantic and Gulf coasts. Residing in salt marshes, mangroves, and
tidal tributaries, the terrapin is the only North American turtle that lives exclusively in brackish water. One of the
top predators of benthic macrofauna in the estuarine food chain, terrapins may play an important ecological role,
and may thus be particularly suitable for monitoring as an indicator species. Additionally, the terrapin is a species
of conservation concern. The historical harvest resulted in population crashes that, coupled with disappearing
coastal wetlands, have greatly reduced the numbers of terrapins across their range.
Because the vital rates and population structure for terrapins are poorly understood, we initiated an in-depth
mark-recapture study within the Big Sable Creek system of Everglades National Park, southwest Florida. Shortterm
project goals are to characterize habitat use and movement patterns of individuals, and to estimate the size and
geographic extent of the population. Long-term project goals are to compare the habitat use, demographic features,
and genetic profiles of selected Atlantic and Gulf coast populations of the species.
To date, we have conducted three weeklong sampling trips to the Big Sable Creek system to capture, mark,
and recapture terrapins. Captures of terrapins have been concentrated in the upper reaches of creeks in the system.
On each sampling trip, we surveyed the named creeks and their navigable branches systematically for terrapins at
AM and PM low tides. We used dip nets to capture turtles, with new moon tides providing the best conditions for
capture success.
Over the course of the first year of our mark-recapture study, we marked the first 50 terrapins in November
2001, an additional 96 individuals in June / July 2002, and 64 new turtles in December 2002. Thus far we have
recorded 210 unique individuals of which 104 are females and 106 are males, for a population sex ratio of 1:1.
Recapture locations have been clustered around capture sites, suggesting that terrapins display extreme site
fidelity, even across seasons-recapture locations are often only meters away from original capture sites. Our current
recapture rate is 32.4 percent. The summary recapture statistics together with the number of marked animals
per sampling trip (Table 1) allow us to make initial estimates of population size.
Table 1. Mark-recapture summary statistics with Schnabel population estimate.
SAMPLING DATE # MARKED # RECAPTURED SCHNABEL
PERIOD ESTIMATE
1 Nov. 2001 50 ----
2 June/July 2002 96 15
3 Dec. 2002 64 53 N = 692
156
We used the Schnabel population estimator because it is appropriate for closed population studies with multiple
mark and recapture periods. We assumed that every individual in the population has the same capture probability
for a given sampling occasion, but that the capture probabilities can vary among sampling periods. We plan to update
the population estimate after each of our next two sampling periods, scheduled for May and November 2003.
The Big Cape Sable terrapin population presently consists primarily of adult animals. Analysis of the age
composition data revealed that 80 percent of females and 92 percent of males captured to date are in the adult life
stage. We have recorded no females less than 5 years of age and no males less than 4 years of age, suggesting we
have not encountered any juveniles during our surveys. Despite considerable and repeated efforts to sample as far
up each creek as possible (to the limit of canoe penetration), we have not yet found young animals in the population.
We will continue to mark and recapture terrapins in the Big Sable Creek system throughout 2003. Additionally,
we will study the movement of individual females by radiotracking 10 tagged individuals. We also hope to use
satellite telemetry to better understand the movement of nesting females once they leave the Big Sable Creek system
to find dry upland habitat suitable for egg-laying. Future analysis of microsatellites obtained from genetic samples
will help to further define population structure and gene flow among individuals. These data will help to define the
extent of a mangrove terrapin population and will delineate an ecologically and genetically relevant management
unit for terrapin conservation.
Contact: Hart, Kristen, U.S. Geological Survey, Center for Coastal and Watershed Studies, 600 Fourth Street
South, St. Petersburg, FL and Duke University, Nicholas School of the Environment Marine Laboratory, 135 Duke
Marine Lab Road, Beaufort, NC 28516, Phone: 252-504-7571, Fax: 252-504-7648, kristen.hart@duke.edu
157
Environmental Fluctuation and Population Dynamics of Two Species of
Freshwater Crayfish (Procambarus spp.) in the Florida Everglades
By A. Noble Hendrix1, Joel Trexler2, and William F. Loftus3
1University of Washington, Seattle, WA., USA
2Florida International University, FL., USA
3U.S. Geological Survey, Florida Center for Water and Restoration Studies, University of Miami,
Coral Gables, FL., USA
Much effort has been directed by theoreticians to determine the response of species to environmental fluctuations
by treating the physical environment as an unpredictable or stochastic factor. Applied ecologists have
increasingly sought to understand and even replicate the periodicity of natural environmental fluctuation as a management
tool to attain or restore "natural" ecological regimes. Thus, understanding the role of environmental fluctuation
in promoting species coexistence, or facilitating the dominance of a single species, has gained additional
urgency in natural resource management. Two species of crayfish have been identified from the freshwater habitats
of the Everglades, the Everglades crayfish (Procambarus alleni) and slough crayfish (P. fallax). Crayfish burrow in
periodic environments, and this behavior may provide a mechanism for persistence in dry periods. Everglades crayfish
typically burrow during the dry season, and they have been collected from burrows throughout their range.
Slough crayfish on the other hand have been captured largely from flooded habitats. The population dynamics of
each species may therefore be uniquely affected by hydrology. Hendrix and Loftus (2000) found that species composition
was a function of flooding duration in both spatial and temporal domains. Yet, the mechanisms responsible
for these observations are unknown. Using field samples and a mesocosm experiment, we investigated how drought
frequency affected mortality and recruitment rates of two coexisting crayfish species, and how these mechanisms
shaped patterns of their density and relative abundance in the Everglades.
The time series data were obtained from crayfish
collected at a short (site 50, inundated < 180 days
per year), a long (site 06, inundated approximately
360 days per year ) and an intermediate hydroperiod
site (site 23 affected by shifts in hydromanagement in
the 1950's) between 1985 and 1998. Species relative
abundance was calculated from adult males and
regressed against the number of years since drought
(fig 1). Everglades crayfish were the dominant species
soon after drought events (species ratio < 0.5),
whereas slough crayfish were dominant at relatively
longer times since drought. Crayfish relative abundance
responded differently to flooding at each site.
Namely, site 50 shifted from Everglades crayfishdominated
to slough crayfish-dominated communities
quicker than the other two sites as the years since
a drought increased.
To examine the effect of drought on each species,
we simulated a two-week dry-down event in
mesocosm tanks. Each tank received six crayfish of a single species, which approximated average field densities
of 1.91 m-2. Tanks were checked three times weekly to measure water depth, feed crayfish dry commercial crustacean
pellet food, estimate number of burrows, and collect mortalities. In mesocosm tanks, both species had higher
survival in flooded tanks than in simulated drought events. Results of the experiment also suggested that relative
survival was higher for slough crayfish in wet treatments, whereas survival of Everglades crayfish was higher in dry
treatments. Everglades crayfish constructed more burrows in both treatments than slough crayfish.
0.0
0.2
0.4
0.6
0.8
1.0
0 1 2 3 4 5 6
Years since drought
P. fallax/Total males
site06
site23
site50
linear 06
linear 23
linear 50
Figure 1. Species composition (slough crayfish males/total
males) as a function of years since drought for sites 6, 23, and
50. Site 6 had the fewest drought events (N = 3), site 23 was
intermediate (N = 5), and site 50 had the most droughts (N = 9)
in a14-year time series from 1985-1998. Lines were fitted using
logistic regression.
158
We estimated stock recruitment relationships for each species by examining the log -log relationship between
adults and juveniles in wet (flooded for the duration of the calendar year) and dry (dry at least three days) years.
Everglades crayfish recruitment was affected by the hydrologic conditions in the spawning year (best fit model
includes a greater intercept term for dry than wet years, fig. 2). Conversely, slough crayfish recruitment was not
affected by wet versus dry year types (the best model to describe the slough crayfish stock-recruitment relationship
had a common intercept for both years, fig. 2). Both models had a common slope. The log-log linear model used
here was a log-transformed Ricker recruitment function. The intercept term was associated with the slope of the
Ricker function near the origin, thus larger intercept terms had steeper slopes and higher recruitment at low densities
of adults. Everglades crayfish had higher recruitment at low densities in dry years than slough crayfish, however
recruitment at low densities was similar for both species in wet years. The slope term of this log-log linear model is
the stock density at which recruitment is maximized. The slope of the slough crayfish stock-recruitment relationship
was higher than the Everglades crayfish model (fig. 2), indicating that maximum recruitment may occur at higher
adult densities for the slough crayfish.
Species coexistence may be facilitated
by disturbance in some ecosystems.
Two species with different, but overlapping,
environmental tolerances may coexist
when conditions regularly fluctuate
through the optima of both taxa. In the
Florida Everglades, two species of procambarid
crayfish coexist and we investigated
how their population dynamics were
affected by drought frequency. Crayfish
relative abundance was determined by
local hydrological conditions. Everglades
crayfish (Cambaridae; Procambarus
alleni) were dominant when droughts
were frequent, whereas slough crayfish (P.
fallax) dominated when droughts were
infrequent. Differential tolerances to
drought frequency were manifested in species-
specific vital rates. Everglades crayfish
population dynamics were limited by
low recruitment in flooded years, whereas
slough crayfish population dynamics were
regulated by low rates of survival through
droughts as short as two weeks. Because
the crayfish assemblage of the Florida
Everglades is sensitive to drought frequency,
hydromanagement of the region
can alter species relative abundance.
Contact: Hendrix, A. Noble, University of Washington, Box 355020, Seattle, WA, 98195, Phone: 206-221-5457,
Fax: 206-685-7471, anoble@u.washington.edu
Log(Juveniles + 1)
0
0.5
1
1.5
2
0 0.1 0.2 0.3 0.4 0.5
Log(Adults + 1)
b
0
0.5
1
1.5
2
0 0.1 0.2 0.3 0.4
0 0.1 0.2 0.3 0.4 0.5
Log(Adults + 1)
Log(Juveniles + 1)
a
Figure 2. (a) Everglades crayfish stock-recruitment relationship. The
estimated density of juveniles was analyzed in both wet and dry years. The
best-fit model had similar slopes for wet and dry years, but significantly
different intercept terms. (b) Slough crayfish stock-recruitment relationship.
The estimated density of juveniles was analyzed in both wet and dry years.
The best-fit model had a common slope for wet and dry years, and a common
intercept term.
159
Southern Biscayne Bay Nearshore Fish and Invertebrate Community Structure
By David Kieckbusch1, Michael Robblee1, Andr Daniels1, Joan Browder2, and Jeremy Hall2
1U.S. Geological Survey, Center for Water and Restoration Studies, Miami, FL., USA
2NOAA Fisheries, Southeast Fisheries Science Center, Miami, FL., USA
Loss and (or) degradation of coastal wetlands and nearshore estuarine habitats are long-term threats to ecological
function and production of natural resources in Biscayne Bay. Because of its clear, shallow waters, Biscayne
Bay's benthic community is a principal source of productivity and diversity. The seagrass/algae associated animal
community, consisting of small forage fish, juvenile gamefish, and invertebrates such as pink shrimp, Farfantepenaeus
duorarum, is particularly well developed in the shallow nearshore zone adjacent to the mainland and may be
dependent upon freshwater inflow. The purpose of this study is to describe the spatial patterns of faunal community
composition and species abundance in relation to salinity in the shallow, nearshore habitats of southern Biscayne
Bay and ultimately to evaluate the influence of freshwater discharge on community structure.
A random stratified sampling design is being
employed to characterize the spatial and temporal patterns
of fish and invertebrate community structure in
nearshore habitats and to facilitate a throw-trap/commercial
roller trawl comparison in the adjacent deeper water
commercial fishing zone. At present 54 randomly
selected sampling sites, distributed on an areal basis
among three salinity strata and an Elliot Key western
shoreline control site, are being sampled bi-monthly.
The three salinity strata are each subdivided into zones
north and south of Black Point, while a subset of these
sampling sites in deeper water are associated with the
gear comparison.
A 1m2 throw-trap suitable for sampling across the
full range of water depths observed in Biscayne Bay is
being used to collect quantitative samples of fish and
macroinvertebrates. A commercial shrimper, using a 4.4
m roller trawl, is sampling in water deeper than 1 m.
Throw-trap and roller trawl sampling is coordinated to
affect the gear comparison. All fishes and caridean and
penaeid shrimp collected are identified, counted and
sized as appropriate in the laboratory. Each throw-trap
sample is associated with habitat quantitatively using a
variety of techniques: visual, quadrat harvest, and Braun
Blanquet. An emphasis in this study on coupling habitat
(seagrass, algae, hardbottom) with fish and invertebrate
community structure recognizes the importance of habitat,
particularly seagrass habitat, in organizing benthic
communities and to the nursery function of the bay.
Figure 1. Comparison of the fish caught with the roller trawl
versus the sock.
160
Sampling was initiated in the fall of
2002. Preliminary fish results are available
characterizing the fish community in
southern Biscayne Bay. Similar results
are available for caridean shrimp and the
pink shrimp. Figure 1 compares fish
caught in the roller trawl net enclosed in a
smaller mesh net referred to here as a
sock. The sock captures fish and shrimp
that might otherwise pass through the
roller trawl net. Fish abundance in the collections
was relatively low with averages/
trawl of less than 8 for the most
abundant species, Lagodon rhomboides,
the pinfish, and the yellowfin mojarra,
Gerres cinereus. Figure 2 compares fish
caught with the throw-trap. The Elliot
Key area serves as a potential control for
the western shoreline of Biscayne Bay
where changes in salinity patterns due to
restoration of freshwater flow are
expected. The fish fauna observed in Biscayne
Bay is similar to that observed in
western Florida Bay with the exception
that parrotfish are present but absent in
Florida Bay. With the exception that densities
are lower the fish community along
the western shore of Biscayne Bay, dominated
by the rainwater killifish, Lucania

