U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2006-5287

Gulf of Mexico Program

Seagrass Status and Trends in the Northern 

Gulf of Mexico: 1940–2002

U.S. Environmental Protection Agency 855-R-04-003
Cover:  Background, seagrass through surface of water (Tommy Michot, U.S. Geological

Survey). Left, seagrass sampling (Tommy Michot, U.S. Geological Survey). Center, oblique

aerial photograph of seagrass (Tommy Michot, U.S. Geological Survey). Right, manatees in

seagrass habitat (Sirenia Project, U.S. Geological Survey).
Seagrass Status and Trends in the Northern 

Gulf of Mexico: 1940–2002

Edited by L. Handley, D. Altsman, and R. DeMay

U.S. Environmental Protection Agency 855-R-04-003

Scientific Investigations Report 2006–5287

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director 

U.S. Geological Survey, Reston, Virginia: 2007

For product and ordering information:

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U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Handley, L., Altsman, D., and DeMay, R., eds., 2007, Seagrass Status and Trends in the Northern Gulf of Mexico: 

1940-2002: U.S. Geological Survey Scientific Investigations Report 2006-5287 and U.S. Environmental Protection 

Agency 855-R-04-003, 267 p.
iii

Preface

The Gulf of Mexico Program (GMP) is a network of citizens dedicated to promoting the economic 

health of the region by managing and protecting the gulf’s resources. Although administered by 

the U.S. Environmental Protection Agency (EPA), the GMP engages many organizations across 

the Gulf of Mexico coastal region to implement and lead restoration and conservation projects 

that are environmentally and economically sound. The GMP includes representatives from State 

and Federal agencies, nonprofit organizations, the scientific community, business and industry, 

and an organized citizens group. These members are appointed by the five State governors along 

the gulf coast. The GMP focuses on three ecological issues: (1) public health, (2) excess nutrient 

enrichment, and (3) habitat degradation and loss, including the introduction of nonindigenous 

species.

The GMP has long recognized that seagrasses, estuaries, and coastal wetlands are vital in 

providing food and shelter for plants and animals, improving water quality, sediment filtration, 

and flood and erosion control. In 1999, the GMP’s Habitat Focus Team set a goal to restore, 

enhance, or protect 20,000 acres of important coastal habitats of the gulf by 2009. The Habitat 

Team, recognizing that seagrass beds are some of the most productive habitats in nearshore 

waters, set a goal to produce this summary report on gulfwide seagrass status and trends. 

The purpose of the summary report is to provide current baseline information on the status of 

seagrasses in the Gulf of Mexico.

To produce this report, the GMP’s Habitat Team formed a subcommittee, consisting of over 30 

gulf coast seagrass scientists and environmental managers. Committee members provided 

data on seagrass maps, seagrass status and trends, causes of change in seagrass acreage, 

monitoring activities, and restoration efforts important to seagrass areas along the gulf coast. 

The U.S. Geological Survey’s (USGS) National Wetlands Research Center provided extensive 

support in the production of data, maps, writing, and editing for this summary. 

Lastly, Seagrass Habitat in the Northern Gulf of Mexico: Degradation, Conservation, and 

Restoration of a Valuable Resource, written in lay terms and developed for the general public, 

legislators, and Gulf of Mexico stakeholders, is meant to be a companion to this summary 

report. For example, nomenclature of seagrasses in the summary report follows this outreach 

document. Additional information will be available on the USGS National Wetlands Research 

Center’s Web site at http://www.nwrc.usgs.gov and the GMP Web site at 

http://www.epa.gov/gmpo/.
iv

Acknowledgments

The U.S. Geological Survey, National Wetlands Research Center, and the U.S. Environmental 

Protection Agency, Gulf of Mexico Program partnership would like to thank the following scientists and environmental managers for reviewing the Gulf of Mexico seagrass status and trends. 

Your dedication, time, and expertise are greatly appreciated.

Ron Boustany, U.S. Department of Agriculture, Natural Resources Conservation Service

Dr. Ken Dunton, University of Texas

Dr. Steve Jordan, U.S. Environmental Protection Agency

Dr. Michael Lewis, U.S. Environmental Protection Agency

Randy Roach, U.S. Fish and Wildlife Service

Frank Sargent, Florida Department of Environmental Protection, Southwest Florida

Water Management District

Dr. Judy Stout, University of South Alabama

Dr. Sandy Wyllie-Echeverria, University of Washington

Dr. Judy Stout, University of South Alabama

Captain David Yeager, Mobile Bay National Estuary Program

Personnel from the USGS National Wetlands Research Center who played a key role in the 

production of this document included

Pete Bourgeois, cartography

Helena Schaefer, peer review coordination

Blaire Hutchison, data compilation
v

Contents

Preface ..........................................................................................................................................................iii

Acknowledgments .......................................................................................................................................iv

Abstract ..........................................................................................................................................................1

Introduction ....................................................................................................................................................1

References Cited ...........................................................................................................................................6

Statewide Summary for Texas

Background ....................................................................................................................................................7

Statewide Status and Trends Data .............................................................................................................9

Galveston Bay System .........................................................................................................................9

Texas Coastal Bend Region ................................................................................................................9

Laguna Madre System ......................................................................................................................11

Causes of Change .......................................................................................................................................11

Natural Process Changes .................................................................................................................11

Human-induced Changes .................................................................................................................11

Gaps in Data Coverage ..............................................................................................................................12

Bay Systems Lacking Inventories ............................................................................................................12

Data Limitations and Future Needs .................................................................................................12

Overview of Seagrass Restoration Efforts ..............................................................................................13

Seagrass Conservation Plan and Resource Management Needs ............................................13

Overview of Monitoring, Restoration, and Enhancement Opportunities ...........................................13

Monitoring for Seagrass Ecosystem Health ..................................................................................13

References Cited .........................................................................................................................................14

Galveston Bay System

Background ..................................................................................................................................................17

Scope of Area ..............................................................................................................................................17

Methodology Employed To Determine and Document Current Status ..............................................17

Methodology Employed To Analyze Historical Trends ..........................................................................19

Status and Trends ........................................................................................................................................19

Upper Galveston Bay and Trinity Bay..............................................................................................19

West Galveston Bay ...........................................................................................................................21

Christmas Bay .....................................................................................................................................21

Causes of Change........................................................................................................................................21

Upper Galveston-Trinity Bays ...........................................................................................................21

West Galveston Bay ...........................................................................................................................23

Christmas Bay System .......................................................................................................................24

Species Information ....................................................................................................................................24

Monitoring for Seagrass Health ...............................................................................................................24
vi

Mapping and Monitoring Needs ..............................................................................................................25

Restoration and Enhancement Opportunities ........................................................................................25

References Cited .........................................................................................................................................26

Laguna Madre

Background ..................................................................................................................................................29

Scope of Area ..............................................................................................................................................29

Methodology Employed To Determine and Document Current Status ..............................................29

Methodology Employed To Analyze Historical Trends ..........................................................................31

Status and Trends ........................................................................................................................................31

Lower Laguna Madre ........................................................................................................................31

Upper Laguna Madre ........................................................................................................................33

Laguna Madre as a Whole ...............................................................................................................36

Causes of Change........................................................................................................................................36

Lower Laguna Madre ........................................................................................................................36

