r/EPA
United States Environmental
Protection Agency
Office of Water
Washington, DC 20460
EPA822-R-02-014
March 2002
METHODS FOR EVALUATING WETLAND CONDITION
#l Introduction to
Wetland Biological Assessment
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United States Environmental Office of Water EPA 822-R-02-014
Protection Agency Washington, DC 20460 March 2002
METHODS FOR EVALUATING WETLAND CONDITION
#l 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)
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NOTICE
The material in this document has been subj ected 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 Biologi-
cal 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 Environmen-
tal Protection), Mark Gernes (Minnesota Pollution Control Agency), Judy Helgen (Minnesota Pollution
Control Agency), James Karr (University of Washington), Ken Kettenring (New Hampshire Depart-
ment 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
11
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CONTENTS
FOREWORD v
LIST OF "METHODS FOR EVALUATING WETLAND
CONDITION" MODULES vi
SUMMARY 1
PURPOSE 1
INTRODUCTION 2
EVALUATING WETLAND HEALTH 4
BlOASSESSMENT METHODS 8
USING BIOLOGICAL INFORMATION To IMPROVE
MANAGEMENT DECISIONS 19
ACKNOWLEDGMENTS 26
REFERENCES 27
GLOSSARY 3O
APPENDIX 33
LIST OF TABLES
TABLE 1: REPORTS RELATED TO WETLAND
BlOASSESSMENTS IN THE MONITORING
WETLAND CONDITION SERIES 1O
TABLE 2: STRENGTHS AND LIMITATIONS OF ASSEMBLAGES
FOR USE IN WETLAND BIOASSESSMENTS 11
TABLE 3: TYPES OF WATER QUALITY CRITERIA 22
111
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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 1 8
FIGURE 5: FLORISTIC QUALITY ASSESSMENT INDEX PLOTTED AGAINST
A HUMAN DISTURBANCE GRADIENT 1 8
FIGURE 6: NUMBER OF DIPTERA TAXA PLOTTED AGAINST RAPID
ASSESSMENT METHOD (RAM) SCORES, A RAPID
FUNCTIONAL ASSESSMENT 1 8
FIGURE?: A TO-METRIC MACROINVERTEBRATE IB! PLOTTED
AGAINST TURBIDITY 1 8
FIGURES: FRAMEWORK FOR IMPROVING WETLAND MANAGEMENT 2O
FIGURE 9: THE MANAGEMENT CONTEXT OF THE STRESSOR
IDENTIFICATION (SI) PROCESS 25
FIGURE 1O: WATERSHED MANAGEMENT CYCLE 26
IV
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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. Alist 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 EPAs 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). EPArelied
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
V
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LIST OF "METHODS FOR EVALUATING WETLAND
CONDITION" MODULES
MODULE # MODULE TITLE
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 BlOASSESSMENTS 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
1 8 BlOGEOCHEMICAL INDICATORS
19 NUTRIENT LOAD ESTIMATION
2O SUSTAINABLE NUTRIENT LOADING
VI
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SUMMARY
7)i°l°gical assessments (bioassessments)
J-J evaluate the health of a waterbody by di-
rectly 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 commu-
nity of plants and animals will reflect the under-
lying health of the waterbody in which they live.
When a waterbody is damaged by human ac-
tivities, 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 pro-
portion of tolerant individuals typically in-
creases. 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 Biologi-
cal Integrity (IBI) for wetlands. An IBI is an
index that integrates several biological metrics
to indicate a site's condition. A common ap-
proach 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 com-
bined into an IBI, which provides a summary
score that is easily communicated to managers
and the public.
Once wetland bioassessment methods are de-
veloped, 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 manage-
ment practices, such as buffer strips, in restor-
ing and protecting wetland health. Wetland
managers can also use bioassessments to more
effectively target resources for restoring, protect-
ing, and acquiring wetlands. Many States are
developing bioassessments to better incorporate
wetlands into water quality programs.
Bioassessments can help States refine their wa-
ter quality standards to reflect typical conditions
found in wetlands. Using bioassessment infor-
mation, States can refine the components of
water quality standards by designating ecologi-
cally based beneficial uses of wetlands and
adopting numeric and narrative biological cri-
teria (biocriteria). After improving water qual-
ity standards, States can use bioassessments to
determine if wetlands are meeting the identified
beneficial uses, track wetland quality, and in-
corporate wetlands into Clean Water Act Sec-
tion 305(b) water quality reports. Rigorous stan-
dards will also help States improve water qual-
ity certification decisions for activities that re-
quire Federal permits, such as dredge-and-fill
permits. Under Section 401 of the Clean Water
Act, States can certify, grant, or deny State per-
mits if a proposed activity will harm the chemi-
cal, physical, or biological integrity of a wet-
land as defined in their water quality standards.
PURPOSE
r I This module provides an overview of wet-
J. land bioassessments and refers the reader to
other modules for details on particular topics.
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INTRODUCTION
TT/etlands are important components of wa-
r r tersheds and provide many valuable func-
tions to the environment and to society
(Richardson 1994, NRC 1995, Mitsch and
Gosselink 2000). Wetland ecosystem functions
include the transfer and storage of water, bio-
chemical transformation and storage, the pro-
duction of living plants and animals, the decom-
position of organic materials, and the commu-
nities 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, ero-
sion control, food production (shrimp, ducks,
fish, etc.), timber production, recreation (boat-
ing, fishing, bird watching, etc.), winter deer
yards, and habitat for plants and animals, includ-
ing 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, drain-
age and destruction of wetlands were accepted
practices and even encouraged by public poli-
cies, 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 per-
ceptions 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 prevent-
ing wetlands from being converted to uplands.