parva, is typical of the seagrass associated
fish community in Florida Bay.
These results are preliminary. More detailed analyses focusing on evaluating the relationship of fish and invertebrates
to salinity and habitat and comparing the throw-trap and roller trawl gears will be presented.
Contact: Kieckbusch, David, USGS, Water and Restoration Studies Center, Miami, FL, 33178, Phone: 305-348-
6997, Fax: 305-348-4096, david_kieckbusch@usgs.gov
Figure 2. Comparison of the fish caught with the throw-trap north and south
of Black Point and along the western shore of Elliot Key.
161
Landscape Analysis of Gramminoid Habitats to Water Quality and Hydrology in
Arthur R. Marshall Loxahatchee National Wildlife Refuge
By Wiley M. Kitchens
U.S. Geological Survey/Florida Cooperative Fish and Wildlife Research Unit, Gainesville, FL., USA
The northernmost remnant of the intact Everglades habitat is located in the 57,235 ha (200 square mile area)
of the Loxahatchee National Wildlife Refuge. Historically, this system was comprised of a spatially complex mosaic
of wet prairies, saw grass stands, tree islands, alligator holes, and sloughs. However, upon completion of the extensive
Army Corps of Engineers' Central and South Florida Project, the refuge began to experience large scale habitat
conversions associated with altered hydroperiods and agriculturally derived pollution (i.e., contaminants and nutrients).
This area has been subject to a rigidly imposed regime of water deliveries and severely degraded water quality
as a result of the conversion of its primary watershed to agricultural land uses.
A multi-year interdisciplinary study (1986-91) was conducted to resolve the issues of hydrological alterations
and nutrient loading impacts on this important piece of the Everglades system. As a result of altered hydrologic
regimes and excessive nutrient loading, the vegetative habitats of the refuge have responded by conversion to massive
monospecific stands of cattails in areas influenced by runoff waters. There has been a tendency to drown habitats
in the south of the refuge and desiccate those of the north. This study defined gradients of nutrient addition
effects and hydroperiods resulting from the management of water in the refuge. The study employed a communitylevel
investigation of vegetative associations in response to the environmental gradients with a spatial characterization
of the environmental variables in the GIS. We developed a spatial hydrological simulation model, a vegetative
cover database from classified satellite imagery, a spatial coverage of water column/substrate nutrient concentrations,
and landscape topography, all geo-spatially articulated in a GIS. Simultaneous studies of wading bird and
forage fish distributions in response to habitat conditions were conducted to examine the influence of hydroperiod
and water quality on wading birds and their prey base.
In order to spatially portray the various water depths and hydroperiods imposed on the wetlands and examine
vegetative responses, a spatially articulate hydrological model was adapted from an existing model and applied very
successfully to the area. The model incorporated approximately five hundred 1-km cells and was verified using field
data. This capability provided a means hind-casting into the past and recreating the hydroperiod regimes for the past
16 yrs. Patterns of habitat use were influenced strongly by seasonal variation in water levels and decapod and fish
assemblage structure varied among habitats. The bottom line results of the study were that there were indeed
impacts and vegetative change resulting from hydrological alterations, but the principal agent responsible for the
conversion of approximately 8,000 acres to cattail was principally phosphorus in the substrates proximal to agricultural
inflows.
This work was an innovative approach for its time, employing a hierarchical approach spanning landscape
level to community ecology level techniques with GIS technology. The study was however conducted approximately
15 years ago and needs to be upgraded with better imaging, modeling techniques, and community analysis
techniques.
Contact: Wiley M. Kitchens, USGS/Florida Cooperative Fish and Wildlife Research Unit, Gainesville, FL
162
Woody Debris in South Florida Mangrove Wetlands
By KennethW. Krauss1, Thomas W. Doyle1, K.R.T. Whelan2, and R.R. Twilley3
1U.S. Geological Survey, National Wetlands Research Center, Lafayette, LA., USA
2U.S. Geological Survey, Florida/Caribbean Science Center, Miami, FL., USA
3University of Louisiana and Lafayette, Center for Ecology and Environmental Technology, Lafayette, LA., USA
Volume of woody debris in forests provides an often overlooked, yet important, ecosystem service. The slow
recovery, or decomposition, of woody debris following a major disturbance, such as a hurricane, has led to speculation
that coarse woody debris serves to influence positively the long-term persistence and supply of nutrients in a
forest ecosystem. Hence, immediately after a disturbance an acute flux of nutrients via litter and small woody debris
fall occurs. This initial flux is followed by a gradual decrease in the supply of nutrients to some steady state whereby
larger woody debris provides a source of nutrients during the ensuing forest recovery period when nutrients are most
needed.
Woody debris is abundant in hurricane-prone forests. With a major hurricane impacting south Florida mangroves
approximately every 20 years, carbon storage and nutrient retention may be influenced greatly by woody
debris dynamics. In addition, woody debris can influence seedling regeneration in mangrove swamps by trapping
propagules and enhancing seedling growth potential.
Here, we report on line-intercept woody debris surveys conducted in mangrove wetlands of south Florida 9-10
years after the passage of Hurricane Andrew (1992). The volume of woody debris for all sites combined was estimated
at 67 m3ha-1, and varied from 13 - 181 m3ha-1 depending upon differences in forest height, storm circulation
quadrant, and maximum model-generated wind velocities. The greatest amount of woody debris was found in the
eyewall region of the hurricane, with a projected necromass of about 36 t ha-1. Approximately half of the woody
debris biomass was associated as small twigs and branches (fine woody debris) since much of the coarse woody
debris > 7.5 cm was fairly well decomposed. Regressions of woody debris relative to forest height and maximum
Hurricane Andrew windspeeds were developed so that woody debris can be added to existing ecological simulation
models for the region. Including woody debris in model simulations may be important in accounting for a substantial
amount of additional carbon within the system.
Cases of Caribbean mangrove tree mortality have been reported but have not included estimates of downed
wood. Downed woody debris as a component of mangrove forest structure has been explored in two investigations
from the old world tropics but have less relevance to neotropical mangrove swamps. This research provides those
data for hurricane-prone regions of south Florida and provides the associated link to ecological simulation models.
Contact: Contact: Ken W. Krauss, U.S. Geological Survey, National Wetlands Research Center, 700 Cajundome
Blvd., Lafayette, LA, 70506, Phone: 337-266-8882, Fax: 337-266-8592, Email: kkrauss@usgs.gov, Poster, Ecology
and Ecological Modeling
163
Recent Fish Introductions into Southern Florida Freshwaters, with Implications for
the Greater Everglades Region
By William F. Loftus1, Leo G. Nico1, Jeffrey Kline2, Sue A. Perry2, and Joel C. Trexler3
1U.S. Geological Survey, Florida Integrated Science Center, Miami and Gainesville, FL., USA
2Everglades National Park, Homestead, FL., USA
3Florida International University, Miami, FL., USA
Much has been published about introduced fishes in Florida, particularly their ability to invade and potentially
disrupt natural aquatic communities. Approximately 20 species have been recorded as establishing populations in
the extreme southern part of the state, with many others having been collected without evidence of establishment.
Recent papers have examined data collected in southern Florida to evaluate the distribution and relative abundance
of introduced fishes across a variety of habitats. Two sampling programs in the Everglades provided systematically
collected density information over a 20-year period, and documented the first local appearance of four introduced
fishes based on their repeated absence in prior surveys. Freshwater canals, and natural tidal creeks surrounded by
mangrove-dominated wetlands, held the largest introduced-fish populations in the southern Everglades region
However, these combined studies reported fewer species of introduced fishes from the Everglades region when compared
with studies conducted in canals along the developed Florida east coast, indicating that the most likely sites
of introduction for most species is in those canals. Recent information on the appearance of additional species, and
range expansions by established fishes, demonstrates that colonization of the Everglades region is continuing. The
eight established species of introduced fishes known from the Everglades in the 1990s have since been joined by
additional species. What are these fishes, how were they introduced, why are their ranges expanding, and what other
species are likely to colonize the Everglades?
The native inland fish community of the Everglades
region is comprised by about 35 temperate species
with wider distributions in Florida and the southeast
United States. Most previously introduced fishes in the
Everglades were tropical in origin, illegally released,
often from aquaria, and belonged to the family Cichlidae.
One species each of livebearer and clariid catfish also
were established there. Records indicate that most of
those introduced species were released east of the Everglades
and used the canal system to move into the Everglades
system. Although many became widespread in
the system, the majority did not achieve great numbers
except in local situations. We hypothesize that a combination of cold winter temperatures and unfavorable habitat
structure may have limited success in natural habitats by some previously established species.
Several widespread sampling programs employing
electrofishing, trapping, and netting, and shorter-term
research studies, continue to provide information on introduced
species in the Everglades region. Those studies,
and ongoing ichthyofaunal surveys of the Big Cypress NP
and Biscayne NP, are continuing to collect data from
canals, marshes, swamps, and detention areas. In recent
years, several new species have been collected either in
the Everglades or in canals that border the system.
Although several are cichlids (jewelfish, banded severum,
jaguar cichlid, peacock bass), others belong to families
not formerly found in this region (Asian swamp eel,
Pike killifish (Belonesox belizanus). L. G. Nico photo.
164
Homestead population, armored catfishes). In addition, other species are established in the canal system to the east,
from which dispersal towards the Everglades is likely (Asian swamp eel - Miami population, snakehead, grass carp,
various cichlids). While some of these recent introductions are probably aquarium releases, others appear to be illegal
introductions for food or marketing purposes. Apart from the accidental release of blue tilapia from a Miami-
Dade County aquaculture facility, this class of food-fish planting by amateurs is a novel vector for fish introduction.
Analysis of Everglades data collections found
evidence for mainly local effects by introduced
fishes, but the long-term effects of introductions,
particularly with the continuing accumulation of
species, are unclear. Experimental research into the
biotic interactions of introduced fishes and native
species is needed, as is modeling research to
identify species that may pose problems if they
were to be introduced. There should be emphasis
placed on additional monitoring of under-sampled
habitats such as canals. We also suggest that more
efforts be made to educate the public about introduced species and in closing newly identified pathways
for the introduction of additional species identified as potential threats.
Although there have been no dramatic ecosystem effects
such as extinctions or large-scale population declines in
native species identified in southern Florida, we are
uncertain that this condition will continue under the
cumulative effects of future invasions or environmental
change. What can be done to limit the numbers, spread
and effects of introduced fishes? At present, there are few
options available to deal with introduced fishes in the
open habitats of southern Florida. Once a population has
expanded beyond its point of introduction into the main
canal system or into the Everglades marsh, nothing can be
done to eliminate or even control them at this time. Control
may be effective in local situations to meet specific
management objectives. Even then, it will have to be a
sustained effort because of the pool of recruits that exists
in the canal reservoirs. Unlike the research and management
funding used to find and deliver controls for plant or
insect pests, there has been little funding applied to
research into controls for fishes. Increased emphasis on
finding innovative methods for dealing with fish invaders should be a priority. At present, the best way to prevent
the continuing introduction of fishes may be through better public education. Design considerations should include
consequences when planning pump stations, detention areas, new canals, and other constructs that will foster growth,
dispersal, and delivery of non-native fishes, snails, and plants into natural wetland areas. Just "getting the water
right" is not enough if it means the delivery of those waters will change the character of the Everglades biota.
Contact: William, Loftus, 40001 State Road 9336, Homestead, Florida, 33034, Phone: 305-242-7835, Fax: 305-
242-7836, Bill_Loftus@usgs.gov
Asian Swamp Eel (L.G. Nico Photo)
Canals and structures bordering ENP.
165
Fish Community Colonization Patterns in the Rocky Glades Wetlands of
Southern Florida
By William F. Loftus1, Robert M. Kobza1, and Delissa Padilla1, and Joel C. Trexler2
1U.S. Geological Survey, Center for Water and Restoration Studies, Miami, FL., USA
2Florida International University, Miami, FL., USA
As part of a larger effort to assess the role
of aquatic refuges and subterranean habitats in
system restoration, we began collecting baseline
data on the ecology of constituent aquatic communities
of the Rocky Glades in the wet season
of 2000. The Rocky Glades is a threatened,
short-hydroperiod habitat that remains intact
structurally only within Everglades National
Park (ENP), but even there its hydrology has
been adversely affected by drainage. Pre-drainage
accounts indicate that this region once had
higher water levels that likely provided a richer
habitat for aquatic species. Little has been published
about the species composition of animals
that survive below-ground through the dry season,
their community patterns once aboveground,
and their movements back into holes as
water recedes in autumn. The highly eroded
landscape offers dry-season refuge to aquatic
animals in solution holes, which also allow them
access to groundwater. As soon as rains flood the area in the early summer, fishes and invertebrates immediately
appear on the wetland surface. We are investigating whether recolonization of the surface is a function of survival
in local refuges, results from rapid, long-distance dispersal, or a combination of both.
In the early 1990s, we observed mass, early wetseason
fish movements in the Rocky Glades, which
sparked this study of the fish communities and dispersal.
In the first project year, we tested methods
designed to detect directional dispersal by using
drift fences and funnel traps along a hydroperiod
gradient. Several questions arose from these preliminary
observations of dispersal in the Rocky
Glades: How rapidly do different species appear in
the arrays? Are the movement patterns of animals
related to water flow? Do the animals disperse from
the main sloughs to recolonize the Rocky Glades, or
are the Rocky Glades acting as a source of animal
colonists for the sloughs? Do roadways act as barriers
to movement? How do composition, sizestructure,
and recruitment of aquatic animals
change during the flooding period?
In 2000, we erected four x-shaped drift-fence
arrays (Arrays 1 to 4: fig. 1), with 12 m wings made of black plastic cloth, along the main park road of ENP. The
Figure 1. Drift-fence Arrays 1-13 in ENP.
Figure 2. Trap retrieval at Array 4.
166
wings of the fences directed animals into traps that face the compass directions (fig. 2). When the wetlands flooded
in June, we made daily collections for the first two weeks, reduced the frequency to twice weekly for three weeks,
and to weekly collections until dry-down. We identified, weighed, and measured all animals in the lab. In 2001, a
more spatially expansive study was implemented
The number of animals in each trap on a particular day seemed to be related to the water flow and depth, with
the highest number taken during the highest flows. Most animals dispersed rapidly after the wetlands flooded. Preliminary
assessments of the data indicated that the direction and degree of rheotaxy varied by species. Fishes and
crayfish often reappeared in the traps on the same day that the wetlands flooded, supporting the case for local subterranean
refuges. However the largest numbers of fishes appeared within two weeks of flooding (fig. 3). It remains
unclear whether they may have been able to disperse for tens of kilometers across the heavily vegetated wetland landscape
from Shark Slough and its estuarine creeks in that time. Hypotheses about dispersal patterns will be tested in
2003-2004 using methods such as stable isotope and otolith microchemistry analyses, and radio-tracking of larger
species.
Subsequent sampling provided data on community-succession patterns as new species appeared in the traps
and relative abundances changed. Size-structure data have been used to document the onset of reproduction. Most
fishes emerging onto the surface were adults that began reproducing within one or two weeks. Small juveniles
appeared in the traps within a month of flooding.
The study of ecological interrelations between surface and subterranean habitats will help determine how
human management has affected this region and what benefits can be anticipated by the restoration of natural hydrology.
The temporal dynamics of the use of Rockland habitats in relation to hydrology have just begun to be described.
This project will provide data important to simulation models, such as whether solution holes in the Rockland function
as sources or sinks for fishes and how hydropattern affects trophic structure and the composition of aquatic animal
communities in this landscape.
This research was funded through the Critical Ecosystem Studies Initiative by agreement between the U. S.
Geological Survey and the U.S. National Park Service.
Contact: Bill, Loftus, U.S. Geological Survey, 40001 State Road 9336, Homestead, Florida, 33034, Phone: 305-
242-7835, Fax: 305-242-7836, Bill_Loftus@usgs.gov, Ecology and Ecological Modeling
0
5
10
15
20
0 1 2 3 5 7 10 15 20 24 28
Week of I nundat i on
Mosquitof ish
Flagf ish
Bluef in killif ish
Sailf in molly
Mar sh killif ish
Golden topminnow
Dollar sunf ish
Sheephead minnow
Least killif ish
Pike killif ish
Bluegill
Ever glades pygmy sunf ish
Spotted sunf ish
Black acar a
Spotted tilapia
Mayan cichlid
Bluespotted sunf ish
Warmouth
Jaguar cichlid
Lake chubsucker Array 4, 2000
0
5
10
15
20
0 1 2 3 5 10 15 20 25 30 35
Week of Inundation
Least killifish
Flagfish
Marsh killifish
Mosquitofish
Black acara
Sailfin molly
Pike killifish
Sheephead minnow
Spotted sunfish
Dollar sunfish
Bluefin killifish
Warmouth
Mayan cichlid
Bluegill
Largemouth bass
Taillight shiner
Golden topminow
Tadpole madtom
Everglades pygmy
sunfish
Array 4, 2001
Figure 3. Appearance of fish species by week of sampling at Array 4 in 2000 and 2001.
167
Population Dynamics of the Snail Kite in Florida
By Julien Martin1, Wiley M. Kitchens1, and W.M. Mooij 2
1U.S. Geological Survey, University of Florida, Gainesville, FL ., USA
2Netherlands Institute of Ecology, Nieuwersluis, The Netherlands
The snail kite (Rostrhamus sociabilis plumbeus) is an endangered raptor that inhabits flooded freshwater
areas and shallow lakes in peninsular Florida and Cuba (Sykes 1984, Sykes et al., 1995). The historical range of the
snail kite covered over 4,000 km2 (2,480 mi2) in Florida, including the panhandle region (Sykes et al., 1995), but is
now restricted mainly to the watersheds of the Everglades, Lake Okeechobee, Loxahatchee Slough, the Kissimmee
River, and the Upper St. Johns River. These habitats exhibit considerable variation in their physiographic and vegetative
characteristics, and include graminoid marshes (wet prairies, sloughs), cypress swamps, lake littoral shorelines,
and even some highly disturbed areas such as agricultural ditches or retention ponds (Bennetts and Kitchens,
1997). Three features that remain constant in the variety of selected habitats are the presence of apple snails, areas
of sparsely distributed emergent vegetation (Sykes, 1983; 1987), and suitable nesting substrates, all of which are
critical to the nesting and foraging success of the snail kite.
Snail kites are dietary specialists, feeding almost exclusively on one species of aquatic apple snail, Pomacea
paludosa (Sykes, 1987; Sykes et al., 1995). The snail kite's survival depends on those hydrologic conditions that
support these specific vegetative communities and subsequent apple snail availability in at least a subset of wetlands
across the region each year (Bennetts et al., 2002). Wetland habitats throughout central and southern Florida are constantly
fluctuating in response to climatic or managerial influences, resulting in a mosaic of hydrologic regimes.
The aim of the snail kite project is to monitor the response of the birds to those changes. This research essentially
focuses on the most critical demographic parameters: survival, reproduction, recruitment and population
growth rate (Bennetts et al., 1999; Dreitz et al., 2001; Bennetts et al., 2002; Dreitz et al., 2002). Because those demographic
parameters are so heavily influenced by the behavior of the birds (i.e. their ability to move and select suitable
habitats), movement studies constitute the other major aspect of the research. The objectives are twofold: First to
evaluate the likelihood of biological hypotheses, which help understand the underlying mechanisms and processes
driving the population dynamics of the kites; and second to provide reliable estimates of demographic parameters
and movement probabilities, which are helpful for decision making using management models (see below). The statistical
framework selected for parameter estimation is maximum likelihood estimation for its well recognized good
statistical properties (Burnham and Anderson 1998). The empirical data consists of mark-resight and radio telemetry
data.
The long-term data set already available
offers the potential to investigate the effect of
hydrological variations across time and space.
Low water years have substantial effects on the
number of nests detected, but do not seem to
greatly affect nesting success (Dreitz et al. 2001),
which suggest that when the hydrological conditions
are unfavorable for kites, birds simply do
not breed. Thus far there is no evidence for an
effect of local drying event on adult survival,
although this aspect needs to be investigated for
juvenile. There is no strong evidence for a very
substantial effect of a fairly widespread drought
event (however, low in intensity) on adult survival
(the 2000-2001 drought, fig. 1). In contrast
the 2000-2001 drought considerably affected
juvenile survival (fig. 1).
168
It was also interesting to note that it is during the wettest year that the highest estimates of juvenile survival
were observed. Bennetts et al. (2002), explain this observation by suggesting that during high water year, more sites
are likely to be suitable for foraging. Hence, during the dispersing period, when juveniles are most vulnerable, an
increase in the surface area of suitable habitat, would reduce the chances of the dispersing juveniles encountering
unsuitable habitat. An important point to make here is that the results provided in this abstract are preliminary. Those
estimates will be refined by incorporating the 2003 field data. Nonetheless, the estimates that this analysis provides
are already valuable for further modeling effort, in particular in the context of the Across Trophic Level Simulation
System (ATLSS), which evaluates the effect of various hydrological regimes on the whole Everglades ecosystem
(DeAngelis et al. 1998; DeAngelis et al. 2002). Indeed the present version of the spatially explicit individual-based
kite model that will be incorporated into ATLSS (Mooij, Bennetts et al., 2002), is presently lacking robust estimates
for survival during drought events.
Another aspect presently under investigation is the response of the bird in terms of movement. By combining
radio telemetry and mark-resight data under a multistate modeling framework (Williams, Nichols et al., 2001), we
intend to estimate yearly movement probabilities between critical habitats, and test biological hypotheses about the
processes driving the long term movement patterns. This information together with some further investigation of
within year movement patterns, should help improve the predictive performance (in particular the spatial component)
of the spatially explicit individual based kite model.
Contact: Julien Martin, Florida Cooperative Fish and Wildlife Research Unit, University of Florida, Gainesville,
FL 32611-0450, email: martinj@wec.ufl.edu
169
The Relationship of Seagrass-Associated Fish and Crustacean Communities to
Habitat Gradients in Florida Bay
By R.E. Matheson1, David Camp1, Mike Robblee2, Gordon Thayer3, Dave Meyer3, and Lawrence Rozas4
1FWC, Florida Marine Research Institute, St. Petersburg, FL., USA
2U.S. Geological Survey, Center for Water and Restoration Studies, Miami, FL., USA
3NOAA, NCCOS, Center for Coastal Fisheries and Habitat Research, Beaufort, NC., USA
4NOAA Fisheries, Estuarine Habitats and Coastal Fisheries Center, Lafayette, LA., USA
Restoration of the Greater Everglades ecosystem will be multifaceted, but a large component of the program
involves reestablishing a more natural hydrological regime. Downstream of the Everglades, changes in the quantity,
timing, and distribution of freshwater flows entering Florida Bay will affect the resident biota. This project was
designed to provide baseline data for one important faunal component of the Florida Bay ecosystem: seagrass-associated
fish, caridean and penaeid shrimp, and portunid crabs. Seagrass beds are one of the most spatially extensive
and important habitats in Florida Bay, and the extent, composition, and health of seagrass beds can definitely be
affected by changes in freshwater inflow. Seagrass-associated faunal communities can be affected directly by salinity
changes or indirectly by changes in the seagrass habitat. This study provides baseline data needed by managers
to create models that can predict what will happen as a result of changes in freshwater delivery to Florida Bay and
to evaluate the success of upstream restoration activities.
We used 1-m2 throw-traps to collect seagrass-associated fauna at 18 sites distributed throughout Florida Bay.
For analytical purposes, our sites can be grouped geographically (fig.1): 1) northeast-Black Betsy, Bob, Butternut,
Deer, Eagle, and Nest Keys; 2) interior-Bob Allen, Buttonwood, Crab, Roscoe, Spy, and Whipray Keys; and 3)
peripheral-Barnes, Joe Kemp, Johnson, Palm, Rabbit, and Sandy Keys. Three habitats (bank, basin, and near-key)
were sampled at each site during wet (October) and dry seasons (April-May) from 1998 through 2000, yielding 360
bank samples, 360 basin samples, and 270 near-key samples. We identified 7,539 fish and 62,786 shrimp and crabs
from these samples.
170
A gradient was apparent in both habitat features and biotic communities across the three regions (table 1).
Northeastern sites had lower, more variable salinities; shallower sediments; less seagrass cover; and lower diversity
and abundance of fish and crustaceans. Levels of these same parameters were often intermediate at interior sites and
highest at peripheral sites.
The abundance patterns of the five dominant fish species were less consistent with this gradient than were the
abundance patterns of the five dominant crustacean species. The abundance of only one fish species, Lucania parva,
strictly followed the gradient of northeast<interior<periphery, and two fish species, Floridichthys carpio and Opsanus
beta, were found at similar abundances in all three regions. Anchoa mitchilli and the sixth-ranked species,
Microgobius gulosus, were both most abundant at northeastern and interior sites; both of these species are often
found in the low-salinity portions of estuaries and are weakly associated (if at all) with seagrass. Among crustaceans,
abundances of the top five species were all low in the northeast, moderate or high in the interior, and high on the
periphery of the bay. The strongest apparent relation between abundance and salinity were observed for Farfantepenaeus
duorarum and Gobiosoma robustum. Both of these species were essentially absent at salinities below 29 ppt
but were among the most abundant species at higher salinities. Greater seagrass-bed development (i.e., greater
density, leaf area, or diversity) was often accompanied by greater abundances of several species, including F. duorarum,
G. robustum, Thor floridanus, and O. beta.
Alterations in the pattern of freshwater inflow could affect most of the physical and biotic patterns which we
observed in Florida Bay. The effects of these alterations on fauna will be species-specific. Our study provides data
for predicting these changes prior to restoration and for documenting these changes after restoration.
Contact: R.E. Matheson, Florida Fish and Wildlife Conservation Commission, Florida Marine Research Institute,
100 8th Avenue SE, St. Petersburg, FL 33701, Phone: (727)896-8626, Fax: (727)8230166, eddie.matheson@
fwc.state.fl.us
Table 1. Characterization of habitats and faunal communities in three regions within Florida
Bay. Seagrass diversity is determined by the relative contribution of each of the species
collected during this study to the overall abundance of seagrass in each region. Only the five
most abundant fish and five most abundant crustacean species are included.
Parameter Northeast Interior Periphery
Salinity low high high
Salinity CV high low low
Sediment Depth low moderate high
Seagrass Shoots low moderate high
Seagrass Biomass low moderate high
Seagrass Diversity low moderate high
Seagrass Canopy Height low moderate high
Fish Abundance low moderate high
Number of Fish Species low low high
Lucania parva low moderate high
Gobiosoma robustum low high moderate
Floridichthys carpio moderate moderate moderate
Opsanus beta moderate moderate moderate
Anchoa mitchilli high high low
Crustacean Abundance low moderate high
Number of Crustacean Species low moderate high
Thor floridanus low high high
Hippolyte zostericola low moderate high
Farfantepenaeus duorarum low moderate high
Alpheus heterochaelis low high high
Periclimenes americanus low moderate high
171
Status of the American Alligator (Alligator mississippiensis) in Southern Florida
and its Role in Measuring Restoration Success in the Everglades
By Frank J. Mazzotti1, Michael S. Cherkiss1, Mark W. Parry1, Kenneth G. Rice2, Laura A. Brandt3, and
Clarence L. Ambercrombie4
1University of Florida, Department of Wildlife Ecology and Conservation, Fort Lauderdale, FL., USA
2U.S. Geological Survey, Center for Water and Restoration Studies, Fort Lauderdale, FL., USA
3U.S. Fish and Wildlife Service, Arthur R. Marshall Loxahatchee National Wildlife Refuge, Boynton Beach, FL., USA
4Wofford College, Spartanburg, SC., USA
The American Alligator (Alligator mississippiensis) was abundant in the pre-drainage Everglades. Alligators
once occupied all wetland habitats in south Florida, from sinkholes and ponds in pinelands to mangrove estuaries
during periods of freshwater discharge (Craighead, 1968; Simmons and Ogden, 1998). Nearly all aquatic life in the
Everglades is affected by alligators (Beard, 1938). As a top predator in their ecosystem, alligators undergo an
extraordinary change in body size, consuming different prey items as they grow (Mazzotti and Brandt, 1994). As
ecosystem engineers, alligators create trails and holes that provide aquatic refugia during the dry season and concentrate
food items for larger predators. Alligator nests provide elevated areas for nests of turtles and snakes, and
for germination of plants less tolerant of flooding (Craighead, 1971; Kushlan and Kushlan, 1980; Enge et al., 2000).
Alligator activity also keeps many small creeks in the freshwater mangrove zone, gator hole sites, and areas around
tree islands from becoming overgrown with vegetation. It is possible the activity creates firebreaks that provide refuge
to woody vegetation and various animal species (Craighead, 1968; Simmons and Ogden, 1998). The water
present in holes during the dry season provides critical habitat for nesting female and juvenile alligators (Mazzotti,
1989; Kushlan and Jacobsen, 1990) and provides open water necessary for alligator mating (Garrick and Lang, 1975).
In Everglades National Park, the largest historical alligator populations occurred in broad marl prairies to the
east and west of the ridge and slough habitats, and in the freshwater mangrove zone. Land development and water
management practices have reduced the spatial extent and changed the hydropatterns of these habitats (Mazzotti and
Brandt, 1994). As a result of these habitat alterations, alligators are now less numerous in the marl prairie, rocky
glades, and mangrove fringe areas. For alligators, an important alteration was the construction of canals. Alligators
initially displaced by development or drainage now reside in canals. The effects of artificial habitats such as canals
on creation and maintenance of alligator holes had not been studied until recently. Everglades canals serve as alligator
refugia throughout the Greater Everglades ecosystem. Adult alligator density (especially of males) is higher
in canal habitats than in the natural marsh interior (FFWCC, unpub. data; Morea, 1999). The canals may provide
suitable habitat for large alligators, but unlike alligator holes, they are not suitable for smaller alligators, smaller
marsh fish, or foraging wading birds. Though this trend may be remedied by proper management practices, characteristics
of alligator habitats have changed with the creation of canal systems now present in the Florida Everglades
(Kushlan, 1974).
Restoration of hydrologic patterns and ecological function in the Everglades is now underway. The relations
among dry season refuge, aquatic fauna, wading birds, and alligators have been identified as key uncertainties in the
Comprehensive Everglades Restoration Plan (CERP; U.S. Army Corps of Engineers, 1999). Due to the alligator's
ecological importance and known sensitivity to hydrology, salinity, habitat productivity, and total system productivity,
the species was chosen as an indicator of restoration success. A number of biological attributes (relative density,
relative body condition, nesting effort, and nesting success) can be measured, standardized methods for monitoring
have been developed, and historical information exists for alligator populations in the Everglades. These attributes
can be used to determine success at different spatial and temporal scales, and are instrumental for constructing ecological
models used to predict restoration effects. The relative abundance of alligators is expected to increase as
hydrologic conditions improve in over-drained marshes and freshwater tributaries. As canals are removed, densities
of alligators in adjacent marshes and occupancy of alligator holes is expected to increase. As hydroperiods and
depths approach more natural patterns, nesting success, alligator growth, and condition are all expected to increase
in areas where they are currently below historic values.
172
REFERENCES
Beard, D.B. 1938. Everglades National Park Project: Wildlife Reconnaissance.U.S. Department of Interior, National
Park Service. Washington, D.C.
Craighead, F.C., Sr. 1968. The role of the alligator in shaping plant communities and maintaining wildlife in the
Southern Everglades. Florida Naturalist. 41:2-7, 69-74, 94.
Craighead, F. C. Sr. 1971. The Trees of South Florida: The Natural Environmentsand Their Succession. University
of Miami Press, Miami, FL.
Enge, K.M., H.F. Percival, K.G. Rice, M.L. Jennings, G.R. Masson, and A.R.Woodward. 2000. Summer nesting of
turtles in alligator nests in Florida. J.Herp. 34: 497-503.
Garrick, L.D. and J.W. Lang. 1975. Alligator courtship. American Zoologist 15: 813.
Kushlan, J.A. 1974. Observations of the role of the American alligator in the southern Florida wetlands. Copeia 993-
996.
Kushlan, J.A. and M.S. Kushlan. 1980. Everglades alligator nests: nesting sites for marsh reptiles. Copeia 1930-
1932.
Kushlan, J. A. and T. Jacobsen. 1990. Environmental variability and the reproductive success of Everglades alligators.
J. Herpetol. 24(2):176-184.
Mazzotti, F.J. 1989. Structure and function. Pages 42-57 in C.A. Ross and S. Garnett, editors. Crocodiles and Alligators.
Weldon Owen Pty. Ltd., Australia.
Mazzotti, F. J. and L. A. Brandt. 1994. Ecology of the American alligator in a seasonally fluctuating environment.
pp. 485-505 In S. Davis and J. Ogden, (eds.), Everglades: The Ecosystem and its Restoration. St. Lucie Press,
Delray Beach, Florida.
Morea, C. R. 1999. Home range, movement, and the habitat use of the American alligator in the Everglades.
Unpublished Thesis, Univ. Florida, Gainesville, Florida.
Simmons, G., and L. Ogden. 1998. Gladesmen. University Press of Florida, Gainesville, FL.
U.S. Army Corps of Engineers. 1999. Final Integrated Feasibility Report and Programmatic Environmental Impact
Statement. Central and Southern Florida Project Comprehensive Review Study. U.S. Army Corps of Engineers.
Jacksonville District.
Contact: Frank J. Mazzotti, University of Florida Fort Lauderdale Research and Education Center, 3205 College
Ave., Ft. Lauderdale, Florida, 33314; Phone: 954-577-6304, FAX: 954-475-4125, e-mail: fjma@mail.ifas.ufl.edu
173
Fish Assemblages of Tidally Flooded Mangrove Forested Habitat Along a Salinity
Gradient in Shark River
By Carole C. McIvor, Noah Silverman, Gary L. Hill, and Katie Kuss
U.S.Geological Survey, Center for Coastal and Watershed Studies, St Petersburg, FL., USA
We have been sampling fishes that directly use tidally flooded mangrove forest habitat along Shark River for
three years. We sample every other month using two passive sampling methods: 2 X 3 m2 bottomless lift nets and
1 X 1.5 m block nets across the mouths of intertidal rivulets. Lift nets are located within the first 16 meters of fringing
forests and yield density data; intertidal rivulet nets are located at the forest/river bank interface and yield CPUE
(catch per unit effort) data as they drain an unknown and variable area. Sites are fixed, and located off Tarpon Bay
upriver (S2), midway along the Harney River (S4), and downriver near the mouth of Shark River about 3 km
upstream of Ponce de Leon Bay (S3).
The 18-month period January 2001 - June 30, 2002 is representative. We captured 25 fish species from 16
families on 8 sampling dates. Average catch per rivulet net was 13.8 fish; average density per lift net was 3.4 fish
/6 m2. Five families dominated the mangrove forest assemblage. Gobies (frillfin, crested), mojarras (silver jenny,
tidewater mojarra), rivulins (mangrove rivulus), anchovies (bay anchovy) and killifishes made up 92 percent of the
catch. Introduced species (walking catfishes, pike killifish, cichlids) were rare, as were juveniles of estuarine transient
species that spawn offshore, e.g., gray snapper, pinfish, and mullets.
Frillfin goby (Bathygobius
soporator) and mangrove
rivulus (Rivulus
marmoratus) were the most
abundant species. Frillfin
gobies appear to be best
suited to higher salinities,
showing a monotonic decline
with decreasing salinity
upstream in Shark River (fig
1). Mangrove rivulus, once
considered a species of special
concern in Florida, is
common along the entire
salinity gradient sampled (fig
2). This species is the most
frequently captured species in
our bottomless lift nets.
Rather than being rare, it is
actually a habitat specialist
poorly captured by traditional
sampling methods. Unlike
other fish species, mangrove
rivulus remains in the forest
over low tide by a combination
of aerial respiration and
use of damp refuges, e.g.,
crab burrows, under wet leaves and wood. Although data analysis is incomplete, three trends are apparent in rivulus
distribution along Shark River:
Average Number of Bathygobius soporator in Rivulet Nets,
and Average Salinities at Sites in Shark River, ENP - 2001 and 2002
Sampling Sites in Shark River
Up-river Mid-river Down-river
Average (+ 1 S.E.)
Number per Net
0
2
4
6
8
10
12
Average (+ 1 S.E.)
Salinity (ppt)
0
5
10
15
20
25
30
Salinity
174
 Individuals tend to be smaller upriver.
 The greatest density occurs at the mid-river location.
 Rivulus have the highest condition factors downriver.
The relative abundance and distribution of these two common species (frillfin goby, mangrove rivulus) can be
used as part of a larger monitoring effort to judge the effects of hydrological modifications made upstream in the
catchment as part of restoration activities.
Contact: McIvor, Carole C., U.S. Geological Survey Center for Coastal and Watershed Studies, 600 Fourth St. S,
St Petersburg, FL 33715, Phone: 727-803-8747, Fax: 727-803-2032, carole_mcivor@usgs.gov
Average Number of Rivulus marmoratus in Lift Nets -
Shark River, ENP - 2001 and 2002
Sampling Sites
Up-river Mid-river Down-river
Average (+ 1 S.E.)
Number per Net
0
2
4
6
8
10
Average (+ 1 S.E.)
Salinity (ppt)
0
5
10
15
20
25
30
Salinity
175
Assessing the Consequence of Hurricane-Induced Conversion of Mangroves to
Mudflats on Fish and Decapod Crustacean Assemblages in the Big Sable Creek
Complex of Southwest Florida
By Carole C. McIvor1 and Noah Silverman2
1U.S. Geological Survey, Center for Coastal and Watershed Studies, St Petersburg, FL., USA
2ETI Professionals, Inc., St Petersburg, FL., USA
Hurricanes routinely cause damage to mangrove forests, generally by breaking and toppling trees. Normally
forests recover through growth of new plants from seedling germination. For reasons that are not completely understood,
the passage of two category 4-5 hurricanes across the Cape Sable peninsula in southwestern Florida (1935,
1960) resulted in permanent damage to some mangrove forests: adult trees were killed, sediments eroded, and no
seedlings germinated. The net result was localized conversion of mangrove forests to unvegetated mudflats. Mangroves
are generally considered to be critical nursery habitat to the juveniles of many species of estuarine transient
fishes whose adults spawn offshore and whose young life history stages use mangrove environments. This project
asks the question "What is the consequence of the conversion of mangrove to mudflat habitat on intertidal assemblages
of fish and decapod crustaceans within the creeks in the Big Sable Creek complex?"
The Big Cape Sable Creek complex is located at the far downstream end of the Everglades restoration area,
but is of interest because it naturally receives little freshwater inflow. The creek complex consists of six tidal creeks
that are a mosaic of mangrove forest and mudflats (fig. 1): both habitats are inundated at high tide. Intertidal rivulets,
i.e., drainage features smaller than first order creeks, also drain both habitats. Rivulets are depressions in the substrate
up to 1 m deeper than the forest floor or mudflat around them. Rivulets fill earlier on flood tides and retain
water later on ebb tides. Rivulets are "hotspots" for the entry and egress of fish and decapod crustaceans (shrimp,
crabs) from intertidal habitats, and are a convenient location for sampling these animals with block nets (fig. 2) to
compare the fish and decapod fauna leaving replicate forest and mudflat habitats.
Figure 1. Big Sable Creek complex.
Intertidal mudflats show up in B&W photo
as light gray openings in an otherwise
continuous dark forest.
Figure 2. Permanent end posts either side of a routinely
sampled intertidal rivulet: posts accommodate block net for
capturing fish and crustaceans leaving the mangrove forest
on an ebb tide.
176
We hypothesize that forested sites will be dominated by small benthic forage fishes (e.g., gobies, killifishes)
that experience a lower risk of predation within complex intertidal vegetation. Alternatively, we expect deeper mudflat
sites lacking vegetation to be dominated by two groups of fishes: water column schooling fishes (e.g., anchovies,
silversides), and large roving predators (e.g., subadult snappers, catfishes), both of whose movements will be unimpeded
by the structural complexity of stems and roots of mangrove trees.
The statistical design is a repeated measures ANOVA. The dependent variable is catch per unit effort (CPUE),
the independent variable is habitat type: catch will be quantified as both numbers and biomass. We are sampling
three replicate creeks, each with a forested and a mudflat site. The rivulet sites are fixed and drain an unknown area
that varies with both tidal height and with location. Sampling will occur every 2 months for 12-18 months. A major
challenge is defining either the area drained by each net, or the volume of water flowing through each net to refine
our measurement of catch.
Species composition will be compared between habitat types using an ordination technique, multidimensional
scaling (MDS), followed by analysis of similarity (ANOSIM) to ascertain statistical significance of species groupings.
Very preliminary analysis of the first data collected in fall 2002 indicates compositional differences in the fish
faunas of the two types of intertidal habitats.
Contact: Silverman, Noah. U.S.Geological Survey; 600 Fourth Street South, St Petersburg, FL 33701,
Phone: 727-803-8747, Fax: 727-803-2032, nsilverman@usgs.gov
177
Projecting Future Population Dynamics of the Florida Snail Kite in Relation to
Hydrology by Means of a Suite of Models
By W.M. Mooij1 and D.L. DeAngelis2
1Netherlands Institute of Ecology, Centre for Limnology, Nieuwersluis, The Netherlands
2U.S. Geological Survey, Center for Water and Restoration Studies, University of Miami, Coral Gables, FL., USA
The basic information for any model that projects future population dynamics should be good empirical studies.
A large number of empirical studies have been done on the Florida Snail Kite. Such studies provide basic information
on the biology of the species. They also provide the correlative relations between specific aspects of the snail
kite life-history and behavior with the hydrology of the system. These relations form the building blocks of any
hydrology-driven population-dynamical kite model.
Opinions differ on whether the best approach to modeling the life history of a population should be by means
of a system-wide deterministic matrix model or, alternatively, a spatially-explicit stochastic individual-based model.
We argue that rather than choosing among these two approaches, it is better to implement both concurrently. Next to
the system-wide deterministic matrix model and the spatially-explicit stochastic individual-based model two other
versions were implemented: a system-wide stochastic matrix model and a spatially explicit deterministic individualbased
model. With these four tools in hand, we approached the challenge of making reliable projections of future
population development of the snail kite under various hydrological scenarios.
Next to having a rigorous and transparent model structure, two issues are central to getting a reliable kite
model: how to parameterize the model and how to set ranges of uncertainty to its output. The preferred statistical
framework to solve both issues would be maximum likelihood estimation. In principle, the Maximum Likelihood
Method provides a formal and rigorous approach to deal with the five sources of uncertainty: structural uncertainty,
uncertainty in the hydrological input, uncertainty in the biological parameters, uncertainty due to demographic stochasticity,
and finally uncertainty due to errors in the empirical data on basis of which the model is parameterized.
There is optimism that the kite model will be among the first applied population dynamical models that succeeds
in disentangling and integrating these sources of uncertainty in a formal way. The current implementation of
the model (Everkite 3.00), that has already been applied to evaluate hydrological scenarios and is ready to analyze
new scenarios as they come, provides an excellent starting point for these new developments.
Contact: Wolf M. Mooij, Netherlands Institute of Ecology, Centre for Limnology, Rijksstraatweg 6, 3631 AC
Nieuwersluis, The Netherlands; Phone: +31 294 239352, Fax: +31 294 232224, w.mooij@nioo.knaw.nl
178
Habitat Selection and Home Range of American Alligators in the
Greater Everglades
By Michael L. Phillips1, Kenneth G. Rice2, Cory R. Morea3, H. Franklin Percival4, and Stanley R. Howarter4
1University of Florida, Department of Wildlife Ecology and Conservation, Ft. Lauderdale, FL., USA
2U.S. Geological Survey, Center for Water and Restoration Studies, Ft. Lauderdale, FL., USA
3Florida Fish and Wildlife Conservation Commission, Tallahassee, FL., USA
4University of Florida, Florida Cooperative Fish and Wildlife Research Unit, Gainesville, FL., USA
Regional development and water management practices have drastically altered the spatial extent and traditional
hydropatterns of the Greater Everglades. Proposed restoration plans will dramatically affect the Everglades
ecosystem. Alligators are a keystone species that have an important role in the trophic dynamics of the Everglades
by engineering trails, "gator" holes and caves that are important refugia for many species of plants and animals
(especially fish and amphibians) during the dry season. Canals (one focus of restoration plans) serve as refugia for
alligators throughout the Everglades. Alligator life history patterns (including movement and habitat selection) are
expected to change in response to restoration efforts.
For this study, the American alligator was selected (Alligator mississippiensis) as an indicator of the success
of restoration efforts. The objective was to collect information that can be used in ecological models for predicting
and evaluating alternatives of the Comprehensive Everglades Restoration Plan (CERP). The success of restoration
efforts will rely on models such as the Across-Trophic Level System Simulation that require valid estimates of alligator
response to habitat restoration.
Radio telemetry was used to examine habitat selection and home range of alligators in the Greater Everglades.
The size and shape of home ranges as well as selection of cover types within home ranges reflect the quality and
condition of available resources. As canals are removed and alligators move back into adjacent marsh habitat, we
anticipate that resource selection (and ultimately demography) will depend on where the alligator is located in the
Greater Everglades. Therefore, alligators were observed inthree contrasting Everglades habitats: marsh in Water
Conservation Area 3A North (WCA), marsh in the Everglades National Park (ENP), and canals in both the WCA
and ENP (Canal). Weekly locations for 66 alligators (WCA = 11, ENP = 22, Canal = 33 alligators) and intensive
daily locations for 31 alligators (WCA = 6, ENP = 7, Canal = 18 alligators) were recorded in the 3 habitats. Weekly
locations were recorded using aerial telemetry, while the daily locations were recorded using ground-based telemetry.
Home range for all alligators was estimated using a 95 percent daptive kernel model, which is a more robust
and conservative estimate of home range size. However, we used a 100 percent. Minimum Convex Polygon (MCP)
to estimate the proportion of habitat available to alligators in our examination of habitat selection. A 100 percent
MCP included all habitats used by each alligator. We used compositional analysis to examine the selection of cover
types with the 100 percent MCP. We examined seven cover types for the daily locations. The number of cover types
was restricted by sample size. Cover types for daily locations included: 1) sawgrass (Cladium jamaicense), 2) emergent
vegetation - including spikerush (Eleocharis cellulosa) and cattails (Typha spp.), 3) uplands - tree islands and
shrub islands, 4) floating vegetation - mainly water lilies (Nuphar spp., and Nymphaea spp.), 5) open water - areas
with little or no vegetation, 6) "gator" hole, and 7) canal. For weekly locations the same 7 cover types included in
the daily locations were examined, but levee break, gator trail and airboat trail were added.
Mean home range was larger for alligators in canals (111.2  27.1 ha, x  SE) than either WCA (55.5  17.7
ha) or ENP (79.7  25.2 ha) marshes. There was no difference in home ranges for alligators in the marsh of WCA
and ENP. Mean male home range (144.34  22.3 ha) was larger than female home range (35.91  16.76 ha).
179
Alligators frequently selected deeper water marsh in WCA (table 1) for both daily (P < 0.05) and weekly locations
(P < 0.001). Floating vegetation was selected more than any other cover type for both daily and weekly locations.
Weekly location data also indicated selection for emergent vegetation, levee breaks, and airboat trails that was
greater than other cover types.
Alligators were frequently located in gator holes (table 1) in ENP during both daily (P < 0.01) and weekly
locations (P < 0.0001). Daily locations also indicated a selection for emergent vegetation not observed for weekly
locations. Spikerush and cattails often surround gator holes in ENP. More intensive daily locations were more likely
to record locations in the surrounding emergent vegetation while alligators were using holes.
As expected, canal alligators strongly selected canals over all other cover types (table 1) for both daily
(P < 0.0001) and weekly locations (P < 0.0001). The creation of canals in the Greater Everglades has influenced alligator
movement and habitat selection. Canal alligators spend most of their time in canals and move greater distances
(i.e., have larger, more linear home ranges) than alligators in WCA or ENP marshes. The response of alligators to
the proposed removal of canals may depend on adjacent habitat. Alligators are able to restore abandoned alligator
holes or create new holes in the peat dominated slough of ENP, but they may be drawn to deeper water marsh, such
as found around floating vegetation or in levee breaks in the WCAs.
Table 1. Selection ratios (i.e., the ratio of the proportion of cover types used to the proportion of cover types available) for
American alligators radiotracked in the Greater Everglades from November 1996 to August 1999 .
Contact: Michael L. Phillips, University of Florida, Ft. Lauderdale Research and Education Center, 3205 College
Ave., Ft. Lauderdale, FL 33314-7799; Phone: 954-577-6306, FAX: 954-475-4125, mlphillips@usgs.gov
A. Daily Locations (n = 31 alligators)
Sawgrass
Emergent
Upland Floating
Open
water
Gator
hole
Canal
WCA 0.42 3.36 0.002 13.47 0.41 0.08 NA
ENP 0.27 9.57 1.17 0.001 0.01 7.41 NA
B. Weekly Locations (n = 66 alligators)
Sawgrass
Emergent
Upland Floating
Open
water
Gator
hole
Levee
break
Gator
trail
Airboat
trail
Canal
WCA 0.21 3.24 0.001 3.47 1.20 0.07 2.58 0.63 2.33 NA
ENP 0.03 0.02 0.32 0.003 16.40 17.79 1.00 0.11 0.33 NA
Canal 0.03 0.98 0.01 0.02 0.20 0.35 0.20 0.05 0.09 3.90
180
Movements and Habitat Requirements of Radio Tagged Manatees in Southwest
Florida-Implications for Restoration Assessment
By James P. Reid, Susan M. Butler, Dean E. Easton, and Brad Stith
U.S. Geological Survey, Center for Aquatic Resources Studies, Sirenia Project, Gainesville, FL., USA
A study on West Indian manatees (Trichechus manatus) in southwestern Florida is being conducted to determine
the relative abundance, distribution, movements, and habitat use of manatees associated with coastal waters
and rivers. As part of the study, an individual-based ATLSS model is being developed to predict manatee response
to changes in hydrology caused by the Comprehensive Everglades Restoration Plan (CERP). A large proportion of
the southwest Florida manatee population occurs throughout the Everglades National Park (ENP) and northwest
into the Ten Thousand Islands (TTI). Ongoing research in this region shows that manatees make frequent movements
up tidal creeks to obtain freshwater for drinking and to find thermal refugia during cold weather. Alteration
of the freshwater and estuarine ecosystems associated with restoration of the Everglades and Southern Golden Gate
Estates (SGGE) is likely to affect this manatee population. We hypothesize that manatee distribution, relative abundance,
habitat use, and movement patterns will change because of altered water management regimes and resulting
changes in near shore salinity. Aerial surveys and radio tracking tagged manatees provide valuable means of documenting
the response of manatees to natural and human-induced fluctuations in freshwater inflow. This information,
combined with water-quality data obtained from monitoring stations, is being incorporated into the manatee ATLSS
model, which will be used to better understand and predict manatee response to different restoration scenarios. This
project also fills a significant void in our knowledge of manatee ecology, as there is very little existing information
on manatee population biology and habitat use in southwestern Florida. Recent advances in tracking technology
have made this project logistically feasible and cost-effective.
Data from manatees radio tagged in the TTI documented the pre-restoration use of habitat by manatees within
the region affected by the SGGE restoration. During the initial phase of this study, three captive, rehabilitated adult
manatees were tagged and released in July 2000. Eight more wild manatees were captured and radio-tagged at Port
of the Islands in February and March 2001. Two others tagged by Mote Marine Lab near Charlotte Harbor were
moved into the Ten Thousand Islands during summer 2001. During January 2002, five more manatees were captured
and radio-tagged at Port of the Islands, bringing the total number of manatees tagged and tracked in this study to 20
individuals.
We relied on several technologies to acquire geographic locations from tagged manatees. Most manatees were
fitted with satellite-based Argos transmitters, which have a serviceable battery life of six months and provide locations
along with data on temperature and transmitter activity. A location class (LC) designating the accuracy of each
position is also recorded; quality locations include LC 1 <1000m, LC 2 <350m, and LC 3 <150m. Tagged manatees
relayed an average of six quality locations per day, with a frequency of approximately two per day from each location
class. In addition to the Argos satellite-monitored tags, we opportunistically attached a datalogging GPS tag to
six manatees. The GPS tag provides locations which are much more accurate than the Argos data (approx. 30 m vs.
150 m) every 15-30 minutes, but the battery life expectancy is much shorter (8 weeks vs. 6 months). In combination,
the Argos data provided region-wide, long-term coverage suitable for revealing general patterns of habitat use, while
the GPS data showed fine details of travel pathways and time spent in specific areas. Newly developed Argos-linked
GPS tags were recently deployed on individuals. This tag relays GPS locations as sensor data through the Argos
satellite link, enabling detailed tracking data to be acquired remotely. All tagged manatees were periodically located
and observed in the field using standard VHF tracking techniques. All location data were formatted using the SAS
statistical software for error checking, analyses, and display in ArcView. Databases were correlated with temperature,
salinity, and tidal data collected throughout the region.
181
From 2000 through July 2002, a total of 4,563 tracking days were recorded from 36 tag deployments on the
20 manatees. Two of the males traveled to areas more than 100 km north of the Ten Thousand Islands. Most remained
within the study area, however, providing the first detailed movement data collected across seasons from wild manatees
in the region. Warm season use areas for some individuals included seagrass beds off Cape Romano and the
canals of Marco Island. Other manatees moved southeast into the northwest region of Everglades National Park, relying
on inland creeks for fresh water. These data provide the first details on manatee use patterns in the TTI/ENP
region.
Movement patterns for all individuals suggest a preference for foraging on seagrass beds in marine areas with
brief trips to inland creeks and canals, which provide a source of fresh water. These inland trips, undertaken approximately
four to eight times per month, reveal the reliance of these marine animals on accessible freshwater. Individual
movements were linked to a network of travel corridors connecting seagrass beds and sources of freshwater,
identified by manatee locations during GPS tag deployments. Movements were often rapid and direct. The deep
canals at Port of the Islands provide access to freshwater at the spillway, as well as a passive thermal refuge for manatees
during brief cold winter weather. Individual site fidelity for some manatees varied with season and calving
events.
Feeding areas were documented within Thalassia, Syringodium, and Halodule seagrass beds along the outer
islands. Spatial distribution of submerged aquatic vegetation, temporal fluctuations in freshwater areas, and bathymetry
influenced movement and use patterns of manatees within the region. Salinity of inshore waters fluctuated with
winter dry periods and summer rains. Abundance and species composition of submerged vegetation within inland
bays may vary with these seasonal changes, thus influencing manatee feeding patterns. Additional studies are
planned to assess manatee habitats including characterizing and mapping the distribution of submerged aquatic vegetation
in areas used by tagged manatees for foraging.
Tracking data and field observations of tagged manatees revealed that the spatial distribution of submerged
aquatic vegetation, availability of freshwater, and bathymetry influenced manatee movements and use patterns
within the TTI and northern Everglades. Manatees routinely traveled from offshore seagrass beds to inland freshwater
areas. We expect that altered water management regimes and resulting environmental changes may affect manatee
habitat use and movement patterns within the region. These data are being integrated into the ATLSS model that will
attempt to predict manatee responses to management actions.
Contact: James Reid, Sirenia Project  USGS, Center for Aquatic Resources Studies; 412 N.E. 16th Avenue,
Room 250, Gainesville, FL 32601; Phone:(352)372-2571; FAX:(352)374-8080; http://www.fcsc.usgs.gov.
182
Inventory and Monitoring of the Amphibians and Reptiles of Biscayne
National Park
By Kenneth G. Rice1, Amber D. Dove2, Marquette E. Crockett2, and J. Hardin Waddle2
1U.S. Geological Survey, Center for Water and Restoration Studies, Ft. Lauderdale, FL., USA
2Florida Cooperative Fish and Wildlife Research Unit, University of Florida, Gainesville, FL., USA
Declines in amphibian populations have been recognized worldwide over many regions and habitat types
(Alford and Richards, 1999). No single cause for declines has been found, although acid precipitation, environmental
contaminants, the introduction of exotic predators, disease agents, parasites, and the effects of ultraviolet radiation
have been suggested. In fact, several factors may interact in such a manner as to threaten populations (Carey
and Bryant 1995). A major factor in the loss of amphibian and reptile populations has been and continues to be the
loss of habitat.
In response to concerns about the lack of basic knowledge of the amphibians and reptiles inhabiting Department
of Interior (DOI) lands, inventory programs are being instituted nationwide. The Center for Water and Restoration
Studies of the U.S. Geological Survey is conducting a reptile and amphibian inventory of Biscayne National
Park (BISC) in cooperation with the Florida Cooperative Fish and Wildlife Research Unit. BISC is primarily an
aquatic park with small islands and spans over 173,000 acres.
We have established 16 permanent inventory sites that are sampled on a monthly basis in BISC. During each
sampling occasion, a 20m radius circular plot is searched using standard visual encounter survey (VES) techniques,
and a 10-minute vocalization survey is conducted to detect calling anurans (frogs and toads). The locations of these
sites were chosen randomly within habitat strata. Four of these sites (two in scrub habitat and two in mangrove
habitat) are on the mainland portion of the park. Eight monthly sampled sites (three in scrub habitat, two in prairie
habitat, and three in mangrove habitat) are on Elliott Key, the largest island in BISC. Two monthly sites (one in mangrove
habitat and one in hammock) exist on both Sands Key and Boca Chita Key. In addition to the 16 monthly sites,
we also have conducted surveys at six other random sites. These have all been in scrub and mangrove habitat sites
on the mainland and on Elliott Key. Our goal is to continue to add random sites until all habitats on islands and the
mainland have been surveyed.
Sampling for amphibians and reptiles in (BISC) began on May 2, 2002. As of November 30, 2002 a total of
22 sites have been surveyed during 76 sampling occasions. A total of 65 individuals of 12 species during VES surveys
(table 1) and 7 species of anurans by vocalizations (table 2) have been observed.
Nine amphibian species have been detected in BISC, all anurans. Three of the nine amphibian species are
introduced in south Florida: the greenhouse frog (Eleutherodactylus planirostris), the Cuban treefrog (Osteopilus
septentrionalis), and the marine toad (Bufo marinus). These species have been detected on the islands and mainland
of BISC. Five of the native amphibian species detected, the green treefrog (Hyla cinerea), the squirrel treefrog (Hyla
squirrella), the leopard frog (Rana sphenocephala), the Florida cricket frog (Acris gryllus), and the pig frog (Rana
grylio) have only been detected in mainland parts of the park. The narrowmouth toad (Gastrophryne carolinensis)
is the only native frog detected on the islands to date.
Six species of reptiles, four lizards, and two snakes have been detected. Of the lizards, the brown anole (Anolis
sagrei) and the tropical house gecko (Hemidactylus mabouia) are both introduced in south Florida. Tropical house
geckoes are especially abundant on the buildings of Elliot Key. The green anole (Anolis carolinensis) and the Florida
reef gecko (Sphaerodactylus notatus) are native to south Florida. The two snakes, the ringneck snake (Diadophis
punctatus) and the Florida water snake (Nerodia fasciata pictiventris) are both native. Each of these has only been
observed once.
183
Monthly sampling of the 16 permanent plots will continue through July 2003. In addition, random points
throughout the park will be sampled. Each of these will be sampled at least twice during the study. We expect the
number of species encountered to increase as this study continues, especially the number of reptiles.
Although the final inventory may include many species not encountered to date, the substantial constituency
of exotic amphibian and reptiles inventoried in BISC during this study calls for some concern.
Table 1. Number of reptiles and amphibians counted during visual encounter surveys in Biscayne national Park during 2002
Table 2. Locations of anuran species detected during vocalization surveys in Biscayne National Park during 2002
REFERENCES
Alford, R.A., and S. J. Richards, 1999, Global amphibian declines: a problem in applied ecology. Ann. Rev. Ecol.
Syst. 30:133-165.
Carey, C., and C. J. Bryant, 1995, Possible interrelations among environmental toxicants, amphibian development,
and decline of amphibian populations. Environ. Health Perspec. 103 (Suppl. 4):13-17.
Contact: Amber D. Dove, Florida Cooperative Fish and Wildlife Research Unit, Everglades National Park, 40001
SR 9336, Homestead, FL 33034; Phone: 305-242-7800 x7333, email: amber_dove@usgs.gov.
Mainland Elliott Key Sands Key Boca Chita Key
Hyla cinerea 3 0 0 0
Osteopilus septentrionalis* 5 4 0 0
Rana sphenocephala 1 0 0 0
Anolis sagrei* 2 25 2 5
Anolis carolinensis 0 0 1 0
Diadophis punctatus 1 0 0 0
Bufo marinus* 0 0 0 0
Eleutherodactylus planirostris* 0 9 2 1
Gastrophryne carolinensis 0 1 0 0
Hemidactylus mabouia* 0 2 0 0
Nerodia fasciata pictiventris 0 1 0 0
Sphaerodactylus notatus 0 0 1 0
*These species have been introduced to BISC.
Mainland Elliott Key Sands Key Boca Chita Key
Acris gryllus X
Bufo marinus* X X
Eleutherodactylus planirostris* X X X X
Hyla cinerea X
Hyla squirrella X

