OFFICE OF RESEARCH AND DEVELOPMENT
National Health and Environmental Effects Research Laboratory
AQUATIC ECOSYSTEMS PROTECTION
Ecocriteria	and We
PROGRESS REPORT
JUNE, 1998

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CONTENTS
Introduction	..	 2
Summary of the Aquatic Ecosystems Protection Research Program 	3
Regulatory and Programmatic Context
Program Goal
Office of Water's Water Quality Criteria Program
NHEERL's Research Strategy
FY97-98 Program Highlights 	 	6
Program Progress
Aquatic Ecocriteria	7
Characterizing Stressors and their Effects
Factors that Control or Modify Aquatic Toxicity
Wetlands 	....		14
Role of Wetlands in the Landscape
Wetland Structure and Function
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INTRODUCTION

The purpose of this report is to communicate progress in the Aquatic Ecosystems
Protection Research Program of EPA's National Health and Environmental Effects
Research Laboratory (NHEERL).

This report contains
•	a summary of the NHEERL Aquatic Ecosystems Protection Research Program,
including an explanation of its regulatory and programmatic context, the overall
program goal, the rationale for the program, and the research strategy;
•	a section that highlights recent key findings (FY97-98 Program Highlights); and
•	a more detailed description of the NHEERL Aquatic Ecosystems Protection
Research Program, by program area, including a summary of recent research
accomplishments and anticipated progress for the near future.
Additional progress reports relevant to this research area include Global Climate Change
(May, 1996) and Ecosystems Protection: Contaminated Sediments (August, 1997).
The format of this report is still evolving, and we welcome comment. Readers with
comments, questions, or requests for further information are encouraged to contact:
Jennifer Orme-Zavaleta, Assistant Laboratory Director
National Health and Environmental Effects Research Laboratory (MD-51A)
U.S. EPA
Research Triangle Park, N.C. 27711
Phone: (919) 541-3558 or FAX: (919) 541-0642
E-mail: ormezavaleta.jennifer@epamail.epa.gov
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AQUATIC ECOSYSTEMS PROTECTION
RESEARCH PROGRAM SUMMARY
Aquatic ecosystems protection is authorized
by the Clean Water Act (CWA), which was
enacted to "restore and maintain the
chemical, physical, and biological integrity of
the nation's waters." Under the CWA, EPA is
required to develop criteria (water quality
criteria, biocriteria, and whole effluent toxicity
tests) that limit pollutants entering lakes,
streams, rivers, estuaries, oceans, and
wetlands. The CWA also authorizes EPA to
conduct research on the harmful effects of
pollutants and other stressors, such as
urbanization, on aquatic ecosystems. This
research is conducted by EPA's Office of
Research and Development (ORD).
ORD's Ecosystems Protection Research
Program is part of a comprehensive, peer-
reviewed ecological research strategy whose
goal is to produce sound scientific data for
conducting ecological risk assessments. The
program is subdivided into the following
components: the Environmental Monitoring
and Assessment Program (EMAP), Ecological
Risk Assessment Methods, Contaminated
Sediments, Aquatic Ecocriteria, and Wetlands
Protection. NHEERL conducts effects-based
research in each of these areas. A progress
report on NHEERL's research on
Contaminated Sediments was completed in
August of 1997, and a report on EMAP and
Ecological Risk Assessment Methods is
forthcoming. The present document com-
bines and discusses NHEERL's research on
Aquatic Ecocriteria and Wetlands Protection,
highlighting some recent accomplishments in
these areas.
To provide sound scientific data that improve
our ability to characterize risks and protect
aquatic ecosystems.
Our Nation's aquatic ecosystems, which are
home to valuable renewable resources, are
threatened by a variety of anthropogenic
stressors and disturbances. Wetlands, for
example, are habitats and spawning grounds
for many fish and wildlife, yet they are subject
to degradation and destruction from chemical
contamination, agricultural development, and
urbanization. In order to protect these
systems, EPA administers federal programs
aimed at limiting pollutants entering surface
waters, preventing ecosystem degradation,
and restoring impaired ecosystems. To assist
in these programs, EPA develops criteria as
tools in watershed management. Under the
water quality criteria program, EPA develops
chemical-specific criteria, biocriteria, and
toxicity assessment methods.
>• Chemical-specific criteria are developed
to protect human health, aquatic life, sediment
quality, and wildlife. The objective of human
health criteria is to protect uses for recreation
and fishing and to protect sources of drinking
water. Aquatic life criteria serve as an interim
goal of water quality for the protection and
propagation of fish and shellfish. Sediment
quality criteria are developed for persistent
toxic chemicals not controlled by water
column criteria. Wildlife criteria address those
pollutants that bioaccumulate in the food
chain, potentially affecting wildlife growth and
reproduction.
>- Biocriteria provide a direct measure of the
condition of the aquatic community of plants
and animals and their response to multiple
stresses, including chemicals, point and
nonpoint sources, and habitat degradation or
loss.
> Toxicity assessment methods include
whole effluent toxicity tests, which assess the
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aggregate toxic effect of an effluent, and
sediment toxicity and bioaccumulation tests,
which provide a direct measure of toxicity and
uptake of bioaccumulative contaminants and
are used to evaluate the hazards of dredged
materials.
To ensure that the Agency is equipped with
scientific and technical data relevant to the
formulation of sound environmental policy,
ORD operates a research program founded
on principles of risk assessment. In the area
of ecological effects, research is conducted in
accordance with EPA's ecological risk
assessment framework, developed in 1992
(Figure 1). This risk paradigm consists of
three fundamental steps that support
ecological risk management decisions:
problem formulation, analysis of exposure and
effects, and risk characterization. NHEERL's
ecological research programs adhere to this
risk-based strategy.
FIGURE 1. Elements of ecological risk
assessment.
Problem
Formulation
Exposure
Effects
Analysis
Analysis
Risk
Characterization
R
E
S
E
A
R
C
H
NHEERL is responsible for conducting
effects-based research within ORD. Our
objective is to develop test methods,
predictive models, and scientific data that
strengthen risk assessment and inform
regulatory/policy decisions. Environmental
effects research is conducted by each of our
ecology divisions: the Mid-Continent Ecology
Division (MED) in Duluth, MN; the Atlantic
Ecology Division (AED) in Narragansett, Rl;
the Western Ecology Division (WED) in
Corvallis, OR; and the Gulf Ecology Division
(GED) in Gulf Breeze, FL.