During the 1970s and 1980s, Federal and State
agencies did not focus many resources on wet-
land quality. They were attempting to slow the
rate of wetland loss and increase the rate of wet-
land 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. Ac-
cording 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 com-
pared with the period between the mid-1970s
and mid-1980s. Various factors have contrib-
uted to the decline in the loss rate, including
implementation and enforcement of wetland pro-
tection measures, strengthened Federal and State
wetland regulatory programs, and elimination of
some incentives for wetland drainage. Public
education and outreach about the value and func-
tion of wetlands, private land initiatives, coastal
monitoring and protection programs, and wet-
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land restoration and creation actions have also ity of wetlands. The main goal of the Clean
helped reduce overall wetland losses. Water Act is to "maintain and restore the chemi-
. ^ , T . , . . . . « cal, physical, and biological integrity of the
As the Nation draws closer to achieving a no -T . , . , ,. , ,
it ^ , . . , . . Nation s waters, including wetlands. However,
net loss in wetland acreage, it is becoming in- , 1-111 , ^
. . ^ ^ ^ ^ . ° we know very little about the quality of our
creasmgly apparent that more attention and re- -T . , ,, ,,,
if j ,.,.. ,, , Nation s wetlands and whether or not we are
sources must be devoted to addressing the qual-
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
andOstro 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).
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-500,000
1950s-
1970s*
1970s-
1980s*
1980s-
1990s*
2005
Goal**
* U.S. Fish and Wildlife Service National Wetland Inventory, 2000
** U.S. EPA goal (U.S. EPA 1998b)
FIGURE 1: ANNUAL AVERAGE RATE OF WETLANDS LOSS.
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 man-
agement 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
TT/'etlands and other waterbodies are shaped
r r by 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 wa-
tershed 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 eco-
nomically important. Many wetlands have been
shaped over thousands of years by complex in-
teractions 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
andChu 1999).
Certain human activities can alter the interac-
tions between wetland biota and their chemical
and physical environment. Figure 2 provides a
simplified illustration of the relationship be-
tween (a) the health of biological communities
of wetlands and (b) human disturbances to wet-
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lands and their watersheds. When human ac-
tivities within a wetland or its watershed are
minimal, the biological communities are resil-
ient and continue to resemble those that were
shaped by the interaction of biogeographic and
evolutionary processes. At this end of the con-
tinuum of biological condition, the community
is said to have biological integrity, which is the
ability to "support and maintain a balanced adap-
tive community of organisms having a species
composition, diversity, and functional organiza-
tion 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 degrada-
tion of the biological community creates an un-
healthy 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 du-
ration 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 dimin-
ished 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 distur-
bances are alleviated. The amount of time re-
quired to move back up the continuum will de-
pend on the severity and nature of the distur-
bance. It may take some wetlands hundreds of
years to recover.
The challenge facing wetland biologists is to
develop practical ways to measure the biologi-
cal condition of wetlands in order to make in-
formed resource management decisions aimed
at minimizing loss of wetland acreage and func-
tion. It is neither scientifically nor economically
o Pristine
c
o
0
O
o T
o
m
s
"c
0>
(0 Nothing
(5 Alive
Biological Integrity
healthy = "''-
sustainable ' .
T\
^
-i-'
unhealthy = "-,
unsustainable
,
No or minimal Severe
disturbance Disturbance
Gradient of Human Disturbance
FIGURE: 2: CONTINUUM oir HUMAN DISTURBANCE ON BIOI OGICAI CONDITION OF
WETI ANDS (ADAPTED FROM KARR 2OOO).
5
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practical to monitor every way that human ac-
tivities can damage wetlands. For instance,
wetlands can be dredged, filled, mowed, logged,
plowed, drained, inundated, invaded by non-
native or invasive organisms, grazed by live-
stock, and contaminated by countless kinds of
pesticides, herbicides, and other toxic sub-
stances. Therefore, wetland biologists must fo-
cus on measuring the attributes of wetlands that
will reflect biological condition without having
to measure each and every disturbance that con-
tributes 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 organ-
isms with each other and their environment can
be altered chemically, physically, or biologically
(Figure 3). For example, pesticides and herbi-
cides applied to a golf course can enter and
chemically alter a wetland after a rainstorm, re-
sulting in lethal and sublethal affects to aquatic
animals. Humans can physically damage wet-
land biological communities by plowing a wet-
land or discharging stormwater runoff into wet-
lands and altering wetland hydrology. Wetland
biological communities can be biologically al-
tered by introducing non-native or invasive
plants. Wetlands are rarely damaged by a single
stressor. Rather, a mixture of chemical, physi-
cal, 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 con-
dition 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 measure-
ments (Yoder and Rankin 1995, Karr and Chu
1999). A focus on physical parameters is im-
practical 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 bio-
logical stressors.
In addition to reflecting the cumulative effects
of multiple stressors, biological communities in-
tegrate the effects of stressors overtime, includ-
ing short-term or intermittent stressors. In con-
trast, 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 it-
self. Some chemicals can enter a wetland, dam-
age the biological community, and be biochemi-
cally 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 sedi-
ment chemistry samples make it far too expen-
sive to sample with enough frequency to detect
many chemicals. Physical alterations can also
pose problems with respect to the ability to de-
tect changes in biological condition over time.