Osteopilus septentrionalis* X X
Rana grylio X
*These species have been introduced to BISC.
184
The Effects of the Cuban Treefrog (Osteopilus septentrionalis) on Native Treefrog
Populations within Everglades National Park
By Kenneth G. Rice1, J. Hardin Waddle2, Marquette E. Crockett3, and Amber D. Dove3
1U.S. Geological Survey, Center for Water and Restoration Studies, Ft. Lauderdale FL., USA
2U.S. Geological Survey, Big Cypress Field Station, Ochopee FL., USA
3USGS Florida Cooperative Fish and Wildlife Research Unit, Everglades Field Station, Homestead FL., USA
Native amphibian fauna throughout south Florida are currently threatened by the presence of an exotic competitor,
the Cuban treefrog (Osteopilus septentrionalis) (fig. 1). First reported in the Florida Keys (Barbour, 1931),
Cuban treefrogs expanded their range and were present in Everglades National Park as early as the 1950's (Meshaka,
2001). Cuban treefrogs compete with native treefrogs for breeding space and food sources.
In addition, Cuban treefrogs and their tadpoles are carnivorous and prey
upon other frog species (Meshaka, 2001; Babbitt and Meshaka, 2000).
Despite anecdotal evidence, no study has shown the extent to which Cuban
treefrogs reduce populations of native hylids in natural areas. The goal of
this study is to examine the direct effect Cuban treefrogs have on native
treefrog populations within Everglades National Park. Native treefrogs
studied included the Green (Hyla cinerea; Hci), and Squirrel (Hyla squirella;
Hsq).
Population estimates for treefrogs were obtained through a mark-recapture
study using PVC refugia. Five study plots were selected within Everglades
National Park (2 mangrove and 3 pine rockland sites). Two of these
sites are near disturbed areas, while all others are fairly remote. After initial
population estimates were obtained, Cuban treefrogs were removed
from sites to examine the recovery of native populations. Additionally,
predation of hylids by Cuban treefrogs was quantified through stomach content analysis of removed animals.
To date, approximately 2,200 individual frogs have been included in this study. Preliminary results indicate
Cuban treefrogs are more numerous in plots 501 and 101, which are located near disturbed areas, while remote sites
contained larger populations of native species (fig. 2). Initial results indicate that native populations significantly
increase as Cuban treefrogs are removed. The largest population increases occurred at sites where Cuban treefrogs
were originally most dense (table 1). Preliminary analysis of stomach contents suggest that predation on hylid treefrogs
is higher in mangrove than pine rockland sites.
Figure 1: Cuban Treefrog (Osteopilus
septentrionalis) in Everglades National
Park
0
100
200
300
400
500
600
700
800
101 501 Shark LPK-W LPK-E
Ose
Native
Figure 2. Total captures of Cuban
(Ose) and native treefrogs in
study plots within Everglades
National Park from November
2000 to November 2002.
185
To adequately monitor the effects of Cuban treefrogs on native populations, this study will continue until Fall
2003. After completion, the results of this study may be used to identify factors that facilitate or obstruct dispersal
of Cuban treefrogs into natural areas. In addition, this information will be incorporated into an ArcInfo model of the
potential spread and impact of Cuban treefrogs on native species in protected areas. Data will be available to cooperating
agencies and the public.
REFERENCES
Babbit, K.J., and W.E. Meshaka, 2000, Benefits of eating conspecifics: Effects of background diet on survival and
metamorphosis in the Cuban treefrog (Osteopilus septentrionalis). Copeia 2000(2): 469-474.
Barbour, T., 1931, Another introduced frog in North America. Copeia 1931(3): 140.
Meshaka, W.E., 2001, The Cuban Treefrog in Florida-Life History of a Successful Colonizing Species. University
Press of Florida.
Contact: Marquette E. Crockett, USGS-Florida Cooperative Fish and Wildlife Research Unit, Everglades
Field Station, 4001 SR 9336, Homestead FL 33314; Phone: 305-242-7800 x7333, FAX: 305-242-7834;
marquettecrockett@hotmail.com.
Table 1. Mean number of captures per visit of Cuban (Ose), Green (Hci) and Squirrel (Hsq) treefrogs
before and after removal of Cuban treefrogs in sites 101 and 501 (* statistically significant)
Site and species
N (number visits)
pre-removal
N (number visits)
post-removal
Mean captures
pre-removal
Mean captures
post-removal
501-Ose 30 8 28.100 ( 5.497) 30.375 ( 5.928)
501-Hci * 30 8 1.533 (0.328)* 19.500 ( 6.743)*
501-Hsq * 30 8 0.267 ( 0.117)* 1.500 (0.886)*
101-Ose 29 7 15.414 (3.260) 13.714 (2.476)
101-Hci 29 7 1.517 (0.411) 0.143 (0.143)
101-Hsq * 29 7 0.379 (0.104)* 3.571 (1.343)*
186
Impacts of Off-Road Vehicle Use on Wildlife in the Prairie Ecosystem of Big
Cypress National Preserve
By Kenneth G. Rice1, J. Hardin Waddle2, and Frank J. Mazzotti3
1U.S. Geological Survey, Center for Water and Restoration Studies, Ft. Lauderdale, FL., USA
2Florida Cooperative Fish and Wildlife Research Unit, Department of Wildlife Ecology and Conservation, University
of Florida, Gainesville, FL., USA
3Department of Wildlife Ecology and Conservation, University of Florida, Ft. Lauderdale, FL., USA
The use of off-road vehicles (ORVs) has been a popular recreational activity in Big Cypress National Preserve
(BCNP) for many years, and recently more than 2000 individuals per year have received ORV permits (National
Park Service 2000). The repeated rutting of marl prairies due to ORV use has caused extensive damage to many
areas within the preserve. A management plan has been implemented to mitigate this damage (National Park Service,
2000).
Although the degree of ORV use is well documented in the marl prairies of BCNP, the impact of ORVs on
wildlife species is not well known. However, human recreation may result in alterations in behavior and reduce survival
(Swarthout and Steid, 2001) or fitness (Parent and Weatherhead, 2000) of wildlife populations.
ORVs in the prairie habitats of BCNP may also have indirect effects on wildlife species. ORV use can impact
the vegetation, hydrology, water quality, and soil structure of prairies (National Park Service, 2000). Duever et al.
(1981) documented changes in plant species composition and abundance in prairies with high ORV use. The extent
to which these environmental changes affect wildlife populations in the prairies of BCNP is poorly understood.
Amphibians and small mammals may be affected directly and indirectly by ORV use in prairies. Further, these
animals are particularly suited for this study on the impacts of ORV use on wildlife because they are likely to spend
their entire lives completely within or near the same homogenous prairie habitat. Also, they are easily sampled with
traps and should occur in great enough abundance to allow the estimation of a variety of population parameters like
abundance and survival using mark-recapture analysis.
We will investigate the effects of ORVs on amphibians and small mammals by using mark-recapture techniques
to estimate population parameters at sites with varying degrees of ORV use. The two most important population
parameters used in this study will be survival and abundance. Our efforts will focus on two groups of species:
treefrogs that will be captured in PVC pipe refugia and rodents that will be captured with Sherman live traps.
Grids of 3.5cm PVC pipes will be erected in prairie habitat in BCNP. These pipes are very effective at capturing
treefrogs (Boughton et al. 2000). Approximately 50 pipes will be used per site at as many as nine locations.
These locations will be classified as having light, moderate, or heavy ORV use. Three replicate sites will be used
for each category of ORV use.
PVC pipes will be examined for treefrogs once every two weeks. Captured animals will be carefully removed
from the pipe to avoid harm. They will also be identified to species, age, and sex whenever possible, measured snoutto-
vent (SVL) and massed using a Pesola(tm) hanging scale. Frogs will be marked using a commonly accepted toeclipping
scheme (Donnelly et al. 1994). Toes will be removed quickly with a pair of sharp scissors. No more than
two toes per limb will be removed, and the first toe on any limb will not be removed. Scissors and other equipment
will be cleaned with alcohol to avoid disease transmission. All methods used have been approved by the American
Society of Ichthyologists and Herpetologists and the Society for the Study of Amphibians and Reptiles (http://
www.asih.org/pubs/herpcoll.html). Each frog will be released as soon as possible after capture to minimize stress
on the animal.
187
Mammals will be trapped and handled in a similar manner. Grids of Sherman live traps will be baited with
rolled oats to capture rodent species. The grid design will allow us to calculate a density of the animals (Jones et al.
1996). Trapping will be conducted one week each month at each site. Each captured rodent will be identified to
species, sex, and approximate age. The body length, tail length, and the mass of each captured animal will also be
noted. Finally, each captured rodent will be uniquely marked with an individually numbered ear tag.
In addition to providing important information about ORV impacts on key wildlife species of the prairie habitat,
these data will be used with hydrologic data to determine how hydrology affects these species. Specifically,
changes in abundance and survival across seasonal hydrological gradients will be observed on sites stratified by ORV