Our overarching goal for Aquatic Ecocriteria
and Wetlands Protection is to improve the
scientific understanding of aquatic eco-
systems and the impact of stressors on these
systems.1 Our data are meant to ensure the
scientific defensibility of criteria and toxicity
tests and to expand the scientific basis for risk
assessment. In order to include a broad and
representative range of ecological conditions,
habitats, and stressors, we are conducting our
research in strategically chosen watersheds,
such as the Atlantic and Gulf coastal areas
and the Great Lakes.
Two key questions drive our research efforts:
What are the ecological constraints on
aquatic ecosystems, and how do these
constraints affect aquatic organisms and
wildlife?
Under the CWA, EPA is charged with
restoring, maintaining, and protecting the
integrity of the nation's waters and aquatic
ecosystems. The structure and function of
ecosystems is naturally bounded by various
physical, chemical, and biological constraints
(e.g., temperature, nutrients, predators). Our
hypothesis is that stressors interact or modify
the constraints on ecosystems. Developing
approaches to determine constraints on
aquatic ecosystems will help create a
mechanistic foundation for identifying
sensitive systems and diagnosing causes of
impairment.
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How do we characterize the relationship
between a stressor and ecosystem
response?
Aquatic ecosystems are subject to a complex
and dynamic array of physical, chemical, and
biological stresses that affect the ability of
systems to withstand or recover from insult
(ecosystem sustainability). A major area of
uncertainty in our understanding is the
relationship between stressor and response.
A mechanistic understanding of this
relationship is essential for making realistic
predictions of responses to chemical,
physical, or biological stressors. Stressor-
response relationships can be affected by any
number of variables. Characterizing these
relationships leads to a better understanding
of the basis for aquatic toxicity, leading to
more informed and rational regulatory
decisions.
An important aspect of ecosystems protection
research is defining current ecosystem status and
attributes of ecosystem "health." Much of this work falls
under our Environmental Monitoring and Assessment
Program (EMAP), a comprehensive, nationwide
monitoring program designed to describe the condition
of our nation's ecological resources. EMAP, along with
our program in Ecological Risk Assessment Methods-
which focuses on the development of test methods for
use under the Toxic Substances Control Act (TSCA)
and the Federal Insecticide, Fungicide, and Rodenticide
Act (FIFRA)--will be featured in separate progress
reports and will not be discussed here.
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AQUATIC ECOSYSTEMS PROTECTION
FY97-98 PROGRAM HIGHLIGHTS
Our senior ecology management and scientific staff organized an eco-planning meeting in
June, 1997, to develop a conceptual approach forNHEERL's aquatic ecosystem research.
An Aquatic Ecosystem Protection Research Strategy is currently under development.
•	During FY97, we completed our report of a ten-year research effort on the effects of low
dissolved oxygen on coastal and estuarine species in the Virginian Province. This research
led to the development of limits on dissolved oxygen exposures.
•	In October of 1997, we hosted an interagency workshop on harmful algal blooms (HABs) to
discuss major uncertainties surrounding the cause and the effects of HABs and their
relationship to human health and ecosystem vitality. We are the only ORD Laboratory with
an in-house program on HABs, and GED is leading the development of the ORD Research
Strategy for HABs.
•	GED has established an experimental research facility in Gulf Breeze which will be one of
only a few laboratories in the U.S. dedicated to harmful algal bloom research. It will be the
focal point for controlled studies of HAB toxin production and effects on aquatic animals.
In studies of the uptake and bioconcentration of TCDD by aquatic species, we have shown
1) that benthic invertebrates can accumulate high concentrations of TCDD with no toxic
effects and 2) that the bioconcentration factor of TCDD in some fish is considerably higher
than previously reported; Both of these findings have implications for the transfer and
biomagnification of TCDD through aquatic food webs.
•	We reported on the condition of Gulf of Mexico estuaries.
•	We currently are writing the draft update to the previous (1984-1985) freshwater aquatic life-
criterion for ammonia.
We are in the final stages of developing a Nitrogen Research Plan, which targets ORD's
response to concerns regarding nitrogen pollution and its environmental effects.
In separate studies, we have associated land use and hydrology or hydrologically related
functions: we showed that landscape modifications in urban areas--in particular, the
construction of impermeable surfaces-affects both wetland water levels and habitat function.
•	In April, 1998, GED hosted a workshop on wetlands research in which the regulatory and
Administration needs outlined in Vice President Gore's Clean Water Action Plan were
discussed. NHEERL is a key figure in studying the role of wetlands in the landscape.
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AQUATIC ECOSYSTEMS PROTECTION
PROGRAM PROGRESS
Our research in Aquatic Ecocriteria is
designed to achieve a better understanding of
stressors and their effects. There are three
important steps to this process. The first is to
identify and characterize the stressors, which
helps diagnose causes of ecosystem
degradation. Much of our effort in this area
focuses on the over-enrichment of aquatic
ecosystems by nitrogen and phosphorus
(from sources such as fertilizer runoff); when
these nutrients exceed normal levels, they
can overburden ecosystems, resulting in
undesirable eutrophic effects. The second
step of the process is to characterize the
response of aquatic ecosystems to stress.
Our research in this area involves the
development of test methods for assessing
ecotoxic effects in aquatic organisms-and the
design and application of models for
predicting the response of entire ecosystems
to stress. As part of this effort, we develop
and maintain the toxicity databases ECOTOX
and EVISTA, which are useful sources of
information on aquatic effects caused by
chemical contaminants. The final step in
understanding stressors and their effects is
the study of factors that control or modify
aquatic toxicity. We are studying factors both
internal and external to the organism, such as
contaminant bioavailability, bioaccumulation in
the food chain, and wafer temperature. This
information helps us understand the basis for
toxicity and enhances our ability to interpret
the ecological significance of toxicity test
results.
CHARACTERIZING STRESSORS AND
THEIR EFFECTS
Historical Reconstruction. One way in
which we are diagnosing the cause(s) of
degradation within aquatic ecosystems is by
reconstructing stressor input. In the early
1990s, we examined historical changes in
stressor inputs to an urban estuary,
Narragansett Bay. Our objective was to
determine how these stressors may have
contributed to current ecosystem status. We
focused on organic contaminants, and our
experimental approach was to characterize
contaminant input by constructing a sediment-
ary record. We collected and analyzed
sediment cores, and then developed a mass
balance model by comparing sedimentary flux
estimates with directly measured inputs. Our
results, published in FY96, established a
"reference state" for this estuary. From these
data, we have been able to evaluate the
current ecological integrity of the system and
better understand anthropogenic impact. We
intend to use this information to assess future
impact to the estuary.
