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P09 1-1d2Sl !>
EPA/600/C-91/080
CRITERIA TO PROTECT WETLAND ECOLOGICAL INTEGRITY
by
William Sanville
U.S. Environmental Protection Agency
Environmental Research Laboratory-Duluth
6201 Congdon Boulevard
Duluth MN 55804
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CRITERIA TO PROTECT WETLAND ECOLOGICAL INTEGRITY
INTRODUCTION:
Wetlands are very complex ecological systems. They range
from riverine and lacustrine wetlands associated with rivers and
lakes, respectively, to isolated wet meadows. Most have surface
water during part of the year but others may have short periods
of surface water inundation with varying periods of soil
saturation. Wetlands frequently occupy depressions in the
landscape where surface and ground water accumulate and may be
readily polluted by a variety of anthropogenic sources.
Wetlands have been a minor element in EPA's water quality
regulatory frame but their importance will expand following their
mandatory inclusion into Waters of the States in 1993 (EPA 1990).
They have historically been regulated under Section 404 of the
Clean Water Act, and although water quality is an issue in 404
decisions, it has not been the driving variable. The "no-net-
loss" of wetland area and function as proposed by The
Conservation Foundation (1988) and advocated by the president
will also impact wetland regulations.
The goal of wetland regulation is to protect wetland
ecological integrity. Figure 1 is a simplified diagram
illustrating this relationship. The ultimate management
objective is to achieve a state of ecological integrity, an
acceptable condition of wetland health; the central circle in
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figure 1. The middle circlo of this diagram represents factors
which define ecological integrity. For the wetland to be
healthy, these factors must collectively be at some level of
acceptability. The outer ring represents examples of stresses
which impact the middle ring elements. If one or a combination
of the stressor exceeds the capacity of the wetland to maintain a
"healthy" condition, ecological integrity will no longer be
attained.
This presentation is based on the premise that a range of
criteria are necessary to protect wetland ecological integrity,
the center ring of figure 1, from a range of stressors. I will
discuss possible protective criteria, some in use in existing
regulatory programs and otners under development. The order of
presentation is biological, aquatic life, l^ydrologic, sediments
and wildlife criteria. In the conclusion, I briefly discuss
using landscape approaches to extrapolate criteria to spatial
scales beyond the traditional site-specific analysis used in most
water quality decisions.
DISCUSSION:
Biological Criteria
Biological criteria are a necessary part of wetland
standards and criteria development. The existing aquatic life
numeric criteria provide tools to protect the wetlands from
specific contaminants while the biological criteria will provide
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tools to assess the wetland biological condition. Biological
criteria are the measures of regulatory success. They also offer
techniques to quantify effects of disturbance other than
traditional contaminants, e.g., habitat alteration.
Biological criteria are being developed for surface waters
and several states have included them in their state water
quality standards. The approach used for wetland biological
criteria development will likely follow that used for other
surface waters. A very simplified description includes 1)
wetland classification, 2) selection of reference sites based on
spatial considerations and/or wetland types, 3) collection of
biological data from the reference wetlands, 4) development of
biological measures to analyze the reference sites, and 5)
assignment of a range of acceptability to the biological
measures.
There will also.be differences in the development of wetland
biological criteria.' Wetland distribution and their relationship
to the landscape is not as clearly defined as that for other
surface waters. Wetland macroinvertebrates and fish communities
are less well documented than those of surface waters and it will
require extensive research to develop community measures using
these organisms. Wetlands are frequently dominated by vegetation
and biological criteria based on vegetative characteristics will
be required.
Biological criteria may also be developed for specific
functional processes. For example, nitrification/denitrification
rates may provide a means of estimating the health of the
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microbiota and this could be related to general wetland health.
Bird indices may provide measures to integrate trophic levels for
wetlands similar to fish community structure and trophic
information for surface waters. Biological criteria will be
necessary components of habitat protection and biological
diversity.
Example Research Needs:
]. Classification of wetlands for determination of
reference sites.
2. Biological assessments of reference sites.
3. Development of biological measures of ecological
integrity.
4. Testing biological criteria over a range of wetland
types.
Aquatic Life Criteria
The existing aquatic life numeric criteria are the primary
surface water effluent regulatory tools. They are generally
chemical specific and are derived using specific test protocols
(Stephan et. al., 1985). There have been questions raised on the
applicability of these criteria to wetlands because of some
important physical, chemical and biological characteristics that
differ between wetlands and many other surface waters.
Differences which have caused concern include a wider pH range,
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higher organic carbon content, water level fluctuations ranging
from flooded to dry, a different faunal composition, and a
biomass dominated by higher plants.