use. The presence, abundance, and behavior of the amphibian and small mammal species changes with the transition
from dry season to wet season in this habitat will also be examined. Collectively, this information will be valuable
for evaluating hydrologic and human-use impacts during Everglades restoration.
REFERENCES
Boughton, R. G., J., Staiger, and R. Franz, 2000, Use of PVC pipe refugia as a sampling technique for hylid treefrogs.
American Midland Naturalist 144:168-177.
Donnelly, M. A., C. Guyer, J. E. Juterbock, and R. A. Alford, 1994, Techniques for marking amphibians. in W. R.
Heyer, M. A. Donnelly, R. W. McDiarmid, L. C. Hayek, and M. S. Foster, editors. Measuring and monitoring
biological diversity: standard methods for amphibians. Smithsonian Institution Press, Washington, D.C.
Duever, M. J., J. E. Carlson, and L. A. Riopelle, 1981, Off-road vehicles and their impacts in the Big Cypress
National Preserve. National Audubon Society, Ecosystem Research Unit.
Jones, C., W. J. McShea, M. J. Conroy, and T. H. Kunz, 1996, Capturing mammals. Pages 115-155 in D. E. Wilson,
F. R. Cole, J. D. Nichols, R. Rasanayagam, and M. S. Foster, editors. Measuring and monitoring biological
diversity: standard methods for mammals. Smithsonian Institution Press, Washington D.C.
National Park Service, 2000, Final recreational off-road vehicle management plan supplemental environmental
impact statement. U.S. National Park Service, Big Cypress National Preserve, Ochopee, FL, 603 pp.
Parent, C., and P. J. Weatherhead, 2000, Behavioral and life history responses of eastern massasauga rattlesnakes
(Sistrurus catenatus catenatus) to human disturbance. Oecologia 125:170-178.
Swarthout, E. C., and R. J. Steidl, 2001, Flush responses of Mexican spotted owls to recreationists. Journal of Wildlife
Management 65:312-317.
White, G. C., and K. P. Burnham, 1999, Program MARK: survival estimation from populations of marked animals.
Bird Study 46 supplement: 120-138.
Contact: J. Hardin Waddle, Florida Cooperative Fish and Wildlife Research Unit, Box 110430, University of
Florida, Gainesville, FL 32611, Phone: 353-392-2861, hardin_waddle@usgs.gov
188
Using Proportion of Area Occupied to Estimate Abundance of Amphibians in
Everglades National Park and Big Cypress National Preserve
Kenneth G. Rice1, J. Hardin Waddle2, and H. Franklin Percival2
1U.S. Geological Survey, Center for Water and Restoration Studies, Ft. Lauderdale, FL., USA
2U.S. Geological Survey, Florida Cooperative Fish and Wildlife Research Unit, University of Florida, Gainesville,
FL., USA
Declines in amphibian populations have been documented for many regions and habitat types worldwide
(Alford and Richards, 1999). No single cause for declines has been determined, and it seems likely that several factors
interact to threaten populations (Carey and Bryant, 1995). In response to concerns about amphibian population
declines, the Department of Interior (DOI) received funding from Congress to institute long-term surveys of the status
and trends of amphibians on DOI lands. The U.S. Geological Survey has been conducting inventories of
amphibian species in Everglades National Park (ENP) and Big Cypress National Preserve (BCNP) from 2000 to
present.
Together ENP and BCNP comprise a contiguous protected area of more than 890,000 ha. This landscape,
unique in the United States, contains a diverse array of different wetland and upland habitats. The amphibian fauna
of the Everglades and Big Cypress region comprises 15 native species, all derived from temperate zone fauna, and
three non-indigenous species from the tropics. Although historical and recent survey and inventory work on
amphibians has been done on DOI lands in south Florida (Duellman and Schwartz, 1958, Meshaka et al., 2000),
there is a need for a current inventory and estimate of the abundances of the amphibians of ENP and BCNP. This
project uses data on detection of amphibian species after repeated sampling at a site to estimate the occupancy rate
of various amphibian species (MacKenzie et al., 2002).
Sampling locations were chosen randomly throughout ENP and BCNP using a Geographic Information System
(GIS), and all sampling was stratified by major habitat type. We divided the parks into six natural habitats:
pineland, rocky glades, tropical hardwood hammock, mangrove forest, cypress dome, and freshwater slough. These
habitat designations were based loosely on the vegetation classification scheme of Madden et al. (1999), and their
map was used as the basis for site selection. We selected points at random within each of the major habitat types.
Six of these sites in each habitat type at each park were used as monthly sampling locations. These were visited
once within each calendar month for one year. Other random locations were sampled at least twice during times
when they were accessible. A total of 118 sites in ENP and more than 75 sites in BCNP were sampled.
The primary method of sampling was a standard visual encounter survey (VES) technique combined with a
10-minute auditory survey for calling anurans (Heyer et al., 1994). Each sampling event lasted 30 minutes and all
were conducted after dark. Each area searched was a 20-m radius circle (1,256 m2 area) around the randomly chosen
point. Each individual found was identified to species, sex, age, and snout-to-vent length. We measured the air
temperature and relative humidity using a digital thermohygrometer. Cloud cover, wind speed, whether the plot was
inundated with water, and water temperature (if applicable) were also noted.
Data were organized into capture history matrices where detection of species was denoted by a "1" for a given
site and month. Non-detection of a species was denoted with a "0", and a "-" was used in cases where a site was
not visited during a particular month. These data were analyzed using the program PRESENCE to calculate a proportion
of sites occupied (PAO) by each species within each habitat (MacKenzie et al., 2002).
We observed 1,788 individual amphibians in ENP and more than 2000 in BCNP during VES surveys. Not
all of the anurans were observed a sufficient number of times to allow calculation of proportion of sites occupied in
ENP. Data collection and analysis for BCNP is still underway. For some of the more abundant anurans it was possible
to estimate the site occupancy by habitat (table 1).
The results obtained for site occupancy may serve as a baseline for long term monitoring of amphibians in
the national parks of south Florida. Estimating the total abundance of any of these species is practically impossible
due to the large area involved and complicating variables like weather and phenology of amphibian behavior. How-
189
ever, by estimating the site occupancy rate of each species at randomly chosen sites within each habitat, it is possible
to produce an estimate of the proportion of that habitat in which a species occurs. This number does not indicate the
abundance of individuals, but it does permit estimates of the abundance of populations. This can serve as the basis
for tracking changes in population abundance over time.
The sampling protocol developed here for these parks is considered appropriate for future monitoring of
amphibians in the Everglades ecosystem. The methods are relatively inexpensive, and replication should be straightforward.
Tracking changes in site occupancy over time will help identify trends in amphibian populations and serve
as an early warning if any amphibian populations are truly declining in south Florida. Plans for future work include
using PAO with hydrologic models of the Everglades ecosystem to predict how populations of species might react
to hydrologic change. With estimates of the proportion of sites occupied by each species in amphibian assemblages
in areas with different hydrology, it will be possible to predict how the assemblage will change during restoration.
This will assist managers in assessment of proposed hydrological changes and restoration success.
REFERENCES
Alford, R. A., and S. J. Richards. 1999. Global amphibian declines: a problem in applied ecology. Annual Review
of Ecology and Systematics 30:133-165.
Carey, C., and C. J. Bryant. 1995. Possible interrelations among environmental toxicants, amphibian development,
and decline of amphibian populations. Environmental Health Perspectives 103:13-17.
Duellman, W. E., and A. Schwartz. 1958. Amphibians and reptiles of southern Florida. Bulletin of the Florida State
Museum 3:179-324.
Heyer, W. R., M. A. Donnelly, R. W. McDiarmid, L. C. Hayek, and M. S. Foster. 1994. Measuring and monitoring
biological diversity: standard methods for amphibians. Smithsonian Institution Press, Washington, DC.
MacKenzie, D. I., J. D. Nichols, G. B. Lachman, S. Droege, J. A. Royle, and C. A. Langtimm. 2002. Estimating site
occupancy rates when detection probabilities are less than one. Ecology 83:2248-2256.
Madden, M., D. Jones, and L. Vilchek. 1999. Photointerpretation key for the Everglades vegetation classification
system. Photogrammetric Engineering & Remote Sensing 65:171-177.
Meshaka, W. E., W. F. Loftus, and T. Steiner. 2000. The herpetofauna of Everglades National Park. Florida Scientist
63:84-103.
Table 1: Proportion of sites occupied by amphibian species by habitat in ENP.
Contact: Kenneth G. Rice, U.S. Geological Survey, UF-FLREC, 3205 College Ave., Ft. Lauderdale, FL 33314,
Phone: 954-577-6305, FAX: 954-577-6381, e-mail: ken_g_rice@usgs.gov
Habitat Acris gryllus
Bufo
quercicus
Bufo terrestris
Gastrophryne
carolinensis
Hyla
cinerea
Hyla squirrella
Rana
grylio
Rana sphenocephala
Pineland 0.63 1.00 1.00 0.64 0.95 0.94 0.33 0.38
Rocky Glades 0.84 0.60 0.21 0.46 0.99 0.61 0.90 1.00
Hammock 0.85 0.00 0.49 0.67 0.96 0.39 0.91 0.76
Cypress 0.84 0.00 0.00 0.66 0.90 0.97 0.78 0.68
Mangrove 0.00 0.00 0.47 0.40 0.49 0.53 0.27 0.35
Slough 1.00 0.00 0.39 0.28 1.00 0.24 1.00 0.76
190
Evaluating the Effect of Salinity on a Simulated American Crocodile
(Crocodylus acutus) Population
By Paul M. Richards1, Wolf M. Mooij2, and Donald L. DeAngelis3
1Florida State University, Tallahassee, FL., USA
2Netherlands Institute of Ecology, Nieuwersluis, The Netherlands., USA
3U.S. Geological Survey, Center for Water and Restoration Studies, University of Miami, Department of Biology,
Coral Gables, FL., USA
Everglades restoration will alter the hydrology of the endangered American crocodile's (Crocodylus acutus)
estuarine habitat of south Florida, affecting both water depth and salinity levels. Juvenile American crocodiles are
thought to be sensitive to high salinity levels, suffering reduced mass, and potentially reduced survivorship and
recruitment, thereby negatively impacting the population recovery. To answer the question of how the crocodile population
will respond to alterations in hydrology we developed a spatially explicit individual based model designed
to relate water levels, salinities, and dominant vegetation to crocodile distribution, abundance, population growth,
individual growth, survival, nesting effort, and nesting success. The nature of the relation between salinity and

growth was based on physiological measures in the lab that include only individuals smaller than 450 grams. The
core of this model assumes that this relationship applies to the field, and to some extent, to individuals of all sizes
(fig.1). Four different combinations of base parameterizations and initial population size were examined with sensitivity
analyses and a factorial manipulation of model salinities, to evaluate the effects of each on population size,
nest number, and survivorship of young of the year (YOY) crocodiles.
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0 5 10 15 20 25 30 35 40 45
50g
500g
1000g
5000g
10000g
50000g
100000g
500000g
Salinity (ppt)
Daily % mass change (MaxMass)
Figure 1. Daily percent change in mass (MaxMass) as a function of salinity for model C. acutus from
50g to 500kg.
191
Two types of sensitivity analysis were used, individual parameter perturbation (IPP) and uncertainty analysis.
IPP examines the effect of small changes in individual parameter values on model output while holding all other
parameters constant and uncertainty analysis examines the effect of random combinations of parameter values on
model output. For IPP analysis we individually altered each nominal parameter by +/- 1 percent for continuous values
and +/- 1 unit for integer values while holding all other parameters constant. For uncertainly analysis we
employed the modified Latin hypercube parameter sampling method with 100 Monte Carlo simulations. Each continuous
parameter was cut into 100 equidistant values within its range and each integer parameter was cut into 100
integer pieces within its range. From these sets we randomly selected parameters without replacement to construct
the 100 parameter sets.
The rank ordering from the IPP analysis failed to give consistent rankings between populations. Because of
this lack of consistency, for any output variable it is difficult to use these results to select a set of parameters that the
model may be particularly sensitive to, independent of the population initial conditions or parameterization. In contrast,
the uncertainty analysis consistently ranked parameters between populations, and therefore, it can inform us
about parameters to concentrate on for further research and management.
Based on this result we conclude that to better understand C. acutus population dynamics, we suggest that
research focus on survivorship and growth rate parameters, because these were ranked high by uncertainty analysis.
The parameter with the largest effect on model output was survival of large individuals, which is not unusual for
long-lived organisms. It may be difficult to measure survivorship for large individuals, but since it is consistently
highly ranked as a parameter to which population size is sensitive, greater effort should be made to collect this sort
of data.
To examine the model under possible management alternatives, we varied the application of salinity to the
model in a fully crossed three way ANOVA. The model can alter timing of peak salinity, duration of salinity levels,
and the spatial distribution of salinity ranges. Each of these factors were manipulated at three levels. Timing of the
salinity peak was altered by one month (30 days), earlier and later than the base model value of day 144 (May 24).
Salinity duration was compared at three levels, short, medium (base), and long. Regional salinity range values were
also compared, raising these 5 ppt, and 10 ppt above base model runs.
Increasing regional salinity significantly reduced population size, nest number, and YOY survivorship in all
base parameterizations. This effect was probably because at highest regional salinity treatment, even the lowest salinity
habitats were at salinities for part of the year where small crocodiles would lose mass regardless of other conditions.
Delaying the peak salinity level by one month, which placed it at the beginning of hatching season,
significantly reduced the number of nests for only one parameterization. No other parameterizations were significantly
affected by alterations in timing of peak salinity. Duration of salinity spread had no significant effect.
This model shows that research should focus on estimates of annual survivorship for large individuals. Similarly,
conservation priority should be placed on reducing anthropogenic sources of mortality on large individuals,
such as road mortality. Everglades restoration, through its effects on water flow to estuaries may benefit crocodile
populations if increased freshwater flow reduces the chances that regional salinity levels exceed levels where small
individuals lose mass.
Contact: Paul M. Richards, School of Computational Science and Information Technology, 400 Dirac Science
Library, Florida State University, Tallahassee, Fl 32306-4052; Phone: 850-644-0178 paul@csit.fsu.edu.
192
Fish and Shrimp in Relation to Seagrass Habitat Change in Johnson Key Basin,
Western Florida Bay (1985-1995)
By Michael B. Robblee, and Andr Daniels
USGS, Center for Water and Restoration Studies, Miami, FL., USA
In the fall of 1987, a widespread, rapid die-off of
the dominant seagrass, Thalassia testudinum, began in
dense seagrass habitats in western Florida Bay. Increasingly
extensive and persistent turbidity and algal blooms,
apparently linked to the loss of turtle grass, were associated
with active seagrass die-off sites initially and have
characterized western and central Florida Bay generally
since 1991. In Johnson Key Basin denuded bottom was
rapidly colonized by shoal grass, Halodule wrightii, following
the loss of turtle grass. Syringodium filiforme,
manatee grass had disappeared from the basin by 1995
possibly in response to reduced light availability.
In 1985, prior to seagrass die-off, thirty sampling
stations had been established in Johnson Key Basin. Stations
had been located generally with no a priori consideration
of the seagrass habitat present and were evenly
stratified among the principal seagrass macro-habitat
types present in Florida Bay: bank, basin, and near key.
These thirty stations were sampled on an approximately
five-year interval (January 1985, May 1985; May 1989,
January 1990; January 1995, and May 1995) providing
the opportunity to observe fish and invertebrate community
responses in numbers and species composition to
change in seagrass habitat within the basin over the
decade, 1985-1995. Quantitative animal samples of seagrass
associated fish and invertebrates, including the pink
shrimp, were collected using a 1m2 throw-trap. The
throw-trap operated over the full range of water depths
occurring in Johnson Key Basin with a sampling efficiency
estimated to exceed 95 percent for seagrass associated
fish and invertebrates. Each animal sample was
coupled with measurements estimating seagrass canopy
structure and local environmental conditions: standing
crops of seagrass and associated macroalgae, seagrass
blade densities by species, sediment texture and organic
content, water and sediment depth, compaction, salinity
and temperature.
Unlike some areas in western Florida Bay, seagrass die-off in Johnson Key Basin was patchy with severe to
no visible impacts among the thirty stations. Seagrass habitat change was most extensive between 1990 and 1995
when algal blooms were always present in the basin. The cumulative affect of seagrass loss and recovery and
reduced water clarity between 1985 and 1995 was a shift away from a turtle grass dominated seagrass meadow to
one exhibiting greater habitat heterogeneity. Over the decade the standing crop of Thalassia declined by 71 percent
in Johnson Key Basin (fig. 1). Standing crop of Halodule increased by 24 percent.
Figure 1. Comparison of habitat changes and associated
caridean shrimp, and fish communities in Johnson Key
Basin over the decade 1985 to 1995.
193
Over the decade, the standing crop of Thalassia declined by 71 percent in Johnson Key Basin (fig. 1). Standing
crop of Halodule increased by 24 percent in the basin. Syringodium had disappeared from the thirty stations sampled
though it was reported as present in the basin. Thalassia, the dominant seagrass in 1985 at 17 stations in Johnson
Key Basin was the dominant at only 9 in 1995. Halodule, present at 13 stations in 1985, was found at 18 by 1995.
By 1995 bare sediment, not present as an appreciable habitat type in 1985, characterized the bottom in Johnson Key
Basin at 4 of the thirty stations.
Faunal changes were observed accompanying these habitat changes. Comparing 1985 to 1995 the abundance
(January and May averaged) of seagrass associated caridean shrimps had declined by about 65 percent while seagrass
fishes had declined by 81 percent (fig.1). Densities of pink shrimp, Farfantepenaeus duorarum, in 1995 were
half that observed in 1985, (1.9/m2 vs 4.0/m2, respectively). Salinity and water temperature conditions, during sampling
in 1985 and 1995, did not differ appreciably (31.5 vs 28.4; 25 oC vs 24.9 oC, respectively).
The fish and shrimp communities changed dramatically over the decade in Johnson Key Basin. In 1985, the
killifish, Lucania parva and the caridean shrimp, Thor floridanus dominated numerically (62 and 81 percent of individuals,
January and May averaged, respectively). By 1995 these populations had declined to 3 percent and 27 percent
of fish and caridean shrimp collected, respectively. Six fishes, Anchoa mitchilli, Sardinella aurita, Achirus
lineatus, Gobiosoma robustum, and Hippocampus zosterae. were numerically more abundant in 1995 and accounted
for 65 percent of fish collected. Five caridean shrimps, Periclimenes americanus, Alpheus heterochaelis, Thor floridanus,
Hippolyte plueracanthus, and Hippolyte zostericola, accounted for 81 percent of the caridean shrimps collected
in 1995.
A preliminary factor analysis (non-rotated PCA) was used to reduce 9 habitat variables to 4 interpretable components.
PC1 accounting for 25.3 percent of the variability among the original habitat variables was interpreted as a
Thalassia gradient. Halodule is negatively correlated with Thalassia on PC1. PC2 (16 percent) was interpreted as a
shallow water Halodule gradient. PC3 (12.4 percent) was interpreted as a Syringodium gradient. PC4 (10.4 percent)
was interpreted as a macro algal gradient. Interpretation of PC's 1-3 indicate Thalassia and Syringodium decline in
abundance with time while Halodule increases over time.
Individual species and species groups relate to habitat differently in Johnson Key Basin. The pink shrimp, an
abundant penaeid shrimp, is significantly correlated to PC2 and 3 indicating an affinity for shallow water shoal grass
and manatee grass habitats. The killifish, Lucania parva, was significantly correlated to PC1 and 2. In Johnson Key
basin this fish is associated with seagrass generally and is most abundant, as is the pink shrimp, in shallow water
shoal grass habitats. The dominant caridean shrimp, Thor floridanus, is a ubiquitous species in the Johnson Key
Basin grass beds, abundant in 1985 and scarce in 1995. It was positively associated with each of the 4 principal components.
More detailed analyses focusing on defining seagrass canopy and seagrass habitat change with time, the
relation of pink shrimp size to seagrass habitat and individual species relation with seagrass habitat will
be presented.
Contact: Robblee, Michael, Water and Restoration Studies Center, Miami, FL 33178, Fax: 305-242-7855, Phone:
305-242-7832, mike_robblee@usgs.gov
194
The ATLSS American Alligator Population Model: Results from Restoration
Alternatives
By Daniel H. Slone1, Kenneth G. Rice2, Jon C. Allen3, and H. Franklin Percival4
1U.S.D.A. Forest Service, Southern Research Station, Pineville, LA., USA; 2U.S. Geological Survey, Center for
Water and Restoration Studies, Fort Lauderdale, FL., USA; 3Department of Ecology, Evolution and Marine Biology,
University of California, Santa Barbara, CA., USA; 4U.S. Geological Survey, Florida Cooperative Fish and Wildlife
Unit, Gainesville, FL., USA
The American alligator (Alligator mississippiensis)
is a top consumer in south Florida that also physically
influences the Everglades landscape through construction
and maintenance of alligator holes and trails (Mazzotti and
Brandt 1994). The existence of this species is important to
the faunal and floral character of the Everglades as it has
evolved. The U.S. Geological Survey (USGS) and its
cooperators are using empirical data collection and model
simulations to apply information on wildlife community
patterns to the Everglades restoration process. The ATLSS
(Across Trophic Levels System Simulation) project is a

large-scale spatially explicit system of interacting landscape
models of hydrologic processes, and plant and animal
responses. ATLSS is designed to evaluate the effects
of alternative water management plans on plant and animal
abundance across the Greater Everglades Ecosystem.
ATLSS requires an alligator population model to simulate
the south Florida ecosystem under varying management
strategies. The current project provides estimates of population
parameters and modeling frameworks for an ATLSS
American alligator population model (APM).
Current water management practices have resulted
in a high and unpredictable rate of nest flooding. The natural
predictability of the system has been lost (Kushlan
and Jacobsen, 1990). Historically, alligators were abundant
in prairie habitats of the eastern floodplain. Pre-drainage
occupancy of deep- water central sloughs was
relatively low. Marsh alligator densities are now highest in
the central sloughs and canals (Kushlan and Jacobsen,
1990) and relatively low in the edge habitats. Modified
hydrologic conditions might be expected to increase nesting
effort, nesting success, and abundance of alligators in
the aforementioned edge habitats. There may also be a corresponding
increase in the number and occupancy of alligator
holes that serve as drought refugia.
The Everglades is believed to be a harsh environment
for alligators. Everglades alligators weigh less than alligators of the same length from other parts of their range
(Jacobson and Kushlan 1989, Barr, 1997). In addition, maximum length is decreased, and sexual maturity is delayed
(Kushlan and Jacobsen, 1990, Dalrymple, 1996). Jacobsen and Kushlan (1989) model for growth in the Everglades
of south Florida suggests alligators reach a mere 1.26 meters in 10 years and require at least 18 years to reach sexual
Figure 1. Comparison of habitat changes and associated
caridean shrimp, and fish communities in Johnson Key
Basin over the decade 1985 to 1995.
195
maturity. It is currently suspected that the reason for this reduced condition is a combination of low food availability
and high temperatures (Jacobson and Kushlan, 1989, Dalrymple, 1996; Barr, 1997). Through the development of the
APM, restoration alternatives will be evaluated and restoration performance measures will be assessed. By applying
the APM to proposed restoration alternatives and predicting population responses, alternatives can be chosen that
result in biotic characteristics that approximate historical conditions, and future research needs can be identified.
The APM uses water data from historical measurements, and alternatively simulated water data from the various
restoration alternatives. Daily water levels were modeled by the South Florida Water Management District. The

APM also obtains input from the ATLSS American alligator production index (API). Finally, the API model uses the
water data in combination with the underlying topography and vegetation distribution to predict the probability that
(1) a female alligator in a model cell will breed and construct a nest that year, (2) that the nest will not flood, and (3)
that the habitat is favorable for nesting.
The core model component is a 3-D matrix that records the density of each stage of alligator in each 500x500m

spatial location. The density matrix interacts with survival and condition matrices calculated for each time step based
on water level, crowding, etc. To disperse alligators, a discrete spatial convolution method is used. The effect is similar
to a "blur filter" used by many image-processing computer programs, and is a process that takes the contents of
a cell and redistributes it according to a mathematical dispersal kernel. Dispersal kernels are sized according to the
average dispersal distance of each alligator stage determined by field studies.
Output of the model is a 3-D alligator density matrix, with space along two axes (x and y), and the stage classes
along the third axis (z). Also included in the matrix is a "running average" of the historical health and survival rates
of each stage in each cell. This construct can easily be summed to obtain the total alligator population, or subsampled
to verify agreement with field data. Instantaneous densities and local rates-of-change can be calculated from this
model.
Using the historical calibration water dataset, which simulates actual hydropatterns from 1979-1995, the
model output was compared to historical counts of alligators conducted along various airboat trails at night with a
spotlight. Preliminary model results of overall alligator abundance along the airboat trails are within the maximum
and minimum estimates derived from the surveys. Preliminary comparisons of base conditions (1995 and 2050) to
alternatives (ALT D13R) suggest that conditions would improve, and populations of alligators would be reestablished
in short hydroperiod wetlands such as the Rocky Glades in Everglades National Park (ENP). Habitats such as
Shark River Slough in ENP that are projected to have increased water depths under proposed restoration alternatives
are expected to maintain populations or experience slight declines. The results of these simulations agree with observations
of crocodilian biologists working in the Everglades. Full model simulations and comparisons of base versus
alternative scenarios are available for comment.
REFERENCES
Barr, B., 1997, Food Habits of the American alligator, Alligator mississippiensis, in the southern Everglades.
Unpublished Ph.D. Thesis, Univ. Miami, Florida.
Dalrymple, G.H., 1996, Growth of American Alligators in the Shark Valley Region of Everglades National Park.
Copeia. 1996(1): 212-216.
Jacobsen, T., and J.A. Kushlan.,1989, Growth dynamics in the American alligator (Alligator mississippiensis).
J. Zool., Lond. 219(2): 309-328.
Kushlan, J.A., and T. Jacobsen, 1990, Environmental variability and the reproductive success of Everglades
alligators. J. Herpetol. 24(2):176-184.
Mazzotti, F.J., and L.A. Brandt, 1994, Ecology of the American alligator in a seasonally fluctuating environment, in
S. Davis and J. Ogden, (eds.), Everglades: The Ecosystem and its Restoration, St. Lucie Press, Delray Beach,
Florida., p. 485-505. .
Contact: Daniel H. Slone, USDA Forest Service, Southern Research Station, 2500 Shreveport Hwy., Pineville,
LA 71360, Phone: (318) 473-7202, e-mail: dslone@fs.fed.us.
196
Mangrove Die-Off in Florida Bay: A Recurring Natural Event?
By Thomas J. Smith III1, Lenore Fahrig2, Paul W. Carlson3, Thomas V. Armentano4, and Gina M. Peery5
1U.S. Geological Survey, Center for Water & Restoration Studies, St. Petersburg, FL., USA; 2Carleton University,
Ottawa, Ontario, Canada; 3Florida Marine Research Institute, St. Petersburg, FL, USA; 4South Florida Natural
Resources Center, Everglades National Park, Homestead, FL., USA; 5ETI Professionals, Inc., St. Petersburg, FL.,
USA
The phenomenon of "mangrove die-off" has been reported from Florida Bay periodically for decades. Botanical
explorations of the Everglades, Florida Bay and the keys from the late 1800s and early 1900s by Small and
others, reported salt barrens with standing dead stems on islands in the bay and along the northern mainland shoreline.
Following the seagrass die-off in the bay in the 1980s, fishermen and scientists, reported a noticeable thinning
of the mangroves on several bay islands and new interest was generated in mangrove die-off. Most recently Florida
Bay-Watch reported renewed die-off in early 2001.
In the mid 1990s permanent vegetation plots were established at 11 sites (both island and mainland) in Florida
Bay: Crocodile Point, Munroe Lake, North Dump Key, Roscoe Key, Samphire Key, Clive Key, Little Rabbit Key,
Low Key, East Key, Little Butternut Key and Duck Key. At each site, two transects were established to overlay on
a pre-existing network of sediment porewater sampling wells. Transects had been aligned to run from the shoreline
into the interior salt barren at each location. The porewater well served as the center of the plot. All stems >1.4m in
height and <3m from the center, were identified, measured for diameter at breast height (dbh), and mapped, using
distance and bearing from the center. Stem density and basal area were calculated. Herbaceous vegetation and mangrove
seedlings were sampled using three randomly placed 1m2 quadrats within each plot. All species within the
quadrat were recorded and the number of "hits" for each species on a 10x10 grid counted. This yielded a percent
cover for each species. A subset of plots was resampled during the summers of 1999 and 2000. Change in a stem's
dbh was used to calculate growth between the two samplings. Historical aerial photographs dating from 1927 were
examined for each study location and the vegetation / cover was visually interpreted.
At almost all sites mangrove stem density decreased exponentially away from the shoreline. Rhizophora was
most abundant towards the shore, with Avicennia dominant away from the shore. Laguncularia was seldom encountered.
The number of living mangrove stems increased from the first to the second sampling. However, at many sites
growth of individual mangrove stems is minimal. An exception was on Clive Key where significant growth occurred
in all plots, particularly for Rhizophora (fig. 1). A pulse of recruitment (new mangroves reaching 1.4m in height)
was also measured at this location.
Rhizophora Growth: Clive Key
0
2
4
6
8
10
Distance From Shore
Stem Diameter
1995 2000
0 10 20 30
Figure 1. Increase in average stem diameter for Rhizophora mangle at Clive Key from
1995 to 2000.
197
Total cover of herbaceous vegetation changed dramatically over the short time period studied, with both
increases and decreases observed. During the initial sampling in 1995, the interior portions of several sites were
nearly devoid of vegetation, especially at Crocodile Point and North Dump Key. The tops of the porewater wells,
which protruded above the sediment level, were easily seen. In 2000, these areas were covered with vegetation and
the porewater wells obscured (to the point they were very difficult to find, fig. 2). Increase in herbaceous cover was
due primarily to abundant growth by the succulents Batis maritima, Salicornia virginica, and S. bigelovii at the interior
end of the transects. Herbaceous cover decreased shoreward at most locations, possibly due to increased growth
of the mangrove canopy causing lower light at the forest floor.
Interpretation of the aerial photographs revealed the presence of interior barren areas on numerous islands in
Florida Bay in 1927, and their persistence through time. This record, combined with our short-term observations,
highlight the dynamic nature of these coastal habitats and their ability to respond rapidly to short-term environmental
change.
Contact: Smith, T.J., III. USGS, Center for Water & Restoration Studies, 600 Fourth St., South, St. Petersburg,
FL 33701. Phone 727-803-8747 x 3130, FAX 727-803-2030, Email Tom_J_Smith@usgs.gov, Question 4.
Dump Key
0
25
50
75
100
125
Distance From Shoreline
Percent Cover
1995 2000