Laboratory and Field Studies:
Eutrophication. In. addition to analyzing
historical trends, we are characterizing
stressors and their effects by conducting
controlled laboratory experiments and field
studies. We are especially interested in
eutrophication. Undesirable eutrophic effects
include harmful algal blooms, which can lead
to both ecological and human health effects,
and hypoxia (oxygen depletion), which can
result in fish kills. An important aspect of this
problem is the relationship between nutrient
levels, water quality (as measured by such
endpoints as dissolved oxygen and light
transmission), and biota (e.g., phytoplankton
communities).
In studies of coastal eutrophication in the
northeast, AED scientists have conducted
field and microcosm experiments in the
Chesapeake Bay in order to better
understand nitrogen and phosphorus inputs
and cycling. During FY95, we analyzed
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annual input-export budgets for total nitrogen
and phosphorus for the Chesapeake Bay and
several of its tributaries and found that direct
relationships exist between annual rates of
nutrient input, water-column and sediment
nutrient stocks, and nutrient losses via
denitrification and burial in sediment. We also
identified sources of major uncertainty in the
data, such as estimates of atmospheric
deposition, contributions of nutrients via
groundwater, and sediment rates used to
calculate nutrient burial rates. We confirmed
the findings of an earlier published report
showing significant regional degradation due
to hypoxia.
In the southeast, problems with nutrient
enrichment in Gulf of Mexico estuaries
prompted the formation of a coastal
eutrophication research team in GEO. The
team's goal is to understand eutrophication
and its effects in Gulf estuaries and off-shore
waters. The first step was to assess current
conditions in Gulf estuaries in order to
establish baseline data and acquire the
necessary information for designing field and
lab experiments. This assessment was
carried out during FY96-97 in Escambia and
Pensacola Bays and the freshwater systems
of the Escambia River watershed. Various
measures of water quality (dissolved oxygen,
pH, salinity, temperature, and light penetra-
tion), sediment quality, biotic resources
(phytoplankton abundance, diversity, and
productivity) and nutrient levels (ammonia,
phosphate, nitrate and nitrite) were recorded.
From these data, we developed an overview
of ecological conditions for each ecosystem.
Using GIS-based landscape analysis, we
estimated potential nutrient enrichment
scenarios, and in FY97 we began to study the
effects of nutrient enrichment from nitrogen
and phosphorus. Initial experiments were
conducted in the laboratory. Changes in
phytoplankton biomass in response to nutrient
enrichment were measured. Corresponding
field studies on phytoplankton in Gulf
estuaries are currently underway, and. in order
to perform these studies, we have had to
develop and apply specialized field
techniques. We have found that phosphorus
is the limiting nutrient in brackish waters, while
nitrogen is the limiting nutrient at higher
salinities. Using the Escambia River water-
shed and other Gulf estuaries as model
systems, we are developing simulation
models to relate eutrophication potential with
phytoplankton grazing. Preliminary evidence
from these models suggests that both
nitrogen and phosphorus may be required to
elicit phytoplankton growth, and the ratio of
the two nutrients may be an important
controlling factor in predicting response to
eutrophication. Our future plans are to
examine changes in community structure and
function in response to increases in nutrient
loading using higher levels of biological
organization (benthos, fish species, sub-
merged aquatic vegetation, and corals). We
also intend to develop a nutrient dynamics
model for the Pensacola Bay ecosystem that
can be used to assess nutrient cycling, to
predict the effects of nutrient enrichment on
selected endpoints, and to evaluate different
management or mitigation scenarios.
Another component of this project is the
investigation of specific instances of Gulf
coastal eutrophication in real-world settings.
For this study, we selected a hypoxic zone in
the Louisiana Delta and monitored key
endpoints (hypoxia, loss of habitat, increases
in phytoplankton blooms, and changes in
productivity) to assess the effects of nutrient
enrichment. Results in the field were
compared to results obtained in the laboratory
through controlled studies in highly special-
ized and unique experimental facilities.
Through these combined studies, the critical
features of the dissolved oxygen (DO) cycle
were ascertained and mimicked in the lab. In
FY96, the team developed requirements for a
marine DO criteria by relating field
observations with laboratory investigations of
DO tolerances in fish and shellfish. This type
of "real-world" analysis will provide significant
information for determining the crucial break-
points in observed DO regimes that result in
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continued sustainability or loss of vital
habitats. This information will be useful in
setting an ecologically defensible DO criteria.
Another NHEERL Division studying DO and
its relationship to hypoxia is AED. During
FY97, AED completed its report describing a
ten-year research effort on the effects of low
DO on coastal and estuarine species in the
Virginian Province (a region between Cape
Cod, MA, and Cape Hatteras, NC). The
report describes an approach for deriving DO
protection limits that can be applied to other
coastal regions. Our research led to the
development of a minimum DO limit that
provides protection for survival for short time
periods, and a higher value that provides
protection for growth should hypoxia continue
for longer time periods. In developing these
limits, we broke new ground by emphasizing
population effects and by addressing
intermittent as well as continuous low DO
exposures. These data currently are being
evaluated by the Office of Water for possible
adoption as aquatic life criteria.
Laboratory and Field Studies: Harmful
Algal Blooms (HABs). Our research efforts
in eUtrophication are rapidly expanding as we
begin to conduct research on HABs, which
are thought to be related to nutrient loadings
of aquatic systems. In. October of 1997, we
hosted an interagency workshop on HABs to
discuss uncertainties surrounding their
formation and their effects. Identification of
HAB species, characterization and detection
of toxins, and bioom dynamics and control
were discussed. We are helping define the
Agency's research priorities within the context
of a national research strategy, and we are
preparing ORD's Research Strategy for
HABs. This Strategy will be closely linked to
an interagency plan for studying HABs and
the recently identified dinoflagellate,
Pfiesteria.
