United States Environmental

Protection Agency

Office of Water

Washington, DC 20460

EPA 822-R-02-014

March 2002

Methods for evaluating wetland condition

#1 Introduction to

Wetland Biological Assessment
United States Environmental

Protection Agency

Office of Water

Washington, DC 20460

EPA 822-R-02-014

March 2002

Methods for evaluating wetland condition

#1 Introduction to

Wetland Biological Assessment

Principal Contributor

Maine Department of Environmental Protection

Thomas J. Danielson

Prepared jointly by:

The U.S. Environmental Protection Agency

Health and Ecological Criteria Division (Office of Science and Technology)

and

Wetlands Division (Office of Wetlands, Oceans, and Watersheds)
ii

Notice

The material in this document has been subjected to U.S. Environmental Protection Agency (EPA)

technical review and has been approved for publication as an EPA document. The information

contained herein is offered to the reader as a review of the “state of the science” concerning wetland

bioassessment and nutrient enrichment and is not intended to be prescriptive guidance or firm advice.

Mention of trade names, products or services does not convey, and should not be interpreted as

conveying official EPA approval, endorsement, or recommendation.

Appropriate Citation

U.S. EPA. 2002. Methods for Evaluating Wetland Condition: Introduction to Wetland Biological Assessment. Office of Water, U.S. Environmental Protection Agency, Washington, DC.

EPA-822-R-02-014.

Acknowledgments

EPA acknowledges the contributions of the following people in the writing of this module: Candy

Bartoldus (Environmental Concern, Inc.), Robert Brooks (Penn State University), Thomas J. Danielson

(Maine Department of Environmental Protection), Jeanne Difranco (Maine Department of Environmental Protection), Mark Gernes (Minnesota Pollution Control Agency), Judy Helgen (Minnesota Pollution

Control Agency), James Karr (University of Washington), Ken Kettenring (New Hampshire Department of Environmental Services), Richard Lillie (Wisconsin Department of Natural Resources), and Billy

Teels (Natural Resources Conservation Service, Wetland Science Institute).

This entire document can be downloaded from the following U.S. EPA websites:

http://www.epa.gov/ost/standards

http://www.epa.gov/owow/wetlands/bawwg
iii

Contents

Foreword .............................................................................................................. v

List of “Methods for Evaluating Wetland

Condition” Modules........................................................................................... vi

Summary ................................................................................................................. 1

Purpose.................................................................................................................. 1

Introduction ........................................................................................................ 2

Evaluating Wetland Health ............................................................................ 4

Bioassessment Methods ................................................................................... 8

Using Biological Information To Improve

Management Decisions ....................................................................................19

Acknowledgments........................................................................................... 26

References ........................................................................................................ 27

Glossary............................................................................................................. 30

Appendix .............................................................................................................. 33

List of Tables

Table 1: Reports Related to Wetland

Bioassessments in the Monitoring

Wetland Condition Series ...................................................... 10

Table 2: Strengths and Limitations of Assemblages

for Use in Wetland Bioassessments ..................................... 11

Table 3: Types of Water Quality Criteria ........................................... 22
iv

List of Figures

Figure 1: Annual average rate of wetlands loss. ................................ 4

Figure 2: Continuum of human disturbance on biological

condition of wetlands ................................................................ 5

Figure 3: Ecosystem influences on biological integrity. ................... 7

Figure 4: Number of beetle genera plotted against a human

disturbance gradient ................................................................ 18

Figure 5: Floristic quality assessment index plotted against

a human disturbance gradient ................................................ 18

Figure 6: Number of Diptera taxa Plotted against Rapid

Assessment Method (RAM) scores, a rapid

functional assessment ............................................................ 18

Figure 7: A 10-metric macroinvertebrate IBI plotted

against turbidity ......................................................................... 18

Figure 8: Framework for improving wetland management .............. 20

Figure 9: The management context of the Stressor

Identification (SI) process....................................................... 25

Figure 10: Watershed Management Cycle ............................................... 26
v

Foreword

In 1999, the U.S. Environmental Protection Agency (EPA) began work on this series of reports entitled

Methods for Evaluating Wetland Condition. The purpose of these reports is to help States and

Tribes develop methods to evaluate (1) the overall ecological condition of wetlands using biological

assessments and (2) nutrient enrichment of wetlands, which is one of the primary stressors damaging

wetlands in many parts of the country. This information is intended to serve as a starting point for States

and Tribes to eventually establish biological and nutrient water quality criteria specifically refined for

wetland waterbodies.

This purpose was to be accomplished by providing a series of “state of the science” modules concerning

wetland bioassessment as well as the nutrient enrichment of wetlands. The individual module format

was used instead of one large publication to facilitate the addition of other reports as wetland science

progresses and wetlands are further incorporated into water quality programs. Also, this modular

approach allows EPA to revise reports without having to reprint them all. A list of the inaugural set of

20 modules can be found at the end of this section.

This series of reports is the product of a collaborative effort between EPA’s Health and Ecological

Criteria Division of the Office of Science and Technology (OST) and the Wetlands Division of the

Office of Wetlands, Oceans and Watersheds (OWOW). The reports were initiated with the support

and oversight of Thomas J. Danielson (OWOW), Amanda K. Parker and Susan K. Jackson (OST),

and seen to completion by Douglas G. Hoskins (OWOW) and Ifeyinwa F. Davis (OST). EPA relied

heavily on the input, recommendations, and energy of three panels of experts, which unfortunately have

too many members to list individually:

 Biological Assessment of Wetlands Workgroup

 New England Biological Assessment of Wetlands Workgroup

 Wetlands Nutrient Criteria Workgroup

More information about biological and nutrient criteria is available at the following EPA website:

http://www.epa.gov/ost/standards

More information about wetland biological assessments is available at the following EPA website:

http://www.epa.gov/owow/wetlands/bawwg
vi

List of “Methods for Evaluating Wetland

Condition” Modules

1 ................. Introduction to Wetland Biological Assessment

2 ................. Introduction to Wetland Nutrient Assessment

3 ................. The State of Wetland Science

4 ................. Study Design for Monitoring Wetlands

5 ................. Administrative Framework for the Implementation of a

Wetland Bioassessment Program

6 ................. Developing Metrics and Indexes of Biological Integrity

7 ................. Wetlands Classification

8 ................. Volunteers and Wetland Biomonitoring

9 ................. Developing an Invertebrate Index of Biological

Integrity for Wetlands

10............... Using Vegetation to Assess Environmental Conditions

in Wetlands

11 ............... Using Algae to Assess Environmental Conditions in

Wetlands

12 ............... Using amphibians in Bioassessments of Wetlands

13 ............... Biological Assessment Methods for Birds

14 ............... Wetland Bioassessment Case Studies

15 ............... Bioassessment Methods for Fish

16 ............... Vegetation-Based Indicators of Wetland Nutrient

Enrichment

17 ............... Land-Use Characterization for Nutrient and Sediment

Risk Assessment

18............... Biogeochemical Indicators

19 ............... Nutrient Load Estimation

20 .............. Sustainable Nutrient Loading

Module # Module Title
1

Summary

Biological assessments (bioassessments)evaluate the health of a waterbody by directly measuring the condition of one or more

of its taxonomic assemblages (e.g.,

macroinvertebrates, plants) and supporting

chemical and physical attributes. A major

premise of bioassessments is that the community of plants and animals will reflect the underlying health of the waterbody in which they live.

When a waterbody is damaged by human activities, biological attributes such as taxonomic

richness, community structure, trophic structure,

and health of individual organisms will change.

For example, in disturbed systems the number

of intolerant taxa typically decreases and the proportion of tolerant individuals typically increases. The biological community will reflect

the cumulative effect of multiple stressors,

whether they be chemical (e.g., toxic chemical),

physical (e.g., sedimentation), or biological (e.g.,

non-native species).

In recent years, a growing number of State and

Federal organizations have started to develop

bioassessment methods and Indexes of Biological Integrity (IBI) for wetlands. An IBI is an

index that integrates several biological metrics

to indicate a site’s condition. A common approach among these organizations is to first

sample attributes of a taxonomic assemblage in

wetlands ranging from good condition to poor

condition. The data are reviewed to identify

metrics, which are attributes of the assemblage

that show a predictable and empirical response

to increasing human disturbance. After the

metrics are tested and validated, they are combined into an IBI, which provides a summary

score that is easily communicated to managers

and the public.

Once wetland bioassessment methods are developed, wetland managers can use them for a

variety of applications. Wetland managers can

use bioassessments to evaluate the performance

of wetland restoration activities or best management practices, such as buffer strips, in restoring and protecting wetland health. Wetland

managers can also use bioassessments to more

effectively target resources for restoring, protecting, and acquiring wetlands. Many States are

developing bioassessments to better incorporate

wetlands into water quality programs.

Bioassessments can help States refine their water quality standards to reflect typical conditions

found in wetlands. Using bioassessment information, States can refine the components of

water quality standards by designating ecologically based beneficial uses of wetlands and

adopting numeric and narrative biological criteria (biocriteria). After improving water quality standards, States can use bioassessments to

determine if wetlands are meeting the identified

beneficial uses, track wetland quality, and incorporate wetlands into Clean Water Act Section 305(b) water quality reports. Rigorous standards will also help States improve water quality certification decisions for activities that require Federal permits, such as dredge-and-fill

permits. Under Section 401 of the Clean Water

Act, States can certify, grant, or deny State permits if a proposed activity will harm the chemical, physical, or biological integrity of a wetland as defined in their water quality standards.