Upper Laguna Madre ........................................................................................................................37

Monitoring for Seagrass Health................................................................................................................38

Mapping and Monitoring Needs ...............................................................................................................38

Restoration and Enhancement Opportunities.........................................................................................39

Acknowledgments.......................................................................................................................................39

References Cited .........................................................................................................................................40

Texas Coastal Bend

Background ..................................................................................................................................................41

Scope of Area ..............................................................................................................................................41

Redfish Bay..........................................................................................................................................41

Harbor Island.......................................................................................................................................43

Mustang Island ...................................................................................................................................43

Nueces Bay .........................................................................................................................................43

Methodology Employed To Determine and Document Current Status ..............................................43

Classification Scheme .......................................................................................................................43

Methodology Employed To Analyze Historical Trends ..........................................................................45

Status and Trends ........................................................................................................................................46

System Summary ................................................................................................................................46

Status Summary..................................................................................................................................46

Trends Summary .................................................................................................................................46

Causes of Change .......................................................................................................................................52

Redfish Bay .........................................................................................................................................52

Harbor Island ......................................................................................................................................54

Mustang Island ...................................................................................................................................54

Nueces Bay .........................................................................................................................................54

Species Information ....................................................................................................................................55

Monitoring for Seagrass Health ...............................................................................................................55

Mapping and Monitoring Needs ...............................................................................................................56

Restoration and Enhancement Opportunities ........................................................................................56
vii

Propeller Scar Restoration ...............................................................................................................56

Designation of State Scientific Areas .............................................................................................56

Signage and Boater Education Activities.......................................................................................57

Seagrass Restoration Through Beneficial Use Projects ............................................................57

Coastal Bend Bays and Estuaries Program Outreach Strategies ..............................................57

References Cited .........................................................................................................................................58

Statewide Summary for Louisiana

Background ..................................................................................................................................................60

Statewide Status and Trends ....................................................................................................................60

Reference Cited ...........................................................................................................................................60

Chandeleur Islands

Background ..................................................................................................................................................62

Scope of Area ..............................................................................................................................................62

Methodology Employed To Determine and Document Current Status ...............................................62

Methodology Employed To Analyze Historical Trends ..........................................................................64

Status and Trends ........................................................................................................................................64

Causes of Change........................................................................................................................................64

Species Information ....................................................................................................................................66

Monitoring for Seagrass Health................................................................................................................66

Mapping and Monitoring Needs ...............................................................................................................66

Restoration and Enhancement Opportunities.........................................................................................71

References Cited .........................................................................................................................................71

Statewide Summary for Mississippi

Background ..................................................................................................................................................72

Statewide Status and Trends ....................................................................................................................72

Causes of Change Statewide ....................................................................................................................72

Gaps in Data Coverage ...............................................................................................................................74

Overview of Seagrass Restoration Efforts ..............................................................................................74

Overview of Monitoring, Restoration, and Enhancement Opportunities ...........................................74

References Cited .........................................................................................................................................74

Mississippi Sound and the Gulf Islands

Background ..................................................................................................................................................76

Scope of Area ..............................................................................................................................................78

Methodology Employed To Determine and Document Current Status ...............................................78

Methodology Employed To Analyze Historical Trends ..........................................................................80

Status and Trends ........................................................................................................................................80

Causes of Change........................................................................................................................................80

Seagrass Health...........................................................................................................................................83

Species Information ....................................................................................................................................84

Monitoring, Restoration, and Enhancement Opportunities ..................................................................84

References Cited .........................................................................................................................................84
viii

Statewide Summary for Alabama

Background ..................................................................................................................................................86

Natural Environment ..........................................................................................................................86

Context of Human Influences ...........................................................................................................88

Scope of Area...............................................................................................................................................90

Historical Documentation ..........................................................................................................................90

Statewide Status and Trends.....................................................................................................................90

Historical Surveys ..............................................................................................................................90

Methodology Employed To Determine and Document Current Status .....................................91

Current Status and Changes ............................................................................................................91

Causes of Change........................................................................................................................................93

Seagrass Health ..........................................................................................................................................93

Species Information ....................................................................................................................................93

Monitoring, Restoration, and Enhancement Opportunities ..................................................................94

References Cited .........................................................................................................................................94

Statewide Summary for Florida

Background ..................................................................................................................................................98

Species Information ....................................................................................................................................98

Scope of Area ............................................................................................................................................100

Methods Used To Determine Current Status of Seagrasses in the State of Florida ......................100

Status and Trends .....................................................................................................................................100

Causes of Change .....................................................................................................................................105

Mapping and Monitoring Problems and Information Needs .............................................................107

Data Problems ..................................................................................................................................107

Monitoring Needs.............................................................................................................................109

Assessment, Protection, Recovery, and Restoration Opportunities ................................................109

Acknowledgments ....................................................................................................................................111

References .................................................................................................................................................111

Perdido Bay

Background ................................................................................................................................................114

Scope of Area ............................................................................................................................................116

Upper Perdido Bay ...........................................................................................................................116

Middle Perdido Bay..........................................................................................................................116

Lower Perdido Bay ...........................................................................................................................116

Methodology Employed To Document Current Status ........................................................................116

Methodology Employed To Analyze Historical Trends ........................................................................118

Status and Trends ......................................................................................................................................118

Upper Perdido Bay ...........................................................................................................................118

Middle Perdido Bay .........................................................................................................................118

Lower Perdido Bay ...........................................................................................................................118

Entire Study Area..............................................................................................................................118

Causes of Change......................................................................................................................................124

Upper/Middle Perdido Bay .............................................................................................................124
ix

Lower Perdido Bay ...........................................................................................................................124

Species Information ..................................................................................................................................124

Monitoring for Seagrass Health .............................................................................................................125

Mapping and Monitoring Needs .............................................................................................................125

Restoration and Enhancement Opportunities ......................................................................................125

References .................................................................................................................................................126

Oral and Written Communication ...........................................................................................................126

Pensacola Bay

Background ................................................................................................................................................128

Scope of Area ............................................................................................................................................128

Escambia Bay....................................................................................................................................130

East Bay..............................................................................................................................................130

Pensacola Bay ..................................................................................................................................130

Big Lagoon ........................................................................................................................................130

Santa Rosa Sound ............................................................................................................................130

Methodology Employed To Determine and Document Current Status .............................................130

Methodology for Historical Trend Mapping ..........................................................................................132

Status and Trends ......................................................................................................................................132

Escambia Bay....................................................................................................................................132

East Bay..............................................................................................................................................134

Pensacola Bay ..................................................................................................................................134

Big Lagoon and Santa Rosa Sound ...............................................................................................134

Causes of Change......................................................................................................................................134

Species Information ..................................................................................................................................136

Monitoring for Seagrass Health .............................................................................................................136

Epiphytic Coverage ..........................................................................................................................138

Water-quality Monitoring ................................................................................................................138

Light-attenuation Monitoring..........................................................................................................138

Mapping and Monitoring Needs .............................................................................................................138

Restoration and Enhancement Opportunities ......................................................................................140

References Cited .......................................................................................................................................140

Choctawhatchee Bay

Background ................................................................................................................................................142

Scope of Area ............................................................................................................................................144

Western Choctawhatchee Bay ......................................................................................................144

Middle Choctawhatchee Bay .........................................................................................................146