In FY97, GED began developing an
experimental culture and exposure facility to
produce and maintain viable stock cultures of
principal HAB species. As one of only a few
laboratories in the U.S. dedicated to HAB
research, this facility will be the Agency's focal
point for controlled laboratory studies of
HABs. Our plans are to use this facility to
conduct studies of algal toxin effects on
aquatic organisms and to develop a rapid
response capability to monitor algal blooms in
the Gulf of Mexico. In order to monitor HABs,
GED was awarded an Advanced Monitoring
Initiative that will be used to demonstrate the
application of a satellite-mounted SeaWiFS
(Sea-viewing Wide Field-of-view Sensor).
Through cooperative field and monitoring
studies,, we will determine whether HAB
outbreaks can be predicted, and if so, what
parameters or diagnostic indicators are
relevant.
Included in future studies of HABs will be
investigations of the phenomenon known as
"red tide" and studies of Pfiesteria and
"PfiesteriaAike" dinoflagellates. Pfiesteria, a
newly, discovered organism, has been
associated with fish lesions, fish kills, and
human health effects, such as learning and
memory problems. Our Neurotoxicology
Division has already completed research on
rodents exposed to Pfiesteria in order to study
neurobehavioral effects; we found that
Pfiesteria did indeed impair learning and
memory. Our plans are to also study
neuropathological effects and cardio-
pulmonary function. Ecological investigations
are. underway in GED, where we are
conducting a histopathologicaj evaluation of
fish taken from the Pocomoke River during a
Pfiesteria outbreak. Work has been initiated
to refine electron microscopic techniques
required to conclusively identify these
armored dinoflagellates. In the near future,
we will focus efforts on HAB growth dynamics,
the impact of environmental factors on the
chemistry and effects of HAB toxics, and
prevention and mitigation strategies.
Model Development: Great Lakes. The
objective of this project is to develop a suite of
models that can predict responses of large
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aquatic ecosystems to stressors. These
models should also be useful in diagnosing
potential causes of system degradation. This
is a multi-partnership project in which
members are working together to develop a
mathematical modeling framework to predict
response to chemical and biological stressors.
The Great Lakes have been chosen as the
ecosystem for study, and several major issues
are being investigated, including loss of
biodiversity, loss of habitat, persistent toxic
contaminants, and eutrophication.
Over the last decade, NHEERL investigators
have developed a series of computational
models that address increasingly complex
ecosystem components: in the late 1980s, we
designed a suite of models for tributaries.and
connecting channels; in the early 1990s, we
developed models for large embayments; and
currently, we are developing predictive
models for an entire Great Lake. The corner-
stone of our current research is the Lake
Michigan Mass Balance Project, in which we
are linking models for eutrophication,
sediment transport, bioavailability, and food
web bioaccumulation in order to describe
toxic chemical cycling in Lake Michigan. We
recently applied our models to a persistent
toxic contaminant, polychlorinated biphenyls
(PCB). Although a complete account of this
study is still being compiled, our model
simulations predict that PCB concentrations in
walleye fish populations will not fall below the
human consumption target level for over 20
years. We have concluded that PCB
concentrations in fish, benthos, and birds-
along with the effects associated with these
contaminants-will be most effectively
improved by sediment remediation. In
response to these findings, the Wisconsin
Department of Natural Resources is finalizing
strategies for the remediation, of sediment
deposits in the lower Fox River. We are now
turning our attention to trans-nonachlor,
atrazine, and mercury. In FY99, we intend to
complete our Lake Michigan mass balance
model for atrazine, which will improve the
characterization of the effects of . atrazine on
this aquatic ecosystem. In the future, we will
develop an ecosystem productivity model and
attempt to integrate productivity and foodweb-
based bioaccumulation models to relate
stressors and effects.
Toxicity databases. EPA and others need to
have access to toxicity information for use in
predicting the effects of chemical stressors
and for developing water quality criteria. MED
has been instrumental in the development
and maintenance of in vivo toxicity databases
for almost 20 years. The ECOTOXicology
database, or ECOTOX, is the most
comprehensive database of toxic effects
information available, with over 228,000
records for more than 7300 chemicals and
4100 aquatic and terrestrial species. More
than 950 government clients are registered to
use ECOTOX. It is comprised of three
separate databases: AQUIRE, PHYTOTOX,
and TERRETOX. These contain toxic effects
data for aquatic animals and plants, terrestrial
plants, and terrestrial animal species,
respectively. In order to assist in the
interpretation of these aquatic toxicity test
results, we have developed EVISTA
(Evaluation and Interpretation of Suitable
Tests in AQUIRE). EVISTA is designed to
facilitate the derivation of water quality criteria
and benchmarks by providing guidance for
evaluating test results. Our current efforts are
focused on the continued maintenance and
expansion of these databases as new test
data become available.
Ecotoxic effects in aquatic organisms.
During FY95-96, NHEERL scientists
conducted numerous studies to improve our
ability to evaluate adverse effects in aquatic
organisms exposed to toxic contaminants.
The following examples illustrate our efforts in
this area. We developed a single-cell gel
assay designed to detect DNA damage in the
cells of marine organisms, which enhances
our understanding of how chemical stressors
affect genetic systems. We assessed the
statistical performance of the amphipod
mortality test, which provides a point of
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departure for determining ecologically relevant
response from a population perspective. We
related neoplasms in fish from the
Chesapeake Bay to PAH exposures. We
found evidence implicating a parasite in the
symptomatic appearance of withering
syndrome, a devastating disease in
California's black abalone. We evaluated the
toxic effects of metals and organic chemicals
to brown cells in commercially harvested
clams. We studied the toxicity of Malathion
and copper to mussels at different stages of
development, and we analyzed stress protein
accumulation in various tissues of mussels
following exposure to chemical contaminants.
(These studies in mussels are enabling us to
identify tissue systems most susceptible to
damage from particular chemical stressors.)
We evaluated the chronic effects of the
herbicide diuron on wetland and riparian
species of the Pacific Northwest and found a
general decrease in growth--and increase in
mortality and deformity~in frog embryos
exposed to 20 mg/L diuron, with similar
effects in fish and invertebrates. We
developed a method for modeling aquatic
toxicity data based on the theory of
accelerated life testing, which reduces the
amount of toxicity testing required. to
characterize the chronic effects of chemicals.