Purpose

This module provides an overview of wetland bioassessments and refers the reader to

other modules for details on particular topics.
2

Introduction

Wetlands are important components of watersheds and provide many valuable functions to the environment and to society

(Richardson 1994, NRC 1995, Mitsch and

Gosselink 2000). Wetland ecosystem functions

include the transfer and storage of water, biochemical transformation and storage, the production of living plants and animals, the decomposition of organic materials, and the communities and habitats for living creatures

(Richardson 1994). Based on these and other

ecological functions, wetlands provide “values”

to humans and naturally functioning ecosystems.

Important values include, but are not limited to,

flood control, filtering and cleansing water, erosion control, food production (shrimp, ducks,

fish, etc.), timber production, recreation (boating, fishing, bird watching, etc.), winter deer

yards, and habitat for plants and animals, including many rare or endangered species (Box 1).

Wetlands have not always been appreciated for

their many benefits. Historically, wetlands were

perceived as potentially valuable agricultural

land, impediments to development and progress,

and harbors of vermin and disease (Fischer 1989,

NRC 1995, Dahl and Alford 1996, Mitsch and

Gosselink 2000). Prior to the mid-1970s, drainage and destruction of wetlands were accepted

practices and even encouraged by public policies, such as the Federal Swamp Land Act of

1850, which deeded extensive wetland acreage

from the Federal Government to the States for

conversion to agriculture (NRC 1995, Mitsch

and Gosselink 2000). Some people today still

hold many of these beliefs. These public perceptions of wetlands shaped wetland policy and

management during much of the past century.

Consequently, wetland policy and management

have taken a very different path compared to the

policy and management of streams, rivers, and

lakes. These other aquatic systems have also

been damaged by human activities, but they have

not been subject to the same intense onslaught

of development and agricultural pressures as

wetlands. As a result, whereas most Federal and

State policies since the establishment of the

Clean Water Act have focused on maintaining

and restoring streams, rivers, and lakes, most

wetland policies have been focused on preventing wetlands from being converted to uplands.

During the 1970s and 1980s, Federal and State

agencies did not focus many resources on wetland quality. They were attempting to slow the

rate of wetland loss and increase the rate of wetland restoration through various regulatory and

voluntary programs. Today, wetlands are still

being converted to uplands, but the national rate

of wetland loss has decreased over time

(Figure 1).

Even though estimates of wetland acreage are

not exact, they can show general trends. According to the U.S. Fish and Wildlife Service,

more than half of the original wetlands in the

continental United States have been lost. (Wilen

and Frayer 1990). An estimated 105.5 million

acres of wetlands remained in the conterminous

United States in 1997 (Dahl 2000). Between

1986 and 1997, the net loss of wetlands was

644,000 acres. The loss rate during this period

was 58,500 acres/year, which represents an 80%

reduction in the average rate of annual loss compared with the period between the mid-1970s

and mid-1980s. Various factors have contributed to the decline in the loss rate, including

implementation and enforcement of wetland protection measures, strengthened Federal and State

wetland regulatory programs, and elimination of

some incentives for wetland drainage. Public

education and outreach about the value and function of wetlands, private land initiatives, coastal

monitoring and protection programs, and wet-
3

land restoration and creation actions have also

helped reduce overall wetland losses.

As the Nation draws closer to achieving a “no

net loss” in wetland acreage, it is becoming increasingly apparent that more attention and resources must be devoted to addressing the quality of wetlands. The main goal of the Clean

Water Act is to “maintain and restore the chemical, physical, and biological integrity of the

Nation’s waters,” including wetlands. However,

we know very little about the quality of our

Nation’s wetlands and whether or not we are

Box 1: Examples of Wetland Values

 80% of America’s breeding bird population and more than 50% of protected migratory

bird species rely on wetlands (Wharton et al. 1982).

 More than 95% of commercially harvested fish and shellfish in the United States are

directly or indirectly dependent on wetlands (Feierabend and Zelazny 1987).

 Most of the United States’ frogs, toads, and many salamanders require wetlands during

their life cycle for reproduction or survival.

 A mosaic of small wetlands is important for maintaining local populations of turtles,

small birds, and small mammals (Gibbs 1993).

 Although wetlands account for only 3.5% of the United States’ land area, about 50% of

federally listed endangered animals depend on wetlands for survival (Mitsch and

Gosselink 2000).

 Wetlands help prevent flood damage by storing storm runoff and slowly releasing water

to streams and groundwater, thereby decreasing the severity of peak floods (Thibodeau

and Ostro 1981).

 Removal of floodplain forested wetlands and confinement by levees has reduced the

floodwater storage capacity of the Mississippi River by 80% (Gosselink et al. 1981).

The severity of the 1993 Great Midwest Flood, which caused $20 billion of property

damage, was partially increased by the historical loss of wetlands in the Missouri and

upper Mississippi river basins (NOAA 1994, Tiner 1998).

 Wetlands help maintain the quality of streams and rivers by preventing erosion, filtering

runoff, reducing peak floods, maintaining base flows, and providing food for stream

animals. Streams with drainage areas that contain higher percentages of naturally

vegetated land, particularly wetlands, tend to have healthier fish communities, as shown

by biological assessments (Roth et al. 1996, Wang et al. 1997).

 Wetlands enhance water quality in streams and watersheds by trapping sediment and by

accumulating and transforming a variety of nutrients and other chemical substances

(Jones 1976, Mitsch et al. 1979, Lowrance et al. 1984, Whigham et al. 1988, Kuenzler

1989, Faulkner and Richardson 1989, Johnston 1991).
4

meeting this goal. This limited knowledge is

illustrated in the 1998 National Water Inventory

(U.S. EPA, 1999). The quality of only 4% of the

Nation’s wetlands was estimated, and only a

fraction of these estimates were based on actual

monitoring data. State and Federal agencies are

receiving increasing pressure to move away from

using the number of permits issued or number

of wetlands lost as primary data influencing management decisions. Rather, they must develop

and use more meaningful measurements to

evaluate the quality of the environment and to

demonstrate the effectiveness of their programs

at improving the environment.

Evaluating

Wetland Health

Wetlands and other waterbodies are shapedby the landscape and climate in which

they exist (Brinson 1993). Climatic conditions,

topography of the landscape, chemical and

physical characteristics of underlying geology,

and the amount and flow of water within a watershed all contribute to determining what kind

of plants and animals survive in a location. The

collective interaction of plants and animals with

their physical and chemical environment form

what we call wetlands and provide many of the

functions that are both ecologically and economically important. Many wetlands have been

shaped over thousands of years by complex interactions between biological communities and

their chemical and physical environment. The

very presence of a wetland’s natural biological

community means that the wetland is resilient

to the normal variation in that environment (Karr

and Chu 1999).

Certain human activities can alter the interactions between wetland biota and their chemical

and physical environment. Figure 2 provides a

simplified illustration of the relationship between (a) the health of biological communities

of wetlands and (b) human disturbances to wetFigure 1: Annual average rate of wetlands loss.

-290,000

100,000

-458,000

-58,000

-500,000

-400,000

-300,000

-200,000

-100,000

0

100,000

200,000

1950s1970s*1970s1980s*1980s1990s*2005

Goal**

Annual change in wetland acreage (acres)

* U.S. Fish and Wildlife Service National Wetland Inventory, 2000

** U.S. EPA goal (U.S. EPA 1998b)
5

lands and their watersheds. When human activities within a wetland or its watershed are

minimal, the biological communities are resilient and continue to resemble those that were

shaped by the interaction of biogeographic and

evolutionary processes. At this end of the continuum of biological condition, the community

is said to have biological integrity, which is the

ability to “support and maintain a balanced adaptive community of organisms having a species

composition, diversity, and functional organization comparable to that of natural habitats within

a region” (Karr and Dudley 1981). At some

threshold (T), which is difficult to measure over

short time scales, is the point where degradation of the biological community creates an unhealthy situation because a natural community

is no longer sustainable (Karr 2000).

Some human activities are ecologically benign

whereas others can alter the environment to the

point where there are changes in the biological

communities. As the severity, frequency, or duration of the disturbances increase, a wetland

may eventually reach a point where many of its

plants and animals can no longer survive. When

the interaction of wetland plants and animals

with their environment is disrupted, many of the

functions provided by wetlands will be diminished or lost. At a large scale, the subsequent

ecological and economic effects can be dramatic.

A wetland’s biological community may recover

over time and move back up the continuum if

the pressures from the environmental disturbances are alleviated. The amount of time required to move back up the continuum will depend on the severity and nature of the disturbance. It may take some wetlands hundreds of

years to recover.

The challenge facing wetland biologists is to

develop practical ways to measure the biological condition of wetlands in order to make informed resource management decisions aimed

at minimizing loss of wetland acreage and function. It is neither scientifically nor economically

Gradient of Human Disturbance

Biological Integrity

Gradient of Biological Condition

No or minimal

disturbance

Severe

Disturbance

Nothing

Alive

Pristine

T

healthy =

sustainable

unhealthy =

unsustainable

Figure 2: Continuum of human disturbance on biological condition of

wetlands (adapted from Karr 2000).
6

practical to monitor every way that human activities can damage wetlands. For instance,

wetlands can be dredged, filled, mowed, logged,

plowed, drained, inundated, invaded by nonnative or invasive organisms, grazed by livestock, and contaminated by countless kinds of

pesticides, herbicides, and other toxic substances. Therefore, wetland biologists must focus on measuring the attributes of wetlands that

will reflect biological condition without having

to measure each and every disturbance that contributes to that condition.