Some physical alterations to wetlands can
change the structure and composition of biologi-
cal 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-
6
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Alkalinity
Orgnanics
Conductivity
Human-made
chemicals
Nutrients
Chemical
Variables
Transformation
Turbidity Depth
pH Duration
Land Use
Precipita
Runolf
Hydrology
Groundwater
tion
High/Low
Flow Extremes
Reproduction Life Stages
Feeding
Competition
Parasitism Keystone Species
Biotic
Factors
Disease
Sunlight
Organic
Matter
Inputs
Nutrients
Energy
Source
Primary and
Secondary
Production
Seasonal
Cycles
Water Depth
Buffer
Substrate
Composition
Habitat
Structure
Water Flow
Topography
Vegetation
Canopy Erosion
FIGURE 3: ECOSYSTEM INFI UENCES ON BIOI OGICAI INTEGRITY (ADAPTED FROM
KARRETAI 1986.YODER 1995).
duction, their biological communities are still
recovering and are noticeably different from
minimally disturbed wetlands (Randy
Apfelbeck, MT DEQ, pers. comm.).
In summary, the most direct and effective way
of evaluating the biological condition of wet-
lands is to directly monitor the biological com-
ponent of wetlands through the use of
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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 fol-
low up with additional monitoring, help diag-
nose the causes of degradation, and provide data
to make informed management decisions about
protecting and restoring wetlands.
BlOASSESSMENT
METHODS
T^Vuring the past decade, wetland biologists
-t-Xbegan to develop bioassessment methods
to evaluate the condition of wetlands and deter-
mine whether these wetlands are maintaining
biological integrity. Bioassessment methods fo-
cus on measuring attributes of a wetland's bio-
logical community that are reliable indicators
of wetland condition. Many bioassessment
projects also include measures of physical and
chemical attributes that are used to help diag-
nose 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 com-
position of species changes. Typically, the pro-
portion of organisms that are intolerant to hu-
man disturbances will decrease while the pro-
portion of individuals or species that are more
tolerant to the disturbance will increase. In com-
parison to a minimally disturbed site, a plowed
wetland located in a cornfield may have fewer
plant and animal species. It also may be domi-
nated by organisms that can tolerate poor envi-
ronmental conditions. After examining an as-
semblage of plants or animals in wetlands rang-
ing from high quality to poor quality, scientists
can use this known range to estimate the rela-
tive health of other wetlands.
Wetland biologists are fortunate to have sev-
eral decades of knowledge and experience re-
lated 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 devel-
oped for streams and rivers have been adapted
to wetlands, lakes, estuaries, and terrestrial sys-
tems (U.S. EPA 1998a, 2000a, Karr and Chu
1999, Raderetal. 2001).
The U.S. Environmental Protection Agency
(EPA) formed the Biological Assessment of Wet-
lands Workgroup (B AWWQ pronounced "bog")
in 1997 to help State agencies develop and ap-
ply wetland bioassessments (Box 2). Many
B AWWG members are conducting pilot proj ects,
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 in-
troduce the development and application of wet-
land bioassessments, provide recommendations
from B AWWQ 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 assem-
blages to monitor
Classifying wetlands
Selecting wetlands across a gradient of hu-
man disturbance
8
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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
9
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Title
Description
Introduces several wetland classification systems and describes
how they can be used in wetland monitoring programs.
Introduces different study designs available for monitoring
wetlands.
Introduces the process of testing metrics and creating an Index of
Biological Integrity (ffll)
Introduces field sampling and analytical methods available for
using algae in wetland bioassessments.
Introduces field sampling and analytical methods available for
using amphibians in wetland bioassessments.
Introduces field sampling and analytical methods available for
using birds in wetland bioassessments.
Introduces field sampling and analytical methods available for
using macroinvertebrates in wetland bioassessments.
Introduces field sampling and analytical methods available for
using plants in wetland bioassessments.
Describes use of volunteers in wetland bioassessment projects.
Provides case studies of current wetland bioassessment projects
across the country.
Sampling chemical and physical character-
istics of wetlands
Analyzing data
Reporting results
As discussed in Wetland Bioassessment Case
Studies (U.S. EPA, in prep.), BAWWG mem-
bers have used a variety of biological assem-
blages in wetland bioassessments, including al-
gae, 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 select-
ing a biological assemblage (Karr and Chu
1999). The selected assemblage must be cost-
effective 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
-------
TABI.
:.;NGTHS AND LIN
IN WETLANL _..
DNS OF ASSEMBLAGES FOR
,,",SSESSMENTS
Attribute of Assemblage
An IBI has been developed in one or more
States
Prior research in wetland bioassessments
Present and able to be sampled in multiple
wetland types
Social recognition of importance
Difficulty of sampling protocols
(time, effort, etc.)