Eastern Choctawhatchee Bay........................................................................................................146

Methodology Employed To Determine and Document Current Status .............................................146

Methodology Employed To Analyze Historical Trends ........................................................................146

Status and Trends ......................................................................................................................................147

Western Choctawhatchee Bay ......................................................................................................147

Middle Choctawhatchee Bay .........................................................................................................148

Eastern Choctawhatchee Bay........................................................................................................148
x

Causes of Change......................................................................................................................................148

Western Choctawhatchee Bay ......................................................................................................148

Middle Choctawhatchee Bay .........................................................................................................150

Eastern Choctawhatchee Bay........................................................................................................150

Species Information ..................................................................................................................................150

Western Choctawhatchee Bay ......................................................................................................150

Middle and Eastern Choctawhatchee Bay ..................................................................................150

Monitoring for Seagrass Health .............................................................................................................151

Mapping and Monitoring Needs ............................................................................................................151

Restoration and Enhancement Opportunities ......................................................................................151

References Cited .......................................................................................................................................152

St. Andrew Bay

Background ................................................................................................................................................154

Scope of Area ............................................................................................................................................154

St. Andrew Bay Segment ...............................................................................................................156

West Bay Segment ..........................................................................................................................156

North Bay Segment .........................................................................................................................156

East Bay Segment ............................................................................................................................156

St. Andrew Sound Segment ...........................................................................................................156

Methodology Employed To Determine and Document Current Status ............................................156

Methodology Employed To Analyze Historical Trends ........................................................................158

Status and Trends ......................................................................................................................................158

Entire Study Area .............................................................................................................................158

St. Andrew Bay Segment ...............................................................................................................158

East Bay Segment ............................................................................................................................159

North Bay Segment .........................................................................................................................159

West Bay Segment ..........................................................................................................................159

St. Andrew Sound Segment ...........................................................................................................159

Causes of Change .....................................................................................................................................160

Entire Study Area .............................................................................................................................160

St. Andrew Bay Segment ...............................................................................................................160

East Bay Segment ............................................................................................................................160

North Bay Segment .........................................................................................................................165

West Bay Segment ..........................................................................................................................165

St. Andrew Sound Segment ...........................................................................................................166

Species Information ..................................................................................................................................166

Monitoring for Seagrass Health .............................................................................................................166

Mapping and Monitoring Needs ............................................................................................................166

Restoration and Enhancement Opportunities ......................................................................................167

References Cited .......................................................................................................................................167

Florida Big Bend

Background ................................................................................................................................................170

Scope of Area ............................................................................................................................................172
xi

Methodology Employed To Determine and Document Current Status ............................................172

Methodology Employed To Analyze Historical Trends ........................................................................174

Status and Trends .....................................................................................................................................174

Regionwide Mapping Studies ........................................................................................................175

Other Subregional Mapping Studies ............................................................................................176

Causes of Change .....................................................................................................................................179

Hydrologic Alteration of Watersheds ...........................................................................................179

Nutrient Enrichment of Estuaries and Nearshore Coastal Waters .........................................179

Species Information ..................................................................................................................................180

Monitoring for Seagrass Health .............................................................................................................182

Mapping and Monitoring Needs .............................................................................................................182

Restoration and Enhancement Opportunities ......................................................................................185

References Cited .......................................................................................................................................185

Tampa Bay and Saint Joseph Sound

Background.................................................................................................................................................188

Scope of Area.............................................................................................................................................188

Methodology Employed To Determine and Document Current Status .............................................188

Methodology Employed To Analyze Historical Trends ........................................................................190

Status and Trends .....................................................................................................................................190

Tampa Bay .........................................................................................................................................190

Clearwater Harbor and Saint Joseph Sound ..............................................................................192

Causes of Change .....................................................................................................................................192

Monitoring for Seagrass Health .............................................................................................................193

Species Information ..................................................................................................................................194

Restoration and Enhancement Opportunities ......................................................................................194

The Tampa Bay Nitrogen Management Strategy .......................................................................194

Reduction of Seagrass Scarring ...................................................................................................202

References .................................................................................................................................................202

Sarasota Bay

Background ................................................................................................................................................206

Scope of Area ............................................................................................................................................206

Methodology Employed To Determine and Document Current Status ............................................206

Status and Trends .....................................................................................................................................208

Upper Sarasota Bay in Manatee County ......................................................................................208

Upper Sarasota Bay in Sarasota County ......................................................................................208

Roberts Bay .......................................................................................................................................208

Little Sarasota Bay ...........................................................................................................................210

Blackburn Bay...................................................................................................................................210

Causes of Change......................................................................................................................................210

Monitoring for Seagrass Health .............................................................................................................216

Species Information ..................................................................................................................................216

Restoration and Enhancement Opportunities ......................................................................................216

References .................................................................................................................................................217
xii

Charlotte Harbor

Background ................................................................................................................................................218

Scope of Area ............................................................................................................................................218

Methodology Employed To Determine and Document Current Status ............................................221

Southwest Florida Water Management District .........................................................................223

South Florida Water Management District ..................................................................................223

Methodology Employed To Analyze Historical Trends .......................................................................224

Status and Trends .....................................................................................................................................233

Causes of Change .....................................................................................................................................233

Monitoring for Seagrass Health .............................................................................................................236

Species Information .................................................................................................................................237

Mapping and Monitoring Needs ............................................................................................................237

Restoration and Enhancement Opportunities ......................................................................................238

References .................................................................................................................................................239

Oral and Written Communication ...........................................................................................................240

Florida Bay

Background ................................................................................................................................................242

Scope of Area ............................................................................................................................................244

Methodology Employed To Analyze Historical Trends .......................................................................244

Aerial Photography and Interpretation ........................................................................................244

Field Investigations ..........................................................................................................................246

Current Seagrass Change—Florida Bay Fisheries Habitat Assessment Program ........................246

Methods .............................................................................................................................................246

Status and Trends .....................................................................................................................................249

Restoration Opportunities ........................................................................................................................249

References Cited .......................................................................................................................................252

Conclusions 

Importance of Gulf of Mexico Seagrasses ...........................................................................................254

Seagrass Losses .......................................................................................................................................254

Seagrass Decline Leads to Economic and Aesthetic Losses ...........................................................257

Resource Management and Monitoring ...............................................................................................258

Field of Dreams or Empty Meadows: If You Build It, Will They Come? ............................................259

Conservation Is a Necessary and Proactive Management Tool ......................................................259

Towards Restoration and Conservation Success ...............................................................................259

References Cited .......................................................................................................................................260

Appendix 

Appendix 1. .................................................................................................................................................265

References Cited .......................................................................................................................................266
Pensacola Bay

By Lisa Schwenning,1 Traci Bruce,1 and Lawrence R. Handley2

1

 Florida Department of Environmental Protection, Northwest District.

2

 U.S. Geological Survey.

Background

The Pensacola Bay system (fig. 1) has historically 

supported a rich and diverse ecology, productive fisheries, and 

considerable recreational opportunities. It has also provided 

an important resource for commercial shipping and military 

activities and has enhanced area aesthetics and property 

values. Unfortunately, for many years, point and nonpoint 

source pollution, direct habitat destruction, and the cumulative 

impacts of development and other activities throughout 

the watershed have combined to degrade the health and 

productivity of much of the Pensacola Bay system (Northwest 

Florida Water Management District, 1997).