(In FY98, we plan to have software available
for this model and a user's guide for
estimating chronic aquatic toxicity based on
acute toxicity data.) We determined optimal
temperature and salinity ranges for mysid
shrimp, which will be used to increase
culturing efficiency and to develop more
reliable test methods for this important test
species. We studied the life history
characteristics of the inland silversides, a
species of fish used to evaluate the toxicity of
marine and estuarine waters, and found
evidence of size-selective mortality; this
information is being used in population
models to evaluate the significance of larval
growth endpoint responses measured in the
standard inland silverside toxicity test. We
used inland silversides to evaluate the toxicity
of fuel oil, fuel oil dispersants, and fuel
oil/dispersant mixtures and found that the fuel
oil/dispersant combination was the most toxic,
followed by the dispersants. Collectively,
these data provideoiseful information on the
ecotoxicity of aquatic contaminants.
Whole effluent toxicity tests. During FY95-
96, we assessed the acute and chronic
toxicities of ten effluents discharged to near-
coastal areas in Northwest Florida. Our goal
was to assess the ability of a variety of toxicity
tests to differentiate effluent-specific effects.
We included standard toxicity test organisms
(two vertebrates, two fish, and two algal
species) and four non-standard toxicity tests
(three rapid bioassays and an early seedling
growth toxicity test). Our results illustrate the
importance of using invertebrates, especially
algae, as test species for coastal estuaries of
the Gulf of Mexico: seven of the ten effluents
were photostimulatory to algae. We also
compared results from three toxicity tests
(embryo toxicity/teratogenicity test with inland
silversides, the Microtox® acute toxicity test,
and the Ceriodaphnia chronic toxicity test)
and found that all three were predictive of
effluent toxicity. Finally, we have investigated
the relationship between effluent toxicity,
ambient toxicity, and .receiving water impacts
in freshwater and marine environments, and
our results have improved our understanding
of how waste effluents can modify biological
structure in rivers and estuaries.
FACTORS THAT CONTROL OR
MODIFY AQUATIC TOXICITY
Bioavailability and bioaccumulation. We
are focusing our efforts on metals and
persistent organics, which do not readily
degrade and may bioconcentrate or
biomagnify in the food chain.
Metals. NHEERL researchers have been
instrumental in demonstrating the effect of
acid volatile sulfide (AVS) on the bioavail-
ability of metals in the aquatic environment.
We have shown that AVS concentrations can
be used to predict bioavailability and toxicity.
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These important findings are related to our
research program on Contaminated
Sediments, and a more detailed discussion of
this research can be found in a progress
report on Contaminated Sediments distributed
in August of 1997.
Another variable affecting metal bioavailability
and toxicity is speciation. During FY95, we
found that the bioavailability (and toxicity) of
trace metals in surface waters is dependent
upon the physical and chemical form of the
metal. This fundamental understanding of
chemical speciation has important
implications that are being applied to derive
site-specific water quality criteria and
standards similar to those used to permit
effluents. During FY97, we demonstrated that
humic acid reduces the bioavailability and
trophic transfer of copper, which has
important implications for interpretation of
loadings data and effects levels of metals.
Organics. Chlorinated organics are known to
persist in the environment and bioaccumulate
in aquatic organisms. It is difficult to
accurately predict the toxicity of these
compounds without some knowledge of the
extent to which they bioconcentrate.
Therefore, in FY96, we studied several
chlorinated contaminants (chlorinated
benzenes, chlorinated butadienes, and hexa-
chloroethane) and measured their
bioaccumulation factors in blue crabs and
three estuarine fishes. These measurements
provided useful information for relating
environmental concentrations with toxicity.
We also are focusing our efforts on the
uptake and metabolism of chlorinated
organics, which represent key uncertainties in
estimating bioavailability and toxic effects.
During FY95, we investigated the uptake of
dioxin (TCDD) by lake trout embryos and
found little difference in dose-response
relationships based on route of exposure
(maternal transfer to oocytes, waterborne
exposures, or direct injection of fertilized
eggs). During FY96, we discovered that the
uptake of nonplanar PCB congeners by blue
mussels is similar to the uptake of coplanar
PCB congeners, opening up the possibility of
substituting the more easily measured and
less .costly nonplanar PCB analytes for the
more difficult and costly coplanar compounds
in PCB risk assessments. We also observed
that metabolism of PCBs by marine
organisms results in changes in the pattern
and abundance of PCB congeners not only in
the organism, but in water and sediment as
well.
Scientists in GED are developing a simple
test method, using bacteria, to quickly and
precisely determine the bioavailability of
organic contaminants. Efforts are underway
to insert a lux gene into bacterial cells which
will enable the cells to emit small, but
detectable, quantities of light when internal
cell components are exposed to specific
chemicals (or classes of chemicals, such as
PAHs). In addition to indicating bioavailability,
this simple test would assist in determining
the amount of bioavailable target compound
in the environmental medium.
Models. MED is developing physiologically-
based toxicokinetic (PBTK) models to predict
the uptake, disposition, and elimination of
organic chemicals and metals by aquatic
organisms. These models are being
developed in several fish species (trout,
catfish, fathead minnow, and medaka) using
various routes of exposure, including the gills
(branchial), the skin (dermal), and diet. Prior
to FY95, during the first phase of this
research, we developed a three-dimensional
technique for visualizing data generated by
the toxicokinetic models. The technique uses
supercomputers to provide a rapid and easily
understood representation of complex toxico-
kinetic modeling results. During FY95-96, we
combined this technique with in vivo
experiments in fish to model the behavior of
waterborne chloroethanes. We developed an
exposure system capable of separating the
dermal and branchial exchange surfaces, and
we developed a means of simultaneously
sampling blood and expired water- We found
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that while dermal uptake rates were greater in
larger fish (channel catfish vs. rainbow trout),
the dermal route of exposure was actually
relatively unimportant in these fish relative to
branchial uptake. Metabolism research is in
its planning stages and will be directed toward
modeling the rates of parent compound
disappearance and the formation of biotrans-
formation products. Our initial efforts, using
standard laboratory test species, will focus on
developing the necessary state-of-the-art
techniques to identify and measure parent
chemicals and their metabolites in blood,
urine, bile, gill water, and major organs. One
promising approach for measuring the rate of
formation of metabolic products in real time
involves the use of microdialysis, a technique
we developed in the early 1990s. In the
future, we intend to develop PBTK models for
other vertebrates, such as amphibians.