Ease of identification (number of species,
relative skill required to identify to genus or
species)
Laboratory analysis (time, cost)
Taxonomic richness (effects ability to
identify metrics)
Relative knowledge of taxa life history
requirements, tolerances, habits
Short time lag of response to stressor
Integrate effects over time
Integrate effects over broad landscape
Reflection of individual wetland condition
Reflection of connectivity to other wetlands
and natural habitats
Sensitivity to nutrient enrichment
Sensitivity to metals and contaminants
Sensitivity to herbicides
Sensitivity to pesticides
Sensitivity to hydroperiod alteration
Sensitivity to habitat alteration of individual
wetland
Ability to discern individual health
(malformations, deformities, lesions) from
exposure to wetland conditions
Ability to diagnose potential stressor
Algae
2
2
1
3
1°
3
29
1
1
1
2
3
1
3
1
3K
1
3
2
3
3
1
Amph
3
3
2
1
3C
1°
2
3'
2
2
1
1
2
1
3
2
2
2
1
2
1
3
Birds
2
2
1
1
3C
2e
1
2
1
3
1
1
3
2
3
2
3
2
3
2
2m
3
Fish
2
2
3a
1
2
2
1
3'
1
2
1
2
2
2
2
2
3
2
3
2
r\\\\
3
Invert
1
1
1
3
2
3T
3n
1
2
1
1
2
1
1
1
1'
2
1
2
2
1
2
Plants
1
1
1
2
2
2
1
1
3
3
1
2
2"
3
1
2'
1
3
1
1
2
2
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.
1 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.
1 1
-------
limited degree but offer an inexpensive and ef-
fective alternative for some wetland types (U.S.
EPA2002c). Amphibians offer many advantages
but have insufficient taxonomic diversity in
some regions for traditional bioassessment meth-
ods (U.S. EPA 2002d). The mobility of birds
makes them well suited for landscape-level as-
sessments (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 wet-
lands 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 recom-
mend sampling two or more assemblages be-
cause it provides more confidence in manage-
ment decisions and substantially improves the
ability to diagnose the causes of degradation.
with a variety of factors, including its landscape
position, hydrologic characteristics, water chem-
istry, underlying geology, and climatic condi-
tions. Each type of wetland consists of plants
and animals with adaptations to survive and re-
produce in a certain range of environmental con-
ditions. For example, organisms that inhabit salt
marshes must have physical, chemical, or be-
havioral adaptations to withstand variable salin-
ity and alternating wet and dry periods. In con-
trast, organisms that inhabit oligotrophic bogs
must have adaptations to tolerate acidic condi-
tions 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 commu-
nity of a salt marsh. No one would disagree that
it is inappropriate to directly compare the bio-
logical communities of a salt marsh to a bog.
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 chal-
lenge 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. wet-
land types (Cowardin et al. 1979, Mitsch and
Gosselink 2000, Brinson 1993). One way to
simplify the evaluation is to classify the wet-
lands 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 meth-
ods 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
The validity of making other comparisons is
often debated. For example, is it appropriate to
compare the biological communities of an emer-
gent marsh on the edge of a pond to an emer-
gent 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, how-
ever, to ensure scientific validity of the
bioassessment results and management deci-
sions. The use of a classification system pro-
vides a framework for making these decisions.
For purposes of developing bioassessment
methods, the goal is to establish classes of wet-
lands that have similar biological communities
that respond similarly to human disturbances.
As discussed in Wetland Classification (U.S.
EPA2002f), a variety of wetland classification
systems have already been developed for a vari-
ety of purposes. BAWWG members have used
many of these classification systems (U.S. EPA
12
-------
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. B AWWG mem-
bers suggest starting with one or more ex-
isting methods and, if necessary, modifying
the classification to establish classes of bio-
logically similar wetlands. Developing an
entirely new system should not be necessary.
Classification is often an iterative process.
Researchers often start with one or more sys-
tems 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) devel-
oped its IB I, it used ecoregions as a first tier
and then further separated wetlands by land-
scape position and other characteristics (e.g.,
acidity and salinity). MT DEQ later deter-
mined 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 communi-
ties (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 classifica-
tion. 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. Ecolo-
gists need to develop wetland classes that
are broad enough to allow comparisons of
several wetlands, yet narrow enough to pro-
vide biologically meaningful comparison.
All ecologists are faced with a dilemma: the
more ecologists learn about natural systems,
the more they realize how little they actu-
ally know. As a result, it is tempting to delve
ever deeper into biology to help identify dif-
ferences between wetlands and develop
more subclasses. However, ecologists are
faced with another dilemma: limited finan-
cial and staff resources. For each wetland
class that is identified, a new set of wetlands
must be sampled to calibrate analytical meth-
ods. The endpoint therefore represents a bal-
ance 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 lim-
iting factor when classifying wetlands is
having enough wetlands of each class to cali-
brate 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 ob-
tain 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 identi-
fying 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 docu-
ment how a biological assemblage responds to
increasing levels of anthropogenic stressors
(U. S. EPA 2002g). A common way of portray-
ing bioassessment results is to create a graph
with a measure of human disturbance along the
X-axis and a biological endpoint along the Y-
13
-------
axis (Figure 2). As discussed in Developing
Metrics and Indexes of Biological Integrity (U.S.
EPA 2002g), no standard method for establish-
ing gradients of human disturbance exists. Some
BAWWG members have tried to quantify dis-
turbance by using surrogates such as the per-
centage of impervious surfaces or agriculture in
a watershed. Other projects have used qualita-
tive indices of human disturbance that incorpo-
rate a combination of watershed and wetland in-
formation. Regardless of the gradient used, it is
crucial to select wetlands that range from mini-
mally disturbed reference sites to severely de-
graded wetlands, with some sites in between.
BAWWG members have the following obser-
vations and recommendations about gradients
of human disturbance:
Do not become preoccupied with disturbance
gradient. It is impossible to develop a distur-
bance gradient that incorporates every way
that humans can damage wetlands. The dis-
turbance gradient should provide a gross es-
timate 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 evalu-
ating wetland condition than the disturbance
gradient (Karr and Chu 1999).