During the 1800s and early 1900s, extensive logging 

of hardwood trees occurred on tributaries entering the 

Pensacola Bay system (Rucker, 1990). Historically, it is 

likely that the timber industry adversely impacted the upper 

bays of the system. Blackwater Bay and lower reaches of the 

Blackwater River and Pond Creek were covered with sawdust 

from mills in Bagdad, Fla. Sawn timber and sawdust are 

rich in turpines and other toxic substances. During logging 

operations, turbidity, nutrient concentrations, biological 

oxygen demand, and chemical oxygen demand were probably 

high, and dissolved oxygen levels were probably low. Benthic 

communities may have been scarce or nonexistent while the 

mills were operating at peak levels (Northwest Florida Water 

Management District, 1991).

Barge traffic and log rafting from tributaries to the Port 

of Pensacola unquestionably resuspended fine sediments in 

shoal areas of the system. Fairly extensive dredging of the 

Blackwater River was authorized and completed in 1916 

by the U.S. Army Corps of Engineers (1990). Moskovits 

(1955) reported general silting problems in Pensacola Bay 

during 1949–50, as well as settlement of fouling organisms 

(barnacles, serpulid worms, hydroids, bryozoans, sponges, 

jingle shells, and Mytilus sp.) on artificial substrata. 

These organisms tend to settle in relatively clear water, 

so the presence of these animals suggests that suspended 

sediment loads were not sufficient to inhibit the settlement 

of zooplankton and that water quality may have been better 

during the early to mid-1950s (Northwest Florida Water 

Management District, 1991).

Predominant land uses within the riverine watershed 

include forestry, agriculture, military, and public conservation 

and recreation, as well as residential and other urban land uses 

around several communities. Much of the economic base of 

this area is provided by the extraction of natural resources, 

primarily timber and agriculture, but there are also indirect 

economic benefits provided by military activities and the 

service sector. Major public landholdings include portions 

of Eglin Air Force Base, Blackwater River State Forest 

(Northwest Florida Water Management District, 1997), and 

water management district lands along the Escambia and 

Blackwater Rivers.

Population growth and development apply the greatest 

pressure to the environment of Florida’s coastal areas. 

As population increases, so do the demands on coastal 

resources. Over 75% of Florida’s residents live in coastal 

counties, and a 50% increase is estimated by 2020 (Florida 

Department of Environmental Protection, 1998). In the three 

counties included in the Florida portion of the Pensacola Bay 

watershed, there has been a 220% increase in population since 

1960. As a result of the population increase, there has been a 

dramatic change in land use of the Pensacola Bay area from 

agricultural to urban. Escambia County alone lost 13,247 ha 

(32,732 acres) of agricultural lands between 1992 and 1997; 

during the same time, the county gained approximately 6,071 

ha (15,000 acres) of urban land use.

Scope of Area

The Pensacola Bay system consists of about 50,992 ha 

(126,000 acres), including its coastline of 885 km (550 mi) 

and open surface waters of about 373 km2 (144 mi2). The 

watershed covers nearly 18,130 km2 (7,000 mi2). The final 

outlet for the system is the Gulf of Mexico at the mouth of 

Pensacola Bay. The watershed of the Pensacola Bay system 

includes many different counties, cities, and incorporations. 

Approximately 65% of the entire watershed is located outside 

of Florida State lines; Alabama counties—including portions 

of Covington, Escambia, Conecuh, Butler, Crenshaw, Pike, 

Bullock, Montgomery, and Coffee—make up 11,632 km2
Y ellow R iver

E scambia R iver

C onecuh R iv e r

Blackwater R iver

65 

E a st Ba y R i v er

Pensacola 

Ferry Pass 

Fort Walton Beach 

10 

Pensacola Bay

Pensacola Bay 

Watershed boundary 

City 

Interstate highway 

River 

Gulf Intracoastal 

Waterway 

County line 

Gulf of Mexico

20 10 0 km 40 30 

15 10 5 0 mi 20 25 

N

Figure 1. Watershed for the Pensacola Bay system.

130 Seagrass Status and Trends in the Northern Gulf of Mexico: 1940–2002
(4,491 mi2

) of the Pensacola Bay system (Florida Department 

of Environmental Protection, 1998).

Approximately 857 km2

 (331 mi2) (45%) of Escambia 

County form the western portion of the Pensacola Bay 

watershed. Nearly all of the 2,631 km2

 (1,016 mi2) of 

Santa Rosa County, located to the east, are included in the 

watershed. Seventy-five percent of Okaloosa County (1,940 

km2

, or 749 mi2) lies in the watershed. Within Okaloosa 

County are the Yellow and Shoal Rivers, their tributaries, and 

the other half of Santa Rosa Sound. Only 648 km2

 (250 mi2) 

(20%) of Walton County drain into the Pensacola Bay system 

and contain a portion of the Shoal River and tributaries. 

The western portion of the basin is predominantly urban, 

whereas the eastern portion is primarily low density, rural, 

and undeveloped.

The Pensacola Bay system has been divided into five 

segments: Escambia Bay, East Bay, Pensacola Bay proper, Big 

Lagoon, and Santa Rosa Sound (fig. 2).

Escambia Bay

Escambia Bay may be the most vulnerable of the 

Pensacola Bay segments. It is located north of the line 

between Garcon Point to the east and Magnolia Point to the 

west. Escambia Bay is commonly divided into upper and 

lower parts, with Interstate 10 delineating the boundary. This 

dividing line falls in an area that divides species between 

the dominant brackish water plant water celery (Vallisneria 

americana) in the upper bay and the dominant seagrass shoal 

grass (Halodule wrightii) in the lower part of the bay.

East Bay

East Bay is located east of the line between Garcon Point 

and Redfish Cove. East Bay, like Escambia Bay, is commonly 

divided into upper and lower segments, but with Robinson 

Point delineating the boundary. The area north of Robinson 

Point harbors all brackish water submerged aquatic vegetation. 

The area south of Robinson Point, or East Bay proper, contains 

shoal grass and turtle grass (Thalassia testudinum).

Pensacola Bay

Pensacola Bay is west of the Garcon Point Bridge. 

Escambia and East Bays drain into Pensacola Bay, along with 

Bayous Texar, Chico, and Grande. Pensacola Bay empties into 

the Gulf of Mexico at the Pensacola Pass.

Big Lagoon

Big Lagoon is oriented west to east and connects lower 

Perdido and Pensacola Bays. It is bordered on the south by 

Perdido Key and on the north by Pensacola Naval Air Station.

Santa Rosa Sound

Santa Rosa Sound is oriented west to east and connects 

Choctawhatchee and Pensacola Bays. It is bordered on the 

south by Santa Rosa Island and on the north by the Gulf 

Breeze Peninsula.

Methodology Employed To Determine 

and Document Current Status

The most current mapping study of seagrass coverage for 

the Pensacola Bay area was conducted more than 10 yr ago 

by the U.S. Geological Survey (USGS) National Wetlands 

Research Center (NWRC) by using natural-color aerial 

photography taken in 1992 at a 1:24,000 scale as part of the 

northeastern Gulf of Mexico seagrass mapping project.