0 10 30 40 20
Figure 2. Increase in herbaceous vegetation cover at Dump Key from 1995 to 2000.
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A Decade of Mangrove Forest Change Following Hurricane Andrew
By Thomas J. Smith III1, Kevin R.T. Whelan2, Gordon H. Anderson2, Christa L. Walker3, Jeffrey S. Dismukes4, and
Thomas W. Doyle5
1U.S. Geological Survey, Center for Water and Restoration Studies, St. Petersburg, FL., USA; 2U.S. Geological
Survey, Center for Water and Restoration Studies, Miami, FL., USA; 3Dyncorp Systems & Solutions LLC, U.S.
Geological Survey, Homestead, FL., USA; 4ETI Professionals, Inc., USGS Center for Coastal and Watershed
Studies, St. Petersburg, FL., USA; 5U.S. Geological Survey, National Wetlands Research Center, Lafayette, LA., USA
Hurricane Andrew crossed the southern Florida Peninsula on the morning of August 24, 1992. Following the
storm, the National Park Service conducted an Environmental Damage Assessment to gauge its impacts on the natural
resources of south Florida Park Service holdings. Although hurricanes had impacted Park's lands, such as the
Everglades, in the past, no systematic, permanent sampling scheme had ever been established to monitor long-term
recovery (or lack of recovery) following catastrophic disturbance.
In October 1992, six large plots were established in the heavily damaged areas of mangrove forest on the
southwest coast of the Everglades, along the Lostmans and Broad Rivers. The plot network was expanded during
the next 24 months and now encompasses more than 20 permanent plots. Each plot is circular. For each stem >1.4
m in height, the distance and bearing from the stem to a permanent center stake was measured. The stem was identified
to species and its diameter at breast height measured. The condition of each stem was recorded (alive or killed
by Andrew). Each living stem was marked with an aluminum tree tag for future identification. Since establishment,
each plot has been sampled from 6-9 times. During a resampling, all tagged stems were located and their dbh and
condition recorded. Recruits (previously untagged stems now having grown to 1.4m in height) were identified, measured
and mapped. Changes in condition of all stems were noted (e.g. mortality from various causes). Increases or
decreases in biomass were calculated for individual stems based on allometric equations relating biomass to dbh.
Total biomass was determined by summing individual changes and changes due to addition of recruits and losses
from mortality. Coincident with the establishment of the permanent vegetation plot network, researchers from the
USGS were constructing a network of hydrological monitoring stations in the southwest coastal Everglades. Each
hydrology monitoring station has one or more vegetation plots nearby (but not all vegetation plots have an adjacent
hydrology station).
The trajectory of vegetation change, growth, mortality and recruitment has been highly variable among plots.
Indeed, most plots have followed unique patterns. The only overall pattern was the increase in stem density observed
in all plots. The species that dominated recruitment varied, sometimes being Rhizophora, often Laguncularia, but
never Avicennia. The rate of stem density increase varied among plots. After 10 years, Second Onion Bay had
>1,900 stems, whereas Johnson Mound Creek had 325, about an order of magnitude difference. Individuals are continuing
to recruit into the population at all plots except at Lostmans Ranger Station and Broad River Mid. The 10th
year survey at both of these showed slight declines in stem density (figs. 1 and 2).
Mortality is occurring at all sites. Sources of stem death have included: continuing mortality from damage
initially induced by Hurricane Andrew; and stems being killed by falling debris, lightning, wind-throw during winter
cold fronts, freeze, fire and several smaller hurricanes since Andrew such as George, Harvey, Irene and Mitch. Stems
in the smaller size classes are beginning to perish due to suppression (that is, being overtopped and heavily shaded
by larger neighbors).
Growth by stems that survived Andrew or which have since recruited into the plots is difficult to explain. Productivity
cannot be explained simply by sediment porewater nutrient concentrations, which are highly variable.
Salinity and hydrologic parameters seem most promising to explain patterns of biomass increase following the catastrophic
disturbance from Hurricane Andrew. Sampling of these plots will continue in order to monitor the effect
of increasing freshwater inflow that will occur as a major component of the Everglades restoration.
Contact: Smith, Thomas J., III; USGS, Center for Water & Restoration Studies, 600 Fourth St., South, St. Petersburg,
FL, 33199. Phone: 727-803-8747 x 3130, FAX 727-803-2030, Email Tom_J_Smith@usgs.gov. Ecology &
Ecological Modeling.
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200
201
Invasive Exotic Plant Management at the Arthur R. Marshall Loxahatchee National
Wildlife Refuge, an Integrated Approach
By Allison G. Snow1, William Thomas, Jr.2, and Laura A. Brandt2
1U.S. Geological Survey Center for Water and Restoration Studies, Miami, FL., USA
2U.S. Fish and Wildlife Service - A.R.M. Loxahatchee NWR, Boynton Beach, FL., USA
Invasive exotic plants pose a severe threat to natural ecosystems worldwide including south Florida's unique
and imperiled Everglades ecosystem. The sub-tropical climate, international commerce, and ornamental plant trade
industry are factors, which significantly increase the susceptibility of Florida's habitats to invasion. The Everglades
are already threatened by human encroachment, rampant development, and fragmentation of adjacent buffer lands.
The Arthur R. Marshall Loxahatchee National Wildlife Refuge (the refuge) represents a unique remnant of the northern
Everglades ecosystem, whose native species and ecological integrity are slowly yielding to the influx of invasive
exotic plants. Old World climbing fern (Lygodium microphyllum) is decimating tree islands by smothering native
vegetation, toppling trees, altering fire ecology, creating tangled mats capable of ensnaring wildlife, and preventing
native species establishment. Melaleuca quinquenervia forms dense stands that are impenetrable to wildlife, alter
hydrologic patterns, fire ecology, and native plant communities. In addition, other Florida Exotic Pest Plant Council
Category I and II plant species occur with associated detrimental impacts to native plant communities and wildlife.
In response to this threat, the refuge has developed a multi-faceted program incorporating detection, control, monitoring,

and research, while working closely with other government and private organizations; a truly integrated pest
plant management approach. The primary goals of this program are to reduce invasive plant populations to controllable
levels where impacts to native plant communities and wildlife are minimized and to further understand the
underlying causes and consequences of exotic plant invasions to native plant communities and wildlife.
To address the increasing populations of invasive exotic plants, a detection and treatment program was implemented.
The refuge conducts Surveillance and Reconnaissance Flights (SRF) as the primary mode of detecting
visible infestations of invasive exotic plants. These surveys are coordinated with the South Florida Water Management
District (SFWMD) and the National Park Service (NPS) to ensure a consistent data set, providing complete
coverage of invasive exotic plant infestations on the refuge as well as infestations on a regional level for all of south
Florida. These SRF results are used to direct field operations by both private contractors who concentrate on heavier
infestations over large acreages and refuge crews who concentrate on isolated populations and outliers. The preferred
management strategy is to contain and treat small and (or) outlier populations. The most effective method to date for
the most problematic species remains herbicides, which are applied using a variety of techniques. Refuge crews and
volunteers deal with ancillary exotics on an individual basis. Along with conventional control methods, refuge staff
are also active on the biological control front, working closely with the U.S. Department of Agriculture (USDA) to
coordinate the release of insects such as the Melaleuca psyllid, a potential biocontrol agent for Melaleuca quinquenervia,
and by implementing vegetation studies on L. microphyllum infested tree islands in collaboration with private
parties such as the Institute for Regional Conservation (IRC) to provide baseline information on the impacts of L.
microphyllum for future biological control releases. To combat aquatic invasive plants such as water lettuce (Pistia
stratiotes) and water hyacinth (Eichhornia crassipes), the refuge collaborates with the SFWMD to ensure waterways
are clear and navigable to maintain effective water flow and drainage and to ensure public recreational activities such
as fishing and canoeing are not adversely impacted.
Areas that have undergone eradication efforts are monitored to document impact to and re-growth of the
targeted invasive plant species and of surrounding native vegetation. These two parameters are then used to gauge
the effectiveness of the treatment programs, improve efficiency, and provide modifications for future treatment protocols.
This monitoring program includes establishing plots on islands where Melaleuca and Lygodium have been
treated via ground-based herbicide applications. Though ground applications appear to be effective when performed
correctly, they may not be cost efficient due to the severe infestations now occurring within all refuge habitats.
To evaluate an alternative control technique refuge staff, in cooperation with the SFWMD and University of Florida
202
(UF) scientists, are also examining the effectiveness of aerial application of two herbicides at two concentrations on
two strand tree islands severely infested with L. microphyllum. In addition to monitoring post-treatment efforts, the
refuge supports and facilitates several research projects on invasive plant species through cooperative efforts as well
as through the issuance of Special Use Permits. Keeping with one of the primary functions of the National Wildlife
Refuge system, refuge staff are examining an often-overlooked impact of invasive plant species; the toll these plants
take on the wildlife. By studying the relationship between L. microphyllum infestations and vegetation and wildlife
diversity, biologists hope to provide insight into the interactions between invasive exotic plants, native plant communities,
and wildlife populations.
Research is also underway to develop tools to aid land managers in effective detection of invasive plant
species as an alternative to the SRF. The SFWMD is conducting research to determine the feasibility of using
IKONOS (satellite) data to detect infestations of L. microphyllum. Another crucial question for effective management
is the ability to determine those areas at high risk of invasion as a result of exposure to an invasive seed/spore
source. To address this concern, refuge staff are collaborating on yet another project to examine the distance
L. microphyllum spores can be dispersed from existing infestations. By determining areas of highest spore deposition,
refuge staff can concentrate their detection, control, and eradication efforts in areas most prone to invasion.
This data set will have a dual function, also being integrated into a larger project conducted by USGS and the
University of Tennessee (UT). This venture will incorporate current distribution maps, life history attributes of
L. microphyllum, dispersal data, control mechanisms, and hydrology to develop a computer simulation model. This
program will allow land managers to input parameters (current infestation coverage, funding for control, control
method, and hydrological limitations) and view the potential outcome of different scenarios, thereby facilitating
managerial decisions on the appropriate resources needed for efficient treatment and the type and location of treatments
needed to achieve the most effective control to limit spread and invasion to new areas.
Early detection, treatment, and monitoring are critical components of a successful exotic plant management
program. The refuge is aggressively addressing this problem, and is taking the necessary steps to monitor and reduce
populations of invasive plants on the refuge while strengthening its efforts by collaborating with other private, local,
and federal and state agencies including the SFWMD, USDA, Florida Department of Environmental Protection, UF,
UT, USGS, Florida Atlantic University, and the IRC. Collaboration is essential; a variety of agencies throughout
south Florida are battling invasive plants on a landscape level, encompassing a plethora of federal, state, local, and
private buffer lands. By working together and with the help of volunteers, refuge staff are helping ensure the reduction
of current exotic plant populations across south Florida.
Contact: Allison G. Snow, U.S. Geological Survey, A.R.M. Loxahatchee NWR, 10216 Lee Road, Boynton Beach,
FL, 33437, Phone: 561-732-3684, Fax: 561-369-7190, Email: allison_snow@usgs.gov
203
Clipping as a Substitute for Fire to Study Seasonal Fire Effects on Muhly Grass
(Muhlenbergia capillaris var. filipes)
By James R. Snyder
U.S. Geological Survey, Center for Water and Restoration Studies, Ochopee, FL., USA
The Cape Sable seaside sparrow is a Federally listed endangered species whose range is almost entirely within
Everglades National Park and Big Cypress National Preserve. Its preferred nesting habitat is the short-hydroperiod
grassland known as marl or muhly (for Muhlenbergia capillaris var. filipes) prairie found on either side of the Shark
River and Taylor Sloughs. Muhly is a perennial bunch grass with needle-like leaves generally less than one meter in
height. Recent concerns about the survival of the Cape Sable seaside sparrow result from population declines attributed
to prolonged flooding in the sparrow range west of Shark River Slough during the 1990's.
Muhly prairies can burn almost any time of the year. The area burned by wildfire is greatest during April, May,
and June (Snyder, 1991), which is the peak of the Cape Sable seaside sparrow breeding season (Nott et al., 1998).
Prescribed burning is recommended to prevent large wildfires from denuding significant portions of the critical habitat.
It is often done during the cooler winter months because of more predictable and favorable burning conditions.
Prescribed burning during the transition from dry to wet season, when fires normally burn the greatest area, is generally
avoided because of potential control problems and because sparrows are nesting. While fire is a natural and
necessary phenomenon in muhly prairies, the interaction of fire and flooding can have profound effects on vegetation
structure and composition. Fire followed by flooding can result in high mortality of plants that normally resprout
vigorously (Herndon et al., 1991).
We have proposed to address two related questions relevant to fire management and the endangered Cape
Sable seaside sparrow: 1. How does season of burning effect the rate of recovery of muhly? 2. How does season of
fire effect the ability of muhly to tolerate flooding? These questions will be addressed through two experiments, one
in the field and one under more controlled conditions. Because experimental prescribed burns are relatively expensive
to conduct and are difficult to apply consistently over time, the clipping of muhly plants was proposed as a substitute
for fire. There is ample evidence that clipping and removal of litter can result in responses similar to those
observed following fire (Hulbert, 1988). The results of a preliminary experiment intended to compare the response
of muhly to clipping and burning are reported here.
The experiment was conducted in an area of muhly prairie burned by a wildfire that occurred on May 7, 2001,
along U.S. 41 in Big Cypress National Preserve. On May 22, 20 burned muhly clumps were marked, about 50 m
south of the road and within 20 m of the fire edge. The plants had resprouted about 10 cm since the fire. In the adjoining
unburned area to the east 80 unburned muhly clumps were marked. Ten randomly selected clumps were clipped
about 2 cm above the ground, matching the amount of grass that remained after burning. Groups of 10 randomly
selected plants were clipped on five additional dates through July 12 to see if the seasonal timing of top removal
affected plant response. Twenty marked plants were not clipped and served as controls. The heights of the tallest
leaves in the marked muhly clumps in the burned area were recorded each time plants were clipped. By the latter
part of June, there had been substantial rainfall and the ground was wet. At the last clipping date on July 12 there
was standing water in low spots. The heights of a few plants clipped at different times were measured to compare
rates of regrowth after clipping and burning.
Figures 1 and 2 show regrowth of the burned and clipped plants, respectively. The figures cannot be compared
directly because the growth of plants burned on May 7 was observed for up to 66 days; whereas, plants were clipped
at various times up to 51 days before July 12. Therefore, the period during which leaf growth was observed differed
in the two situations. The closest comparison is between plants clipped 15 days after the fire, which were slightly
under 60 cm tall 50 days after clipping, to burned plants, which were slightly over 60 cm tall 50 days after burning.
It therefore appears that growth is similar, but that burned plants may resprout more vigorously than clipped plants.
It is possible that the ash fertilizes the grass after burning and enhances regrowth.
204
In October, the number of flowering culms in each clump was counted. In the unburned area, the 20 unclipped
plants had no flowering culms. This was considered likely because flowering is seldom observed in muhly that has
not recently burned. In the burned area the plants showed substantial flowering. Only 17 of the 20 plants originally
marked in the burned area were relocated and they had a mean of 6.5 flowering culms per plant, with a range of
0 (2 plants) to 15 culms per plant. In contrast, a single flowering culm was found on a plant clipped on June 22; the
other 59 clipped plants had no flowers. Therefore, the conclusion drawn is that clipping as done in this experiment
is not an adequate substitute for fire, even though vegetative regrowth was similar between burned and clipped
plants.
A few possible reasons that flowering is not stimulated by clipping include the lack of a nutrient pulse, excess
residual litter, or a lack of stimulation to belowground parts by heat. Even though a 2-cm stubble is left after a fire,
the tissues above ground are undoubtedly dead. This is not the case with clipped plants.
As a consequence of this preliminary study, a method to burn individual muhly clumps in the field relatively
easily and safely has been developed. Experimental burning treatments addressing the issue of season of burning
and the response of muhly will begin in January 2003 and continue through the early part of the wet season.
REFERENCES
Herndon, A., L. Gunderson, and J. Stenberg. 1991, Sawgrass (Cladium jamaicense) survival in a regime of fire and
flooding. Wetlands 11:17-27.
Hulbert, L.C. 1988, Causes of fire effects in tallgrass prairie. Ecology 69: 46-58.
Nott, M. P., O. L. Bass, Jr., D. M. Fleming, S. E. Killeffer, N. Fraley, L. Manne, J. L. Curnutt, T. M. Brooks,
R. Powell, and S. L. Pimm. 1998, Water levels, rapid vegetational changes, and the endangered Cape Sable seaside-
sparrow. Animal Conservation 1:23-32.
Snyder, J. R. 1991, Fire regimes in subtropical South Florida. Proceedings Tall Timbers Fire Ecology Conference
17:303-319.
Contact: Snyder, James R., USGS, Big Cypress Field Station, HCR 61, Box 110, Ochopee, FL 34141,
Phone: 239-695-1180, Fax: 239-695-3007, jim_snyder@usgs.gov
0
20
40
60
80
0 10 20 30 40 50 60 70
Days since fire
Height (cm)
Figure 1. Approximate heights of tallest leaves
resprouting from muhly clumps burned on
May 7, 2001.
0
20
40
60
80
0 10 20 30 40 50 60 70
Days since clipping
Height (cm)
Figure 2. Heights (on July12, 2001) of tallest
resprouting leaves from several clipped plants.
205

Modeling Manatee Response to Restoration in the Everglades and
Ten Thousand Islands
By Bradley M. Stith, Jim Reid, Dean Easton, and Susan Butler
USGS, Center for Aquatic Resources Studies, Sirenia Project, Gainesville, FL., USA
The coastal waters of southwest Florida harbor nearly a third of the Florida population of the Federally listed
West Indian manatee (Trichechus manatus). A large proportion of this population occurs within the Everglades
National Park (ENP) and the Ten Thousand Islands (TTI), yet only limited information is available from this remote
region. Aerial surveys conducted by ENP personnel in the early 1990s revealed heavy use of both inshore and offshore
areas during most of the year. Manatees feed almost exclusively on submerged aquatic vegetation (SAV), and
most individuals show a strong preference for marine seagrasses. Bcause manatees lack the ability to drink saltwater
(mariposia), they need to drink freshwater periodically. Thus, manatees depend on resources in marine, estuarine,
and freshwater zones, making them excellent indicators of the health and restoration success across all of these
zones.
A primary goal of this research is to develop an individual-based ATLSS model to simulate manatee response
to changes in hydrology caused by the Comprehensive Everglades Restoration Plan (CERP). In support of this goal
we have analyzed manatee telemetry data from the study area to parameterize and calibrate the model. We have also
conducted aerial surveys in the TTI region to provide information on the distribution and abundance of manatees that
could be used to validate the model.
Analysis of Telemetry Data
Data was analyzed from 20 tagged animals between June 2000 and July 2002, representing 4,563 manatee
tracking days. The attached Argos transmitters were programmed to fix at least one location during four time-windows
each day, when satellite overpass geometry was optimal. The actual number and accuracy of fixes obtained
varied due to animal behavior or equipment performance. Filtering out all points with poor spatial accuracy resulted
in 12,600 fixes, a decrease of 31 percent over what could be obtained under optimal conditions. We also deployed
GPS tags for 104 manatee days; these tags were programmed to obtain fixes at 15- or 20-minute intervals.
The Argos telemetry data provided valuable information on coarse-scale patterns of manatee behavior that
were incorporated into the ATLSS model. We classified the landscape into four simple aquatic zones: offshore, travel

corridors, inshore bays, and inland riverine systems or canals. We used a GIS overlay analysis to determine the
aquatic zone for each telemetry point. Most manatees showed a consistent pattern of feeding on marine seagrass beds
in offshore zones for a period of several days, followed by large movements of 5 to 20 km or more up rivers and
canals, presumably to obtain freshwater. Several animals also made heavy use of inshore bays where they could feed
on a suite of SAV different from the offshore areas. The home ranges of all animals incorporated one or more inland
sites which supply freshwater, as well as offshore areas that provide food resources.
Comparison of the number of inland forays made during wet versus dry season showed a slightly higher number
during the dry season, but the difference was not significant. Manatees made inland forays in the wet season,
even when freshwater was available at the mouth of rivers or canals. During periods of significant cold weather, manatees
greatly decreased their use of offshore areas and increased their use of inshore locations with favorable thermal
buffering (typically deeper sections of canals, rivers, and inshore holes).
GPS data provided valuable fine-scale information on manatee behavior, which could not be obtained from
the Argos data. Distribution of movement rates between GPS points fitted an inverse distribution, with a mean and
mode well below 1 km/hour, and maximum speeds approaching 3 km/hour. Directionality of movement was highly
biased towards small turn angles, and the GPS data provided precise movement pathways through the complex
aquatic landscape in TTI and ENP.
206
The telemetry data provided valuable information needed to parameterize and structure the ATLSS model.
The broad movement patterns provided by the Argos data were nicely complemented by the detailed data provided
by the GPS tags.
Model Structure
The manatee ATLSS model is being developed in C++ using object-oriented techniques. The model is individual-
based, spatially-explicit, and simulates the movements of individuals on a raster image (20-m cell size) of
southwest Florida. A network data structure of arcs and nodes is used to direct the movement of manatees in an efficient
manner. This network structure was developed from telemetry locations and aerial survey data, and consists
of nodes representing primary drinking areas, feeding areas, and thermal sheltering areas, connected by travel paths
represented as arcs. Standard algorithms from graph theory are used to access and query this network structure.
Home range allocation-Each manatee is allocated a portion of the total network that includes one or more freshwater
sites and offshore seagrass beds. The initial network portion allocated to each manatee at the start of a simulation
is drawn from a distribution of home range sizes and geographic positions along the coast as determined from
telemetry data. Manatees born after the creation of the initial cohort inherit their mother's network, to reflect maternal

transmission of home range.
Movement rules-Manatees move on a network of nodes representing destination sites for feeding, drinking, and
thermal sheltering, all connected by arcs representing travel corridors. Low water depths limit the movement of
manatees along some portions of the network. Manatees can shift their home range to different parts of the total
network if freshwater or seagrass becomes unavailable within their subset of the network.
Incorporation of environmental variables-Salinities, temperature, and water depth are modeled only along this network,
rather than across the entire grid, to increase computational efficiency. Until linkages exist to hydrologic models
such as TIME, we are relying on simple surrogate models that simulate observed patterns and possible
restoration scenarios.
Manatee behavioral state switching-A Markov Chain approach is used to simulate the transition of manatees into
different behavioral states that drive the movement patterns of each individual. Only a few, simple behavioral states
(feeding, drinking, traveling, resting) inferred from the telemetry data are modeled. Transition probabilities were
developed from the telemetry data and from previous research on manatee time budgets in other areas.
Manatee learning-Several simple learning modules simulate freshwater site switching by manatees. These modules
determine how quickly manatees shift their use of different parts of the network in response to positive or negative
reinforcement in the availability of freshwater at sites within the home range of each manatee. The simplest
algorithm, the real-time linear operator model, assumes that animals maintain an estimate of resource availability at
time t, which is incremented or decremented during each time step, depending on whether the resource was found
or not.
Key assumptions-A key component of the model is the manatee-learning module, which determines how quickly
manatees shift their use of different parts of the network in response to positive or negative reinforcement in the
availability of a critical resource. Sensitivity analyses will be used to evaluate the importance of different assumptions
and uncertainty associated with poorly understood parameters. As additional telemetry data are collected, the
model will be refined to incorporate new insights from these data. Radiotracking and aerial surveys will provide an
important means of monitoring manatee response to natural environmental fluctuations and human-induced alterations
associated with restoration activities.
Contact: Brad Stith, USGS, Center for Aquatic Resources Studies, Sirenia Project, 412 NE 16th Ave., Room 250,
Gainesville, FL 32601. Phone: (352)333-3814, fax: (352)374-8080, bradley_stith@usgs.gov.
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Abundance and Diet of Rana grylio Across South Florida Wetlands
By Cristina A. Ugarte1 and Kenneth G. Rice2
1Department of Biological Sciences, Florida International University, Miami, FL., USA
2U.S. Geological Survey, Center for Water and Restoration Studies, Fort Lauderdale, FL., USA
Federal and state agencies are attempting to project the impact of hydrologic restoration on the Everglades
ecosystem. Current modeling efforts have focused on primary producers (e.g. macrophytes and periphyton) or
organisms of higher trophic levels (e.g. panther, deer, birds). Amphibians are a vital intermediate link within the
Everglades food web (ATLSS 1997, Ligas 1960). Even though amphibians are known to comprise a large portion
of the faunal biomass within wetland systems, they remain underrepresented in restoration efforts (Burton and
Likens, 1975). The biphasic lifecycle of pigfrogs (Rana grylio) makes them extremely sensitive to hydrologic
change. Unfortunately, little is known about their abundance, ecology, and importance to the greater Everglades ecosystem.
This study investigated temporal changes in Rana grylio abundance and diet in south Florida wetlands from
August 2000 to September 2002. The goal of this study was to link changes in hydrology to the abundance and condition
of this species throughout south Florida wetlands.
A total of 551 one kilometer transects were surveyed at night via airboat to compare the monthly abundance
of R. grylio across large areas of Water Conservation Areas 3A, 3B, and Everglades National Park (ENP). Abundance
estimates were calculated using a double-observer approach (Nichols et. Al, 2000). Capture-recapture techniques
were used within three one-hectare plots at each site in order to estimate abundance and growth parameters
on a smaller scale. We collected 684 frogs from throughout the study areas from 1999-2002 to examine stomach
content among sites. A drought occurred during 2001, which allowed us to assess how this species responds to a
severe prolonged dry-down.
Stomach contents were greatest during the mid to late dry season at all three sites (fig. 1). Frogs in 3A had
less food in their stomachs than those in either 3B or ENP. Growth was highest from December to March. Frogs
were most abundant from March through September (fig. 2). Recruitment of metamorphs appears to peak from July
through September. It appears that as water levels decrease, food may become more available to the frogs, allowing
them to grow or invest in reproduction during this time. The study sites in WCA 3A rarely dried down. These frogs
rarely contained fat bodies or food in their stomachs; this may be due to prolonged flooding in this area. Frogs are
both smaller and more abundant in WCA 3A than in ENP or WCA 3B. This is probably due to a combination of
both frog harvesting and high water throughout the year. Final results including models of the effects of hydrology
on this species will be available in Fall 2003.
REFERENCES
ATLSS. 1997. Across trophic level ecosystem simulation: An approach analysis of south Florida Ecosystems.
USGS-BRD. Miami, Florida.
Burton, T. M. and G.E. Likens. 1975. Salamander populations and biomass in the hubbard Brook Experimental
Forest, New Hampshire. Copeia 3:541-546.
Ligas, F.J. 1960. The everglades bullfrog: Life history and management. Florida Game and Freshwater Fish
Commission. Tallahassee, Florida.
Nichols, J.D., J.E. Hines, J.R. Sauer, F.W. Fallon, J.E. Fallon, and P.J. Heglund, 2000. A double-observer approach
for estimating detection probability and abundance from point counts. Auk 117: 393-408.
Contact: Cristina A. Ugarte, Department of Biological Sciences, OE 167, University Park, Florida International
University, Miami, 33199, Phone: 305-348-1235, e-mail: ugartec@fiu.edu
208
Figure 1. Mean total stomach volume of Rana grylio from three study sites in the Everglades during 2001-2002.
Figure 2. Mean abundance (animals/km) of Rana grylio from Water Conservation Area 3A.
Mean stomach volume of Rana grylio by month in WCA 3A
F(10,182)=13.06; p<.0000
MONTH
SQRT volume
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Mar 99 Jul 00 Sep Nov Jan 01 Feb Mar Apr Jun Jul Feb 02
Mean stomach volume of R. grylio by month in B
MONTH Main Effect
F(7,184)=4.42; p<.0001
MONTH
SQRTVOL
0.2
0.4
0.6
0.8
1.0
1.2
1.4
May 99 Jul 00 Aug Sep Oct Nov Jan Feb 02
Mean stomach volume of R. grylio by month in ENP
F(5,164)=5.34; p<.0001
MONTH
SQRT Volume
0.2
0.4
0.6
0.8
1.0
1.2
1.4
May 00 July Aug Sep Oct Feb 02
209
Short-Term Dynamics of Vegetation Change Across a Mangrove-Marsh Ecotone
in the Southwest Coastal Everglades: Storms, Sea-Level, Fire, and Freeze
By Christa L. Walker1, Thomas J. Smith III2, and Kevin R.T. Whelan3
1Dyncorp Systems & Solutions LLC, USGS Everglades Field Station, Homestead, FL., USA
2U.S. Geological Survey, Center for Water & Restoration Studies, St. Petersburg, FL., USA
3U.S. Geological Survey, Center for Water & Restoration Studies, Miami, FL., USA
Understanding the potential impacts of Global Climate Change, such as sea-level rise, on the newly initiated
Comprehensive Everglades Restoration Plan (CERP) are crucial to its success. The position of the mangrove-marsh
ecotone (MME) is known to have changed through time at several locations in coastal Everglades and Florida Keys.
Shifts in the upstream position of the MME have been suggested as a means of monitoring sea-level impacts and to
serve as an indicator of global climate change in places such as Australia and Southeast Asia.
The ecology of a MME has been examined in detail for over seven years. The site is located along the Harney
River, in Everglades National Park. We established a transect across the MME, which spans a distance of >350 m
running from a tall mangrove forest at the river bank, into a sawgrass dominated plain. Five sediment porewater sampling
sites are located along the transect. At each porewater site there are six porewater sippers, three at 30 cm depth
and three at 60cm depth. These sippers were sampled weekly for the first year (1997) and then bi-weekly thereafter.
Porewater for nutrient analyses was collected at infrequent intervals. Permanent plots for measuring changes in the
mangrove forest canopy and in the abundance of mangrove seedlings were established in 1998 and have been sampled
yearly. An experiment was established to examine the impacts of a marsh fire on the subsequent establishment
and growth of mangrove seedlings. Change in the position of this ecotone since 1927 has been determined by the
analysis of aerial photographs.
The river edge is dominated by tall mangrove forests, particularly Rhizophora mangle and Laguncularia racemosa.
Avicennia germinans is present in low numbers over the first 200 m of the transect (fig. 1). Forest height and
average stem size decrease inland. Both Rhizophora and Avicennia disappear from the inland areas of the transect,
leaving Laguncularia as the only mangrove species where the forest gives way to a marsh dominated by sawgrass
(Cladium jamaicense).
Density: Avicennia, Laguncularia, Rhizophora, Cladium
0
1000
2000
3000
4000
5000
6000
7000
8000
1 2 3 4 5
Position Across Ecotone
Stems / Hectare
RIVER EDGE SAWGRASS
Figure 1. Stem density for the dominant species across the Harney River mangrove marsh ecotone
transect (multiply Cladium by 100).
210
Long term change in the position of the ecotone has occurred. In 1927 the MME was approximately 100 m
from the river bank. By 1994, the MME was 350 m from the river bank, an inland shift of approximately 250 m, a
distance readily measurable on the photographs. Stumps of the Cabbage Palm (Sabal palmetto) can be found inside
of the current mangrove forest and provides strong evidence for a change in the vegetation. Our physical data indicate
that this transect, located on a large coastal island, is disconnected from upstream hydrologic signals. We thus
feel that the movement of this ecotone over the past 70 years is related to a rise in sea level.
Gross sediment nutrient concentrations vary significantly from river edge to interior marsh. Total nitrogen
increases from just over 1 ppm (mg per gm wet sediment) in the riverine mangrove forest to more than 2 ppm in the
sawgrass. The trend for phosphorus is the reverse. Sediment P is highest in the riverine forest (1.2 ppm) and least in
the sawgrass (0.4 ppm).
Tree mortality has been observed from a variety of sources over seven years including: wind (from both hurricanes
and winter cold fronts), freezing temperatures, fire and lightning (fig. 2). Freezes and fires are more likely
to affect stems at the ecotone. Both fires and freezes "top killed" numerous individuals of Laguncularia along the
ecotone. This species stump sprouts readily. The frequent occurrence of fires and freezes may account to the large
number of Laguncularia that are multi-stemmed.
In terms of fire impacts, the preliminary results from our seedling transplant experiment are interesting.
We hypothesized that seedlings planted into a recently burned sawgrass marsh would have higher survival rates than
ones planted under an unburned sawgrass canopy. For all three mangroves, however, the reverse was true. Individuals
in the unburned marsh had greater survival. The largest effect, however, was among species. Avicennia, in both
burned and unburned marshes, died rapidly, whereas 45 percent or more of both Laguncularia and Rhizophora
survived for at least 200 days.
Results of this study indicate the mangrove-marsh ecotone is a dynamic component of landscape, capable of
changing and being changed over relatively short time periods. Mangrove -marsh ecotones at more upstream locations
in the Everglades ecosystem will be useful locations at which to monitor the effects of increasing freshwater
inflow.
Contact: Walker, Christa L. Dyncorp Systems & Solutions LLE, c/o USGS, Beard Center, Everglades National
Park, 40001 SR 9336, Homestead, FL 33034. Phone: 305-242-7800, FAX 305-242-7836, Email:
christa_walker@usgs.gov POSTER, Ecology & Ecological Modeling
Figure 2. Causes of short term mortality along the Harney River transect. Storm related mortality is
common near the river edge and in the interior forest. Freeze and fire are the major mortality factors
at the mangrove - marsh ecotone.
Mangrove Mortality:
0
1000
2000
3000
4000
5000
1 2 3 4 5
Position Across Ecotone
Stems / Hectare
Storm Freeze Fire
RIV ER SAWGRASS
211
Characteristics of Lightning Gaps in the Mangrove Forests of Everglades
National Park
By Kevin R. T. Whelan1 and Thomas J. Smith III2
1U.S. Geological Survey, Center for Water and Restoration Studies, Miami, FL., USA
2U.S. Geological Survey, Center for Water and Restoration Studies, St. Petersburg, FL., USA
Lightning gaps have been identified as a common disturbance in mangroves throughout the world. Lightning
created canopy gaps are abundant in the mangrove forests of Florida. An average 9,900 cloud to ground strikes occur
annually in Florida, the highest level found in the United States. The dynamics of Florida mangrove systems may
result from the interactions of small-scale lightning gaps, large-scale hurricane disturbances, and sea-level rise.
In addition to these ecosystem forcing functions is the Greater Everglades restoration effort, known as the Comprehensive
Everglades Restoration Plan (CERP). CERP will greatly influence hydrological flow through much of the
100,000 ha of mangroves in south Florida. Clearly, to understand how the mangrove ecosystems may change in
response to restoration it is important to determine how these mangrove ecosystems respond to small- and large-scale
disturbance along with sea-level rise.
The goal of this project is to characterize the role of lightning generated gaps within south Florida mangrove
ecosystems. This is being accomplished by: following short-term changes in community level and environmental
processes; evaluating community characteristics in a time series of gaps along a known salinity gradient; and appraising
the regional signal for mangrove gap dynamics. Here we present findings of 39 gaps from the general region for
canopy and expanded gap size and direction of orientation. Additionally, we present initial findings of habitat characteristics
for six gaps of differing successional age located in the lower Shark River Region.
The mean canopy gap area was 212 m2 and the expanded gap was 299 m2 for the general gap survey. Gaps
were slightly elliptical in shape with an average eccentricity of 1.28. There was a preferential directional bias to the
longest axis of the gaps. However, there was no evidence of wind extensions to the gaps. Thirty-three percent of the
variation in gap size was explained by average surrounding canopy height.
To understand the successional process it is important to determine a relative age of the recovering gap.
The aging of tropical gaps has been a problem in a number of environments. Here we have developed a hypothetical
relative aging of gaps based on the ratio of the coarse woody debris of the gap compared to the average of coarse
woody debris amount for the study island. The average coarse woody debris was 52.52 tons ha-1 for the study island.
The gap coarse woody debris varied from 16.7 to 182 tons ha-1. There is a linear relationship between relative gap
age and the amount of coarse woody debris present with older gaps having a higher ratio of coarse woody debris
relative to younger gaps (fig. 1).
It appears that roots within the lightning created gaps die as a consequence of above ground tree mortality and
possibly from the lightning itself. Root death causes the physical properties of the sediment to differ from the surrounding
forest type. We assessed sediment parameters for six gaps of different successional age and found that compaction
is significantly lower in gaps (0.094 kg/cm 2) and higher in the surrounding closed canopy forest (0.124
kg/cm2). The same was true for sediment shear strength (gap mean = 7.4 kg/cm2 and forest mean = 8.8 kg/cm2).
Shear strength and soil compaction taken together indicates soil cohesiveness. There is a linear relation between
these parameters and our data supports this linear relation; however, all samples from gaps are consistently grouped
towards lower end of this relation (fig. 2). Sediment shear strength and compaction are usually correlated with bulk
density, however, our study does not support this finding. In addition, there was no difference in sediment bulk density
between gaps and the surrounding forest. There are plans to extend this type of investigation of lightning gaps
to the mid-stream and upstream areas of the Shark River Region. In this way we will investigate the effect of salinity
on the recovery process.
212
Contact: Whelan, Kevin R.T., USGS, c/o Department of Biological Sciences, OE Building, Room 167, Florida
International University, Miami, FL 33199. Phone: 305-348-6047; FAX 305-348-3096; Email: whelank@fiu.edu
Poster, Ecology and Ecological Modeling
Relative age of gaps
Ratio
Coarse Woddy Debris (tons ha -1)
10
20
30
40
50
60
70
80
90
100
0.2 0.6 1.0 1.4 1.8 2.2 2.6
- older gap
- med age gap
- new gap
Figure 1. Hypothesized relation between gap age and the amount of coarse woody debris.
Soil compaction versus soil shear strength
Compaction = 0.042+0.009*Shear strength
F (1,92) = 67 p <0.001 r 2=.42
Soil Shear Strength kg / cm2
Soil compaction kg / cm2
0.02
0.06