Food web interactions. Food web
interactions are a fundamental concern when
predicting potential toxicity. Several of our
studies have shown that bioaccumul&tiori of
contaminants in the food chain may be
greater than previously thought. In FY95, our
study of the uptake of TCDD by medaka (a
fish) demonstrated a bioconcentration factor
of over 500,000. This figure is considerably
higher than that previously reported for this
compound, and it suggests a greater risk from
accumulated TCDD than previously
estimated. In FY96, we found that benthic
invertebrates can accumulate high concentra-
tions of TCDD (over 9500 ng/g lipid) with no
toxic effects. This may have repercussions at
higher trophic levels because it may permit
TCDD to be transferred-and biomagnified--
through aquatic food web's to potentially
sensitive vertebrate species.
In an effort to improve estimates of bio-
accumulation at different trophic levels, we
have conducted research that distinguishes
between low and high trophic levels. In FY95,
we quantified contaminant concentration and
histological effects in bivalve species,
providing an important link between chemical
inputs and bio log foal effects in lower trophic
levels of the food chain. At higher trophic
levels, we investigated the uptake of
contaminants in turtles, seals, and dolphins,
integrating the effects of fower-level impacts.
In addition to issues of bioaccumulation,
effects due to changes in the food web should
be considered when interpreting laboratory
toxicity test results. In studies examining the
effect of pesticides on fish growth conducted
in FY95, we found that diflubenzuron (used to
control gypsy moths) caused reduced growth
in bluegills. The effect, however, was not due
the direct toxicity of the pesticide; instead, it
was due to reductions in preferred insect prey
caused by pesticide application. These
findings imply that effects on ecosystems may
occur at chemical concentrations lower than
those expected based on direct laboratory
toxicity data, and it underscores the need to
understand the ecological mechanisms by
which effects occur.
Water quality characteristics. During FY95-
96, our studies of water quality showed that
characteristics such as pH, hardness, and
dissolved organic carbon can affect the
toxicity of aquatic contaminants in ways not
previously understood. Temperature also
affects the habitat and biology of freshwater
species. In a study conducted in FY95, we
predicted the effects of changing water
temperatures on the distribution of 57 species
of freshwater fish. We utilized an extensive
database of field measurements to estimate
fish temperature tolerance and predict the
effects of rising temperatures on fish
distribution. We found that redistribution of
fish species may be a major impact of
temperature shifts, such as those that could
occur with global climate change. These field
measurements were then used to develop a
model that simulates fish habitat in lakes and
streams, as defined by temperature and
dissolved oxygen concentrations. This model
is being used to predict the effects of rising
temperatures on habitat.
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In another study of water temperature
conducted during FY96-97, we conducted
temperature preference experiments using'
species indigenous to the wetlands and
riparian areas of the Pacific Northwest (frogs,
toads, salamanders, and turtles). These
studies were performed in exposure
chambers in which cameras recorded the
location of animals in response to an array of
temperatures. Preliminary results indicate
that for some species, animals position
themselves at only one or two temperatures,
indicating selection of specific temperatures.
Our plans are to create a response database
sufficient to establish water quality require-
ments for protection of these species.
We also are investigating the ways in which
temperature may affect invading species. We
are presently studying ruffe, a species
recently introduced to the Great Lakes, and
are examining the influence of temperature on
hatching and development. Our findings will
assist efforts to develop control or prevention
strategies for these species.
Another water quality parameter of impor-
tance to the health of aquatic ecosystems is
sedimentation. During FY95-96, two of our
divisions analyzed the physical condition of
rivers and estuaries by modeling sediment
transport. Scientists in AED developed an
innovative technique for modeling coastal
sediment transport, and investigators in MED
developed a model to predict the transport of
fine-grained sediment in the Buffalo River.
Both of these models successfully predicted
sediment transport, which improves our
understanding of the physical drivers of
aquatic ecosystems.
Another important area of uncertainty lies in
our understanding of wetlands, which form the
interface between terrestrial and aquatic
ecosystems and therefore have a large
influence on the landscape. Through
theoretical, empirical, and field studies,
NHEERL investigators are evaluating the
functional roles of wetlands in providing
habitat and in regulating water quality and
hydrology. A variety of stressors that
contribute to wetlands degradation are being
studied, including hydrologic modification,
physical alteration, sedimentation, nutrient
loading, and toxic contaminants. Relation-
ships that affect wetland function, such as
urbanization, are also being examined.
Research is being conducted at the scale of
watersheds and ecoregions. We are using
the information from these studies to develop
models that enable us to more effectively
predict the impact of stressors on aquatic
ecosystems and determine likely causes of
adverse effects.
ROLE OF WETLANDS IN THE
LANDSCAPE	
Our research in this area focuses on defining
the role of wetlands in the landscape and
understanding the ways in which stressors
affect these roles. Our goal is to better
understand landscape processes and
characteristics critical to establishing and
maintaining wetlands. Because controlled
studies at the landscape level are difficult to
execute, we conduct theoretical investigations
and empirical analyses in addition to our field
studies.
Theoretical investigations. Research by
investigators in WED has led to the
development of a method enabling us to
assess multiple stressor impacts to wetlands
in a landscape setting. The method is
referred to as a synoptic approach, and it
produces landscape-level assessments of
wetland functions and land-use impacts.
Developed in the early 1990s, this approach
uses indicator data and Best Professional
Judgment to assess the relative condition,
landscape effects, and restorability of wetland
functions across a broad spatial area at a
given time. The main product of the synoptic
assessment is a spatial map showing relative
values of the indicators across the landscape.
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In order to make these results more
meaningful to resource managers, we
developed a theoretical model (called
Qualitative Structural Equation Modeling, or
QSEM) that can provide a systematic
appraisal of these values and assess the
effects of human activities at the landscape
scale. During FY96, we used this model to
calculate landscape-level effects of land use
activities on wetlands and to assess the
effects of changes in network structure due to
changes in the hydrologic flow regime.
Currently, we are in the process of conducting
a synoptic assessment of the Prairie Pothole
Region, which will serve as a case study of
how this approach can be used to address a
realistic management problem. The method
is proving to be a powerful tool for predicting
cumulative impacts to wetlands, and it can be
applied to regional prioritizations of
environmental issues.
Empirical analyses. We presently are
involved in a collaborative study with the U.S.
Geological Service (USGS) to examine the
relationship between stream water quality and
regional hydromorphology within coastal plain
freshwater wetlands. The Delmarva
Peninsula in Delaware was selected for study
because of problems with nonpoint source
pollution in Delaware Bay. Our most recent
data suggest that riparian buffers may not.
always provide water quality benefits; instead,
their function may depend on landscape
factors, such as regional hydrogeo-
morphology. In FY99, we plan to release a
report oh our hydrogeologic assessment of
the water quality function of these wetlands.