As mentioned earlier, wetlands are shaped by

the interaction of biological communities with

their physical and chemical environment. The

plants and animals have evolved over time to

survive within a given range of environmental

conditions. The interaction of wetland organisms with each other and their environment can

be altered chemically, physically, or biologically

(Figure 3). For example, pesticides and herbicides applied to a golf course can enter and

chemically alter a wetland after a rainstorm, resulting in lethal and sublethal affects to aquatic

animals. Humans can physically damage wetland biological communities by plowing a wetland or discharging stormwater runoff into wetlands and altering wetland hydrology. Wetland

biological communities can be biologically altered by introducing non-native or invasive

plants. Wetlands are rarely damaged by a single

stressor. Rather, a mixture of chemical, physical, and biological stressors typically impacts

them. Measuring all of the stressors that could

affect a wetland in a way that is ecologically

meaningful is virtually impossible. The only

way to evaluate the cumulative effect of all the

stressors is to directly measure the condition of

the biological community.

The most direct and cost-effective way to

evaluate the biological condition of wetlands is

to directly measure attributes of the community

of plants and animals that form a wetland. With

limited financial and staff resources, it is not

practical to focus the evaluation of wetland condition on chemical endpoints because there are

too many to monitor. Also, the interaction of

many chemicals in the environment is poorly

understood. Stream bioassessment programs

have also found that bioassessments are less

expensive than many of the chemical measurements (Yoder and Rankin 1995, Karr and Chu

1999). A focus on physical parameters is impractical because our knowledge of interactions

of biological communities and many physical

parameters is incomplete. In addition, focusing

monitoring efforts on physical parameters would

overlook damage caused by chemical and biological stressors.

In addition to reflecting the cumulative effects

of multiple stressors, biological communities integrate the effects of stressors over time, including short-term or intermittent stressors. In contrast, it is often difficult to detect changes in

chemical and physical stressors over time. The

biological effect of many chemicals is often

much longer lasting than the pollution event itself. Some chemicals can enter a wetland, damage the biological community, and be biochemically or photochemically altered rather quickly.

Even if researchers are attempting to detect a

chemical, they may completely miss it unless

they are sampling at the right time. The high

costs associated with processing water and sediment chemistry samples make it far too expensive to sample with enough frequency to detect

many chemicals. Physical alterations can also

pose problems with respect to the ability to detect changes in biological condition over time.

Some physical alterations to wetlands can

change the structure and composition of biological communities for years after the ability to

observe the physical alteration has been lost. For

example, more than 50 years after some farmed

wetlands in Montana were removed from pro-
7

In summary, the most direct and effective way

of evaluating the biological condition of wetlands is to directly monitor the biological component of wetlands through the use of

duction, their biological communities are still

recovering and are noticeably different from

minimally disturbed wetlands (Randy

Apfelbeck, MT DEQ, pers. comm.).

Figure 3: Ecosystem influences on biological integrity (adapted from

Karr et al. 1986, Yoder 1995).

Alkalinity

Orgnanics

Nutrients Turbidity

Transformation

pH

D.O.

Human-made

chemicals

Conductivity

Chemical

Variables

Evapotranspiration Depth Frequency

Duration

Land Use

Precipitation

Runoff

Groundwater

Flow High/Low

Extremes

Hydrology

Reproduction Life Stages

Feeding Disease

Competition

Parasitism Keystone Species

Biotic

Factors BIOLOGICAL

INTEGRITY

Nutrients

Sunlight

Seasonal

Organic Cycles

Matter

Inputs Primary and

Secondary

Production

Energy

Source

Water Depth Topography

Buffer

Vegetation

Substrate

Composition

Water Flow

Canopy Erosion

Habitat

Structure
8

bioassessments and to support that information

with chemical and physical data. Relying on

surrogate measurements (e.g., water chemistry)

or using monitoring tools designed for other

purposes (e.g., rapid functional assessments)

may provide incomplete and misleading results.

Bioassessments can help prioritize where to follow up with additional monitoring, help diagnose the causes of degradation, and provide data

to make informed management decisions about

protecting and restoring wetlands.

Bioassessment

Methods

During the past decade, wetland biologistsbegan to develop bioassessment methods

to evaluate the condition of wetlands and determine whether these wetlands are maintaining

biological integrity. Bioassessment methods focus on measuring attributes of a wetland’s biological community that are reliable indicators

of wetland condition. Many bioassessment

projects also include measures of physical and

chemical attributes that are used to help diagnose potential sources of degradation.

Bioassessments are based on the premise that

the community of plants and animals living in a

wetland will reflect the health of a wetland.

When a wetland is damaged, the diversity of

animals and plants often decreases and the composition of species changes. Typically, the proportion of organisms that are intolerant to human disturbances will decrease while the proportion of individuals or species that are more

tolerant to the disturbance will increase. In comparison to a minimally disturbed site, a plowed

wetland located in a cornfield may have fewer

plant and animal species. It also may be dominated by organisms that can tolerate poor environmental conditions. After examining an assemblage of plants or animals in wetlands ranging from high quality to poor quality, scientists

can use this known range to estimate the relative health of other wetlands.

Wetland biologists are fortunate to have several decades of knowledge and experience related to evaluating the biological condition of

streams and rivers to help guide them. Although

wetlands and their biological communities are

different from streams and rivers, many of the

approaches and experiences from stream

bioassessments can be applied to any biological

system. In fact, bioassessment methods developed for streams and rivers have been adapted

to wetlands, lakes, estuaries, and terrestrial systems (U.S. EPA 1998a, 2000a, Karr and Chu

1999, Rader et al. 2001).

The U.S. Environmental Protection Agency

(EPA) formed the Biological Assessment of Wetlands Workgroup (BAWWG, pronounced “bog”)

in 1997 to help State agencies develop and apply wetland bioassessments (Box 2). Many

BAWWG members are conducting pilot projects,

which are described in Wetland Bioassessment

Case Studies (U.S. EPA, in prep.). BAWWG

has produced a series of reports to help other

State, Federal, and Tribal agencies develop and

implement bioassessment methods for wetlands

(Table 1). The remainder of this report will introduce the development and application of wetland bioassessments, provide recommendations

from BAWWG, and refer to the other reports in

the series for more detailed information.

Wetland bioassessments involve the following

six general stages of development:

 Selecting one or more biological assemblages to monitor

 Classifying wetlands

 Selecting wetlands across a gradient of human disturbance
9

Box 2: The Biological Assessment of Wetlands Workgroup (BAWWG)

The Biological Assessment of Wetlands Workgroup (BAWWG, pronounced “bog”) was

formed in 1997 to help advance the science and application of wetland bioassessments.

Many people have participated in BAWWG meetings over the years, but the following list

of people includes the core BAWWG members who have dedicated a considerable amount

of time to advancing the goals of the workgroup. The New England Biological Assessment

of Wetlands Workgroup (NEBAWWG) was formed in 1998 and its members have also

helped advance wetland bioassessments.

Paul Adamus, Oregon State University

Bill Ainslee, U.S. EPA, Region 4

Randy Apfelbeck, Montana Department of Environmental Quality

Rob Brooks, Penn State Cooperative Wetlands Center

Mark Brown, University of Florida, Center for Wetlands

Tom Danielson, Maine Department of Environmental Protection

Jeanne DiFranco, Maine Department of Environmental Protection

Naomi Detenbeck, U.S. EPA, Ecology Division

Mike Ell, North Dakota Department of Health

Sue Elston, U.S. EPA, Region 5

Chris Faulkner, U.S. EPA, Office of Wetlands, Oceans, and Watersheds

Russ Frydenborg, Florida Department of Environmental Protection

Mark Gernes, Minnesota Pollution Control Agency

Mike Gray, Ohio Environmental Protection Agency

Judy Helgen, Minnesota Pollution Control Agency

Denice Heller Wardrop, Penn State Cooperative Wetlands Center

Doug Hoskins, Connecticut Department of Environmental Protection

Susan Jackson, U.S. EPA, Office of Science and Technology

James Karr, University of Washington

Ryan King, Duke University Wetlands Center

Don Kirby, North Dakota State University

Peter Lowe, USGS Biological Resources Division

John Mack, Ohio Environmental Protection Agency

Ellen McCarron, Florida Department of Environmental Protection

Mick Micacchion, Ohio Environmental Protection Agency

Steve Pugh, U.S. Army Corps of Engineers, Baltimore District

Klaus Richter, King County Department of Natural Resources, Washington

Matt Schweisberg, U.S. EPA, Region 1

Don Sparling, USGS Biological Resources Division

Art Spingarn, U.S. EPA Region 3

Jan Stevenson, Michigan State University

Linda Storm, U.S. EPA, Region 10

Rich Sumner, U.S. EPA, Environmental Research Laboratory

Billy Teels, NRCS Wetlands Science Institute

Doreen Vetter, U.S. EPA, Office of Wetlands, Oceans, and Watersheds
10

 Sampling chemical and physical characteristics of wetlands

 Analyzing data

 Reporting results

 Choosing Assemblages

As discussed in Wetland Bioassessment Case

Studies (U.S. EPA, in prep.), BAWWG members have used a variety of biological assemblages in wetland bioassessments, including algae, amphibians, birds, fish, macroinvertebrates,

and vascular plants. Each assemblage has its

own strengths and limitations for developing

wetland bioassessment methods. Convenience,

money, and time are often key factors in selecting a biological assemblage (Karr and Chu

1999). The selected assemblage must be costeffective to sample and identify. However, a

number of other factors affect an assemblage’s

practical usefulness and ability to reflect real

changes in wetland condition (Table 2). Plants

and macroinvertebrates are the most commonly

used assemblages in wetland bioassessments.