0.10
0.14
0.18
0.22
0 2 4 6 8 10 12 14 16
Forest =1
Gaps =0
Figure 2. Relation between soil compaction and soil shear strength for mangrove forested sites (squares)
and gap sites (diamonds).
213
Ecosystem History of Central Biscayne Bay Based on Sediment Core Analyses
By G.L. Wingard1, T.C. Cronin1, D.A. Willard1, J.B. Murray, R. Stamm1, C.W. Holmes2, G.S. Dwyer3,
S.E. Ishman4, and C. Williams4
1U.S. Geological Survey, Reston, VA., USA
2U.S. Geological Survey, Center for Coastal and Watershed Studies, St. Petersburg, FL., USA
3Duke University, Durham, NC; 4Southern Illinois University, Carbondale, IL., USA
During the last century, Biscayne Bay has been greatly affected by anthropogenic alteration of the environment
through urbanization of the Miami/Dade County area and alteration of natural freshwater flow. Changes in the
sources, timing, delivery, and quality of freshwater flow into the Bay have altered shoreline and sub-aquatic vegetation
to unknown degrees. Land management agencies that focus on the restoration of natural flow of freshwater into
Biscayne and Florida Bays can benefit from paleoecological and geochemical analyses documenting the impacts of
past changes in freshwater input.
To establish targets and performance measures for restoration, research is being undertaken to determine prealteration
baseline conditions and natural variation within the system. The USGS, in conjunction with South Florida
Water Management District, Biscayne National Park, Duke University, Southern Illinois University, and University
of Miami, is examining the natural patterns and causes of temporal change in salinity, water quality, vegetation, and
benthic fauna in Biscayne Bay over the last 100-300 years.
The current studies extend prior knowledge of Biscayne Bay environmental history by obtaining cores from
new sites, obtaining series of radiocarbon dates, evaluating lead-210 dating of Biscayne Bay sediments, utilizing
multiple paleoenvironmental proxies, and applying quantitative methods of faunal and geochemical analyses. These
analyses build on an expanding methodology utilized in research conducted in Florida Bay (1995 - ongoing) and
Biscayne Bay (1996-2000) (Brewster-Wingard, et al, 2001; Cronin, et al., 2001; Dwyer and Cronin, 2001; Holmes,
et al, 2001; Ishman, 1998).
Three sets of replicate cores were collected in March 2002 from sites in central Biscayne Bay, Featherbed
Bank, and an unnamed bank [herein referred to as No Name Bank, equivalent to Black Shoal of Wanless (1969)]
(fig. 1), and southern Biscayne Bay at Card Bank. Analyses of the two cores from central Biscayne are nearly complete.
A preliminary age model using lead-210 geochronology places the base of the 2002 Featherbed Bank Core at
1741 and the base of No Name Core at 1874. Age models developed from radiocarbon and lead-210 dating of the
1997 and 2002 cores indicate mean sedimentation rates for Card, Featherbed, and No Name Banks were 0.25 cm yr-
1, 0.85 cm yr-1 and 1.22 cm yr-1, respectively. The Card, Featherbed, and No Name cores yield paleoecological and
geochemical records spanning the past 900, 500, and 150 years, respectively.
Analyses of fossil ostracode and molluscan faunal assemblages indicate a major shift in benthic communities
in both central and southern Biscayne Bay during the late 1500's through 1600's, when epiphytal species indicative
of seagrass (Thalassia) habitats became abundant. Moreover, there is preliminary evidence that a decline in seagrassdwelling
epiphytal species, unprecedented in the past 400 years, occurred at both No Name and Featherbed Banks
during the mid-20th century. It is unclear what caused this decline; however, it may be due to changes in mean salinity,
increased turbidity, nutrient influx, or other factors.
Ostracode shell magnesium to calcium (Mg/Ca) ratios, a proxy for salinity, indicate considerable short-term
variability in Mg/Ca at No Name Bank during the past 150 years (fig. 2). The paleosalinity patterns are generally
similar to those observed at Featherbed Bank and from Russell Bank in Florida Bay.
214
Compilation of the data from the 2002 cores will provide additional data on the timing and causes of salinity
variability and its relation to benthic faunal variability and benthic habitats. Comparisons will be made to cores collected
in Biscayne Bay between 1996-99, to determine trends in salinity, subaquatic vegetation, and shoreline vegetation
for Biscayne Bay. A comparison to Florida Bay cores will provide information on ecosystem-wide changes.
These data will provide the essential data necessary to establish performance criteria and restoration targets for
CERP (Comprehensive Everglades Restoration Plan) and the agencies responsible for implementing CERP.
REFERENCES
Brewster-Wingard, G.L., Stone, J.R., and Holmes, C.W., 2001, Bull. American Paleo., no. 361, p. 199-232.
Cronin, T.M., Holmes, C.W., Brewster-Wingard, G.L., Ishman, S.E., Dowsett, H.J., Keyser, D., and Waibel, N.,
2001. Bull. American Paleo., no. 361, p. 159-198.
Dwyer, G.S., and Cronin, T.M., 2001, Bull. American Paleo., no. 361, p. 249-276.
Holmes, C.W., Robbins, J., Halley, R., Bothner, M., Brink, M.T., and Marot, M., 2001, Bull. American Paleo.,
no. 361, p. 31-40.
Ishman, S.E., 1998, Jour. Coastal Research, sp. issue 26, p. 125-138.
Wanless, H.R., 1969, Sediments of Biscayne Bay - Distribution and depositional history: University of Miami
Institute of Marine and Atmospheric Sciences, Technical Report.
Contact: Wingard, G. Lynn, U.S. Geological Survey, MS 926A National Center, Reston, VA 20192.
Phone: 703-648-5352, Fax: 703-648-6953, lwingard@usgs.gov, Coastal Systems.
Figure 1. Map showing core locations in central
Biscayne Bay. NN, No Name Core. FB,
Featherbed Core.
Figure 2. Ostracode Mg/Ca ratios from No Name Bank
Core, Biscayne Bay.
215
Evidence of Freshwater Influx into Rankin Basin, Central Florida Bay, Everglades
National Park, Prior to 1900
By G. Lynn Wingard1, Thomas M. Cronin1, William Orem1, Charles W. Holmes2, Eugene Shinn2, and Gary S. Dwyer3
1U.S. Geological Survey, Reston, VA., USA
2U.S. Geological Survey, Center for Coastal and Watershed Studies, St. Petersburg, FL., USA
3Duke University, Durham, NC., USA
Preliminary data from analyses of a core
(GLBW601-RL1) taken in Rankin Basin in June
2001 indicate significant environmental changes have
occurred at the site over the last two centuries. The
core was collected at a site of documented seagrass
die-off in 1987-1988 (P.R. Carlson, Florida Marine
Research Institute; written communication, 2001).
The purpose of the core collection was to document
the long-term sequences of events leading up to the
die-off event. Analyses have been conducted to
examine faunal changes in the ostracodes and
mollusks, biochemistry of the ostracode shells,
geochemical changes in the sediment, and the influx
of atmospheric dust. The faunal assemblage analyses
provide information on the salinity and benthic habitat
at the site. These data, when compiled, will
provide a means to test hypotheses of cause and effect
in seagrass die-off, and will illustrate decadal-scale
patterns of change that may contribute to die-off
events.
The molluscan faunal analyses show two
important results. First, at some point prior to 1900, a
significant influx of freshwater occurred in Rankin
Basin. Second, immediately prior to the documented
seagrass die-off, the mollusks indicate an increase in
the amplitude of salinity fluctuations. Figure 1 shows
freshwater mollusks present in the lowest 20 cm of
the core, reaching a high of 24 percent of the molluscan
fauna at 138 cm. Small percentages of terrestrial
gastropods (Polygyridae) and a clam, Polymesoda
maritima, also are present in this segment of the core.
Polymesoda maritima is found in oligohaline to lower mesohaline waters (5-12 ppt), so it is an indicator of reduced
salinities. This assemblage is similar to that seen in the lowest portions of a core from Taylor Creek. At approximately
50 cm in the Rankin core a significant increase occurs in Brachidontes exustus and Anomalocardia auberiana,
two species that tolerate fluctuations in salinity; these species are typical of the Northern Transition Zone of
Florida Bay. When the geochronology of the Rankin core is complete, these changes can be placed into temporal
context and compared to natural and anthropogenic events affecting Florida Bay.
Contact: G.L. Wingard, U.S. Geological Survey, MS 926A, National Center, Reston, VA 20192, Phone: 703-648-
5352, Fax: 703-648-6953, lwingard@usgs.gov,
216
Molluscan Shells as Recorders of Environmental Change in South Florida
By G.L. Wingard, R. Stamm, and J.B. Murray
U.S. Geological Survey, Reston, VA., USA
The most critical issue in the Comprehensive Everglades Restoration Plan (CERP) is to restore more natural
patterns of freshwater flow through the terrestrial ecosystem and into the estuaries and coastal areas. In order to recreate
natural freshwater flow patterns, it is essential to understand the natural patterns of variation prior to significant
human alteration of the system and the natural sources of water. Seasonality of water delivery is especially critical
because the reproductive cycles of many of the organisms within the environment are tied to these seasonal patterns
of flow. A number of studies have documented the utility of mollusks as indicators of environmental change (Dodd
and Crisp, 1982; Dettman, et al., 1999; Rodriguez, et al. 2001; Surge, et al., 2001) and the term sclerochronology
has been applied to this type of research (Schne, et al., 2002). Current U.S. Geological Survey research is applying
this methodology to determining historical salinity patterns and sources of freshwater influx in Florida Bay.
Mollusks grow incrementally, secreting calcium carbonate layers that preserve information about the water
at the time of secretion. Analyses of the individual growth bands of mollusks allow detailed comparisons of seasonal
change over time. Shells analyzed from radiometrically-dated sediment cores taken throughout the region allow
reconstruction of seasonal salinity variations and freshwater sources in the past, prior to significant human alteration
of the system. These data will provide the resource managers (SFWMD, USACE, and ENP) with restoration targets
and performance measures that will allow them to "get the water right."
Significant progress has been made on developing sclerochronology for application to south Florida ecosystem
restoration by means of three discrete types of experiments: 1) growth studies on selected molluscan organisms;
2) salinity tolerance experiments and calibration of shell chemistry to water chemistry (both in the lab and in the
field); and 3) testing of instrumentation for conducting analyses. Determining an accurate growth rate is important
because the timing of seasonal changes in the estuaries is critical to ecosystem health. In order to use mollusk shells
for determining these seasonal changes, it is essential to understand average growth rate and the timing of growth.
For example, if growth only occurs during certain seasons, then the mollusk will not capture the full spectrum of
seasonal salinity changes. Previously, determination of growth rates was only assumed or measured. Currently, we
have focused our experiments and analyses on Chione cancellata. Chione was selected as the initial test organism
for several reasons: 1) the thickness of the shell makes sectioning and analyses of individual layers easier; 2) early
salinity tolerance experiments have demonstrated that this clam will survive in a wide range of salinities (10-68 ppt);
and 3) field evidence suggests it is one of the longer lived (3-7 years) molluscs present in Florida Bay.
Growth experiments, salinity tolerances, and calibration studies are conducted both in the field and in the lab.
Tanks are set up in the lab and maintained at specific salinities (15, 25, 35, and 45 ppt). Animals are removed periodically
and digitally photographed to determine growth, water is tested daily, and water samples are removed
weekly for analysis and calibration to the shell chemistry. Mortality is checked daily, and shells are removed and
frozen immediately to be preserved for biochemical analyses. Additional experiments on salinity extremes and
survivability have been conducted by increasing the salinity to 65 ppt. In the field, habitats are located close to water
monitoring stations so data on water chemistry can be obtained. Animals are collected, tagged, digitally photographed,
and placed in the habitat. Habitats are checked approximately every 90 days, and dead specimens are
removed, saved for analysis, and replaced with a newly tagged and photographed specimen; live specimens are
photographed and returned to the habitat.
Four instruments have been tested for analyzing the individual growth layers of mollusks:
(1) SHRIMP-Sensitive High Resolution Ion Microprobe; (2) Cameca 4F SIMS - Secondary Ionization Mass
Spectrometer; (3) LA-ICP-MS - Laser Ablation Inductively Coupled Plasma Mass Spectrometry; and (4) JEOL
Electron Microprobe with multi-wavelength dispersive spectrometers (WDS). The same specimens of Chione have
been analyzed on these instruments allowing for comparison. A specimen from the mouth of Little Madeira Bay
(FB8-1) has been analyzed on the LA-ICP-MS, the JEOL, and the SHRIMP for Mg/Ca ratios. The similar results
217
from all three instruments indicate that the techniques are comparable. A specimen from Bob Allen mudbank in
central Florida Bay also was analyzed for Mg/Ca and for Sr/Ca on the LA-ICP-MS and the JEOL. The trends on the