The mapping protocol consisted of stereoscopic 

photointerpretation, cartographic transfer, and digitization 

in accordance with strict mapping standards and 

conventions.Other important aspects of the protocol 

included the development of a seagrass classification 

system, groundtruthing, quality control, and peer review.

The information derived from the photography was 

subsequently transferred by using a zoom transfer scope 

onto a stable medium overlaying USGS 1:24,000-scale 

quadrangle base maps. The primary data source was 

1:24,000-scale natural color aerial photography flown by 

the National Aeronautics and Space Administration Stennis 

Space Center in fall 1992. In those cases where the data 

were inadequate or incomplete, contemporary supplemental 

data were acquired from other sources and used to complete 

the photographic coverage.

The seagrass classification system that was developed 

(see appendix for full discussion) consisted of two classes of 

open water—RIV (riverine, fresh water) and EST (estuarine 

or marine open water)—and five classes of seagrass habitats. 

One seagrass habitat class is continuous seagrass, CSG, for 

which no density distinction was made. The other four classes 

are patchy seagrass based on percent ground cover of patches 

in 5% increments: PSG1 (0%–10%, very sparse), PSG2 

(15%–40%, sparse), PSG3 (45%–70%, moderate), and PSG4 

(75%–95%, dense).

The groundtruthing phase included the participation of 

field staff from Gulf Islands National Seashore, U.S. Fish 

and Wildlife Service, Dauphin Island Sea Lab, Mississippi 

State University, Alabama Department of Conservation and 

Natural Resources, and Florida Department of Environmental 

Protection. Draft maps were sent out to these agencies 

for review and comments. All comments received were 

incorporated into the final maps.

Methodology Employed To Determine and Document Current Status 131
1

2

3

4

5

Segment

Gulf Intracoastal Waterway

Escambia BayEast Bay

Santa Rosa Sound

Pensacola Bay

Big Lagoon

1

2

3

4

5

East Bay

Garcon Point

Redfish Cove

Choctawahatchee Bay

Yellow River

 River

Escambia

Blac

wk

ater River Coldwater River

Perdido

 Bay

Gulf Breeze

Gulf Islands National Seashore

Pensacola Beach

Navarre

Avalon Beach

RobinsonPoint

Pensacola

Pensacola Naval Air Station

Eglin Air Force 

Base

Gulf of Mexico

Santa Rosa Sound

Pensacola Bay

Big Lagoon 

Escambia Bay

Santa Rosa Island

Perdido Key

km

mi 5

5 0

0 10

10

Study area

N

Florida

Figure 2. Scope of area for the Pensacola Bay vignette.

132 Seagrass Status and Trends in the Northern Gulf of Mexico: 1940–2002
Methodology for Historical 

Trend Mapping

In 1999, the NWRC produced historical seagrass maps 

from 1:20,000-scale black and white aerial photography 

from 1964 for the U.S. Fish and Wildlife Service’s Panama 

City Ecological Services and Fisheries Resources Office to 

use in the development of a trend analysis for Pensacola and 

Escambia Bays, Santa Rosa Sound, and Big Lagoon. These 

seagrass maps for 1964 and the previously described seagrass 

maps from 1992 were used to develop the trend analysis. The 

aerial photography from 1964 was analyzed with stereoscopic 

visual equipment; seagrasses were delineated onto Mylar® 

overlays by using a zoom transfer scope and USGS 1:24,000-

scale topographic quadrangles as the base maps. The overlays 

were digitized by using ArcInfo (Environmental Systems 

Research Institute, Inc., Redlands, Calif.) and converted into 

Arc format files. The black and white aerial photography was 

of good to high quality for delineating seagrasses.

Classification of the seagrasses for the trend analysis 

followed the same protocol as that followed in the 

development of the northeastern Gulf of Mexico seagrass 

mapping using the 1992 aerial photography (see appendix 1). 

Draft maps were sent out to the U.S. Fish and Wildlife 

Service for review and comments. All comments received 

were incorporated into the final maps. No groundtruthing 

took place for the historical seagrass delineations for 1964.

The NWRC currently holds the aerial photography, the 

interpreted overlays, and the Mylar® overlays for the 

1964 maps.

Status and Trends

Seagrass beds that were extensive in 1949 were 

documented in 1975 as having receded or disappeared in most 

areas of the Pensacola Bay system (Northwest Florida Water 

Management District, 1997). In the 1940s and early 1950s, 

seagrass was abundant in all segments of the system, but less 

than 5%–10% of these levels remain. Figures illustrating these 

documented losses in all segments are available in chapter 

12 of Environmental and Recovery Studies of Escambia Bay 

and the Pensacola Bay System, Florida (U.S. Environmental 

Protection Agency, 1975).

Escambia Bay

The loss of seagrass in Escambia Bay may be the most 

significant in the system, affecting the biological quality 

of the entire Pensacola Bay system (table 1; fig. 3). The 

earliest documented assertions of seagrass bed loss were in 

a 1955 report to the Florida State Board of Conservation by 

Murdock (1955) after an industrial plant began operating and 

discharging under permit into the Escambia River. 

The Murdock report clearly linked the loss of seagrasses in 

Escambia Bay with industrial discharges into the drainage 

basin (Hopkins, 1973).

During the 1940s, seagrass was sparse in lower Escambia 

Bay. Transient beds, usually small, appeared, disappeared, 

and reappeared several times during the 50 yr of survey. For 

example, a recession and disappearance of most of Escambia 

Bay’s true seagrass occurred from 1950 to 1975. In 1960 (fig. 

4; table 2), Escambia Bay had approximately 105 ha (259 

acres) of seagrass. Attempts in the 1970s to reestablish shoal 

grass in lower Escambia Bay were not successful. Seagrass 

beds were believed to have disappeared completely by 1976. 

By 1980 (fig. 5; table 3), it was found that 24 ha (60 acres) of 

mostly patchy beds were present. A greater reestablishment of 

several small beds was observed in the late 1980s, and by 1992 

(fig. 6; table 4), patchy beds were observed, mostly around the 

mouths of bayous, totaling approximately 178 ha (441 acres).

Table 1. Seagrass area for the Pensacola Bay system. 

[Values are given in hectares (acres)]

Escambia 

Bay East Bay Pensacola Bay

Big 

Lagoon

Santa 

Rosa 

Sound

1960 105 

(259)

476 

(1,175)

372 

(918)

271

 (670)

2,634 

(6,508)

1980 24 

(60)

99 

(245)

55

 (137)

236 

(582)

1,489 

(3,680)

1992 178 

(441)

165 

(408)

114

 (282)

218 

(538)

1,140 

(2,816)

Escambia

Bay East Bay Pensacola

Bay Big Lagoon Santa Rosa

Sound

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

1960

1980

1992

Seagrass Coverage

Figure 3. Summary of seagrass coverage in the Pensacola Bay 

system, 1960, 1980, and 1992.

Status and Trends 133
Land

Seagrass, continuous Seagrass, patchy Water

Gulf of Mexico

0 2 4 6 8 km

mi

N

0 1 2 3 4 5

Figure 4. Distribution of seagrass in the Pensacola Bay system, 1960.

134 Seagrass Status and Trends in the Northern Gulf of Mexico: 1940–2002
Table 2. Seagrass area in the Pensacola Bay system for 1960.