Vegetation is a convenient assemblage because

it occurs in most wetland types and there are

well-established sampling protocols; however,

identifying metrics can be challenging (U.S. EPA

2002a). Macroinvertebrates have been widely

used in stream bioassessments and show a lot

of promise for wetlands, but current sampling

methods focus on wetlands with standing water

(U.S. EPA 2002b). Algae have been used to a

Table 1: Reports Related to Wetland Bioassessments in the

Monitoring Wetland Condition Series
11

Numerical Scores: 1 = best, 2 = intermediate, 3 = worst.

a Fish are restricted to small number of wetland types.

b Sampling methods are easy, but may require multiple site visits.

c Analysis will likely require multiple site visits during season.

d Adults are easy to identify, but some larvae are difficult to identify and may require rearing for positive identification.

e Many amateurs are sufficiently trained to identify birds.

f Identification of diatoms is aided by pictorial keys, but relatively few people are trained.

g Wisconsin DNR is attempting to develop family-level assessment methods instead of identifying macroinvertebrates to genus and species.

h Dip net and especially stovepipe samples can involve a lot of time-consuming picking; however, Minnesota PCA uses method to reduce

time. Activity traps generally require less picking because they do not pick up as much detritus.

i Amphibians and fish may have insufficient taxonomic diversity to be effectively used in bioassessment in some wetland types or parts of the

country.

j Historical land use practices and immediate landscape have significant influence on community.

k Algae are sensitive to copper sulfate.

l Many of these chemicals have very high affinities to charged particles and end up in higher concentration in the sediments than in the water

column. Minnesota PCA has found strong responses in the plant community to sediment concentrations of Cu, Zn, Cd, and other metals.

m Deformities, lesions, etc. have been found in the field, but typically appear only in highly contaminated situations.

Table 2: Strengths and Limitations of Assemblages for Use

in Wetland Bioassessments
12

limited degree but offer an inexpensive and effective alternative for some wetland types (U.S.

EPA 2002c). Amphibians offer many advantages

but have insufficient taxonomic diversity in

some regions for traditional bioassessment methods (U.S. EPA 2002d). The mobility of birds

makes them well suited for landscape-level assessments (U.S. EPA 2002e). Fish have many

advantages that have been demonstrated in other

waterbodies, but the fish assemblage is limited

to a few wetland types, such as emergent wetlands on the fringes of lakes and estuaries. In

summary, different assemblages have different

advantages depending on the purpose of the

project, region of the country, and wetland types

being evaluated. BAWWG members recommend sampling two or more assemblages because it provides more confidence in management decisions and substantially improves the

ability to diagnose the causes of degradation.

Classifying Wetlands

The goal of bioassessments is to evaluate the

condition of wetlands as compared to reference

conditions and determine if wetlands are being

damaged by human activities. An obvious challenge facing wetland scientists is to distinguish

changes in biological communities caused by

human disturbances from natural variations.

This challenge is complicated by the natural

variation found among the variety of U.S. wetland types (Cowardin et al. 1979, Mitsch and

Gosselink 2000, Brinson 1993). One way to

simplify the evaluation is to classify the wetlands and only compare wetlands with others

within the same class. BAWWG members have

found that some type of classification method is

necessary when developing bioassessment methods for wetlands (U.S. EPA 2002f).

Consider an easy example of comparing a salt

marsh to an oligotrophic bog. Each wetland is

shaped by the interaction of plants and animals

with a variety of factors, including its landscape

position, hydrologic characteristics, water chemistry, underlying geology, and climatic conditions. Each type of wetland consists of plants

and animals with adaptations to survive and reproduce in a certain range of environmental conditions. For example, organisms that inhabit salt

marshes must have physical, chemical, or behavioral adaptations to withstand variable salinity and alternating wet and dry periods. In contrast, organisms that inhabit oligotrophic bogs

must have adaptations to tolerate acidic conditions and obtain and retain scarce nutrients. An

organism adapted for life in a bog would not

likely survive in a salt marsh, and vice versa. As

a result, the biological community of a bog will

be much different from the biological community of a salt marsh. No one would disagree that

it is inappropriate to directly compare the biological communities of a salt marsh to a bog.

The validity of making other comparisons is

often debated. For example, is it appropriate to

compare the biological communities of an emergent marsh on the edge of a pond to an emergent marsh on the edge of a slow-moving river?

Are the biological communities similar enough

to lump into one class or do they need to be split

into two classes? There are no easy answers to

these questions. They must be answered, however, to ensure scientific validity of the

bioassessment results and management decisions. The use of a classification system provides a framework for making these decisions.

For purposes of developing bioassessment

methods, the goal is to establish classes of wetlands that have similar biological communities

that respond similarly to human disturbances.

As discussed in Wetland Classification (U.S.

EPA 2002f), a variety of wetland classification

systems have already been developed for a variety of purposes. BAWWG members have used

many of these classification systems (U.S. EPA
13

2002f; in prep.) to avoid “comparing apples to

oranges” and have come up with the following

list of observations and recommendations:

 Do not reinvent the wheel. BAWWG members suggest starting with one or more existing methods and, if necessary, modifying

the classification to establish classes of biologically similar wetlands. Developing an

entirely new system should not be necessary.

 Classification is often an iterative process.

Researchers often start with one or more systems and then lump or split classes as needed

to end up with an appropriate number of

groups of biologically distinct wetlands. For

example, when the Montana Department of

Environmental Quality (MT DEQ) developed its IBI, it used ecoregions as a first tier

and then further separated wetlands by landscape position and other characteristics (e.g.,

acidity and salinity). MT DEQ later determined that it could lump the wetlands of two

ecoregions because their macroinvertebrate

communities were similar and responded

similarly to anthropogenic stressors. While

establishing classes, examine other natural

factors that may affect wetland communities (e.g., size, successional stage, age of the

wetland, salinity) to determine if they should

be included in the classification system.

 Do not become preoccupied with classification. Even though proper classification is

necessary to minimize natural differences

among wetlands, the goal of this exercise is

not to develop a new classification method.

Rather, the goal is to improve the ability of

wetland scientists to detect signals from the

biology about the condition of wetlands.

 Classify wetlands to a suitable level. Ecologists need to develop wetland classes that

are broad enough to allow comparisons of

several wetlands, yet narrow enough to provide biologically meaningful comparison.

All ecologists are faced with a dilemma: the

more ecologists learn about natural systems,

the more they realize how little they actually know. As a result, it is tempting to delve

ever deeper into biology to help identify differences between wetlands and develop

more subclasses. However, ecologists are

faced with another dilemma: limited financial and staff resources. For each wetland

class that is identified, a new set of wetlands

must be sampled to calibrate analytical methods. The endpoint therefore represents a balance of (1) a need to have broad inclusive

classes that will facilitate the comparisons

of many wetland types, (2) a desire to have

a narrow classification that includes detailed

bioassessment data, and (3) constraints on

financial and staff resources. Another limiting factor when classifying wetlands is

having enough wetlands of each class to calibrate analytical methods.

 Recognize that the wetland classification

and classes used for one assemblage may

not be suitable for another assemblage. For

example, wetland classes developed to obtain biologically similar macroinvertebrate

communities may not work when applied to

another assemblage, such as plants. Always

test existing wetland classes to ensure that

they are biologically meaningful in identifying the effects of human disturbances on

the selected assemblage(s).

Selecting Wetlands Across a

Disturbance Gradient

After classifying wetlands, researchers select

sampling sites across a disturbance gradient for

each wetland class. These sites are used to document how a biological assemblage responds to

increasing levels of anthropogenic stressors

(U.S. EPA 2002g). A common way of portraying bioassessment results is to create a graph

with a measure of human disturbance along the

X-axis and a biological endpoint along the Y-
14

axis (Figure 2). As discussed in Developing

Metrics and Indexes of Biological Integrity (U.S.

EPA 2002g), no standard method for establishing gradients of human disturbance exists. Some

BAWWG members have tried to quantify disturbance by using surrogates such as the percentage of impervious surfaces or agriculture in

a watershed. Other projects have used qualitative indices of human disturbance that incorporate a combination of watershed and wetland information. Regardless of the gradient used, it is

crucial to select wetlands that range from minimally disturbed reference sites to severely degraded wetlands, with some sites in between.

BAWWG members have the following observations and recommendations about gradients

of human disturbance:

 Do not become preoccupied with disturbance

gradient. It is impossible to develop a disturbance gradient that incorporates every way

that humans can damage wetlands. The disturbance gradient should provide a gross estimate that can be used in the site selection

process and the calibration of metrics. The

biological information will ultimately be

much more reliable and trustworthy in evaluating wetland condition than the disturbance

gradient (Karr and Chu 1999).