Define and describe the expected distur-
bance 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. EPA2002h), statistical sampling de-
signs provide many advantages when at-
tempting 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) docu-
ment the condition of a biological
assemblage at the two extremes and (2) cali-
brate 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 bioassess-
ment project will depend on the taxonomic as-
semblage and wetland class being sampled. Spe-
cific sampling methods for each assemblage, ex-
cept fish, are described in the reports listed in
Table 3. Regardless of the assemblage selected,
BAWWG members have the following obser-
vations and recommendations:
Use standardized sampling methods. It is
very important to standardize sampling
methods and establish quality assurance pro-
tocols 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 ev-
ery stage of sampling from collection to
transportation of samples and laboratory pro-
cedures (U.S. EPA 1995b).
Ensure that sampling methods are repeat-
able. BAWWG members recommend test-
ing all sampling methods to make sure that
they provide repeatable and consistent re-
sults in different wetlands and with differ-
ent field technicians.
Standardize the sampling period. The com-
position and abundance of taxa in a biologi-
cal assemblage will change during the course
of a year. Individual taxa within a biologi-
cal assemblage breed at different times of
the year, mature at different rates, and have
14
-------
a variety of behavioral and physical adapta-
tions for life in wetlands. Depending on the
assemblage, sampling the same wetland at
different times of the year can yield strik-
ingly 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 lo-
gistically practical.
Retain some flexibility in sampling period.
Although it is important to maintain a stan-
dard sampling period, it helps to retain some
flexibility in scheduling sampling. Annual
climatic variations can delay or accelerate
biological processes. For example, a par-
ticularly warm winter can cause adult am-
phibians to breed much earlier than they
normally would. It is important to pay at-
tention to these variations and adjust the
sampling scheme accordingly to secure
samples that are not biased toward certain
taxa and do not misrepresent relative abun-
dance.
Consider time and resource constraints. Bi-
ologists are often tempted to create elabo-
rate sampling designs using several meth-
ods 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 avail-
able. Remember that the goal of the assess-
ments is to evaluate the condition of a wet-
land relative to a known range of condition
from wetlands across a disturbance gradi-
ent. It is not necessary to monitor every-
thing within a wetland to detect differences
in biological communities across this gradi-
ent. Rather, the sampling effort should be
focused on identifying characteristics of bio-
logical communities that show measurable
and consistent relationships. For example,
the Maine Department of Environmental
Protection is focusing macroinvertebrate
monitoring in emergent wetlands at the tran-
sition zone between open water and emer-
gent vegetation rather than attempting to
sample every microhabitat within a wetland
(Jeanne Difranco, Maine DEP, pers. comm.).
Recognizing that wetlands are often mosa-
ics of different vegetative communities and
microhabitats, the Minnesota Pollution Con-
trol 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 appro-
priate for estimating wetland health because they
do not adequately reflect the condition of bio-
logical communities. The ability to infer bio-
logical condition from physical and chemical
data is often limited to severely altered or pol-
luted conditions. Water chemistry, in particu-
lar, 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 stres-
sors such as the effects of pesticides. Physical
and chemical information can be very useful
while classifying wetlands, interpreting biologi-
cal 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)
-------
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, per-
cent natural vegetation, nearest wetland)
These chemical/physical data provide valuable
information for interpreting biological data, veri-
fying wetland class, and diagnosing potential
stressors. However, these data should not be
used alone to infer biological condition. Sev-
eral States have found that using chemical data
to infer the biological condition of streams is
dangerously misleading. States that have in-
vested in strong stream bioassessment capabili-
ties 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 stan-
dards 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 biologi-
cal condition of wetlands would likely produce
similar misleading and inaccurate results. Ex-
periences 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 Biologi-
cal 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
andChu!999).
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 De-
partment of Environmental Quality uses canoni-
cal correspondence analysis and TWINSPANto
evaluate wetland algal data. Magee and others
used canonical correspondence analysis and
TWINSPAN to illustrate the extent to which wet-
lands 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
16
-------
disturbance (Karr 1981). Each metric is scored
individually. These scores are then combined
into an overall index. The process of identify-
ing 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 scat-
ter plots, i.e., plot each measure for an attribute
(Y variable) against a measure for human dis-
turbance (X variable). Some attributes (e.g.,
abundance, density, production) typically form
shotgun patterns because they are naturally vari-
able. Figure 4 provides an example of an at-
tribute 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 po-
tential metrics, researchers select the best per-
forming 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. EPA2002g). For a metric such as the num-
ber 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 usu-
ally 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 sys-
tem 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 107
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 addi-
tional 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 recom-
mend that all sampling and analytical meth-
ods, including metrics, should be tested, veri-
fied, and calibrated to regional conditions
before they are used in a new area of the
country (U.S. EPA2002g).
Investigate outliers. Scatterplots of the met-
ric or IBI values of individual wetlands plot-
ted against a disturbance gradient often have
outliers, or values that are inconsistent with
the maj ority. 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. In-
vestigation 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,
17
-------
z
8 30
w
< 25
° 20
15
10
0123456789 10 11
Relative Disturbance Rank
10=least disturbed
FIGURE 5: FLORISTIC QUALITY
ASSESSMENT INDEX PLOTTED AGAINST
A HUMAN DISTURBANCE GRADIENT
(SOURCE: OHIO EPA).
f
b
16
14
12
10
8
6
0
0 10
poor quality
20
RAM Score
30 40
good quality
FIGURE 6: NUMBER OF DIPTERA TAXA
PLOTTED AGAINST RAPID ASSESSMENT
METHOD (RAM) SCORES, A RAPID
FUNCTIONAL ASSESSMENT
(SOURCE: OHIO EPA).