two machines are nearly identical as noted for specimen FB8-1. In addition, the Mg/Ca and Sr/Ca trends are parallel.
Sr/Ca is primarily dependent upon salinity. Mg/Ca, however, depends on temperature and salinity, but it has been
argued that in sub-tropical to tropical environments Mg/Ca primarily reflects salinity. Analyzing both ratios provides
reassurance that salinity - the critical variable for this project - is the variable being measured.
After completing these analyses, it has been determined that there is no single best instrument. Each instrument
is capable of detecting differences in Mg/Ca ratios in different areas of the Chione shells, and parallel trends
in Mg/Ca and Sr/Ca indicate salinity is the primary controlling variable on Mg/Ca. Each instrument tested potentially
has application to specific aspects of this study. The SHRIMP, JEOL, and LA-ICP-MS all produce comparable
results for Mg/Ca ratios. The SHRIMP is the most expensive and least accessible, but the most accurate. The JEOL
is the least expensive and the most accessible, but the least accurate. The Cameca is currently the only choice for
isotopic analyses, except for micromilling, which we have not tested. The Cameca may be suitable for Mg/Ca analyses
as well, but we have not adequately tested this capability. The next step is to complete testing of the Cameca
using Woods Hole Oceanographic Institute instruments. Woods Hole is preferred because (1) they have machines
that can do both isotopic and elemental analyses and (2) they work with biogenic carbonate materials and thus have
the expertise to contribute to the interpretation of the resulting data.
Assuming the results on the Woods Hole machine are comparable to the other tested instruments, the plan is
to begin detailed analyses of Chione from the experimental tanks and habitats early in Spring 2003, in order to calibrate
shell chemistry to water chemistry. These tests will be followed up with analyses of Chione shells from cores
collected throughout Florida Bay to determine historical seasonal patterns of salinity change. Salinity estimates
derived from molluscan sclerochronology will be compiled with standard paleoecologic faunal and floral analyses
of the cores and with Mg/Ca analyses of ostracode shells (see Cronin, et al. abstract, this volume). Combined, these
biochemical and paleoecologic analyses of cores will provide an accurate picture of the patterns of salinity change
in Florida Bay over the last 100-200 years.
REFERENCES
Dettman, D.L., et al., 1999, Geochimica et Cosmochimica Acta, v. 63, p. 1049-1057.
Dodd, J.R., and Crisp, E.L., 1982, Palaeo., Palaeo., v. 38, p. 45-56.
Rodriguez, C.A., et al., 2001, Conservation Biology, v. 15, p. 249-258.
Schne, B.R., et al., 2002, The Veliger, v. 45, p. 45-54.
Surge, D., et al., 2001, Palaeo., Palaeo. Palaeo, v. 172, p. 283-296.
Contact: Wingard, G. Lynn, U.S. Geological Survey, MS 926A National Center, Reston, VA 20192.
Phone: 703-648-5352, Fax: 703-648-6953, lwingard@usgs.gov, Question 1.
218
Patterns of Movement of Florida Gar (Lepisosteus platyrhincus) in the Everglades
Revealed by Radio Telemetry
By Lawrence F. Wolski1, Joel C. Trexler1, Jason Knouft2, Carl Ruetz III32, and William F. Loftus4
1Florida International University, Miami, FL., USA
2Washington University, St. Louis, MO., USA
3Annis Water Resources Institute, Muskegon, MI., USA
4U.S. Geological Survey, Center for Water and Restoration Studies, Miami, FL., USA
To build credible simulation models for the Everglades fish community
for use in the restoration process, information on fish movement patterns and
habitat use is a critical need. In this pilot project, we are testing the feasibility
of using implanted radio transmitters to trace the movements of Florida gar
across the open Everglades landscape. Beginning in March 2002, we monitored
the movements of Florida gar (fig. 1) in the Everglades Wildlife Management
Area, Conservation Area No. 3A (WCA-3A). An initial group of 20
was monitored from March to July and monitoring of the second group of 20
began in August and is ongoing. We collected gar using standard electrofishing
techniques from an airboat, weighing and measuring each gar as it was
collected. Fish were anesthetized in a solution of MS-222 for surgical implantation
of transmitters (SB-2, Holohil Systems, Ltd.). Transmitters were
inserted into the body cavity of the gar through a ventral incision posterior to
the pelvic girdle, which was closed with three to five sutures and SuperGlue
(fig. 2). The transmitter size maximizes the range and lifespan of the transmitter
but cause no harm or mechanical interference to the fish. Each fish was
released at the point from which it was captured and was monitored for the lifetime of the transmitter (approximately
3 months for the first group of fish). We captured the fish in two widely separated areas of WCA-3A, one shorthydroperiod
area to the west (site 3; 26.014 N, 80.82 W), and a second, longer hydroperiod area in central 3-A (site
1; 25.86 N, 80.73 W). We tracked the gar using a Wildlife Systems receiver from an airboat. Fish that were unable
to be located from the airboat were tracked by helicopter or airplane.
We tracked gar from the first group an average of 52 days
between transmitter insertion to the time of last field record (Max.
= 128, Min. = 1). Fish tracked at site 1 were monitored for an average
of 50.5 days (Max. = 128, Min. = 3) and moved an average of
2.62 kilometers from the point of release (Max. = 7.339, Min. =
0.010). The majority of fish moving long distances swam to the
southeast (fig. 3). At site 3, the shorter hydroperiod site, the average
tracking duration was nearly the same (54.8 days), but the average
distance travelled was much less (0.913 km; Max = 2.96, Min. =
0.004). There was no trend in the direction of movements at that
site, in contrast to the fish marked at site 1. This difference in movement
may be related to local hydrology. At site 3, the gar travelled
the greatestdistances during the periods of March 12-24 and June
16- July 1. Water depth at site 3 dropped substantially between
March 24 and June 16 as the dry season progressed. Between May
6 and June 14, site 3 was unreachable because of low water levels.
There was also a decrease in the distance per day travelled during
this period (fig, 4), which was probably related to the declining
water depths.
Figure 1. The Florida gar,
Lepisosteus platyrhincus.
Figure 2: Ventral surface of gar after
insertion of transmitter.
219
We are presently monitoring a second group of gar at sites 1 and 3 that were tagged at the height of the 2002
wet season. We are tracking 14 individuals, of which four have moved beyond the range of our equipment. We
believe this is a result of the deep, wet-season water depths that enable the gar to move longer distances than in the
dry season.
In addition to long-term monitoring of the gar, we collected intensive diel movement and habitat-use data at
both study sites by locating all fish at each site every 2 hours during a 24-hour period. As of November 2002, two
diel studies have been completed from site 1 and two from site 3. Both diurnal sampling events from site 1 involved
the most recent group of tagged gar, while at site 3, we collected one diurnal data set from each group. Preliminary
analysis indicates that for 3 of the 4 tracks, there was no directional pattern to the movement of gar and no change
between day and night movements. However, in one case (site 3, Group 1) the fish became more active at night and
traveled longer distances. This coincided with shallow water depths at site 3; gar were found in alligator holes and
deeper areas of the marsh during the day, moving into shallower areas during the night. This variation indicates that
hydroperiod, and weekly variation in water depth at a particular site, play an integral role in the movement of gar.
This study demonstrates the feasibility and effectiveness of using radio transmitters to describe movement patterns
of large, mobile fishes across the wetland landscape. By collecting and analyzing movement data, we aim to develop
a deeper understanding of survival, dispersal, and habitat use by these and other aquatic predators in the Everglades.
This research was funded by a cooperative agreement between the U. S. Geological Survey and FIU, under the CESI
initiative (CA 1445-CA09-95-0112, Sub-agreement No. 1). Mention of specific manufacturers does not imply
endorsement.
Contact: Lawrence, Wolski, Department. of Biological Sciences, Florida International University, University Park,
Miami, FL 33199, Phone: 305-348-4032, Wolskil@fiu.edu, Ecology and Ecological Modeling
Figure 3. Gar dispersal from release point at Site 1. Figure 4. Distance traveled per hour for gar at Site 3.
220
Body Condition Analysis for the American Alligator for Use in Everglades
Restoration
By Christa L. Zweig1, Frank J. Mazzotti1, Kenneth G. Rice2, Laura A. Brandt3, and Clarence L. Abercrombie4
1Department of Wildlife Ecology and Conservation, University of Florida, Ft. Lauderdale, FL., USA
2U.S. Geological Survey, Center for Water and Restoration Studies, Fort Lauderdale, FL., USA
3U.S. Fish and Wildlife Service, A.R.M. Loxahatchee National Wildlife Refuge, Boynton Beach, FL., USA
4Wofford College, Spartanburg, SC., USA
The American alligator (Alligator mississippiensis) is an integral part of the Everglades ecosystem. They
effect and are affected by the landscape and changes in hydrology, which makes them an excellent organism to use
in evaluating current Everglades restoration efforts. Information on alligators (census data, capture or morphometric
data, blood chemistry, and reproduction statistics) has been collected in the Everglades since the 1950's. Available
historical information includes a suite of life history characteristics and population parameters (health and condition,
nesting effort, growth rate and survival, and density) that are useful for evaluating restoration. However, some
life history traits (e.g. absolute density and survival) are difficult to accurately measure and can require decades of
data to detect trends. In contrast, body condition can be measured using indices and requires less data to begin an
analysis. If used properly, condition can be a useful monitoring tool to assess the health of a population and thus the
health of its ecosystem. This project evaluated morphometric measurements taken for the American alligator, available
condition indices and, using a stepwise process, recommends an appropriate index for use in ecological applications
such as Everglades restoration.
Condition indices have been used to analyze the fitness of animal populations for the last 50 years. However,
the indices are complex and can be used inappropriately if one is unfamiliar with the constraints. For example, condition
for crocodilians has been calculated numerous times using Relative K (length/volume ratio), developed for
fisheries in 1951 (LeCren 1951). Relative K is useful for comparing the condition of a population over time, but not
appropriate among populations.
Alligators were captured during March, April, and October from 1999 to 2002 by a multi-agency team that
consisted of members from U.S. Fish and Wildlife Service, U.S. Geological Survey, University of Florida, and the
Florida Fish and Wildlife Conservation Commission. Study areas were A.R.M. Loxahatchee NWR (LNWR, 1 site),
Water Conservation Areas 2 (WCA2, 1 site) and 3A (WCA3A, 2 sites), and Everglades National Park (ENP, 2 sites:
ENP-SS Shark River Slough, ENP-EST Estuaries). Animals were captured from all study areas in marsh habitats
only.
We analyzed morphometric measurements of the captured animals to determine which are measured most
accurately and are appropriate for condition analyses. Condition indices are functions of a body length indicator and
a volumetric measurement, and are only as accurate as the measurement used. Head length (HL), snout-vent length
(SVL) and total length (TL) are suitable for body length indicators and tail girth (TG), neck girth (NG), chest girth
(CG), and mass can all be used as volumetric measurements. We then compared four condition indices and two models
of volume/length relations for their ability to distinguish between populations with known qualitative condition
differences. Condition indices were Fulton's K, Relative K, a simple length/volume ratio, and relative mass. We also
modeled volume/length with a residual index and ANCOVA.
It was determined through ANOVA/LSD analysis of the condition indices that the HL/Mass combination of
Fulton's K and the SVL/Mass combination of ANCOVA were best able to distinguish differences in condition
between areas of the Everglades. ANCOVA is best for determining temporal differences between populations.
However, it cannot be used to compare differences across populations, unless strict assumptions can be met.
HL/Mass Fulton's K can be used to spatially compare populations of the American alligator, and is suggested by
this study as the best condition factor to use for that purpose.
221
Condition is a very fluid measurement. Water management practices and rainfall can dramatically change
condition of animals in a relatively short amount of time, because so many aspects of their life history (feeding,
courtship, and nesting) depend on seasonally fluctuating water levels. In this study, we found that ENP-SS alligators
had the highest condition (fig. 1), but Dalrymple (1996) and Barr (1997) observed Shark Slough alligators to be in
very poor condition only five or six years earlier. Water levels were high during capture periods for these earlier studies,
possibly affecting food availability.
Because the alligator's life history is so closely linked to hydropattern, body condition can reflect the impacts
of changes in hydrology. The condition indicies recommended here should provide a monitoring tool of alligator
population health for the current restoration process.
REFERENCES
Barr, B. 1997. Food habits of the American alligator, Alligator mississippiensis, in the southern Everglades. PhD.
University of Miami, Miami, FL.
Dalrymple, G. H. 1996. Growth of American alligators in the Shark Valley region of Everglades National Park.
Copeia(1): 212-216.
LeCren, E. D. 1951. The length-weight relationship and seasonal cycle in gonad weight and condition in the perch
(Perca fluviatilis). Journal of Animal Ecology 20(2): 201-219.
Contact: Christa L. Zweig, Department of Wildlife Ecology and Conservation, University of Florida, 3205 College
Ave., Fort Lauderdale, FL 33314; Phone: 954-577-6304, e-mail: czweig@ufl.edu
Figure 1. Hierarchy of body condition of alligators in several
study sites in the Everglades of south Florida from 1999-2002
using a Fulton's K analysis (n = 395). Brackets indicate condition
does not differ significantly within that group.
Highest
Mid
Mid to Low
ENP-SS
WCA3-Both areas
LOX
ENP-Est
WCA2
Area
Condition Group
222
224
Contents
Section IV: Information Systems
Development of Digital Aerial Photography Archives for the Greater Everglades of South Florida
By Peter R. Briere, Thomas J. Smith III, Ann M. Foster, Alisa W. Coffin, Ken Rutchey,
John W. Jones, Carson Van Arsdall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
Creation of a Geodatabase of the Digital Aerial Photography Archives for the Greater Everglades
of South Florida and the Southern Inland and Coastal System
By Alisa W. Coffin, Heather Henkel, Heather Mounts, Peter R. Briere, Ann M. Foster,
Thomas J. Smith and Robert R. Wertz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
Data in the Key of ZZZ: Development of a Network to Establish Vertical Reference Datum for
Research Stations in the Southwest Coastal Everglades
By Nancy T. DeWitt, B.J. Reynolds & Thomas J. Smith III, Gordon H. Anderson. . . . . . . . . . . . . 229
The South Florida Information Access (SOFIA) Website
By Heather S. Henkel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
The South Florida Satellite Image Map Series: A Tool for Research, Monitoring, and Education
By John W. Jones, Jean-Claude Thomas, Angel Gonzalez, and Heather Henkel . . . . . . . . . . . . . . 233
South Florida Information Access System (SOFIA)
By Roy S. Sonenshein . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
Metadata for the U.S. Geological Survey Greater Everglades Place-Based Studies
By Jo Anne Stapleton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
225
Development of Digital Aerial Photography Archives for the Greater Everglades of
South Florida
By Peter R. Briere1, Thomas J. Smith III2, Ann M. Foster3, Alisa W. Coffin4, Ken Rutchey5, John W. Jones6,
Carson Van Arsdall6, and William B. Perry7
1DynCorp Systems and Solutions LLC, Gainesville, FL., USA; 2U.S. Geological Survey, Center for Water &
Restoration Studies, St. Petersburg, FL., USA; 3U.S. Geological Survey, Center for Aquatic Resources Studies,
Gainesville, FL., USA; 4University of Florida, Gainesville, FL., USA; 5South Florida Water Management District,
West Palm Beach, FL., USA; 6U.S. Geological Survey, Reston, VA; 7Everglades National Park, Homestead, FL.,
USA
Currently, a restoration effort, guided by the Comprehensive Everglades Restoration Plan (CERP), is underway
in central and southern Florida. A basis for the restoration must be a clear understanding of pre-management
wetland characteristics in order to establish a gauge for future performance and impacts of CERP. An increase in
studies related to pre-management wetland characteristics has resulted in an increased demand for historical data
from the Greater Everglades region. Aerial photographs provide one form of historical data documenting past effects
of flood protection and water supply management measures on south Florida ecosystems.
More than 25,000 historical aerial photographs of the Everglades and south Florida, some flown as early as
the mid 1920's, are known to currently exist in print or negative form at various locations. This estimate only includes
photographs whose physical location is known and accessible, many of which are temporarily situated at the USGS
Gainesville facility. The USGS Florida Integrated Science Center (FISC), in collaboration with USGS Eastern
Region Geography, processed some of these photographs in 2001 and 2002 (see fig.1). The primary goals of this
project were to (1) catalog available photographs in a database, (2) convert these print and negatives to digital form,
(3) make the digital files readily accessible via publication, and (4) orthorectify the files for future spatial data analyses.
Figure 1. Example of 1940 Rectified Imagery, south Florida and Florida Bay.
226
To date, this effort has produced one USGS Open-File Report on CD-ROM with rectified 1927 topographic
sheets (t-sheets). Other Open-File Reports containing digital files of 1940 and 1987 aerial photography are currently
in review. Another report with 1964 aerial photography is being prepared. Over 8,000 entries have been added to
the database, documenting quality and quantity of available photographs. More than 2,000 photographs have been
scanned at 800 dots per inch (dpi) or close to 31.75 microns. Thousands more photos have been scanned at 300 dpi
to generate mosaics that establish flight information. The mosaics and flight lines will also facilitate future orthorectification
and are used for publication purposes.
Another related product resulted from the conversion of 820 digital ortho quarter quads (DOQQs) to 54 south
Florida basemaps extending from Lake Okeechobee to Florida Bay. These basemaps are 2-meter resolution mosaics
in contrast to the 1-meter DOQQs. Using 2m basemaps makes storage and retrieval more efficient compared to the
DOQQs, and thus reduces the time necessary for orthorectification. Each basemap is a mosaic of 8-16 DOQQs
derived from aerial photography flown in 1994.
The aerial photographs, converted to digital files and published so far, represent a segment of the existing
prints and negatives available. Many aerial flights covered portions of the south Florida area and these photographs
remain in analog form. A small technical staff of 1-3 may require 4-12 years of full-time effort to convert the remaining
photographs to orthorectified and published form given current available hardware and software capabilities.
This assumes future storage needs will be accounted for. An associated project will make all the digital images and
linked attribute databases available via the Internet.
Contact: Peter Briere, DynCorp Systems and Solutions LLC, 412 NE 16th Ave., Room 250, Gainesville, FL
32601, Phone: 352-372-2571x26, Fax: 352-374-8080, Email: peter_briere@usgs.gov, Poster, Information Systems.
227
Creation of a Geodatabase of the Digital Aerial Photography Archives for the
Greater Everglades of South Florida and the Southern Inland and Coastal System
By Alisa W. Coffin1, Heather Henkel2, Heather Mounts3, Peter R. Briere4, Ann M. Foster5, Thomas J. Smith2, and
Robert R. Wertz2
1University of Florida, U.S. Geological Survey, Center for Aquatic Resources Studies, Gainesville, FL., USA; 2U.S.
Geological Survey, Center for Coastal and Watershed Studies, St. Petersburg, FL., USA; 2GIS Solutions,
St. Petersburg, FL., USA; 4DynCorp Systems and Solutions, LLC, Gainesville, FL., USA; 5U.S. Geological Survey,
Center for Aquatic Resources Studies, Gainesville, FL., USA
The project to create a digital archive of historical aerial photographs for the Greater Everglades is an important
first step in the development of an understanding of the pre-drainage vegetation in the south Florida landscape.
This knowledge is essential in the development of "endpoints, restoration goals and performance measures to gauge
restoration success" (Smith and Foster, 2002). Work on the digital archive has progressed with the creation of two
open file reports publishing maps from 1927-35 and imagery from 1940 (Smith and others, 2002; in press). In addition
to these two sets, scanning of photographs dating from 1952 and 1987 has progressed, with an open file report
of the 1987 set due to be published in the near future.
Concurrent with the development of the digital archive, information about the photography was recorded in a
relational database using Microsoft Access. The data recorded included information on the flight, the photography,
the scanning process and detailed information on each individual photograph.
After scanning the photography, georeferenced
mosaics of the flight lines were constructed
indicating the general locations of the photography.
From these mosaics, approximate center points of
each photograph were recorded in the database,
thereby providing general locations to which the
photographic metadata could be linked (fig. 1).
The utility of linking the metadata with physical
locations became readily apparent. It would be even
more useful if the metadata about the photograph
could be linked to each georeferenced raster image
in the archive.
It has always been the intention of the digital
archives project to create georeferenced imagery of
the south Florida photography. However, in order for
the imagery to be useful as a tool, it must be integrated
into a geographic information system (GIS).
This presents a challenge to users because, as individual
files, the raster images are very large thus limiting
their use to small study areas, and effectively
restricting their use in landscape-scale analyses. The
challenge of incorporating raster images with large
file sizes (for example, 160 MB) into a geographic
information system is resolved in the ArcGIS geodatabase
system using ArcSDE and Oracle database
management software.
To test the geodatabase system as it applies to
the Digital Aerial Photography Archives for the
Greater Everglades of south Florida, a limited area
Figure 1. Map showing approximate center points of
photography in the Digital Aerial Photography Archives
for the Greater Everglades.
228
was selected as a pilot project. The project consists of a geodatabase that includes georeferenced raster imagery from
1940, 1964, and 1987 incorporated with tables of detailed information about the photographs. It also includes vector
files and raster imagery of the T-sheets that are based on a 1927 aerial photographic survey (Smith and others, 2002).
The selected area corresponds to the Southern Inland and Coastal System (Area 6) of the Everglades. The geodatabase
is part of the South Florida Information Access (SOFIA) clearinghouse and can be searched and used free of
charge by accessing the SOFIA web address (http://sofia.usgs.gov/exchange/).
Contact: Alisa, Coffin, University of Florida, Department of Geography, Land Use and Environmental
Change Institute (LUECI), TUR 3141 P.O. Box 117315, Gainesville, FL 32611-7315; Phone: 352-846-2860,
acoffin@ufl.edu , or USGS, Florida Integrated Science Center, Center for Aquatic Resources Studies, 412 NE 16th
Ave, Room 250, Gainesville, FL 32601, Phone: 352-372-2571 ext. 27, Fax: 352-374-8080, alisa_coffin@usgs.gov
Poster, Information Systems
229
Data in the Key of ZZZ: Development of a Network to Establish Vertical Reference
Datum for Research Stations in the Southwest Coastal Everglades
By Nancy T. DeWitt1, B.J. Reynolds1, Thomas J. Smith III2, and Gordon H. Anderson3
1U.S. Geological Survey, Center for Coastal and Watershed Studies, St. Petersburg, FL., USA
2U.S. Geological Survey, Center for Water and Restoration Studies, St. Petersburg, FL., USA
3U.S. Geological Survey, Center for Coastal and Watershed Studies, Homstead, FL., USA
Some of the most remote locations in all of the National Park Service system in the lower 48 states are located
in the southwestern, coastal areas of Everglades National Park. Highland Point lies on the coast between the mouths
of the Lostmans and Broad Rivers and is more than 40km from the nearest trail-head. This mangrove and marsh
dominated coastal wilderness is at the southern end of the Everglades, where the "River of Grass" meets the Gulf of
Mexico. It encompasses over a third of the Park's total acreage.
As the Comprehensive Everglades
Restoration Plan (CERP) is
implemented, questions have arisen
related to monitoring restoration success
in this region. Since 1996 the
USGS/BRD has established and maintained
a network of study sites for sampling
hydrology, sediments and
vegetation (fig 1). Benchmarks were
established and set to a relative datum
at a total of 13 hydrological stations.
This network of benchmarks has been
used as a starting point to develop a
broader survey of vertical elevation.
Thirteen of the benchmarks have been
installed by driving a pipe to refusal,
capping it, and setting the mark with
cement to maintain a stationary point of
occupation that is separate from the
wooden platforms constructed for fieldwork
measurements. Ten other control
locations are temporary locations consisting
of a PK nail hammered into the
top of a hydrologic station platform
with the assumption that the platform
remains stable through time.
The elevation factor Z is the critical
variable for much of the work in the Everglades as well as Florida Bay and the Florida Keys Reef Tract. An
accurate reliable key of Z is needed to convert field measurements into metrics that are cross-comparable. It also
serves to satisfy the vertical variable in flow models. Essentially, an accurate elevation will become an established
pivot point for data comparison among the scientific studies of various disciplines such as biology, water, remote
sensing, and geology that are underway within the Everglades.
An accurate elevation for the Everglades portion currently exists for only one site of this network. To begin
to bridge this gap, annual surveys have begun starting in June 2000 with long-term, repetitive occupation time from
8 hours to 24 hours upon selected benchmarks. These surveys are tied to the closest National Geodetic Survey (NGS)
sites available having the best vertical control published. These sites include FLGPS Thompson, FLGPS GEB, and
Figure 1. Graphic of south Florida displaying locations where benchmarks have
been occupied to date for determination of the "key of Z."
230
Tidal 8724948EH7. The surveys will begin to establish a strong reliable network for the original 13 stations. High
precision Ashtech GPS receivers and antennas are the instruments used for receiving the L1 and L2 signals from the
satellite constellation which are then post processed to obtain the horizontal and vertical (XYZ) information for each
benchmark. Thirty-four stations in total have been occupied in the last two years three of, which are NGS control
points that will be the tie to the National Geodetic Survey's network.
Because technology is rapidly improving and this elevation survey is relatively young, the post processing
method has been carried out using three different methods. The first method uses PNAV post processing software.
This software calculates vectors between locations and based upon the repetition of vectors and their quality, it calculates
coordinates for the location. The second method is Automated Gipsy by the Jet Propulsion Lab. This
method can be applied when a location cannot be tied into an established network like an NGS location. Submission
of long occupation times to Automated Gipsy will produce a location in an ITRF## format which can be transformed
into NAVD88. The third method utilizes OPUS (Online Positioning User Service) located on the NGS website.
This method requires submittal of a GPS file and OPUS determines the three best CORS stations (Continuously
Operating Reference Station) for processing the location of the submitted file. Both OPUS and Automated Gipsy
are automated and require minimal file preparation, whereas, PNAV is controlled solely by the user allowing choice
selections of vector inclusion and exclusion to maintain accurate results.
Contact: DeWitt, Nancy T., U.S.Geological Survey, Center for Coastal & Watershed Studies, 600 Fourth Street,
South, St. Petersburg, FL 33701. Phone: 727-803-89747, FAX 727-803-2030, email: ndewitt@usgs.gov
POSTER, Other Coastal Ecosystems
231
The South Florida Information Access (SOFIA) Website
By Heather S. Henkel
U.S. Geological Survey, Center for Coastal and Watershed Studies, St. Petersburg, FL, USA (http://sofia.usgs.gov/)
The south Florida ecosystem, encompassing the Kissimmee River Valley, Everglades, Florida Bay, urban
areas, developed agricultural areas, rangelands, and wetlands, has been altered greatly over the past 100 years.
Resource managers, Federal, State, and local agencies, and other groups are seeking to reverse environmentally damaging
actions taken during that period. The U. S. Geological Survey (USGS) began a research program in support of
the restoration of the Everglades and south Florida ecosystem in 1995. USGS personnel have been conducting
research projects designed to provide sound scientific information upon which resource managers can base their
decisions. The USGS also has recognized the need for a central site to provide all interested parties with information
from this research and access to these data. The South Florida Information Access web site (SOFIA) was created as
a 'one-stop-shopping' access point for research on south Florida. All USGS South Florida Place-Based Studies
research projects, ranging from mercury contamination in the Everglades to coral reef decline, are online at this site.
The site provides project descriptions, proposals, publications, data (through our data exchange site), presentations,
and contact information, as well as general interest items, such as photographs and posters. The SOFIA site also is
a portal through which you can access our extensive database and internet map server (IMS).
The SOFIA site has grown tremendously since its initial development in 1996. The site increased from fewer
than 100 pages in 1996 to over 3,600 webpages in 2002. The site also contains over 250 publications: circulars, fact
sheets, open file reports, lectures, papers, posters, and reports. Included are not only publications created by the south
Florida program, but historical documents dating to the early 1970's as well. This effort involves locating and digitally
scanning historical documents from all disciplines. By 2003 we will have an extended search interface to our
publications that will allow users to customize their searches based on a variety of parameters.
Within the last year, we have enhanced our data exchange site and added new sections to the site, including
the ability to view projects by topic, region, scientists, or program. The data exchange site includes a variety of data,
including hydrology, biology, ecology, mapping, and chemistry. We also maintain a robust metadata collection that
is FGDC-compliant and acts as a member-node of the National Spatial Data Infrastructure (NSDI).
Figure 1. SOFIA's current publications interface (2002).
232
Contact: Heather, Henkel, U.S.Geological Survey, 600 Fourth Street South, St. Petersburg, FL, 33701, Phone:
727-803-8747 ext. 3028, Fax: 727-803-2032, hhenkel@usgs.gov, Question: Information Systems.
Figure 2. South Florida Information Access (SOFIA) homepage.
233
The South Florida Satellite Image Map Series: A Tool for Research, Monitoring,
and Education
By John W. Jones1, Jean-Claude Thomas1, Angel Gonzalez1, and Heather Henkel2
1U.S. Geological Survey, Eastern Region Geography, Reston, VA, USA
2U.S. Geological Survey, Center for Coastal and Watershed Studies, St Petersburg, FL, USA
Satellite image maps provide an empirical foundation for the study of the temporally dynamic and spatially
complex nature of Everglades land surfaces. They help laboratory and field scientists plan instrument placement and
field experiments. They provide spatial context for the interpretation of data related to Everglades research, modeling,
and restoration activities. They constitute baseline data for Everglades monitoring. Several satellite image maps
covering the region south of Lake Okeechobee have been distributed as USGS Miscellaneous Investigations Series
publications (Jones and Thomas, 2001; Thomas and Jones, 2002). Each map (for example, fig. 1) covers the largest
area possible given high-quality, mass-printing limitations for 1:100,000 scale National Mapping Accuracy Standards.
Every map was designed to meet a variety of needs. For example, the first publication (fig. 2) was constructed
with both scientists and the general public in mind. Driven by research requirements, the boundaries of the western
sheet encompass a focus area for hydrologic modeling. The eastern sheet allows the general public to view the urban
development of the Atlantic Coast adjacent to the Everglades wetlands and contains descriptions of map development
and interpretation in terms that can be understood by a broad spectrum of readers. Together, these two parts
serve as an intuitive backdrop for discussion of important environmental, economic, and social issues. They allow
viewers to understand some of the interrelations among Everglades wetland condition and agricultural, industrial,
and residential activities. Some environmental features like the impact of fires and the status of nutrient removal
areas are obvious (fig. 1). Others require closer image map inspection. For example, visual comparison of the first
and third maps in the series uncovers subtle, high frequency variations. Their source images were collected only
9 days apart (that is, 2/5/00 and 1/27/00, respectively). However, water level data recorded in an area of image overlap
show that water levels dropped approximately 8 cm over that short period (fig. 3), creating impacts that are
detected with careful examination of full-resolution renditions of the image maps.
Recent burn
areas
Nutrient
removal
areas
Figure 1. A thumbnail view of the
Northern Everglades image map in the
series of 1:100,000 scale image maps
distributed in both printed and digital
forms as part of the USGS
Miscellaneous Investigations Series.
234
The creation of such information-rich satellite image maps required a great deal of research and forethought.
Multivariate statistical analysis was combined with the knowledge of remote sensing physics to select a combination
of satellite measurements that yields desired colors, minimizes adverse impacts of the Earth's atmosphere on image
clarity, and maximizes contrasts and information content. Image colors change as the data are transferred from digital
to paper formats. Therefore, previous experience and repeated trials were used to further digitally manipulate
the data to produce visually appealing, easily interpreted colors across all final image maps. Project research also
developed a mathematical procedure to sharpen urban and other features by merging multiple satellite image data
sets. To make the image maps as useful as possible in the field, the classroom, and the conference room, they have
been made widely available in a variety of formats. Printed maps can be obtained at low cost through the U.S. Geological
Survey Earth Science Information Center (1-888-ASK-USGS). In addition, following Library of Congress
policies, printed image maps were scanned with sufficient resolution to reproduce them to scale without loss of
information. Also, these output files were sub-sampled for other uses. Finally, one file for each map was converted
to Geotiff format for use in Geographic Information Systems. Each map has been featured on the South Florida
Information Access website upon publication, where all digital files are freely available (http://sofia.usgs.gov).
References
Jones, John W., and Thomas, J.C., 2001, Southern Everglades: Miscellaneous Investigations Series Map I-2742
(Eastern and Western Sections).
Thomas, J.C., and Jones, J.W., 2002, Northern Everglades. Miscellaneous Investigations Series Map I-2756.
Jones, John W., and Thomas, J.C., in review., Big Cypress - Pine Island: Miscellaneous Investigations Series Map.
Contact: John W. Jones, 521 National Center, Reston, VA 20192. Phone: 703/648-5543, Fax: 703/648-4063,
email: jwjones@usgs.gov.
Figure 2. A mosaic of the two southern
Everglades image maps in the series.
While this area is printed on two 1:100,000
scale maps, the maps were combined
before digital distribution.
Figure 3. Recorded stage for
one Big Cypress National
Preserve station number 8.
One area of
overlap among
image maps
where impacts
of changes in
water levels
are obvious
0
0.2
0.4
0.6
0.8
1/15/2000 1/25/2000 2/4/2000 2/14/2000
date
stage(m)
235
South Florida Information Access System (SOFIA)
By Roy S. Sonenshein
U.S. Geological Survey, Center for Water and Restoration Studies, Miami, FL., USA
The South Florida Information Access (SOFIA) system was created by the U.S. Geological Survey (USGS)
in 1995. Its mission is to provide easy access to information about research projects and products generated as part
of the USGS South Florida Placed-Based Studies (PBS) and other Federal, state, and local science providers. SOFIA
provides this service by integrating information systems and tools enabling efficient storage, organization, and
search and retrieval of scientific information about the south Florida ecosystem.
A principal objective of the USGS South Florida PBS is to assist resource managers who require an improved
scientific information base to resolve or prevent complex resource conflicts or environmental problems in southern
Florida. SOFIA is an integral element of this program and is a primary resource for providing the USGS scientific
information to resource managers and scientists working to preserve and restore the south Florida ecosystem. SOFIA
was designed to benefit three major user groups: USGS program managers and scientists working with the South
Florida PBS, managers and scientists working for other organizations involved with Everglades restoration, and
members of the public interested in USGS research and/or the science behind the Everglades restoration effort. Program
managers and scientists working within the South Florida PBS use the SOFIA website in various ways: (1)
coordination and sharing of scientific research information; (2) access to announcements and registration links for
upcoming workshops, conferences, and seminars; (3) monitoring of current ecosystem conditions through the realtime
data pages; and (4) access to synthesis of topic-specific research results to benefit from lessons learned and
avoid duplication of effort.
The users of the SOFIA site have a variety of interests and informational needs. Information is provided at
many levels of detail, catering to users from a wide range of technical understanding. The general public uses the
site to understand the problems and research behind Everglades restoration. The site provides information for children
and adults, including summaries already adapted for use in classroom, museum, and other public venues, as
wells as for journalists, government, and non-government organizations. SOFIA is used by stakeholders who follow
USGS activities in the community and outdoorsmen to track research as well as monitor real-time conditions in planning
activities.
SOFIA is an evolving and dynamic system that builds on the ever-increasing sophistication of new information
technology. The current architecture consists of three tiers. The top tier is the web browser; the middle tier is the web
server with business logic, and static web pages and data files; and the bottom tier is the SOFIA database. A map
server using geographic information system (GIS) technology is being developed to provide a map-based interface
to the database and the website.
Data is served by three mechanisms on the SOFIA website. The Data Exchange (URL http://sofia.usgs.gov/
exchange/) provides access to files organized by project. The projects are further organized using six primary themes:
biology, chemistry, ecology, geology, hydrology, and mapping. Data are stored in various file formats, such as ASCII
text files, spreadsheets, and databases. For each data set, additional information is provided, including a description
of the method of data collection, an explanation of the data file format, and a listing and a map of the data collection
locations. The Data Exchange provides an efficient means of providing data to users who are familiar with a project
and would like to obtain the project data sets.
The second mechanism of serving data is through a web interface (URL http://www.envirobase.usgs.gov) to
an SQL-based database. The SOFIA database is currently being developed using PostgeSQL 7.2 as the database
engine. The web interface is being developed using PHP, a server-side scripting language developed for the web. The
database consists of over 50 tables, providing a means of storing the data and associated metadata. Included in the
tables are the data values as well as information about methods of data collection, data-collection locations, and associated
projects, publications, and photographs. Many of the database objects provide links to related information on
the SOFIA website.
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The third mechanism of serving data is through a web-based map server. The map server, which is being
developed using ArcIMS software, will provide a means of accessing information stored in the SOFIA database and
the SOFIA data exchange website through a geospatial query. The spatial data will be served using the ArcSDE software,
which provides a mechanism for storing spatial data in a relational database. The spatial database will contain
point data sets showing data-collection locations presented on the SOFIA website, published maps, such as bathymetric
contours, geologic surfaces, and vegetation grids, as well as background data sets, such as political boundaries,
hydrography, and roads. The map server will provide access to related information stored on the SOFIA
website and in the SOFIA database.
Contact: Sonenshein, Roy, U.S. Geological Survey, 9100 NW 36th Street, Suite 107, Miami, FL, 33178,
Phone: 305-717-5824, Fax: 305-717-5801, sunshine@usgs.gov, Information Systems
237
Metadata for the U.S. Geological Survey Greater Everglades Place-Based Studies
By Jo Anne Stapleton
U.S. Geological Survey, Reston, VA., USA
The south Florida ecosystem, encompassing Everglades National Park, urban areas on the coast, intensely
developed agricultural areas, rangelands, and wetlands, has been altered greatly over the last 100 years. In 1995, the
U.S. Geological Survey (USGS) began a research program in support of the restoration of the Everglades and south
Florida ecosystem. Early in the program, the need for information to document the projects and later the resulting
datasets was recognized. Metadata allow for the documentation and discovery of data. They also provide lasting
information about the data in the event the data producer is no longer available. Use of standardized terminology
facilitates searches for data by all users.
In 1994, Executive Order 12906 was issued, which mandated that digital data produced by a Federal agency
be documented with metadata specified by the Federal Geographic Data Committee (FGDC) Content Standards for
Digital Geospatial Metadata. Members of the South Florida Information Access (SOFIA) metadata team conducted
a survey of the project chiefs on the usefulness of metadata and their willingness to provide FGDC-compliant metadata
for their projects and datasets. The overwhelming majority of the respondents agreed that metadata were very
important, but funds and personnel were needed to create the metadata. Furthermore, most of them felt that the
FGDC standard was confusing and cumbersome to use. The survey results led to the decision to create a metadata
team for generating the required metadata. This would result in more consistent metadata, and the scientists would
not have to become familiar with the FGDC standard to document only one or two projects or datasets a year.
The initial metadata records were created by interviewing the project chiefs and using their project proposals
to fill in the elements in the FGDC standard. The project chiefs then reviewed the resulting records and the team
made the indicated changes or corrections. The records were then posted on the SOFIA web site and indexed for
searching on the FGDC National Spatial Data Infrastructure (NSDI) node as the south Florida Ecosystem database.
Several methods have been used to create the FGDC metadata records. Initially, a template was created using
a word processing program. The required FGDC elements were populated, and the file was output in ASCII text
format. For the last several years, the commercial software program Spatial Metadata Management System (SMMS)
has been used. SMMS is currently a product of the Intergraph Corporation. This program is not perfect but is a great
improvement over the word processing template. Output from this program is also in ASCII text for input to the
USGS program "mp," which is used to parse the metadata records for conformance with the correct parent-child relationships
for FGDC metadata. This program also allows output of the records in various formats, such as the outline
or standard FGDC format, a question and answer format that uses "plain English" statements for the metadata information,
SGML to index the records for the FGDC NSDI node, ASCII text, XML, and several other formats not used
on SOFIA. Other options for creating metadata include USGS in-house software XTME for UNIX-based systems
and TKME for Windows-based systems. Metadata created from a word processing template must be run through
preparser software "cns," also from the USGS. This program formats ASCII text files into the outline format for
input to mp.
Current work on the metadata involves updating the project records and creating records for all the datasets
available on the Data Exchange pages on SOFIA. Information to update the metadata is being gleaned from project
annual summaries, proposals, work plans, and published reports, such as USGS Open-File Reports, Water Resources
Investigations Reports, fact sheets, conference abstracts, and journal papers. The updated records are sent to the
project chiefs for review. Recently, the SOFIA program manager decided to document types of data rather than individual
datasets. This necessitates combining records already on SOFIA into one record for each type of data collected
by a project chief. It also will reduce the number of metadata records to be maintained. The plan is to have
all fiscal year (FY) 2003 projects documented with FGDC-compliant metadata by the GEER conference in April
238
2003. By the end of the fiscal year, the data sets for FY03 will also have current FGDC metadata records. Metadata
for projects and datasets that have been completed also will be updated but at a lower priority. Another lower priority
goal is to document relevant historical datasets with metadata to enhance the ability to do time-series studies
for the Everglades area. Links will be provided to other organizations' metadata applicable to the Everglades restoration
effort.
Undocumented data are of little use other than to the collector. Information about the data must be available
to ensure its future use. The FGDC metadata standard provides standardized element names and information. This
allows potential users to search for and evaluate the data for their use. It also preserves the usefulness of the data if
the original data collector leaves the organization. Data generated by the USGS as part of the research into the Everglades
restoration effort need to be available to other researchers in the future and will enhance data collection efficiency.
Documenting projects and datasets with proper metadata can help prevent duplication in data collection.
Information on XTME, TKME, cns, and mp can be found at http://geology.usgs.gov/tools/metadata/.
An explanation of Metadata in plain language can be found at http://geology.usgs.gov/tools/metadata/tools/doc/ctc/.
The FGDC metadata standard is available at http://www.fgdc.gov/metadata/contstan.html.
Information on SMMS is available at http://www.intergraph.com/gis/smms/.
The metadata for the USGS Place-Based Studies research in south Florida are on the SOFIA Web site at
http://sofia.usgs.gov/.
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the
U.S. Government.
Contact: Jo Anne, Stapleton, U.S. Geological Survey, 12201 Sunrise Valley Drive, MS 521, Reston, VA 20192,
Phone: 703-648-4592, Fax: 703-648-4614, jastapleton@usgs.gov, Information Systems
240
Contents
Section V: Fact Sheets and Flyers
Fact Sheets and Flyers Produced under the Greater Everglades Science Program Place-Based
Studies Initiative
By Heather S. Henkel, Arturo E. Torres, G. Ronnie Best, Aaron L. Higer, and Robert Mooney. . . 241
241
Fact Sheets and Flyers Produced under the Greater Everglades Science
Program: Place-Based Studies Initiative
By Heather S. Henkel1, Arturo E. Torres2, G. Ronnie Best3, Aaron L. Higer4, and Robert Mooney5
1USGS, Center for Coastal and Watershed Studies, St. Petersburg, FL., USA; 2USGS, Center for Water and
Restoration Studies, Tampa, FL., USA; 3USGS, Coordinator, Greater Everglades Science Program, Miami, FL.,
USA; 4USGS, Center for Water and Restoration Studies, retired, Boca Raton, FL., USA; 5USGS, Center for Water
and Restoration Studies, West Palm Beach, FL., USA
The Greater Everglades Science Program: Place-Based Studies Initiative has produced a total of about 475
publications (see Section V- Bibliography in this volume) during the period 1995-2002. Among this total, 85 Fact
Sheets and Flyers have been produced to summarize some of the major accomplishments of the Greater Everglades
Science Program. The Fact Sheets and Flyers are organized according to the restoration objectives of the South Florida
Ecosystem Restoration Task Force: (1) Getting the Water Quantity Right, (2) Getting the Water Quality
Right, (3) Preserving Natural Habitats and Species, and (4) Information Availability.
The history of the USGS Greater Everglades Science Program: Place-Based Studies Initiative is summarized
in the three Fact Sheets listed below. This program, developed by USGS scientist Aaron L. Higer in 1995, was initially
known as the South Florida Ecosystem Program. Upon Higer's retirement in 2000, USGS scientist Dr. G. Ronnie
Best has served as coordinator of the Greater Everglades Science Program.
1. USGS and The Everglades Ecosystems
http://www.fcsc.usgs.gov/Fact_Sheets/everglades.pdf
2. USGS Science for Restoration of South Florida: The South Florida Ecosystem Program (FS-61-99)
http://sofia.usgs.gov/publications/fs/61-99
3. South Florida Ecosystem Program (FS-134-95) http://sofia.usgs.gov/publications/fs/134-95
GETTING THE WATER QUANTITY RIGHT-The 18 Fact Sheets listed below provide a general description
on establishing the volume, quantity, timing and distribution of surface and ground waters to approximate pre-and
development conditions.
1. Comparison of the South Florida Natural System Model with Pre-canal Everglades Hydrology Estimated from
Historical Sources (FS-187-96) / http://sofia.usgs.gov/publications/fs/187-96
2. Coupling Models for Canal and Wetland Interactions in the South Florida Ecosystem (FS-139-96) http://
sofia.usgs.gov/publications/fs/139-96
3. Examining Freshwater-Saltwater Interface Processes with Four Radium Isotopes (FS-065-99) http://
sofia.usgs.gov/publications/fs/65-99
4. Freshwater Discharge to Florida Bay (FS-135-96) http://sofia.usgs.gov/publications/fs/135-96
5. Gauging Flows in Northeastern Florida Bay (FS-130-96)
http://sofia.usgs.gov/publications/fs/130-96
6. Geophysical Mapping of Freshwater/Saltwater Interface (FS-173-96)
http://sofia.usgs.gov/publications/fs/173-96
7. Ground-Water Discharge to Biscayne Bay (FS-131-96) http://sofia.usgs.gov/publications/fs/131-96
8. Hydrogeology of the Surficial Aquifer System in Southwest Florida (FS-158-96)
http://sofia.usgs.gov/publications/fs/158-96
242
9. Internal Surface Water Flows (FS-175-96) http://sofia.usgs.gov/publications/fs/175-96
. An Investigation of the Interrelation of Everglades Hydrology and Florida Bay Dynamics to Ecosystem Processes
in South Florida (FS-049-01) http://sofia.usgs.gov/publications/fs/49-01
10. Magnitude and Distribution of Flows into Northeastern Florida Bay (FS-030-00)
http://sofia.usgs.gov/publications/fs/030-00
11. Quantifying Freshwater Discharge for Coastal Hydraulic Structures in Eastern Dade County, Florida
(FS-123-96) http://sofia.usgs.gov/publications/fs/123-96
12. Regional Evaluation of Evapotranspiration in the Everglades (FS-168-96)
http://sofia.usgs.gov/publications/fs/168-96
13. Review and Evaluation of a Model for Simulating the Natural Hydrology of South Florida (FS-180-96)
http://sofia.usgs.gov/publications/fs/180-96
14. Seepage Beneath Levee 30 in Northern Dade County (FS-132-96)
http://sofia.usgs.gov/publications/fs/132-96