 Define and describe the expected disturbance gradient before sampling sites. If the

disturbance gradient is established after the

sites are sampled, then there is the risk of

sampling too few wetlands at either end of

the gradient.

 Use targeted sampling while developing

bioassessment methods. As discussed in

Study Design for Monitoring Wetlands

(U.S. EPA 2002h), statistical sampling designs provide many advantages when attempting to estimate the percentage of

waterbodies that are meeting their designated

uses. However, BAWWG members have

found that the targeted selection of sampling

sites is preferable when developing

bioassessment methods. It is important to

get sufficient numbers of minimally disturbed

sites and severely degraded sites to (1) document the condition of a biological

assemblage at the two extremes and (2) calibrate analytical methods. Statistical sampling

methods often fail to select enough wetlands

at either end of the disturbance gradient.

Selecting Sampling Methods

Sampling methods used in a wetland bioassessment project will depend on the taxonomic assemblage and wetland class being sampled. Specific sampling methods for each assemblage, except fish, are described in the reports listed in

Table 3. Regardless of the assemblage selected,

BAWWG members have the following observations and recommendations:

 Use standardized sampling methods. It is

very important to standardize sampling

methods and establish quality assurance protocols to ensure the comparability of data.

In addition, equal sample effort must be

given to each wetland. EPA recommends

developing Quality Assurance Project Plans

(QAPP) to help maintain consistency at every stage of sampling from collection to

transportation of samples and laboratory procedures (U.S. EPA 1995b).

 Ensure that sampling methods are repeatable. BAWWG members recommend testing all sampling methods to make sure that

they provide repeatable and consistent results in different wetlands and with different field technicians.

 Standardize the sampling period. The composition and abundance of taxa in a biological assemblage will change during the course

of a year. Individual taxa within a biological assemblage breed at different times of

the year, mature at different rates, and have
15

a variety of behavioral and physical adaptations for life in wetlands. Depending on the

assemblage, sampling the same wetland at

different times of the year can yield strikingly different communities. It is necessary

to establish a standard period of time within

the year to collect samples that (1) minimizes

variation caused by natural, seasonal changes

in community composition; (2) provides

sufficient differentiation of communities

across a disturbance gradient; and (3) is logistically practical.

 Retain some flexibility in sampling period.

Although it is important to maintain a standard sampling period, it helps to retain some

flexibility in scheduling sampling. Annual

climatic variations can delay or accelerate

biological processes. For example, a particularly warm winter can cause adult amphibians to breed much earlier than they

normally would. It is important to pay attention to these variations and adjust the

sampling scheme accordingly to secure

samples that are not biased toward certain

taxa and do not misrepresent relative abundance.

 Consider time and resource constraints. Biologists are often tempted to create elaborate sampling designs using several methods to ensure that all species are captured

and represented in a sample. However, the

complexity of sampling methods must be

balanced with the time and resources available. Remember that the goal of the assessments is to evaluate the condition of a wetland relative to a known range of condition

from wetlands across a disturbance gradient. It is not necessary to monitor everything within a wetland to detect differences

in biological communities across this gradient. Rather, the sampling effort should be

focused on identifying characteristics of biological communities that show measurable

and consistent relationships. For example,

the Maine Department of Environmental

Protection is focusing macroinvertebrate

monitoring in emergent wetlands at the transition zone between open water and emergent vegetation rather than attempting to

sample every microhabitat within a wetland

(Jeanne Difranco, Maine DEP, pers. comm.).

Recognizing that wetlands are often mosaics of different vegetative communities and

microhabitats, the Minnesota Pollution Control Agency targets an area of the wetland

that is representative of the wetland as a

whole and uses a releve sampling method to

evaluate the plant assemblage (U.S. EPA

2002a).

Collecting Chemical and

Physical Data

Used independently, measurements of a

wetland’s physical characteristics or chemicals

in a wetland’s water or sediment are not appropriate for estimating wetland health because they

do not adequately reflect the condition of biological communities. The ability to infer biological condition from physical and chemical

data is often limited to severely altered or polluted conditions. Water chemistry, in particular, is very expensive to analyze, can vary widely

over time, and can be difficult to interpret.

Methods that focus primarily on a wetland’s

physical structure, such as functional assessment

methods, fail to detect damage from subtle stressors such as the effects of pesticides. Physical

and chemical information can be very useful

while classifying wetlands, interpreting biological data, and identifying potential stressors.

BAWWG members use a variety of physical and

chemical data in their projects, including:

 Water chemistry (e.g., nutrients, pH, DO,

conductivity, dissolved metals, turbidity)
16

 Substrate (e.g., type of soil, sediment

chemistry)

 Wetland topography and water depth (e.g.,

functional assessment data)

 Characteristic vegetative structure

 Characteristics of immediate surrounding

land use

 Watershed characteristics (e.g., land use, percent natural vegetation, nearest wetland)

These chemical/physical data provide valuable

information for interpreting biological data, verifying wetland class, and diagnosing potential

stressors. However, these data should not be

used alone to infer biological condition. Several States have found that using chemical data

to infer the biological condition of streams is

dangerously misleading. States that have invested in strong stream bioassessment capabilities have discovered that chemical assessments

vastly overestimated the quality of their streams.

Using the traditional chemical assessments, Ohio

EPA estimated that approximately 30% of

streams were not meeting the minimum standards for maintaining chemical, physical, and

biological integrity. Using their bioassessment

methods, Ohio EPA now estimates that about

70% of the same streams are not meeting their

designated uses (Chris Yoder, Ohio EPA, pers.

comm.). Other States, such as Delaware, have

come to a similar conclusion (John Maxted,

Delaware Department of Natural Resources and

Environmental Control, pers. comm.). Using

chemistry data or physical data to infer biological condition of wetlands would likely produce

similar misleading and inaccurate results. Experiences like these show that one of the most

meaningful ways to evaluate the health of

streams, and arguably any habitat, is to directly

evaluate the plant and animal communities that

live in them.

Analyzing Data

After biologists sample and identify the taxa

in an assemblage, they can prepare a list of taxa

names and the abundance or percent cover for

each. The challenge facing the biologists is to

identify ways to analyze these data to provide

meaningful measures of biological condition.

Remember that the goal is to evaluate the data

and determine to what degree the wetlands are

being damaged by human activities. Both

multimetric indexes, such as Indexes of Biological Integrity (IBI), and statistical approaches

have been used in stream, lake, and estuary

bioassessments (Davis and Simon 1995, Barbour

et al. 1999, U.S. EPA 1996a,b, 1998a, 2000a).

The virtues of the two analytical methods have

been debated in the scientific literature (Norris

and Georges 1993, Suter 1993, Gerritsen 1995,

Norris 1995, Wright 1995, Diamond et al. 1996,

Fore et al. 1996, Reynoldson et al. 1997, Karr

and Chu 1999).

As described in Wetland Bioassessment Case

Studies (U.S. EPA, in prep.), most wetland

bioassessment projects use IBIs to analyze data.

Some States are exploring the use of advanced

statistics to analyze data. Maine Department of

Environmental Protection is exploring the use

of a combination of metrics and statistics to

evaluate macroinvertebrate data. Montana Department of Environmental Quality uses canonical correspondence analysis and TWINSPAN to

evaluate wetland algal data. Magee and others

used canonical correspondence analysis and

TWINSPAN to illustrate the extent to which wetlands in urbanizing landscapes are floristically

degraded in comparison to relatively undisturbed

systems (Magee et al. 1999).

IBIs and related multimetric indexes identify

attributes of an assemblage that show empirical

and predictable responses to increasing human
17

disturbance (Karr 1981). Each metric is scored

individually. These scores are then combined

into an overall index. The process of identifying metrics and developing IBIs is discussed in

detail in Developing Metrics and Indexes of

Biological Integrity (U.S. EPA 2002g). Data

from most attributes can be used to generate scatter plots, i.e., plot each measure for an attribute

(Y variable) against a measure for human disturbance (X variable). Some attributes (e.g.,

abundance, density, production) typically form

shotgun patterns because they are naturally variable. Figure 4 provides an example of an attribute that shows no dose-response relationship

when compared to a disturbance gradient; this

attribute would not be used as a metric. Other

attributes will show clear dose-response patterns

and thus would be considered as potential

metrics. Figures 5 and 6 illustrate attributes with

dose-response relationships when compared to

disturbance gradients; these attributes could be

used as metrics.

After graphically and statistically analyzing potential metrics, researchers select the best performing metrics to include in an IBI. Ideally, an

IBI should consist of approximately 8-12 metrics

(Karr and Chu 1999). One way of combining

metrics into an IBI is to assign values of 5, 3, or

1 to the measures for each metric, where a 5

corresponds with the least disturbed condition,

a 3 corresponds to intermediate disturbance, and

a 1 corresponds to the most disturbed condition

(U.S. EPA 2002g). For a metric such as the number of intolerant taxa, a wetland with a lot of

intolerant taxa may receive a 5 and a wetland

with no intolerant taxa may receive a 1. The

metric scores associated with a wetland are usually added together to calculate the IBI score.