-0.5
0 0.5 1 1.5
Log Turbidity in Water
Invertebrate IBI 10 Metrics
RO
50
40
30
20
10
n -
« Reference
o * D Agriculture
jt * A Urban
sl*^ D
D *E& D6 D AA
^'b AD D
A A A
A D
2 2.5
FIGURE 7: A TO-METRIC
MACROINVERTEBRATE IB!
PLOTTED AGAINST TURBIDITY
(SOURCE: MINNESOTA PCA).
18
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each scored with a 5, 3, or 1 where 5 repre-
sents 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). Simi-
larly, the best potential marsh IBI score
should be a 50 when compared with other
marshes (i.e., 10 metrics x 5 = 50). When
the same metrics are used, avoid establish-
ing a scoring system where a minimally dis-
turbed bog would receive a significantly
lower score (IBI = 25) than a minimally dis-
turbed marsh (IBI = 50).
REPORTING RESULTS
Perhaps the greatest benefit of an IBI is that it
summarizes and presents complex biological in-
formation in a format that is easily communi-
cated 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 valu-
able 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 con-
dition 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 com-
parison to reference conditions of the same
region and wetland type
USING BIOLOGICAL
INFORMATION To
IMPROVE MANAGEMENT
DECISIONS
7)i°l°gical monitoring provides a framework
J-J for improving wetland management, pro-
tection, and restoration. Bioassessments provide
information about a wetland's present biologi-
cal condition compared to expected reference
conditions. By studying biology, wetland sci-
entists 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 man-
agement decisions, including:
Strengthening water quality standards
Strengthening State wetland regulatory pro-
grams
Improving wetland tracking
Improving water quality decisions
Improving plans to monitor, protect, and re-
store biological condition
Evaluating the performance of regulatory,
protection, and restoration activities
Incorporating wetlands into watershed man-
agement
Improving risk-based management decisions
19
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Physical, chemical, evolutionary, and biogeographic processes interact to produce
Landscape position Taxa richness
Geological substrate Species composition
Climate, elevation Tolerance/intolerance
Wetland type Adaptive strategies (ecology,
behavior, morphology)
The baseline without human disturbance is influenced by
Land use (building, farming, logging, grazing, etc.)
Changes in hydrology
Introduction of pesticides, herbicides, and other chemicals
Introduction of non-native plants and animals
which alter the biogeochemical processes to influence one or more of
Wetland hydrology
Physical habitat structure
Water quality
Energy source
Biological interactions
Connectivity to other natural systems
thereby altering
Storage and flow of water Taxa richness
Biogeochemical processes Taxonomic composition
Groundwater interaction Individual health
Accumulation of sediment and organic matter Ecological processes
Evolutionary processes
Unacceptable divergence of
stimulates
Regulations, incentives
Management, conservation, restoration
to protect
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STRENGTHENING WATER
QUALITY STANDARDS
The most common application of wetland
bioassessments is to improve the way wetlands
are incorporated into State water quality stan-
dards. 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 sup-
port beneficial uses such as aquatic life support,
drinking water supply, fish consumption, swim-
ming, and boating. As envisioned by Section
303(c) of the Clean Water Act, developing wa-
ter 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 guid-
ance to help States implement the program and
oversees States' activities to ensure that their
adopted standards are consistent with the re-
quirements of the CWA and relevant water qual-
ity standards guidelines (40 CFR Part 131). EPA
has authority to review and approve or disap-
prove State standards and, where necessary, to
promulgate Federal water quality standards. A
water quality standard defines the environmen-
tal 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 qual-
ity 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 im-
pacted reference areas (Table 3). By comparing
the condition of a wetland to appropriate crite-
ria, States can determine if the wetland is sup-
porting 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 des-
ignated uses or criteria to adequately protect wet-
land biological integrity. In their absence, States
must rely on designated uses and criteria devel-
oped for lakes, streams, or other waterbodies that
often have different ecological conditions. In
addition, States historically focused on devel-
oping chemical and physical criteria based on
sampling ambient water column conditions and
conducting laboratory toxicity tests. The infor-
mation 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 es-
tablish standards and criteria that are ecologi-
cally appropriate for conditions found in wet-
lands. 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 assess-
ing damage from hard-to-detect chemical prob-
lems and nonchemical stressors. Thus,
biocriteria fulfill a function missing from EPA's
traditionally chemical-oriented approach to pol-
lution control and abatement (U.S. EPA 1994d).
21
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Important backstop to numeric
chemical criteria, especially when
one considers that there are
thousands of chemicals with no
established criteria
Often expressed with general
Statements, such as "waters shall
be free from concentrations of
pollutants injurious to aquatic life"
Most of the criteria fall in this
category
Usually expressed as a maximum
or minimum allowed concentration
of a chemical, such as X mg/L of
copper
Important backstop to numeric
physical criteria, especially
because few physical criteria have
been developed
Not as well developed as chemical
criteria
Can include criteria for
temperature, habitat condition, etc.