Because of the complexity of deriving the numeric criteria
and water quality differences between many surface waters and
wetlands, it is important that the numeric criteria be carefully
evaluated before they are indiscriminately applied to wetlands.
An initial evaluation of the application of numeric criteria to
wetlands was done at the Environmental Research Laboratory-
Duluth, MN (ERL-Duluth), by Hagley and Taylor (1990). They
concluded that numeric criteria are probably protective of most
wetland types with standing surface waters. This conclusion is
based primarily on the methodology used in the derivation of
numeric criteria. The testing is designed to maximize the
toxicity to the test organisms; the tests create conditions where
toxicity is most likely to be expressed. Many of the physical
and chemical conditions present in the wetlands would likely
reduce the predicted toxicity as determined by the laboratory
bioassays. For example, the high dissolved carbon content in
wetland waters would likely reduce the toxicity of many nonpolar
organic substances. Where there are questions on the application
of the existing numeric criteria, it is suggested that the
existing site-specific guidelines may provide options for
adjustment. These adjustments may be as simple as using
organisms common to wetlands in the criteria development data set
or may in the extreme case involve a complete toxicological
analysis and development of new numeric criteria specific to
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wetlands.
Whole effluent toxicity testing protocols are alsu being
used to regulate surface water quality and could be extended to
wetlands. This procedure uses a standardized toxicity test to
assess effluent quality. An additional tool in this testing
procedure is the toxicity identification evaluation (TIE), a
tiered approach to identify classes of toxicants. However,
before effluent testing and TIE can be applied to wetlands they
will have to be tested using physical and chemical conditions
typical of wetlands.
Example Research Needs:
1. Evaluation of existing aquatic life numeric criteria to
determine their level of protection for wetlands.
2. Toxicological testing to determine if the exposure,
duration and effects of toxicants on wetland organisms
is similar to those of surface water organisms.
3. Development of toxicological testing protocols specific
to wetland macrophytic vegetation.
Hvdroloqic Criteria:
There are no surface water criteria for the protection of
wetland hydrology. Yet in terms of actual wetland impact,
hydrologic change is the agent most responsible for loss. It is
necessary to consider both insufficient and excess water in
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determining hydrologic criteria. With either condition, major
changes in the wetlands will occur. Similarly, it is important
to consider the hydroperiod because its variation will have
serious structural and functional impacts. Hydrology is also
one of the more complex parameters to monitor because it is
necessary to continuously measure both surface and ground water.
Techniques are, however, under development that relate long-term
hydrologic measures, USGS river sampling data, to surface and
ground water monitoring sites.
Because the knowledge and/or tools to develop hydrologic
criteria are only beginning to be developed, it will likely be
necessary to first regulate hydrology through a narrative
criteria framework.
Example Research Needs:
1. Develop a theoretic.il basis for hydrologic criteria.
2. Develop relationships between hydrology and wetland
structural and functional integrity.
3. Develop relationships between hydrology and the effects
of other anthropogenic inputs, i.e., agricultural
chemical runoff.
4. Develop indicators to assess the hydrologic state of a
wetland.
Sediment Criteria
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It is important to manage both wetland sediment quality and
quantity. Excess sedimentation will modify the wetland
hydrology. It is also necessary to judge whether a sediment is
likely to be toxic if organisms become exposed to it because of
normal habitat occupation or through sediment manipulation, e.g.,
dredge and fill activities.
The developmental philosophy for sediment toxicity criteria
is somewhat different than traditional surface water numeric
aquatic life criteria because the sediment toxicity criteria are
being developed for classes of contaminants and sediment types
rather than specific chemicals. An example of this approach
follows. Acid volatile sulfide (AVS) (Di Toro, D.M., et.al.,
1990} concentration in sediment is related to the capacity of the
sediment to retain 'heavy metals. With increasing AVS, the
sediments are able'to retain additional heavy metals. Thus it is
possible to determine the sediment carrying capacity for heavy
metals and to assess whether this capacity is being exceeded.
The AVS analysis also includes a toxicity identification
component similar to the whole effluent testing procedure's TIE.
It is important to define similar relationships in wetlands,
where significantly different redox conditions exist, before it
is presumed similar criteria are applicable.
Example Research Needs:
1. Determination of the effects of alternating sediment
redox conditions on wetland sediment heavy metal
retention.
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2. Verify TIE approaches " toxicant identification for
wetland sediments.
3. Development of procedures relating sediment carbon
content and the toxicity of nonpolar organ:c
substances.