Figure 7 provides an example of IBI scores of

individual wetlands plotted across a gradient of

human disturbance. The IBI consists of 10

metrics, which were scored using the 5/3/1 system and then added together. Thus the highest

possible IBI score in this example is 50 and the

lowest possible IBI score is 10. Some States

use different scoring values (e.g., 6/4/2/0 or 10/

7/3/0) to make the lowest possible IBI score

equal 0.

On the basis of their experience, BAWWG

members have the following recommendations

related to developing metrics and IBIs:

 Develop a separate IBI for each assemblage.

BAWWG members recommend developing

separate IBIs for each assemblage because

it makes it easier for other organizations to

use or adapt the IBI. Advantages of having

two or more IBIs include (1) having additional data that may reinforce the

bioassessment findings, and (2) a second IBI

may reveal different findings because some

assemblages may respond more to certain

stressors.

 Never use an attribute as a metric without

testing it first. BAWWG members recommend that all sampling and analytical methods, including metrics, should be tested, verified, and calibrated to regional conditions

before they are used in a new area of the

country (U.S. EPA 2002g).

 Investigate outliers. Scatterplots of the metric or IBI values of individual wetlands plotted against a disturbance gradient often have

outliers, or values that are inconsistent with

the majority. BAWWG members have found

that outliers are often the result of

misclassifying the wetland or damage to the

wetland from a stressor that is not accounted

for in the human disturbance gradient. Investigation of outliers can identify important

stressors and land use characteristics.

 Avoid directly comparing the IBI scores of

wetlands in different classes. IBI scores

should be calibrated for each wetland class

as defined by the classification system used.

Consider an IBI consisting of 10 metrics,
18

Figure 4: Number of beetle

genera plotted against a human

disturbance gradient

(Source: Maine DEP).

Figure 5: Floristic quality

assessment index plotted against

a human disturbance gradient

(Source: Ohio EPA).

Figure 6: Number of Diptera taxa

Plotted against Rapid Assessment

Method (RAM) scores, a rapid

functional assessment

(Source: Ohio EPA).

Figure 7: A 10-metric

macroinvertebrate IBI

plotted against turbidity

(Source: Minnesota PCA).
19

each scored with a 5, 3, or 1 where 5 represents good condition and 1 represents poor

condition. The best potential IBI score for a

bog, when compared with similar bogs,

should be 50 (i.e., 10 metrics × 5 = 50). Similarly, the best potential marsh IBI score

should be a 50 when compared with other

marshes (i.e., 10 metrics × 5 = 50). When

the same metrics are used, avoid establishing a scoring system where a minimally disturbed bog would receive a significantly

lower score (IBI = 25) than a minimally disturbed marsh (IBI = 50).

Reporting Results

Perhaps the greatest benefit of an IBI is that it

summarizes and presents complex biological information in a format that is easily communicated to managers and the public. Most people

can more easily understand plant and animal IBIs

than complex statistical calculations or abstract

chemical and physical data. Although an IBI

score is helpful for quickly communicating the

overall condition of a wetland, most of the valuable information lies in the individual metrics.

When reporting bioassessment results, the IBI

score should be accompanied by the following

information:

 Narrative description of overall biotic condition in comparison to reference wetlands

of the same region and wetland type

 Number values (e.g., number of taxa) and

scores (e.g., 5, 3, or 1) for each metric

 Narrative descriptions of each metric in comparison to reference conditions of the same

region and wetland type

Using Biological

Information To

Improve Management

Decisions

Biological monitoring provides a frameworkfor improving wetland management, protection, and restoration. Bioassessments provide

information about a wetland’s present biological condition compared to expected reference

conditions. By studying biology, wetland scientists can better understand how a wetland’s

biological community is influenced by the

wetland’s present geophysical condition and

human activities within a watershed (Figure 8).

Managers, policymakers, and society at large can

use this information to decide if measured

changes in biological condition are acceptable

and set policies accordingly (Courtemanch et al.

1989, Courtemanch 1995, Yoder 1995, Karr and

Chu 1999). As shown by many of the projects

in Wetland Bioassessment Case Studies (U.S.

EPA, in prep.), States can use information from

wetland bioassessments to improve many management decisions, including:

 Strengthening water quality standards

 Strengthening State wetland regulatory programs

 Improving wetland tracking

 Improving water quality decisions

 Improving plans to monitor, protect, and restore biological condition

 Evaluating the performance of regulatory,

protection, and restoration activities

 Incorporating wetlands into watershed management

 Improving risk-based management decisions
20

Figure 8: Framework for improving wetland management

(adapted from Karr and Chu 1999).
21

Strengthening Water

Quality Standards

The most common application of wetland

bioassessments is to improve the way wetlands

are incorporated into State water quality standards. States can use the information from

bioassessments to develop ecologically based

designated uses and biocriteria to determine if

those uses are being met. Under CWA Section

303, States and eligible Tribes develop water

quality standards to ensure that their waters support beneficial uses such as aquatic life support,

drinking water supply, fish consumption, swimming, and boating. As envisioned by Section

303(c) of the Clean Water Act, developing water quality standards is a joint effort between

States and the EPA. The States have primary

responsibility for setting, reviewing, revising,

and enforcing water quality standards.

EPA develops regulations, policies, and guidance to help States implement the program and

oversees States’ activities to ensure that their

adopted standards are consistent with the requirements of the CWA and relevant water quality standards guidelines (40 CFR Part 131). EPA

has authority to review and approve or disapprove State standards and, where necessary, to

promulgate Federal water quality standards. A

water quality standard defines the environmental goal for a waterbody, or a portion thereof, by

designating the use or uses to be made of the

water, setting criteria necessary to protect those

uses, and preventing degradation of water quality through antidegradation provisions (U.S. EPA

1991) (Appendix). Criteria are the narrative or

numeric descriptions of the chemical, physical,

or biological conditions found in minimally impacted reference areas (Table 3). By comparing

the condition of a wetland to appropriate criteria, States can determine if the wetland is supporting its designated uses. For examples of how

States have incorporated wetlands into water

quality standard programs, please refer to the

Wetland Bioassessment Case Studies module

(U.S. EPA, in prep.).

Most States do not have wetland-specific designated uses or criteria to adequately protect wetland biological integrity. In their absence, States

must rely on designated uses and criteria developed for lakes, streams, or other waterbodies that

often have different ecological conditions. In

addition, States historically focused on developing chemical and physical criteria based on

sampling ambient water column conditions and

conducting laboratory toxicity tests. The information on ambient water column conditions and

toxicity tests was then used to infer biological

condition of aquatic habitats. The development

and widespread use of formal biocriteria has

lagged behind chemical-specific and toxicity

based water quality criteria (U.S. EPA 1996a,b).

However, EPA requires that States adopt

biocriteria as part of their water quality criteria

for wetlands (U.S. EPA 1990).

States can use bioassessment methods to establish standards and criteria that are ecologically appropriate for conditions found in wetlands. Biocriteria for aquatic systems describe

(in narrative or numeric criteria) the expected

biological condition of a minimally impaired

aquatic community (U.S. EPA 1992, 1996a).

These criteria can be used to define ecosystem

rehabilitation goals and assessment endpoints.

Bioassessments are especially useful for assessing damage from hard-to-detect chemical problems and nonchemical stressors. Thus,

biocriteria fulfill a function missing from EPA’s

traditionally chemical-oriented approach to pollution control and abatement (U.S. EPA 1994d).
22

Strengthening State Wetland

Regulatory Programs

Wetland bioassessments can help strengthen

State wetland regulatory programs and improve

confidence in management decisions. Ohio Environmental Protection Agency’s (Ohio EPA)

work with an IBI and rapid functional assessment provides a good example. The Ohio Rapid

Assessment Method (ORAM) is a rapid functional assessment, which was developed by the

State for use in reviewing numerous wetland

permit applications. Recognizing that it could

not perform bioassessments with all wetland

permit applications, Ohio EPA calibrated its

detailed bioassessments with ORAM. Ohio EPA

now has more confidence in ORAM results

when the scores are within given ranges. When

ORAM scores are inconclusive, Ohio EPA can

justify delaying a decision on the application to

perform a detailed bioassessment to provide a

more reliable assessment of wetland condition.

Table 3: Types of Water Quality Criteria

(adapted from Elder et al. 1999)
23

Improving Wetland Tracking

Under Section 305(b) of the Clean Water Act

(CWA), States submit reports to EPA every 2

years that summarize the quality of their aquatic

resources. In the 305(b) reports, States summarize the amount of streams, rivers, lakes, estuaries, and wetlands that are (1) meeting their designated uses, (2) partially supporting their designated uses, and (3) not supporting their designated uses. In the 1998 National Water Quality

Inventory, a summary of the State 305(b) reports

provided by EPA to the U.S. Congress, States

determined designated use support for only 4%

of the Nation’s wetlands. Of the 4% that were

included in the report, only a small fraction of

the decisions were based on actual monitoring

data. Wetland bioassessments provide badly

needed information to track wetland condition

and determine if wetlands are supporting their

designated uses. In addition, a number of Federal funding sources are tied to the information

provided in 305(b) reports. By not including

wetlands in the report, States are potentially

missing out on resources for their programs.

Improving Water Quality

Decisions

Water quality standards provide a programmatic foundation for a number of other water

quality programs. By using bioassessment data

to improve water quality standards, States can

also improve these other water quality programs.