[Values are given in hectares (acres). CSG = continuous seagrass; 

PSG = patchy seagrass]

Segment Class Area

Escambia Bay CSG 4 (10)

PSG 101 (249)

East Bay CSG 45 (110)

PSG 431 (1,065)

Pensacola Bay CSG 44 (108)

PSG 328 (810)

Big Lagoon CSG 107 (265)

PSG 164 (405)

Santa Rosa Sound CSG 1,247 (3,081)

PSG 1,387 (3,427)

East Bay

From 1950 to 1975, East Bay experienced a decline 

similar to that in Escambia Bay (Northwest Florida Water 

Management District, 1991). In 1960 (fig. 4; table 2), 476 ha 

(1,175 acres) of seagrass were present. This area declined by 

21% by 1980 (fig. 5; table 3) to 99 ha (245 acres); however, by 

1992 (fig. 6; table 4), 165 ha (408 acres) were mapped in 

East Bay.

Pensacola Bay

According to the U.S. Environmental Protection Agency 

(1975), the disappearance of several small beds near the north 

end of the Pensacola Bay Bridge was documented in 1951 and 

was likely attributable to dredging. In 1960 (fig. 4; table 2), 

372 ha (918 acres) of seagrass were mapped. In that same year, 

the Port of Pensacola was enlarged, which involved extensive 

dredge and fill activities. Additional dredging was done to the 

port in 1967. Most beds declined along the southern shore of 

Pensacola Bay and East Bay and disappeared by 1974. Based 

on historical data, seagrasses in Pensacola Bay declined from 

372 ha (918 acres) in 1960 to 56 ha (137 acres) in 1980 (fig. 5; 

table 3). In 1992 (fig. 6; table 4), seagrass beds had increased 

to 114 ha (282 acres).

Big Lagoon and Santa Rosa Sound

Seagrass disappearance has not been quite as dramatic 

in Big Lagoon or Santa Rosa Sound; however, seagrasses 

have gradually decreased over the years in some areas of 

Big Lagoon and southwestern portions of Santa Rosa Sound 

along the Gulf Breeze Peninsula (Northwest Florida Water 

Management District, 1991).

In Big Lagoon, seagrass beds declined slightly from 271 

ha (670 acres) in 1960 (fig. 4; table 2) to 236 ha (582 acres) 

in 1980 (fig. 5; table 3). Seagrass beds declined even further 

in 1992 (fig. 6; table 4) to 217 ha (538 acres). In contrast to 

the previously mentioned segments, Big Lagoon has not had 

dramatic losses but has had steady, continued decline in its 

seagrass meadows.

Santa Rosa Sound, like Big Lagoon, has experienced a 

steady decline from 1960 (fig. 4; table 2), when it had 2,634 ha 

(6,508 acres), to 1980 (fig. 5; table 3), when there were 1,489 

ha (3,680 acres). There was a further decline by 1992 (fig. 6; 

table 4), when 1,139 ha (2,816 acres) were mapped.

Causes of Change

Major causes of seagrass loss were sewage and 

industrial waste discharges, dredge and fill activities, 

beachfront alteration, and changing watershed and land-use 

characteristics. In the Pensacola Bay system, many factors 

have affected the entire system, with certain factors having 

an increased local effect. Along the southern shore of East 

Bay, bulkheads and groins likely caused changes in nearshore 

water movements and energy; erosion of seagrass beds likely 

occurred as a result. Industrial discharge caused the loss of 

vegetation in the northeast section of Escambia Bay since 

these effluents remained near the shore in that area. For 

instance, the loss of seagrass around the sewage treatment 

plant there was caused first by the laying of a discharge pipe 

directly through the bed and later by sewage effluents (U.S. 

Environmental Protection Agency, 1975).

Although seagrass loss is thought to have occurred 

in the early 1900s, no data have been found to support the 

hypothesis. Two activities occurred in the area that could have 

caused loss. One possible impact was the dredging of the Gulf 

Intracoastal Waterway in Pensacola in 1910. A continuous 

3 by 31 m (9 by 100 ft) channel was completed between 

Apalachicola River in Florida and New Orleans, La., in 1936. 

In 1942, the dimensions of the channel were increased to 4 m 

deep by 38 m wide (12 ft deep by 125 ft wide). The expansion 

of the waterway may account for increased traffic, providing 

indirect effects over a longer period of time.

Pensacola Bay waters have been impacted by numerous 

sources of pollution, resulting in a system that does not have 

the natural biodiversity and productivity expected of a system 

of this complexity. The massive quantities of point source 

waste previously discharged into the Pensacola Bay system 

between 1955 and 1964 have been significantly reduced. 

Based on surveys by the U.S. Environmental Protection 

Agency and its predecessor agencies, the combined quantity 

of waste discharged by the several major dischargers into 

the Escambia Bay drainage area was reduced by 40% for 

biological oxygen demand, 71% for total nitrogen, and 96% 

for total phosphorus by 1975 (U.S. Environmental Protection 

Agency, 1975).

Causes of Change 135
Land

Seagrass, continuous Seagrass, patchy Water

Gulf of Mexico

0 2 4 6 8 km

mi

N

0 1 2 3 4 5

Figure 5. Distribution of seagrass in the Pensacola Bay system, 1980.

136 Seagrass Status and Trends in the Northern Gulf of Mexico: 1940–2002
While it is true today that point sources have decreased 

significantly, nonpoint sources such as stormwater runoff 

are increasing, and pollution continues to degrade water and 

sediment quality throughout much of the system. Santa Rosa 

Sound and Big Lagoon are two of the few remaining bodies 

of water within the Pensacola Bay system that still harbor 

seagrass beds.

Livingston and others (1972) reported that 784,428 m3

(1,025,933 yd3

) of sediments were dredged from Mulatto 

Bayou in 1965 during construction of the Interstate 10 

bridge across upper Escambia Bay. Additional dredging 

occurred in 1970 when finger canals were created for housing 

developments and a narrow channel was dug to open the 

southern portion of the bayou to Escambia Bay. Livingston 

and others (1972) made a compelling case that the creation 

of deep borrow pits within the bayou and the new narrow 

entrance to the bay were nutrient traps that reduced circulation 

and flushing of the bayou and depressed oxygen availability. 

In addition, it has been reported that seagrass beds in Mulatto 

Bayou were replaced by sludge deposits containing hydrogen 

sulfide as a result of dredging (Northwest Florida Water 

Management District, 1991).

Species Information

The Pensacola Bay system contains four species of 

true seagrasses—turtle grass, manatee grass (Syringodium 

filiforme), star grass (Halophila engelmannii), and shoal 

grass—and two brackish water species, water celery and 

wigeon grass (Ruppia maritima).

The upper portion of Escambia Bay contains mostly 

water celery, with a few patches of wigeon grass; the lower 

portion has lost all seagrass. East Bay has lost all seagrass 

with the exception of a few areas in upper East Bay around the 

mouth of the Blackwater River. Big Lagoon and Santa Rosa 

Sound have the last two remaining stands of turtle grass and 

shoal grass in the Pensacola Bay system. Santa Rosa Sound 

holds, in addition, a few patches of manatee grass and 

star grass.

Though shoal grass is a pioneering species and is usually 

the first to colonize an area, no historical data have been found 

supporting transition from one species to another.