Wildlife Criteria:
Wildlife support is one of the most visible and socially
important wetland functional attributes aid criteria to protect
this are critical.' Existing w.ldlife criteria focus on migratory
waterfowl toxicity but they are being expanded to include
additional avian and mammalian species. Criteria being developed
for wildlife endemic to wetlands should have direct application
to wetland organisms. Wildlife criteria may also represent a
means to establish toxicity criteria for those wetlands lacking
standing water. Wetlands of this type may require criteria more
similar to terrestrial systems; criteria depending on cnemical
body burdens.
Example Research Needs:
1. Development of a toxicity database for wildlife
specific to wetlands.
An
wetland
wetland
important additional consideration in the development
protective criteria will be defining "indicators" of
health. These will provide insight into the wetland
of
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condition without the necessity of extensive process level
invest '.gat xons . Ecoloaic"1 irtegnty could be determined by
measuring sur ogates of vegetation, hydrology, sediment or
macroinvertebrate health. Thio research area is also being
supported by EPA's Environmental Monitoring and Assessment
Program (EKAP) and ORP's Wetland Research Program.
An approach integrating wetland protective criteria into a
larger landscape management philosophy is being developed using
landscape ecology principles (Gosslink et al. 1990). Studies
assessing the importance of wetlands to landscape water quality
improvement are being conducted at ERL-Corvallis. The approach
uses a very general synoptic model which initially focuses or,
mapped data. The model will become more precise as additional
model calibration data becomes available. Data derived while
developing wetlands protective criteria will be an important
model data source. The process will be iterative, the model's
ability to estimate the water quality improvement function of
wetlands on a broad spatial scale will become more precise as
more of the data required for criteria development becomes
available.
CONCLUSION:
Crucial to all aspects of wetland standards and criteria
programs is integration of a variety of approaches into protocol
that protect wetlands. Biological criteria are critical and thei
development is a high research priority. They will be extremely
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important in determining regulatory success and protecting
ecological factors which currently lack protective criteria;
e.g., habitat. Analysis of existing chemical specific numeric
criteria suggests they are probably as protective of wetland
water quality as they are of other surface waters. For those
criteria that are not, existing mechanisms within che existing
criteria development framework need to be evaluated as means to
adjust the criteria. Hydrology is a primary driving variable for
wetlands and criteria to protect wetlands from human induced
hydrologic modifications are critical. It is important to
develop narrative criteria because the experimental frame for
numeric hydrologic criteria is lacking. Research into the
development of sediment and wildlife criteria must include
wetland environmental conditions. To extrapolate from the
protection of single wetlands to the protection of the wetland
resource, further landscape model development is essential.
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BIBLIOGRAPHY
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Di Toro, D.M., J.D. Mahony, D.J. Hansen, K.J. Scotc, A.R. Carlson
and G.T. Ankley. 1990. Acid Volatile Sulfide Predicts The Acute
Toxicity of Cadmium and Nickel in Sediments. Submitted to
Nature, September, 1990.
Gosselink, J.G., G.P. Shaffer, L.C. Lee, D. M. Burdick, D. L.
Childers, N.C. Leibowitz, S.C. Hamilton, R. Boumans, D. Cushman,
S. Fields, M. Koch, and J. M. Visser. 1990. Landscape
Conservation in a Forested Wetland Watershed. Bioscience. Vol.
40, No. 8.
Hagley, C.A. and D.L. Taylor. 1990. An Approach for Evaluating
Numeric Water Quality Criteria for Wetlands Protection. U.S.
Environmental Protection Agency, Environmental Research
Laboratory, Duluth, MN.
Stephan, C.E., D.I. Mount, D.J. Hansen, J.H. Gentile, G.A.
Chapman and W.A. Brungs. 1985. Guidelines for Deriving Numeric
National Water Quality Criteria for the Protection of Aquatic
Organisms and Their Uses. PB85-22"7049. National Technical
Information Service, Springfield, Virginia.
The Conservation Foundation. 1988. Protecting America's
Wetlands: An Action Agenda. The Final Report of the National
Wetlands Policy Forum. The Conservation Foundation, Washington,
D.C.
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U.S. EPA. 1990. National Guidance, Water Quality Standards for
Wetlands. U.S. Environmental Protection Agency, Office of Water
Regulations and Standards, Office of Wetlands Protection,
Washington D.C.
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FIGURE 1
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Physical Disturbance
Habitat
Alteration
Pesticides
Wildlife
Fauna
Flora
Ecological
Integrity
Physical
Environment
Chemical
Environment
Hydrology
Sediments
Water
Quality
Nutrients
Toxicants
Suspended Sediments
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