For example, bioassessments can help assess the

impacts from nonpoint-source pollution (CWA

Section 319) or from point-source discharges

(CWA Section 402). States can use

bioassessments to evaluate the effects of

stormwater discharges on the biological condition of wetlands. Another potentially powerful

tool is the water quality certification process.

Under CWA Section 401, States have the authority to grant or deny “certification” of federally permitted or licensed activities that may result in a discharge to wetlands or other

waterbodies. The certification decision is based

on whether the proposed activity will comply

with State water quality standards. Under this

process, a State can use information from

bioassessments to determine if a proposed activity would degrade water quality of a wetland

or other waterbodies in a watershed. If a State

grants certification, it is essentially saying that

the proposed activity will comply with State

water quality standards. Likewise, a State can

deny certification if the project would harm the

chemical, physical, or biological integrity of a

wetland as defined by water quality standards.

A State’s Section 401 certification process is only

as good as its underlying water quality standards.

States can use bioassessments to refine narrative and numeric criteria to make them more

suitable for conditions found in wetlands and

subsequently improve the Section 401 certification process.

Improving Plans To Monitor,

Protect, and Restore

Biological Condition

Wetlands are often damaged by a complex mix

of chemical, physical, and biological stressors.

It can be difficult to pinpoint specific stressors

using biological information or any single source

of information alone. However, properly

planned, designed, and implemented

bioassessments are not performed in a vacuum

(Yoder 1995). Proximity to known sources of

pollution, knowledge of the surrounding landscape, and supporting chemical and habitat data

are all important sources of information to help

identify how and why a wetland is being damaged. Recent advances in stressor identification

and evaluation provide a framework for systematically examining all available data, identifying probable stressors, and documenting the

decisionmaking process (U.S. EPA 2000b). The
24

Stressor Identification framework offers three

approaches to identify probable causes: (1)

eliminate, (2) diagnose, and (3) assess strength

of evidence (Figure 9). The strength-of-evidence

approach will often be the most helpful approach

when the biota exhibits impairment and there is

no clear stressor. In some cases, the stressor

identification process will indicate that additional monitoring of the biological community

is required or will provide a shortened list of

potential chemical or habitat stressors to be investigated. Thus, bioassessments and the stressor identification process can help States identify problem areas and then target the use of more

expensive chemical and physical measurements

on these sites. When the stressor identification

process identifies a probable stressor, appropriate actions can be taken to restore wetland condition. Under Section 303(d) of the Clean Water Act, States are required to submit lists to EPA

of waterbodies that do not attain their designated

uses and criteria, such as biocriteria. Subsequently, States can use bioassessment data and

the stressor identification process to apply a variety of management tools (e.g., total maximum

daily loads, Section 319 nonpoint source pollution reduction, NRCS wetland conservation programs) to improve wetland condition.

Bioassessment data will also be useful for States

and municipalities when they target resources

to protect or purchase easements on high-quality wetlands.

Evaluating the Performance of

Regulatory, Protection, and

Restoration Activities

States can evaluate the success of restoration

activities and best management practices, such

as buffer strips, by requiring followup assessments in management plans. By periodically

conducting bioassessments, States can track the

condition of wetlands and learn which management activities work best. States can use this

information to improve future management

plans and save time and money by targeting the

most effective restoration projects and best management practices that achieve greater environmental benefits. Wetland biologists can also use

bioassessment data to track wetland biota recovery time and to identify which features of wetland restoration projects, such as diverse

microtopography, are most important in improving biological condition. The USGS Biological

Resources Division, NRCS Wetland Science Institute, and EPA Wetlands Division cooperatively worked on a project to develop

bioassessment methods to evaluate the condition of restored wetlands on the Delmarva Peninsula in Maryland.

Incorporating Wetlands into

Watershed Management

The watershed management cycle is based on

sound monitoring data (U.S. EPA 1995a, 1996c).

Collectively, watershed stakeholders employ

sound scientific data, tools, and techniques in

an iterative decisionmaking process (Figure 10).

This process includes:

 Strategic monitoring. Target monitoring to

inform management decisions

 Assessment. Evaluate data to determine condition of waterbodies, identify stressors, or

evaluate effectiveness of prior management

plans

 Assigning priorities and targeting resources.

Rank water quality concerns and decide how

to allocate resources to address priority concerns

 Developing management strategies. Develop clear goals and objectives to address

priority concerns, identify a range of management strategies, and evaluate their effectiveness
25

Figure 9: The management context of the Stressor

Identification (SI) process

 (the SI process is shown in the center box with bold line).
26

Figure 10: Watershed

management cycle.

 Management plans. Specify how goals will

be achieved, who is responsible for implementation, on what schedule, and how the

effectiveness of the plan will be assessed

 Implementation. Implement activities described in management plans

Information from wetland bioassessments is

necessary to evaluate the condition of wetlands,

set environmental objectives, and evaluate the

success of management actions. Without information from bioassessments, watershed management plans will not adequately address or will

completely overlook the biological condition of

wetlands. Wetlands will continue to be included

in watershed management plans as buffers to

maintain streams and lakes, but not as important components of the environment that should

be maintained and protected based on their own

intrinsic functions and values. Failure to protect wetland condition in watershed plans will

likely diminish the health of other aquatic systems in a watershed.

Improving Risk-Based

Management Decisions

By identifying the biological and ecological

consequences of human actions, biological

monitoring provides an essential foundation for

assessing ecological risks (Karr and Chu 1999).

To date, most ecological risk assessments focus

on using laboratory analysis of chemical endpoints and extrapolate the results to the natural

environment because of perceived shortcomings

in ecosystem-level risk assessment (Suter et al.

1993). The combined information from

bioassessments and stressor identification may

fulfill many of the perceived shortcomings of

ecosystem-level risk assessments. Through the

process of developing wetland bioassessments,

wetland biologists identify a biological endpoint

(i.e, a biological assemblage), group wetlands

into classes that respond similarly to stressors,

establish standard sampling methods, determine

what time of year to sample, establish known

reference conditions, and provide a way to measure divergence from biological integrity. Results from bioassessments are combined with

other available data in the stressor identification

process to determine the most probable stressor

causing damage. The combined information

from wetland bioassessments and the stressor

identification process provide a foundation for

improving whole-ecosystem studies. In many

cases, bioassessments may provide more realistic predictions than chemical laboratory tests of

the impacts that stressors have on the natural

environment (Perry and Troelstrup 1988). These

types of analyses also will be useful for projects

involving the cleanup of contaminated

Superfund and RCRA sites.
27

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30

ing or depending on each other for existence.

Competition Utilization by different species

of limited resources of food or nutrients, refugia, space, ovipositioning sites, or other resources necessary for reproduction, growth, and

survival.

Criteria A part of water quality standards. Criteria are the narrative and numeric definitions

conditions that must be protected and maintained

to support a designated use.

Continuum A gradient of change.

Designated use A part of water quality standards. A designated use is the ecological goal

that policymakers set for a waterbody, such as

aquatic life use support, fishing, swimming, or

drinking water.

Disturbance “Any discrete event in time that

disrupts ecosystems, communities, or population structure and changes resources, substrate

availability or the physical environment” (Picket

and White 1985). Examples of natural disturbances are fire, drought, and floods. Humancaused disturbances are referred to as “human

disturbance” and tend to be more persistent over

time, e.g., plowing, clearcutting of forests, conducting urban stormwater into wetlands.

Diversity A combination of the number of taxa

(see taxa richness) and the relative abundance

of those taxa. A variety of diversity indexes have

been developed to calculate diversity.

Dominance The relative increase in the abundance of one or more species in relation to the

abundance of other species in samples from a

habitat.

Ecological risk assessment An evaluation of

the potential adverse effects that human activities have on the plants and animals that make

up ecosystems.

Glossary

Aquatic life use A type of designated use pertaining to the support and maintenance of healthy

biological communities.

Assemblage An association of interacting populations of organisms that belong to the same

major taxonomic groups. Examples of assemblages used for bioassessments include: algae,

amphibians, birds, fish, amphibians,

macroinvertebrates (insects, crayfish, clams,

snails, etc.), and vascular plants.

Attribute A measurable component of a biological system. In the context of bioassessments,

attributes include the ecological processes or

characteristics of an individual or assemblage

of species that are expected, but not empirically

shown, to respond to a gradient of human disturbance.

Benthos The bottom fauna of waterbodies.

Biological assessment (bioassessment) Using

biomonitoring data of samples of living organisms to evaluate the condition or health of a place

(e.g., a stream, wetland, or woodlot).

Biological integrity “the ability of an aquatic

ecosystem to support and maintain a balanced,

adaptive community of organisms having a species composition, diversity, and functional organization comparable to that of natural habitats within a region” (Karr and Dudley 1981).

Biological monitoring Sampling the biota of a

place (e.g., a stream, a woodlot, or a wetland).

Biota All the plants and animals inhabiting an

area.

Composition (structure) The composition of

the taxonomic grouping such as fish, algae, or

macroinvertebrates relating primarily to the

kinds and number of organisms in the group.

Community All the groups of organisms living together in the same area, usually interact-
31

Ecosystem Any unit that includes all the organisms that function together in a given area

interacting with the physical environment so that

a flow of energy leads to clearly defined biotic

structure and cycling of materials between living and nonliving parts (Odum 1983).

Ecoregion A region defined by similarity of climate, landform, soil, potential natural vegetation, hydrology, and other ecologically relevant

variables.