Possibly more important than
narrative chemical and physical
criteria because it is often difficult
to describe conditions of a healthy
biological community in numeric
terms alone
Very general narrative criteria
have been on the books in some
States for years
More need to be developed, and
many of those already on books
need to be made clearer, more
specific, and more applicable to
wetlands
Describe the condition of
biological communities (e.g.,
macro invertebrates) of healthy
waterbodies
Often provide comparisons
between actual condition in a
waterbody to reference conditions
ST R E N GT H E NIN G STAT E W ET LA N13
R EG U L. ATO F?Y PROG R AM S
Wetland bioassessments can help strengthen
State wetland regulatory programs and improve
confidence in management decisions. Ohio En-
vironmental Protection Agency's (Ohio EPA)
work with an IBI and rapid functional assess-
ment provides a good example. The Ohio Rapid
Assessment Method (ORAM) is a rapid func-
tional 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.
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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 summa-
rize the amount of streams, rivers, lakes, estuar-
ies, and wetlands that are (1) meeting their des-
ignated uses, (2) partially supporting their des-
ignated uses, and (3) not supporting their desig-
nated 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 Fed-
eral 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 program-
matic 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 condi-
tion of wetlands. Another potentially powerful
tool is the water quality certification process.
Under CWA Section 401, States have the au-
thority to grant or deny "certification" of feder-
ally permitted or licensed activities that may re-
sult 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 ac-
tivity 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.
AState's Section 401 certification process is only
as good as its underlying water quality standards.
States can use bioassessments to refine narra-
tive and numeric criteria to make them more
suitable for conditions found in wetlands and
subsequently improve the Section 401 certifi-
cation 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 land-
scape, and supporting chemical and habitat data
are all important sources of information to help
identify how and why a wetland is being dam-
aged. Recent advances in stressor identification
and evaluation provide a framework for system-
atically examining all available data, identify-
ing probable stressors, and documenting the
decisionmaking process (U.S. EPA2000b). The
23
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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 addi-
tional monitoring of the biological community
is required or will provide a shortened list of
potential chemical or habitat stressors to be in-
vestigated. Thus, bioassessments and the stres-
sor identification process can help States iden-
tify 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, appropri-
ate actions can be taken to restore wetland con-
dition. Under Section 303(d) of the Clean Wa-
ter Act, States are required to submit lists to EPA
of waterbodies that do not attain their designated
uses and criteria, such as biocriteria. Subse-
quently, States can use bioassessment data and
the stressor identification process to apply a va-
riety of management tools (e.g., total maximum
daily loads, Section 319 nonpoint source pollu-
tion reduction, NRCS wetland conservation pro-
grams) 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-qual-
ity 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 assess-
ments in management plans. By periodically
conducting bioassessments, States can track the
condition of wetlands and learn which manage-
ment activities work best. States can use this
information to improve future management
plans and save time and money by targeting the
most effective restoration proj ects and best man-
agement practices that achieve greater environ-
mental benefits. Wetland biologists can also use
bioassessment data to track wetland biota recov-
ery time and to identify which features of wet-
land restoration projects, such as diverse
microtopography, are most important in improv-
ing biological condition. The USGS Biological
Resources Division, NRCS Wetland Science In-
stitute, and EPA Wetlands Division coopera-
tively worked on a project to develop
bioassessment methods to evaluate the condi-
tion of restored wetlands on the Delmarva Pen-
insula 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 con-
dition 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 con-
cerns
Developing management strategies. De-
velop clear goals and objectives to address
priority concerns, identify a range of man-
agement strategies, and evaluate their effec-
tiveness
24
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Detect or Suspect Biological Impairment
D
-------
H Management plans. Specify how goal swill
be achieved, who is responsible for imple-
mentation, on what schedule, and how the
effectiveness of the plan will be assessed
Implementation. Implement activities de-
scribed 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 infor-
mation from bioassessments, watershed manage-
ment 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 impor-
tant components of the environment that should
be maintained and protected based on their own
intrinsic functions and values. Failure to pro-
tect wetland condition in watershed plans will
likely diminish the health of other aquatic sys-
tems in a watershed.
Management
Cycle
Assigning
Priorities and
Targeting
Resources
Developing
Management
Strategies
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 end-
points 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 mea-
sure divergence from biological integrity. Re-
sults 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 realis-
tic 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.
MANAGEMENT CYCLE,
-------
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GLOSSARY
Aquatic life use A type of designated use per-
taining to the support and maintenance of healthy
biological communities.
Assemblage An association of interacting popu-
lations of organisms that belong to the same
major taxonomic groups. Examples of assem-
blages used for bioassessments include: algae,
amphibians, birds, fish, amphibians,
macroinvertebrates (insects, crayfish, clams,
snails, etc.), and vascular plants.
Attribute A measurable component of a bio-
logical 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 dis-
turbance.
Benthos The bottom fauna of waterbodies.
Biological assessment (bioassessment) Using
biomonitoring data of samples of living organ-
isms 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 spe-
cies composition, diversity, and functional or-
ganization comparable to that of natural habi-
tats 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 liv-
ing together in the same area, usually interact-
ing or depending on each other for existence.
Competition Utilization by different species
of limited resources of food or nutrients, refu-
gia, space, ovipositioning sites, or other re-
sources necessary for reproduction, growth, and
survival.