Monitoring for Seagrass Health

In 1974, the Escambia Bay Recovery Study Team 

obtained photographs from the Florida Department of 

Transportation (FDOT) and used them to develop maps of 

the seagrass beds. Their FDOT file of aerial photographs of 

Escambia and Santa Rosa Counties dated back to 1949. The 

study team project personnel also conducted aerial surveys in 

1974. These overflights of the bays were made sporadically 

and occurred more frequently over areas of greater highway 

construction. (Refer to U.S. Environmental Protection Agency, 

1975, to see these maps.)

In 1996, a study was conducted by Heck and others 

(1996) for the Gulf Islands National Seashore within Big 

Lagoon and Santa Rosa Sound, where two of the last stands of 

seagrass within the Pensacola Bay system remained. Annual 

groundtruthing, inventory of the seagrass community types, 

and water-quality parameters were monitored. The study 

suggested a significant decline in seagrass meadows in the 

area. The investigators of this study hypothesized a lightattenuation problem caused by an increase in turbidity in these 

water bodies (Kirschenfeld, 1999).

In 1999, the Florida Department of Environmental 

Protection was awarded a seagrass monitoring grant from 

the U.S. Environmental Protection Agency’s Gulf of Mexico 

Program to determine the extent of the problem. Seagrass 

monitoring, combined with water-quality and light-attenuation 

monitoring, was conducted over 2 yr, resulting in the 

publication of the Seagrass Management Plan for Big Lagoon 

and Santa Rosa Sound (Florida Department of Environmental 

Protection, 2001).

The seagrass monitoring component of this study 

involved measurements of the depth of growth, percent cover, 

epiphytic coverage, Braun-Blanquet density (the second 

year), species composition, and canopy height (for more 

information on the Braun-Blanquet density, see http://chla.

library.cornell.edu/cgi/t/text/text-idx?c=chla;idno=2917578). 

The monitoring parameters (Hach Environmental, Loveland, 

Colo.) measured were temperature, pH, conductivity, salinity, 

and dissolved oxygen. Water samples were also taken from 

each monitoring site once a month to measure turbidity, color, 

chlorophyll a, total suspended solids, total Kjeldahl nitrogen, 

ammonia, nitrate + nitrite, total phosphorus, orthophosphorus, 

and algal growth potential. The Seagrass Management Plan 

for Big Lagoon and Santa Rosa Sound (Florida Department of 

Table 3. Seagrass area in the Pensacola Bay system for 1980.

[Values are given in hectares (acres). CSG = continuous seagrass; 

PSG = patchy seagrass]

Segment Class Area

Escambia Bay CSG 4 (10)

PSG 20 (50)

East Bay CSG 12 (30)

PSG 87 (215)

Pensacola Bay CSG 10 (24)

PSG 46 (113)

Big Lagoon CSG 193 (477)

PSG 43 (105)

Santa Rosa Sound CSG 860 (2,126)

PSG 629 (1,554)

Monitoring for Seagrass Health 137
Land

Seagrass, continuous Seagrass, patchy Water

Gulf of Mexico

0 2 4 6 8 km

mi

N

0 1 2 3 4 5

Figure 6. Distribution of seagrass in the Pensacola Bay system, 1992.

138 Seagrass Status and Trends in the Northern Gulf of Mexico: 1940–2002
Environmental Protection, 2001) contains an overview of the 

results from the entire monitoring effort.

Epiphytic Coverage

In summary, 17 out of 20 sites monitored in spring 2001 

indicated an increase of epiphytic coverage compared to the 

previous 2 yr, with the most dramatic increase in Big Lagoon. 

This change suggests that there may have been an increase in 

the amount of nutrients over the past 2 yr. If eutrophication 

has taken place, there should be more indications of this in 

other areas of monitoring, such as in water quality (Florida 

Department of Environmental Protection, 2001).

Water-quality Monitoring

Water-quality monitoring was conducted every month 

at each of the 20 monitoring sites. The data were categorized 

into two sets of parameters, Hydrolab and laboratory. The 

Hydrolab parameters were measured on site with a waterquality meter and included temperature, dissolved oxygen, pH, 

and salinity. Secchi depth was also included with the Hydrolab 

parameters. Laboratory parameters required chemical analysis 

and included turbidity, color, conductivity, nonfiltered residue, 

ammonia, Kjeldahl nitrogen, nitrate + nitrite, total phosphate, 

and chlorophyll a.

Algal growth potential was measured every other month. 

Algal blooms and excessive turbidity in the water column 

can reduce the amount of sunlight available to seagrass for 

photosynthesis. One indication of increased algae caused 

by excessive nutrients is an increase in both chlorophyll a 

and color. When turbidity increases but chlorophyll a and 

color remain low, however, stormwater runoff or some other 

stirring mechanism (i.e., boating) may be the cause of light 

attenuation. Results of water-quality monitoring for the 

parameters of chlorophyll a, color, and turbidity suggest 

eutrophication over the past 2 yr. The summer months of 

July and August normally show seasonal trends of increased 

chlorophyll a and color compared to other months of the same 

year. Not only is this trend now evident in the data, but those 

seasonal highs have also increased over the last 2 yr.

Light-attenuation Monitoring

Photosynthetically active radiation (PAR) is the part of 

the spectrum of sunlight, between 400 and 700 nanometers 

(nm), that plants use for energy. Seagrass requires about 

25% of the surface PAR for photosynthetic production. For 

example, if the PAR is 9.5 Moles per square meter per second 

(M/m2

/s) just below the surface of the water, then the seagrass 

requires 2.4 M/m2

/s of PAR for optimal survival. Underwater 

vegetation is less likely to receive sufficient PAR to sustain 

growth when light reaching the plants is reduced because of 

water turbidity and algal blooms.

In this study, light-attenuation monitoring suggested 

that, immediately after a heavy rainfall, stormwater input 

inhibits the amount of PAR available to the seagrass. Figure 7 

illustrates light attenuation at the deep edge of a seagrass bed 

in 1.4 m (4.5 ft) of water. Although the monitored storm event 

lasted only 1 d, the inhibited PAR persisted for several days 

after the rainfall because of increased turbidity and nutrient 

enrichment from stormwater runoff.

Mapping and Monitoring Needs

Although historical data documenting extensive losses 

of seagrass in Pensacola Bay are available, recent (post1992) data are scarce. Turtle grass and shoal grass are nearly 

absent from Pensacola and Escambia Bays; only water celery 

and wigeon grass are surviving in limited areas of upper 

Escambia Bay. These species are also doing well in portions of 

Blackwater Bay, and shoal grass, turtle grass, manatee grass, 

and star grass are surviving in portions of Santa Rosa Sound 

(Northwest Florida Water Management District, 1997) and 

Big Lagoon.

Furthermore, standardized mapping of seagrass beds at 

appropriate temporal and spatial scales should be made every 

5–10 yr. Groundtruthing is recommended for verification of 

those mapping initiatives.

Continuation of a strategic long-term monitoring 

program that includes biotic and abiotic parameters of the 

community is needed. Such parameters include, but are 

not limited to, areal coverage, shoot length, epiphyte load, 

percent coverage, density, and water- and sediment-quality 

indicators. This monitoring should determine causes of 

changes in health, seagrass species composition, density, 

and distribution including total loss or gain. Shoot density 

and faunal communities should be measured to determine 

Table 4. Seagrass area in the Pensacola Bay system for 1992.