In another study of riparian vegetation,
conducted along the Willamette River in
Oregon, we have used aerial photographs to
link the establishment of riparian forests to
processes of floodplain formation. Using
photographs taken from 1936-1996, WED
scientists examined processes leading to the
establishment of black cottonwood forests
along the Willamette. We discovered that
mid-channel gravel bars and islands that
eventually coalesce with riverbanks are
necessary in providing the cottonwoods a
place to grow. Evaluation of the river over
time indicated a de.crease in the formation of
islands and mid-channel bars due to the
construction of reservoirs on tributaries
upstream. Our findings suggest that efforts to
maintain or enhance riparian forests along the
Willamette River should focus on restoring
floodplain formation that fosters the
establishment of early successional stages of
riparian forests.
Field studies. Several field studies of
wetland-landscape interactions are being
conducted by NHEERL investijgators,
including one in Ndrth Dakota in which we are
examining the scales at which interactions
occur, specific to hydrologic response. We
monitored ten wetland sites in the Prairie
Pothole Region during 1995 and found that
there is a strong similarity between the
hydrographs for a given location and the
responses of water level to storm events.
This suggests that surface water hydrology in
prairie pothole basins is controlled by global
(landscape), rather than local (basin), factors.
If true, this would greatly simplify hydrologic
monitoring of prairie wetlands; To test our
hypothesis, we plan to develop regional
hydrographs and precipitation curves, using
them to describe differences in individual
wetland hydrographs as a function of local
deviations from regional precipitation or local
basin characteristics. During FY96-97, we
gathered additional field data in this region in
order to study temporal variability, and we are
including an additional land use (grassland vs.
cropped) in our study.
We also are conducting a field study in the
Pacific northwest. This project, which was
initiated in FY95 by WED, is evaluating the
functional attributes of riparian habitats. Pilot
studies were conducted in 16 alcoves along a
53 km stretch of the Willamette River, where
a variety of physicochemical characteristics
were measured. An analysis of the data
uncovered the role of these riparian zones in
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determining nutrient and chemical flux from
agricultural lands to aquatic ecosystems. We
reported in FY96 that groundwater flow from
surrounding agricultural sites combine with
physical factors to determine attributes of
these habitats. We plan to apply our findings
from these off-channel sites to restoration
activities.
Integrated studies. MED is integrating
results from models and field studies in a
comprehensive study of wetland-landscape
interactions. The study is designed to assess
the degree to which landscape patterns (e.g.,
forest fragmentation) affect the sustainability
of aquatic systems within a series of
watersheds. The role of inland wetlands in
mediating effects is a critical variable being
addressed. The focus of our research is the
Great Lakes, and emphasis is being placed
on developing a watershed/landscape
classification scheme for use in ecological risk
assessments. The field studies involve sites
along streams draining into the western arm
of Lake Superior. Watersheds of different
hydrogeomorphic characteristics were
selected based on gradients of land use
fragmentation and wetland coverage. Our
assessment endpoints include hydrdlogy,
sedimentation, water quality, nutrient
transport, and biotic community structure and
function in streams. In FY95 we reported that
water quality characteristics (turbidity) and
land use characteristics (degree of
urbanization) influence the distribution of fish
populations, which is important to the health
of fish communities in the Great Lakes.
Ultimately, this research will be used as a
case study to test a conceptual model of
watershed sensitivity that could serve as a
basis for watershed classification throughout
the Great Lakes region. In FY98, in an effort
to guide future research in this area, we
conducted a workshop on watershed
management issues and research needs for
the western arm of Lake Superior.
Our research is also aimed at understanding
the functional linkages between ecosystem.
components within watersheds. During FY95,
we evaluated the temporal and spatial
variability of important water quality
parameters in urban wetlands of the
Minneapofis/St. Paul metropolitan area. We
found that the effects of physical disturbances
on wetland water quality were related to
wetland characteristics and surrounding land
use. In another study, conducted in FY96, we
found that the vulnerability of aquatic
ecosystems depended in part on the location
of the system within a watershed and that
differences in hydrology, terrestrial vegetation,
and land use were important factors in the
potential impact of global climate change.
(This research is finked to our Global Climate
Change Research Program.)
During FY98, a report was completed on the
effects of agricultural stressors on wetland
function in the western Combelt ecoregion.
Reports describing the results of studies in
the Prairie Pothole Region are under
preparation.
Finally, we are planning two new studies to
assess the ecological condition of wetlands in
the Juniata River watershed of Pennsylvania
and the Nanticoke. River watershed of
Delaware and Maryland. These studies are
sponsored by EMAP in cooperation with EPA
Region III and the states of Maryland,
Delaware, and Pennsylvania, and they will be
discussed in greater detail in the progress
report for EMAP.
WETLAND STRUCTURE AND
FUNCTION
NHEERL investigators in several ecology
divisions are studying the biological, chemical,
and physical relationships that dictate wetland
function. Results are being used to develop
biological criteria for wetlands and test
indicators of wetland function. Individual
wetlands (or small groups of wetlands) are
emphasized, and we are characterizing
processes that contribute to wetland
functions, wetland responses to environ-
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mental stressors, and wetland assimilative
capacity.
Urban-induced degradation. In collabor-
ation with the University of Massachusetts, we
are investigating the effects of impervious
surfaces, such as roadways, on wetlands.
Wetlands in the Connecticut River Basin were
assessed during FY96, and preliminary
results suggest that the habitat function of
wetlands is affected by the amount of
impervious surface in the watershed. We are
expanding this study in an attempt to develop
specific biological indicators capable of
quantifying the impact of increased
impervious surface on the ecological integrity
of wetlands. As part of this process, we are
exploring the response of bottom-dwelling
organisms to changes in sedimentation rate
and water quality.
In another project, we are examining the
effects of urban-induced degradation on
wetlands in the metropolitan area of Portland,
OR. Our goals are threefold: 1) to document
the effects of urbanization on wetland
structure and function, 2) to identify
relationships between fand use and attainable
quality of wetlands, and 3) to develop
strategies for sampling wetland populations.