Criteria A part of water quality standards. Cri-
teria 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 stan-
dards. 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 popula-
tion structure and changes resources, substrate
availability or the physical environment" (Picket
and White 1985). Examples of natural distur-
bances are fire, drought, and floods. Human-
caused disturbances are referred to as "human
disturbance" and tend to be more persistent over
time, e.g., plowing, clearcutting of forests, con-
ducting 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 abun-
dance 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 activi-
ties have on the plants and animals that make
up ecosystems.
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Ecosystem Any unit that includes all the or-
ganisms 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 liv-
ing and nonliving parts (Odum 1983).
Ecoregion Aregion defined by similarity of cli-
mate, landform, soil, potential natural vegeta-
tion, hydrology, and other ecologically relevant
variables.
Gradient of human disturbance The relative
ranking of sample sites within a regional wet-
land class based on degrees of human distur-
bance (e.g., pollution, physical alteration of habi-
tats, etc.)
Habitat The sum of the physical, chemical, and
biological environment occupied by individu-
als of a particular species, population, or com-
munity.
Hydrology The science of dealing with the
properties, distribution, and circulation of wa-
ter both on the surface and under the earth.
Impact A change in the chemical, physical (in-
cluding habitat), or biological quality or condi-
tion 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 integra-
tive expression of the biological condition that
is composed of multiple metrics. Similar to eco-
nomic indexes used for expressing the condi-
tion of the economy.
Intolerant taxa Taxa that tend to decrease in
wetlands or other habitats that have higher lev-
els of human disturbances, such as chemical pol-
lution or siltation.
Macroinvertebrates Animals without back-
bones (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 re-
gional 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 bio-
logical integrity) A minimally impaired site that
is representative of the expected ecological con-
ditions 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, com-
munity, or sample.
Tolerance The biological ability of different
species or populations to survive successfully
within a certain range of environmental condi-
tions.
Trophic Feeding, thus pertaining to energy
transfers.
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Wetland(s) (1) Those areas that are inundated
or saturated by surface or groundwater at a fre-
quency 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.RR.§
230.3 (t)/USAGE, 33 C.RR. § 328.3 (b)]. (2)
Wetlands are lands transitional between terres-
trial 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 grow-
ing 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 condi-
tions, 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 devel-
opment which have a predominance of perma-
frost soils [Food Security Act, 16 U.S.C.
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APPENDIX: WATER QUALITY STANDARDS
AND CRITERIA
The main objective of the Clean Water Act
(CWA) is to "restore and maintain the chemi-
cal, 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 bound-
aries, including wetlands. Water quality stan-
dards, at a minimum, consist of three maj or com-
ponents: (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 as-
sign designated uses for each waterbody, or seg-
ment of a body of water, within their boundaries.
Typical uses include public water supply, pri-
mary contact recreation (such as swimming), and
aquatic life support (including the propagation
offish and wildlife). States and Tribes develop
their own classification system and can desig-
nate other beneficial uses including fish con-
sumption, shellfish harvesting, agriculture, wild-
life habitat, and groundwater recharge.
Since designated uses can vary, States and
Tribes may develop unique water quality require-
ments 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 wet-
lands, States may establish an entirely different
format to reflect the unique functions and val-
ues 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 main-
taining 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 main-
tain designated uses. Water quality criteria may
include narrative Statements or numeric limits.
States and Tribes can establish physical, chemi-
cal, and biological water quality criteria. Wet-
land biological monitoring and assessment pro-
grams can help States and Tribes refine their
narrative and numeric criteria to better reflect
conditions found in wetlands.
Narrative water quality criteria define condi-
tions 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 wild-
life." In addition, States and Tribes can write
narrative biological criteria to describe the char-
acteristics of the aquatic plants and animals. For
example, a State may specify that "ambient wa-
ter 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 con-
trol mechanisms including best management
practices. Narrative criteria are particularly im-
portant for wetlands, since States and Tribes
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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 param-
eters, 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 maxi-
mum concentrations of pollutants, acceptable
ranges of physical parameters, minimum thresh-
olds of biological condition, and minimum con-
centrations of desirable parameters, such as dis-
solved 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 signifi-
cant 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 character-
istics within a waterbody. Since characteristics
of wetlands (such as hydrology, pH, and dis-
solved 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 ex-
pected 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 bio-
logical assessment methods for streams, lakes,
and rivers, but few States and Tribes have de-
veloped methods for wetlands. Several States,
including Florida, Maine, Massachusetts, Min-
nesota, Montana, North Dakota, Ohio, and Ver-
mont are currently developing biological assess-
ment methods for monitoring the "health" of
wetland plant and animal communities. Wet-
land biological assessment methods are essen-
tial to establish criteria that accurately reflect
conditions found in wetlands.
ANTIDEGRADATION POLICY
All State standards must contain an
antidegradationpolicy, which declares that the
existing uses of a waterbody must be maintained
and protected. Through an antidegradation
policy, States must protect existing uses and pre-
vent 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 sig-
nificant waters as outstanding national resource
waters (ONRWs). ONRWs can include waters
with special environmental, recreational, or eco-
logical 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.
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APPLICATIONS OF WQS Determine if federally permitted or licensed
activities maintain WQS under CWA §401
Water quality standards provide the foundation water quality certification
for a broad range of management activities and _ _ , , ^-r-.uj- ^
, , . Track and report it waterbodies are support-
can serve as the basis to: ^ . , . ^ , , fZ^Ti
mg their designated uses under CWA
Assess the impacts of nonpoint source dis- §305(b)
charges on waterbodies under CWA §319,
Assess the impacts of point source dis-
charges on waterbodies under CWA §402,
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