[Values are given in hectares (acres). CSG = continuous seagrass; 

PSG = patchy seagrass]

Segment Class Area

Escambia Bay CSG 36 (88)

PSG 143 (353)

East Bay CSG 5 (13)

PSG 160 (395)

Pensacola Bay CSG 13 (33)

PSG 101 (249)

Big Lagoon CSG 99 (245)

PSG 119 (293)

Santa Rosa Sound CSG 796 (1,968)

PSG 343 (848)

Mapping and Monitoring Needs 139
0

2

4

6

8

10

12

9.65

2.12

9.97

3.60

7.64

2.07

9.62

3.69

9.12

4.28

9.62

9.43

9.06 9.17 9.39

2.28 2.33 2.29

9.46

3.85 4.02

Date and Time 

P A R (M/ m2/s)

PAR at water's

surface

PAR reaching the 

seagrass bed

Oct. 17, 2000, 7 a.m.

Oct. 17, 2000, 2 p.m.

Oct. 18, 2000, 8 a.m.

Oct. 18, 2000, 3 p.m.

Oct. 19, 2000, 9 a.m.

Oct. 19, 2000, 4 p.m.

Oct. 20, 2000, 10 a.m.

Oct. 20, 2000, 5 p.m.

Oct. 21, 2000, 11 a.m.

Oct. 21, 2000, 6 p.m.

Oct. 22, 2000, 12 p.m.

Oct. 22, 2000, 7 p.m.

Oct. 23, 2000, 1 p.m.

Oct. 24, 2000, 7 a.m.

Oct. 24, 2000, 2 p.m.

Oct. 25, 2000, 2 p.m.

Oct. 26, 2000, 8 a.m.

Oct. 26, 2000, 3 p.m.

Oct. 27, 2000, 9 a.m.

Oct. 27, 2000, 4 p.m.

Figure 7. The amount of photosynthetically active radiation (PAR) was diminished for several days while turbidity settled after 

a storm event at Big Lagoon in Florida. October 18 indicates a normal day, with surface PAR around 9.6 Moles per square meter 

per second (M/m2

/s) and underwater PAR (at grass blade depth) around 3.7 M/m2/s. Available PAR to the seagrass bed is about 

38% of surface PAR. October 20 indicates a storm event with decreased surface and underwater PAR caused by clouds and 

rain. Following the storm event, surface PAR returned to normal, while underwater PAR remained inhibited for days because of 

increased turbidity from stormwater runoff. Available PAR decreased to insufficient levels of around 22%, which persisted for 4 

d before returning to normal.

140 Seagrass Status and Trends in the Northern Gulf of Mexico: 1940–2002
habitat function and productivity. Changes in light quality 

and quantity as they affect seagrass health may be related to 

nutrient loading and stimulation of phytoplankton blooms, 

epiphytes, and drift macroalgae and should be included in 

the monitoring program. Assessment of the biogeochemical 

environment occupied by belowground tissue, such as 

porewater composition, would also be useful, as would the 

monitoring of contaminants in surface water, sediment, and 

seagrass tissue. All of these monitoring activities, however, 

would not be able to be accomplished without a large source 

of funding. The prioritization of activities would be to study 

the parameters related to seagrass health and growth, such as 

areal coverage, density, shoot length, etc. If these attributes 

were found to be declining, then other parameters—such as 

contaminants in water, sediment, and tissue and light quality 

and quantity—would be useful to measure. 

Studies should address the following:

effects of boating impacts (trawling and boat traffic, 

including jet skis, motorboats, and sailboats),

effects of nonpoint pollution sources on seagrass beds,

socioeconomic values and impacts of management, 

on users

effects of the increase in the human population 

(nonpoint nutrient loading, user impacts),

factors involved in repairing propeller scar damage,

dredging effects on light attenuation, and

indirect effects of dredging.

Restoration and Enhancement 

Opportunities

Habitat functions and productivity of natural seagrass 

community types should be identified, as well as should 

linkages with other habitats to support habitat conservation, 

creation, enhancement, and restoration in the Pensacola 

Bay system.

The Florida Department of Environmental Protection is 

working with Federal, State, and local agencies and with local 

businesses, individuals, and civic organizations to promote and 

facilitate a large-scale restoration project. Project Greenshores 

is a habitat restoration project designed to restore an area in 

Pensacola Bay that was once lightly populated with seagrass. 

This project will attempt to restore between 4 and 8 ha (10 and 

20 acres) of oyster reefs and emergent and submerged grasses, 

as well as to educate the public on the importance of seagrass 

communities in estuarine habitats. Seagrasses to be planted 

include turtle grass, shoal grass, and wigeon grass. This 

project will also be used as a template for further restoration 

•

•

•

•

•

•

•

projects in northwest Florida and throughout the Gulf of 

Mexico coastal area.

The Ecosystem Restoration Section of the Florida 

Department of Environmental Protection has initiated many 

local shoreline restoration projects involving emergent 

and submerged vegetation and propeller scar restoration. 

Restoration sites have included Wayside Park in Gulf Breeze, 

the mouth of Bayou Texar, and propeller scarred areas in Big 

Lagoon and elsewhere. The Florida Marine Research Institute 

states that the Pensacola Bay system has, in general, light to 

moderate scarring with a few areas labeled as severe. Propeller 

scar restoration is new to the Pensacola Bay system: few 

restoration attempts have been made within the past 5 yr, but 

restoration opportunities are becoming more attainable.

Future restoration opportunities should include 

experimental research on seagrass bed creation and restoration 

to determine how donor stocks, including drift grass (detached 

plants), should be selected to achieve maximum success. 

The research should also determine if there are methods to 

accelerate natural recruitment of seagrasses.

References Cited 

Florida Department of Environmental Protection, 1998, The 

Pensacola Bay watershed management guide: an integrated 

ecosystem action plan: Pensacola, Florida Department of 

Environmental Protection, Northwest District, 268 p., 5 

appendixes.

Florida Department of Environmental Protection, 2001, 

Seagrass management plan for Big Lagoon and Santa Rosa 

Sound: Pensacola, Florida Department of Environmental 

Protection, Northwest District, 45 p.

Heck, K.L., Jr., Sullivan, M.J., Zande, J.M., and Moncreiff, 

C.A., 1996, An ecological analysis of seagrass meadows 

of the Gulf Island National Seashore—years one, two, and 

three: seasonal assessment and inventory, interaction studies 

and assessment/inventory: University of South Alabama, 

Marine Environmental Science Consortium, executive 

summary, 7 p.

Hopkins, T.S., 1973, Marine ecology in Escarosa: Tallahassee, 

Florida Department of Natural Resources, Coastal 

Coordinating Council, 100 p.

Kirschenfeld, T., 1999, FDEP Northwest District, Ecosystem 

Restoration Section Gulf of Mexico grant proposal: seagrass 

management plan for Big Lagoon and Santa Rosa Sound, 

Pensacola Bay system.

Livingston, R.J., Hopkins, T.S., Adams, J.K., Schnitt, M.D., 

and Welch, L.M., 1972, The effects of dredging and 

eutrophication on Mulat-Mulatto Bayou (Escambia Bay, 

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142 Seagrass Status and Trends in the Northern Gulf of Mexico: 1940–2002