Gradient of human disturbance The relative

ranking of sample sites within a regional wetland class based on degrees of human disturbance (e.g., pollution, physical alteration of habitats, etc.)

Habitat The sum of the physical, chemical, and

biological environment occupied by individuals of a particular species, population, or community.

Hydrology The science of dealing with the

properties, distribution, and circulation of water both on the surface and under the earth.

Impact A change in the chemical, physical (including habitat), or biological quality or condition of a waterbody caused by external forces.

Impairment Adverse changes occurring to an

ecosystem or habitat. An impaired wetland has

some degree of human disturbance affecting it.

Index of biologic integrity (IBI) An integrative expression of the biological condition that

is composed of multiple metrics. Similar to economic indexes used for expressing the condition of the economy.

Intolerant taxa Taxa that tend to decrease in

wetlands or other habitats that have higher levels of human disturbances, such as chemical pollution or siltation.

Macroinvertebrates Animals without backbones (insects, crayfish, clams, snails, etc.) that

are caught with a 500-800 micron mesh net.

Macroinvertebrates do not include zooplankton

or ostracods, which are generally smaller than

200 microns in size.

Metric An attribute with empirical change in

value along a gradient of human disturbance.

Minimally impaired site Sample sites within

a regional wetland class that exhibit the least

degree of detrimental effect. Such sites help

anchor gradients of human disturbance and are

commonly referred to as reference sites.

Most-impaired site Sample sites within a regional wetland class that exhibit the greatest

degree of detrimental effect. Such sites help

anchor gradients of human disturbance and serve

as important references, although they are not

typically referred to as reference sites.

Population A set of organisms belonging to the

same species and occupying a particular area at

the same time.

Reference site (as used with an index of biological integrity) A minimally impaired site that

is representative of the expected ecological conditions and integrity of other sites of the same

type and region.

Stressor Any physical, chemical, or biological

entity that can induce an adverse response.

Taxa A grouping of organisms given a formal

taxonomic name such as species, genus, family,

etc. The singular form is taxon.

Taxa richness The number of distinct species

or taxa that are found in an assemblage, community, or sample.

Tolerance The biological ability of different

species or populations to survive successfully

within a certain range of environmental conditions.

Trophic Feeding, thus pertaining to energy

transfers.
32

Wetland(s) (1) Those areas that are inundated

or saturated by surface or groundwater at a frequency and duration sufficient to support, and

that under normal circumstances do support, a

prevalence of vegetation typically adapted for

life in saturated soil conditions [EPA, 40 C.F.R.§

230.3 (t) / USACE, 33 C.F.R. § 328.3 (b)]. (2)

Wetlands are lands transitional between terrestrial and aquatic systems where the water table

is usually at or near the surface or the land is

covered by shallow water. For the purposes of

this classification, wetlands must have one or

more of the following three attributes: (a) at least

periodically, the land supports predominantly

hydrophytes, (b) the substrate is predominantly

undrained hydric soil, and (c) the substrate is

nonsoil and is saturated with water or covered

by shallow water at some time during the growing season of each year (Cowardin et al. 1979).

(3) The term “wetland” except when such term

is part of the term “converted wetland,” means

land that (a) has a predominance of hydric soils,

(b) is inundated or saturated by surface or ground

water at a frequency and duration sufficient to

support a prevalence of hydrophytic vegetation

typically adapted for life in saturated soil conditions, and (c) under normal circumstances does

support a prevalence of such vegetation. For

purposes of this Act and any other Act, this term

shall not include lands in Alaska identified as

having a high potential for agricultural development which have a predominance of permafrost soils [Food Security Act, 16 U.S.C.

801(a)(16)].
33

Appendix: Water Quality Standards

and Criteria

The main objective of the Clean Water Act

(CWA) is to “restore and maintain the chemical, physical, and biological integrity of the

Nation’s water.” To help meet these objectives,

States must adopt water quality standards (WQS)

for all “waters of the U.S.” within their boundaries, including wetlands. Water quality standards, at a minimum, consist of three major components: (1) designated uses, (2) narrative and

numeric water quality criteria for supporting

each use, and (3) an antidegradation Statement.

Designated Uses

Designated uses establish the environmental

goals for water resources. States and Tribes assign designated uses for each waterbody, or segment of a body of water, within their boundaries.

Typical uses include public water supply, primary contact recreation (such as swimming), and

aquatic life support (including the propagation

of fish and wildlife). States and Tribes develop

their own classification system and can designate other beneficial uses including fish consumption, shellfish harvesting, agriculture, wildlife habitat, and groundwater recharge.

Since designated uses can vary, States and

Tribes may develop unique water quality requirements or criteria for their designated uses. States

and Tribes can also designate uses to protect

sensitive or valuable aquatic life or habitat, such

as wetlands. When designating uses for wetlands, States may establish an entirely different

format to reflect the unique functions and values of wetlands. At a minimum, designated uses

must be attainable uses that can be achieved

using best management practices and other

methods to prevent degradation. States and

Tribes can also designate uses that have not yet

been achieved or attained. Protecting and maintaining such uses may require the imposition of

more stringent control programs.

Water Quality Criteria

Federal water quality regulation requires States

to adopt criteria sufficient to protect and maintain designated uses. Water quality criteria may

include narrative Statements or numeric limits.

States and Tribes can establish physical, chemical, and biological water quality criteria. Wetland biological monitoring and assessment programs can help States and Tribes refine their

narrative and numeric criteria to better reflect

conditions found in wetlands.

Narrative water quality criteria define conditions that must be protected and maintained to

support a designated use. States should write

narrative criteria to protect designated uses and

to support existing uses under State

antidegradation policies. For example, a State

or Tribe may describe desired conditions in a

waterbody as “waters must be free of substances

that are toxic to humans, aquatic life, and wildlife.” In addition, States and Tribes can write

narrative biological criteria to describe the characteristics of the aquatic plants and animals. For

example, a State may specify that “ambient water quality shall be sufficient to support life

stages of all native aquatic species.”

Narrative criteria should be specific enough

that States and Tribes can translate them into

numeric criteria, permit limits, and other control mechanisms including best management

practices. Narrative criteria are particularly important for wetlands, since States and Tribes
34

cannot numerically describe many physical and

biological impacts in wetlands by using current

assessment methods.

Numeric water quality criteria are specific

numeric limits for chemicals, physical parameters, or biological conditions that States and

Tribes use to protect and maintain designated

uses. Numeric criteria establish minimum and

maximum physical, chemical, and biological

parameters for each designated use. Physical

and chemical numeric criteria can include maximum concentrations of pollutants, acceptable

ranges of physical parameters, minimum thresholds of biological condition, and minimum concentrations of desirable parameters, such as dissolved oxygen.

States and Tribes can adopt numeric criteria to

protect both human health and aquatic life use

support. For example, numeric human health

criteria include maximum levels of pollutants

in water that are not expected to pose significant risk to human health. The risk to human

health is based on the toxicity of and level of

exposure to a contaminant. States and Tribes

can apply numeric human health criteria (such

as for drinking water) to all types of waterbodies,

including wetlands.

Numeric chemical or physical criteria for

aquatic life, however, depend on the characteristics within a waterbody. Since characteristics

of wetlands (such as hydrology, pH, and dissolved oxygen) can be substantially different

from other water bodies, States and Tribes may

need to develop some physical and chemical

criteria specifically for wetlands.

Numeric biological criteria can describe the expected attributes and establish values based on

measures of taxa richness, presence or absence

of indicator taxa, and distribution of classes of

organisms. Many States have developed biological assessment methods for streams, lakes,

and rivers, but few States and Tribes have developed methods for wetlands. Several States,

including Florida, Maine, Massachusetts, Minnesota, Montana, North Dakota, Ohio, and Vermont are currently developing biological assessment methods for monitoring the “health” of

wetland plant and animal communities. Wetland biological assessment methods are essential to establish criteria that accurately reflect

conditions found in wetlands.

Antidegradation Policy

All State standards must contain an

antidegradation policy, which declares that the

existing uses of a waterbody must be maintained

and protected. Through an antidegradation

policy, States must protect existing uses and prevent waterbodies from deteriorating, even if

water quality is better than the minimum level

established by the State or tribal water quality

standards. States and Tribes can use

antidegradation Statements to protect waters

from impacts that water quality criteria cannot

fully address, such as physical and hydrologic

changes.

States and Tribes can protect exceptionally significant waters as outstanding national resource

waters (ONRWs). ONRWs can include waters

with special environmental, recreational, or ecological attributes, such as some wetlands. No

degradation is allowed in waters designated as

ONRW. States can designate waters that need

special protection as ONRWs regardless of how

they ecologically compare to other waters. For

example, although the water of a swamp may

not support as much aquatic life as a marsh, the

swamp is still ecologically important. A State

or Tribe could still designate the swamp as an

ONRW because of its ecological importance.
35

Applications of WQS

Water quality standards provide the foundation

for a broad range of management activities and

can serve as the basis to:

 Assess the impacts of nonpoint source discharges on waterbodies under CWA §319,

 Assess the impacts of point source discharges on waterbodies under CWA §402,

 Determine if federally permitted or licensed

activities maintain WQS under CWA §401

water quality certification

 Track and report if waterbodies are supporting their designated uses under CWA

§305(b)