15. The Tides and Inflows in the Mangroves of the Everglades (TIME) Interdisciplinary Project of the South Florida
Ecosystem Program (FS-031-01) http://water.usgs.gov/pubs/FS/fs-031-01
16. Vegetation Affects Water Movement in the Florida Everglades (FS-147-96)
http://sofia.usgs.gov/publications/fs/147-96
17. Vertical Exchange of Ground Water and Surface Water in the Florida Everglades (FS-169-96)
http://sofia.usgs.gov/publications/fs/169-96
GETTING THE WATER QUALITY RIGHT-The 17 Fact Sheets and Flyers listed below provide a general
description on reducing or eliminating pollutants and other undesirable substances from the water.
1. Geochronology of Terrestrial Sediments: South Florida
ttp://sofia.usgs.gov/publications/fs/sed_geochron
2. Interactions of Mercury with Dissolved Organic Carbon in the Florida Everglades (FS-186-96)
http://sofia.usgs.gov/publications/fs/186-96/
3. Mercury and Periphyton in the South Florida Ecosystem (FS-184-96)
http://sofia.usgs.gov/publications/fs/184-96
4. Mercury Contamination of Aquatic Ecosystems (FS-216-95)
http://water.usgs.gov/wid/FS_216-95/FS_216-95.html
5. Mercury Studies in the Florida Everglades (FS-166-96)
http://sofia.usgs.gov/publications/fs/166-96
6. Methodology for the Determination of Nutrient Loads to East Coast Canals (FS-129-96)
http://sofia.usgs.gov/publications/fs/129-96
7. Methyl-Mercury Degradation in Florida Everglades Peat-Sediment
http://sofia.usgs.gov/publications/fs/bactdem
8. Remote Sensing of Turbidity and Sedimentation http://sofia.usgs.gov/publications/fs/sed_turbidity
9. Sedimentation, Sea-Level Rise, and Circulation in Florida Bay (FS-156-96)
http://sofia.usgs.gov/publications/fs/156-96
10. Short-Lived Isotopic Chronometers (FS-73-98) http://sofia.usgs.gov/publications/fs/73-98
11. South Florida Ecosystems: Changes Through Time (FS-171-95)
http://sofia.usgs.gov/publications/fs/171-95
243
12. South Florida Wetlands Ecosystem: Biogeochemical Processes in Peat
http://sofia.usgs.gov/publications/fs/wetland_seds
13. South Florida ecosystems - The Role of Peat in the Cycling of Metals (FS-161-96)
http://sofia.usgs.gov/publications/fs/161-96/
14. Summary of Data from Onsite and Laboratory Analyses of Surface Water and Marsh Porewater from South Florida
Water Management District Water Conservation Areas, The Everglades, South Florida, March 1995 http://
sofia.usgs.gov/publications/fs/merc_carbon
15. Taylor Slough and Eastern Florida Bay: Geochemical Studies in Support of Ecosystem Restoration in South
Florida http://sofia.usgs.gov/publications/fs/taylor_slough
16. Water Flows and Nutrient Loads to the Southwest Coast of Florida (FS-179-96) http://sofia.usgs.gov/publications/
fs/179-96
17. Water-quality assessment of southern Florida-wastewater discharges and runoff (FS-032-98) http://
fl.water.usgs.gov/Abstracts/fs032-98_marella.html
PRESERVING NATURAL HABITATS AND SPECIES-The 40 Fact Sheets and Flyers listed below provide a
general description on providing the needs of the diverse flora and fauna of this ecologically unique area
1. Across-Trophic-Level-System Simulation (ATLSS) Program http://www.fcsc.usgs.gov/atlssflier.pdf
2. ATLSS High Resolution Topography and Hydrology Model http://fl.water.usgs.gov/cesi/
ddl_highresmodeling_proj.htm
3. ATLSS PanTrack Tool Enables Visualization of Florida Panther Movements
http://fl.water.usgs.gov/cesi/ddl_pantrack_proj.htm
4. American Alligator Population Ecology http://www.fcsc.usgs.gov/Fact_Sheets/riceflierv2.pdf
5. Amphibian Inventory of Everglades National Park and Big Cypress National Preserve
http://www.fcsc.usgs.gov/posters/Everglades/Amph_ENP_and_BICY/amph_enp_and_bicy.html
6. Amphibian Inventory of the National Parks of South Florida and the Virgin Islands
http://www.fcsc.usgs.gov/posters/Everglades/Amph_Virgin_Islands/amph_virgin_islands.html
7. An Assessment of Potential Contaminant Effects on Freshwater Mussels in the South Florida Ecosystem
http://www.fcsc.usgs.gov/posters/Ecotoxicology/Contaminants_Effect_Mussels/
contaminants_effect_mussels.html
8. Compilation of America Alligator Data Sets in South Florida for Restoration Needs
http://fl.water.usgs.gov/cesi/rkg_americanalligator_proj.htm
9. Corals Record the Water Runoff History of South Florida http://sofia.usgs.gov/publications/fs/139-96
10. Dispersal and Successional Patterns of the Fish Community of the Rocky Glades of Southern Florida
http://www.fcsc.usgs.gov/posters/Everglades/Rocky_Glades/rocky_glades.html
11. Ecosystem History of Biscayne Bay and the Southeast Coast (FS-145-96)
http://sofia.usgs.gov/publications/fs/145-96
12. Ecosystem History of Florida Bay (FS-144-96) http://sofia.usgs.gov/publications/fs/144-96
13. Ecosystem History: Terrestrial and Fresh-water Ecosystems of Southern Florida (FS-146-96)
http://sofia.usgs.gov/publications/fs/146-96
14. Ecotoxicology Program - Florida Caribbean Science Center http://www.fcsc.usgs.gov/
EcotoxProgBrochure.pdf
15. Effects of the Nonindigenous Treefrog, Osteopilus septentrionalis, on Native Hylids in Protected Areas of
South Florida http://www.fcsc.usgs.gov/posters/Everglades/Cuban_Treefrog/cuban_treefrog.html
244
16. Empirical and Modeling Studies in Support of Florida Bay Ecosystem Restorationhttp://www.fcsc.usgs.gov/
Fact_Sheets/robblee.pdf
17. Everglades Ecosystem Restoration - Florida Apple Snail
http://www.fcsc.usgs.gov/Fact_Sheets/apple_snail.pdf
18. Fire Ecology of South Florida Pinelands
http://www.fcsc.usgs.gov/Fact_Sheets/snyderflier.pdf
19. Florida Caribbean Science Center: Restoration Ecology Branch: Major Research Areas And Initiatives
http://sofia.usgs.gov/publications/fs/res_eco/
20. Home Range and Movement of Alligators in the Everglades
http://www.fcsc.usgs.gov/posters/Everglades/Home_Range_Alligators/home_range_alligators.html
21. Influence of Hydrology on Life-History Parameters of Common Freshwater Fishes from Southern Florida
http://fl.water.usgs.gov/cesi/lwf_influence_proj.htm
22. Life History Parameters and Population Dynamics of Freshwater Fishes of South Florida Canal Systems
http://www.fcsc.usgs.gov/posters/Everglades/Fish_Life_History/fish_life_history.html
23. Mangrove prop-root habitat as essential fish habitat in northeastern Florida Bay
http://www.fcsc.usgs.gov/posters/Coastal_Ecology/Mangrove_prop_root/mangrove_prop_root.html
24. Modeling Alligator Production Probabilities in the Everglades
http://www.fcsc.usgs.gov/posters/Everglades/Alligator_Production/alligator_production.html
25. Modeling Fish Population and Biomass on the Everglades Landscape (ALFISH)
http://fl.water.usgs.gov/cesi/ddl_modelingfish_proj.htm
26. Modeling Hurricane Effects on Mangrove Ecosystems (FS-095-97)
http://sofia.usgs.gov/sfrsf/rooms/coastal/hurrfs.html
27. Modern and Historical Bathymetry of Florida Bay (FS-096-98)
http://sofia.usgs.gov/publications/fs/96-98/print.html
28. Nonindigenous Fishes of Florida, With a Focus on South Florida
http://www.fcsc.usgs.gov/posters/Nonindigenous/Nonind_Fish_of_Florida/nonind_fish_of_florida.html
29. Nonindigenous Species Introduced into South Florida
http://www.fcsc.usgs.gov/posters/Nonindigenous/Nonind_Species_Introduced/
nonind_species_introduced.html
30. SIMSPAR Model Simulates the Impact of Hydrology on the Cape Sable Seaside Sparrow
http://fl.water.usgs.gov/cesi/ddl_simspar_proj.htm
31. Sirenia Project: Manatee Ecology and Population Biology
http://www.fcsc.usgs.gov/manateeecology.pdf
32. Studies of aquatic community structure and dynamics in the seasonally variable wetlands of southern Florida
http://www.fcsc.usgs.gov/Fact_Sheets/loftus.pdf
33. Studies Supporting Restoration of Mangrove Habitat in Everglades National Park: Faunal Component
http://www.fcsc.usgs.gov/Fact_Sheets/mcivor.pdf
34. The Swamp Eel: A New Invasive Fish
http://sofia.usgs.gov/publications/fs/swampeel/
35. The Effects of Canals on Alligators in the Everglades
http://www.fcsc.usgs.gov/posters/Everglades/Effects_of_Canals/effects_of_canals.html
36. The Effects of Harvest on Pig Frog Populations from the Everglades
http://www.fcsc.usgs.gov/posters/Everglades/Pig_Frog_Populations/pig_frog_populations.html
37. Thermoregulation of the American Alligator in the Everglades
http://www.fcsc.usgs.gov/posters/Everglades/Alligator_Thermoregulation/alligator_thermoregulation.html
245
38. Vegetation and Hydrology of Land-Margin Ecosystems
http://www.fcsc.usgs.gov/Fact_Sheets/smithflierv2.pdf
39. U.S. Coral Reefs - Imperiled National Treasures (FS-25-02)
http://geopubs.wr.usgs.gov/fact-sheet/fs025-02
40. Using Proportion of Area Occupied to Estimate Abundance of Amphibian Species in Everglades National Park
http://www.fcsc.usgs.gov/posters/Everglades/Amph_PAO/amph_pao.html
INFORMATION AVAILABILITY-The 7 Fact Sheets and Flyers listed below provide a general description on
exchanging information regarding programs, projects, and activities to promote ecosystem restoration and maintenance
- through South Florida Information Access (SOFIA)
1. Color Infrared Digital Orthophoto Quadrangles for the South Florida Ecosystem Area (FS-163-96)
http://sofia.usgs.gov/publications/fs/163-96
2. Florida Cooperative Mapping Project
http://sofia.usgs.gov/publications/fs/flcoopmap/
3. A GIS Interface for Environmental System Analysis: Application to the South Florida Ecosystem (FS-193-97)
http://sofia.usgs.gov/publications/fs/193-97
4. Reflectance Calibrated Digital Mulitspectral Video: A Test-Bed for High Spectral and Spatial Resolution
Remote Sensing http://sofia.usgs.gov/publications/fs/remote_sens
5. South Florida Ecosystem Program Ecosystem Database Development (FS-174-96)
http://sofia.usgs.gov/publications/fs/174-96/
6. South Florida High-Accuracy Elevation Data Collection Project (FS-162-96)
http://sofia.usgs.gov/publications/fs/162-96
7. Web Site Fact Sheet (FS-155-96)
http://sofia.usgs.gov/publications/fs/155-96/
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248
PBS Bibliography (1995-2003)
1. Abbott, C. A., Berry, M. W., et al., 1997, Computational models of white-tailed deer in the Florida Everglades.:
IEEE Computational Science and Engineering, v. 4, p. 60-72.
2. Abbott, Catherine Ann, 1995, A Parallel Individual-Based Model of White-Tailed Deer in the Florida
Everglades (Thesis), Knoxville, TN, University of Tennessee.
3. Aiken, George, Reddy, Mike, et al., 2000, Interactions between dissolved organic matter and mercury
(abstract), USGS Water Quality Workshop, West Palm Beach, Florida, Available online at
http://sofia.usgs.gov/workshops/waterquality/abstracts/aiken_final.pdf
4. Al-Rabai'ah, H. A., Koh, H. L., DeAngelis, D., et al., 2002, Modeling fish community dynamics in the Florida
Everglades: role of temperature variation: Water Science and Technology, v. 46, no. 9, p. 71-78.
5. Allen, C. R., Pearlstine, L. G., et al., 2001, The spatial distribution of diversity between disparate taxa: spatial
correspondence between mammals and ants across South Florida, USA: Landscape Ecology, v. 16,
no. 5, p. 453-464.
6. Allen, L. H. Jr., Sinclair, T. R., et al., 1996, Evapotranspiration of vegetation in Florida: perpetuated
misconceptions versus mechanistic processes, Soil Crop Science Society Florida Proceedings, 56p.
1-10.
7. Anderson, G., Smith, T. J. III, and Nuttle, W. K., 2002, Restoration of sheetflow to northeast Florida Bay: an
assessment of structural modifications to the C-111 Canal (poster), Available at
http://sofia.usgs.gov/publications/posters/restore_sheet/
8. Anderson, Gordon H., and Smith, Thomas J. III, 2002, Hydraulic conductivity of riparian mangrove forest
peat adjacent to the Harney River, Everglades National Park: a comparative field study of field
saturated and saturated hydraulic conductivity methods (abstract), American Geophysical Union,
Spring Meeting, Program with Abstracts, Washington, D.C., H31A-02 Available online at
http://sofia.usgs.gov/projects/hydro_mangrove/abstract-agu02.htm
9. Anderson, John E., Desmond, Gregory B., et al., 1997, Reflectance calibrated digital multispectral video, a
test-bed for high spectral and spatial resolution remote sensing: PE&RS, v. 63, no. 3, p. 224-229.
10. Arrington, D. A., Winemiller, K. O., et al., 2002, How often do fishes "run on empty"?: Ecology , v. 83, no. 8, p.
2145-2151.
11. Bales, Jerald D., Fulford, Janice M, and Swain, Eric D., 1996, Review and evaluation of a model for
simulating the natural hydrology of South Florida: St. Petersburg, FL, U.S. Geological Survey,
Factsheet FS-96-180, Available online at http://sofia.usgs.gov/publications/fs/180-96/
12. Bales, Jerald D., Swain, Eric D., et al., 1998, Review of selected features of the Natural Systems Model, and
suggestions for applications in South Florida: St. Petersburg, FL, Water-Resources Investigation
Report WRIR-97-4039, 22 p. Available online at http://water.usgs.gov/pubs/wri/wri97-4039/
249
13. Ball, M. H., and Schaffranek, R. W., 2000, Modeling seasonal inundation patterns in the south Florida
Everglades (poster), American Society of Civil Engineers Joint Conference on Water Resources
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288
Authors Index
A
Aiken George ....................... 78, 100
Allen, Jon C. ............................... 194
Ambercrombie, Clarence L. .171,220
Anderson, Gordon H. ............... 20,27,
198,229
Armentano, Thomas V. ............... 196
B
Bates, Anne ................................. 106
Bates, Christine ........................... 102
Beck, Marisa ............................... 106
Bemis, Bryan E. ............. 80,82,96,98
Bennetts, Robert E. ..................... 136
Bernhardt, Christopher ........... 71,128
Best, G. Ronnie ........................... 241
Bhlke, John Karl ......................... 84
Brandt, Laura A. ............ 171,201,220
Briere, Peter R. ..................... 225,227
Browder, Joan A. .................. 134,159
Butler, Susan M. ................... 180,205
Byrne, Michael J. ...................... 23,25
C
Cahoon, Donald R. ........................ 27
Call, Erynn .................................. 130
Camp, David ............................... 169
Campbell, Linda ............................ 80
Carlson, Paul W. .......................... 196
Carr, J.A. ..................................... 90
Cherkiss, Michael S. ................... 171
Childers, Daniel L. ....................... 102
Choi, Jungyill ........................... 29,37
Chopp, Matthew D....................... 132
Ciembronowicz, Katherine T. ..... 153
Coffin, Alisa W. .................... 225,227
Comiskey, E. Jane ................ 149,151
Criales, Maria M. ........................ 134
Crockett, Marquette E. ......... 182,184
Cronin, T. M..................... 85,213,215
Corum, Margo ............................. 106
D
Daniels, Andr ..................... 159,192
Darby, Phil ................................... 136
Dausman, Alyssa ........................... 60
DeAngelis, Donald L. ......... 138,151,
177,190
Dennis, George D. ....................... 153
Desmond, Greg .............................. 31
Deszcz-Pan, Maria ......................... 88
DeWitt, Nancy T. ......................... 229
Dismukes, Jeffrey S. .................... 198
Dixon, Joann ....................................... 60
Donahue, Brian ........................... 153
Dove, Amber D. ................... 182,184
Doyle, Terry J. ............................. 144
Doyle, Thomas W. ......... 140,162,198
Drummond, Angela .................... 108
Dufore, Chris .............................. 121
Duke-Sylvester, Scott M. ...... 33,142
Dwyer, Gary S.................. 85,213,215
E
Earle, Sylvia ................................ 153
Easton, Dean E. ............. 144,180,205
Edwards, Randy .......................... 153
Evans, David ............................... 108
F
Fahrig, Lenore ............................. 196
Fink, Larry E. .............................. 108
Fitterman, David V. ....................... 88
Foster, Ann M. ............... 147,225,227
G
Gaiser, Evelyn E. .......................... 92
Garrison, Virginia E. ................... 153
Gawlik, Dale E. ........................... 130
German, Edward R. ...................... 35
Giesy, J. P. ..................................... 90
Gilmour, Cynthia ......................... 100
Gonzalez, Angel .......................... 233
Gross, Louis J. .......... 33,142,149,151
Gross, Timothy S. ........... 90,115,117
H
Hall, Jeremy ................................ 159
Halley, Robert B. ......................... 153
Hart, Kristen M. .......................... 155
Harvey, Judson W............ 29,37,50,92
Hendrix, A. Noble ....................... 157
Henkel, Heather S. .227,231,233,241
Herzfeld, Iuri .............................. 121
Higer, Aaron L. ........................... 241
Hill, Gary L. ......................... 155,176
Hine, Albert C. ............................ 153
Hittle, Clinton ................... 39,41,134
Holmes, Charles W. ..71,128,213,215
Hosmer, A.J. ................................. 90
Howarter, Stanley R. ................... 178
I
Ishman, Scott ........................ 60,213
J
Jaap, Walter C. ............................ 153
Jackson, Thomas ......................... 134
Jarret, Bret .................................. 153
Jenter, Harry L. ..........................14,93
Jones, John W. ..................... 225,233
K
Karunaratne, Laksiri ................... 136
Kendall, Carol .. 80,82,96,98,111,113
Kendall, R. J. ................................ 90
Kieckbusch, David ...................... 159
Kitchens, Wiley M. ........ 43,161,167
Kline, Jeffrey .............................. 163
Knouft, Jason .............................. 218
Kobza, Robert M. .................. 45,165
Koehmstedt, John ......................... 60
Konnert, Timothy .......................... 48
Krabbenhoft, David P. ............. 82,98,
100,108
Krauss, Kenneth W. ............. 140,162
Kuss, Katie .................................. 173
Krest, James M. .........................50,92
L
Lange, Ted ............. 80,82,96,98,117
Langevin, Christian ............. 52,64,68
Lefebvre, Lynn W. ...................... 144
Lerch, Harry ................................ 106
Lietz, A.C. .................................... 60
Locker, Stan D. ........................... 153
Loftus, William F. ...............................
45,48,157,163,165,218
Lombana, Alfonso V. .................... 66
Lynch, James C. ............................ 27
289
M
Marella, Richard ........................... 60
Martin, Julien .............................. 167
Matheson, R.E. ............................ 169
Mazzotti, Frank J. .......... 171,186,220
McCormick, Paul ........................ 111
McIvor, Carole C. .......... 155,173,175
McPherson, Benjamin F. ............. 102
Mead, Gail .................................. 153
Melder, Marcus ........................... 140
Memberg, Steven .......................... 60
Meyer, Dave ................................ 169

Miller, Ronald L. ......................... 102
Mooij, W.M. .................. 177,190,167
Mooney, Robert ........................... 241
Morea, Cory R. ............................ 178
Mounts, Heather ......................... 227
Murray, J.B. .......................... 213,216
Murray, J. H. ................................. 85
Murray, Mitch ............................... 54
Mylon, Steven ............................... 92
N
Naar, David F. ............................. 153
Newlin, Jessica T.................. 29,37,92
Nico, Leo G. ................................ 163
Niemeyer, Nicole ........................ 108
Noe, Gregory B. .......................... 104
O
Olson, Mark ................................ 108
Orem, William H....... 71,100,106,215
P
Padilla, Delissa ............................ 165
Palmer, Mark ............................... 151
Parry, Mark W. ............................ 171
Patino, Eduardo ............................. 56
Peery, Gina M. ............................ 196
Percival, H. Franklin ........... 132,178,
188,194
Perry, Sue A. ............................... 163
Perry, William B. ........................ 225
Phillips, Michael L. ..................... 178
Poole, Grant .................................. 41
Powers, Erik .................................. 43
R
Reese, Ronald S. ........................... 58
Reich, Christopher ......................... 84
Reid, James P. ....................... 180,205
Renken, Robert A. ......................... 60
Reynolds, B.J. .............................. 229
Rice, Kenneth G. ... 115,132,171,178,
182,184,186,188,194,207,220
Richards, Paul M. ........................ 190
Riscassi, Ami L. ................. 62,64,66
Robblee, Michael B. ....... 85,134,159,
169,192
Rogers, Jeff .................................... 60
Rozas, Lawrence ......................... 169
Ruessler, D. Shane ....................... 117
Ruetz, Carl III .............................. 218
Rumbold, Darren ......................... 108
Rutchey, Ken ............................... 225
Rybicki, Nancy B. ......................... 66
S
Saiers, James E. ............................. 92
Schaffranek, Raymond W......... 62,64,
68,93
Sepulveda, Marisol ....................... 90
Shinn, Eugene ........................ 84,215
Silverman, Noah ................... 173,175
Shuford, Robert ........................... 111
Slone, Daniel H. .......................... 194
Smiley, Nathan ............................ 121
Smith, E. E. ................................... 90
Smith III, Thomas J...... 20,27,93,147,
196,198,209,211,225,227,229
Snyder, James R. ......................... 203
Snow, Allison G. ......................... 201
Sobczak, Robert .......................... 102
Soderqvist, Lars ............................. 56
Solis, Rick ..................................... 54
Solomon, K. .................................. 90
Sonenshein, Roy S. ..................... 235
Stamm, R. ............................. 213,216
Stapleton, Jo Anne ...................... 237
Stith, Bradley M. .................. 180,205
Stober, Q. Jerry .............................. 96
Sullivan, Jason ............................. 140
Sumner, David M. ......................... 35
Swain, Eric ............................... 52,64
T
Taylor, Christine ............................ 92
Telis, Pamela ........................... 60,119
Thayer, Gordon ........................... 169
Thomas, Jean-Claude .................. 233
Thomas, William Jr. .................... 201
Thompson, Craig .......................... 56
Tihansky, Ann ............................... 84
Torres, Arturo E. .......................... 241
Trexler, Joel C. .......... 48,96,157,163,
165,218
Twichell, David C. ...................... 153
Twilley, R.R. ................................ 162
U
Ugarte, Cristina A. ...................... 207
V
Van Arsdall, Carson ................... 225
Van Der Kraak, G. ......................... 90
W
Waddle, J. Hardin ... 182,184,186,188
Walker, Christa L. ............... 198,209
Wang, John .................................. 134
Wankel, Scott D. ........ 82,98,111,113
Wertz, Robert R. .......................... 227
Wetzel, Paul R. ...................... 43,142
Whelan, Kevin R.T. ........ 27,162,198,
......................................... 209,211
Wiebe, Jon J. ........................ 115,117
Wieser, Carla M. .................. 115,117
Willard, Debra A. ............ 71,128,213
Williams, C. ................................. 213
Wingard, G. Lynn...... 85,213,215,216
Wolfert, Melinda ................. 52,64,68
Wolski, Lawrence F. ................... 218
Wood, Molly S. ........................... 119
Y
Yates, Kimberly ........................... 121
Z
Zucker, Mark ................................ 73
Zweig, Christa L. ........................ 220