A variety of stressors are being studied (land
use changes, hydrologic modifications, and
introduced species). The effects of these
stressors on wetland populations are being
identified through a regional, population
approach to sampling. Beginning in 1987, we
sampled sites located in diverse land-use and
hydrogeomorphic settings. We collected data
on site morphology, soil characteristics,
vegetation, and hydrology. In 1993, we
sampled another set of sites, including some
previously studied. We used a spatially and
temporally hierarchical design to obtain data
representing different scales (from population
to individual wetland). We found that of the
wetlands present in 1982 on National Wetland
Inventory maps, 29% had been destroyed by
human activities by 1992: urbanization
accounted for 63% of. the losses and
conversion to agriculture accounted for 31%.
We also showed that overall species richness
decreased for the period 1987-1993, with a
mean loss of 27 taxa per site re-sampled.
During storm events, we found land use was
the single most important factor affecting
changes in wetland water levels: wetlands in
urban settings experienced large~and rapid-
changes in water levels during storm events
relative to rural wetlands. These differences,
we concluded, were due to extensive
landscape modifications in urban areas,
including construction of impermeable sur-
faces that route water quickly to wetlands and
stream channels. This apparent association
between land use and hydrology suggests
that location constrains hydrologically-related
functions (e.g., flood storage), and it further
suggests that management strategies should
be designed so that objectives are compatible
with current and projected land use.
During FY96, we expanded this project and
assessed mitigation programs within the
Portland urban growth boundary. We
sampled 48 naturally occurring wetlands and
49 mitigation projects for plant species
richness, composition, and distribution. Our
environmental variables included water-
control structures/mechanisms and land use.
We found that a higher proportion of native
species exist on naturally occurring wetlands,
and their presence is related to land use: the
less intensive the land use, the greater the
number of native species. Our study further
indicated that current mitigation efforts are not
replacing native wetland plants.
Submerged aquatic vegetation (SAV).
Another focus of our research on wetland
structure and function is our study of sea
grasses and other SAV, which provide
essential habitats for fish and shellfish and
reduce erdsion of coastal shorelines. We are
studying SAV in the northern Gulf of Mexico
and in the Pacific northwest.
Researchers in GED have made significant
progress during the past several years in
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understanding the effects of ecological
disturbance and environmental stress on the
growth, sustainability, and recovery of SAV
communities. Key components of the
research include: 1) the study of factors
affecting growth, distribution, survival, and
recovery of SAV; 2) assessing the limits of
extrapolation of data among northern Gulf
estuarine systems; and 3) developing criteria
and predictive models for promoting the
development/sustainability of healthy
ecosystems.
During FY96-97, we assessed the distribution
and abundance of SAV beds in estuaries of
the northern Gulf region in order to correlate
changes in SAV health with water quality.
Using information gathered from historical
records (e.g., USGS) and data on water
quality (e.g., nutrient levels, water tempera-
true, light penetration), we have begun to
determine the relationship between changes
in water quality and losses or gains in SAV.
As part of this study, we are developing
biomonitoring techniques for assessing the
health of aquatic vascular plants, and we are
characterizing SAV responses to environ-
mental stress. Field experiments are being
conducted to assess the response of SAV
species to transplanting activities, and we are
evaluating the effects of-and recovery from-
chronic light limitation due to such factors as
sedimentation or nutrient-induced algal
blooms. We have shown that chronic light
reduction significantly, reduces plant growth,
but more importantly, we have found that
differences in' light requirements between
species provide an indication of the causes of
succession from one community to another.
Researchers in WED are in the initial stages
of developing an integrated SAV research
program for estuaries of the Pacific coast.
Beginning with Yaquina Bay in Oregon, we
plan to quantify distribution and abundance
patterns of both a native and an exotic
eelgrass species, and examine correlations of
patterns of distribution to that of major
physical variables (light field, temperature,
salinity, sediments, exposure, tidal height).
Basic population data on sea grass will be
collected. Laboratory and field experiments
will be conducted to understand the influence
of both physical and biological factors on
distribution and abundance; our experiments
will include mesocosm experiments on the
effects of possible biotic stressors, such as
burrowing shrimp populations. At the land-
scape level, we will be looking at the relation
of sea grass distribution to land use of the
margin of the surrounding estuary. We will
shoot aerial photos of the estuary, digitize
composite photos into an image of the entire
estuary, and then quantify SAV coverage as
to species based on the spectral signature.
For quantifying SAV coverage subtidally, we
will be exploring the use of various sonars. A
future direction is to attempt to integrate the
data from the various SAV research
components into predictive stressor-response
models. One modeling component is fairly far
along toward developing spatially explicit
population models for evaluating stressor
effects, and we plan to adapt this model to
SAV populations. Finally, we are looking at
green macroalgae, which can be quantified by
remote sensing, as another possible indicator
of estuarine condition.
Integrity of microbial communities. GED is
developing novel methods (biochemical and
genetic) to characterize microbial commun-
ities, an extremely important but often
overlooked component of coastal and near-
coastal ecosystems, their condition, and the
functions they perform.
One aspect of this research relates to the
SAV work described above. We are
performing studies to assess the microbial
ecology of SAV rhizospheres (the soil/root
system), which may be used as an indicator of
SAV health. Microbial communities
associated with the roots of SAVs may be
altered directly by the contaminant or
indirectly in response to the effect of the
contaminant on plant physiology. In either
case, a detected change in microbial
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communities could serve as an indicator of
environmental stress. As part of this
research, we are developing methods to
enumerate and classify bacteria associated
with the roots of sea grasses. We are using
fluorescent ribosomal RNA probes to
elucidate community structure, paying special
attention to nitrifying and sulfate-reducing
bacteria. In FY97, we used our techniques to
isolate and identify sulfate-reducing bacteria
tightly associated with the roots of two species
of estuarine grasses, Thalassia and
Vallisneria. These analyses will be used in
assessments of rhizosphere response to
stress, and, if sensitive, sulfate-reducing
bacteria could become the focus of more
detailed studies to develop microbial
community structure indicators of aquatic
plant health.
Finally, we are developing chemical methods
to investigate the diagnostic value of microbial
lipid biomarkers as indicators of the
abundance, diversity, and status of microbial
communities. Our goal is to use these
methods to determine the responses of
microbial communities to contaminants and
nutrients in order to understand their
relationship to the overall health of estuarine
and marine systems. Additional discussions
of microbial ecology in relationship to
contaminant exposures can be found in our
progress report on Contaminated Sediments
dated August, 1997.
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