United States
Environmental Protection
^ Agency
Generic Ecological
Assessment Endpoints
(GEAEs) for Ecological
Risk Assessment
RISK ASSESSMENT FORUM
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EPA/630/P-02/004F
October 2003
Generic Ecological Assessment Endpoints (GEAEs)
for Ecological Risk Assessment
Risk Assessment Forum
U.S. Environmental Protection Agency
Washington, DC 20460
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DISCLAIMER
This document has been reviewed in accordance with U.S. Environmental Protection
Agency policy. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
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CONTENTS
PREFACE v
AUTHORS, CONTRIBUTORS, AND REVIEWERS vi
1. INTRODUCTION: PURPOSE OF THIS DOCUMENT 1
1.1. Definitions of Assessment Endpoints 1
1.2. Potential Uses for Generic Assessment Endpoints 3
1.3. Criteria for GEAEs 5
2. EPA's INITIAL SET OF GEAEs 7
2.1. Definitions of the GEAEs Organisms 13
2.2. Assessment Populations and Communities 16
3. HOW TO USE THE GEAEs 19
3.1. Using GEAEs in Assessment Endpoint Selection 19
3.2. Making the Generic Endpoints Specific 20
3.3. Other Ecological Assessment Endpoints 21
3.4. Completing a List of Assessment Endpoints for a Specific Assessment 22
4. RECOMMENDATIONS FOR FURTHER PROGRESS 23
4.1. Develop and Support a Continual, Open Process for Reviewing, Amending,
and Creating New GEAEs 23
4.2. Develop a Database to Document and Keep Track of New Rationales,
Precedents, and Assessment Endpoints 24
4.3. Potential GEAEs for Future Consideration 25
5. CONCLUSION 27
APPENDIX A. SUPPORTING INFORMATION 28
APPENDIX B. TYPES OF VALUES ASSOCIATED WITH ASSESSMENT
ENDPOINTS 52
REFERENCES 54
in
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LIST OF TABLES
2-1. Generic ecological assessment endpoints 8
2-2. Generic ecological assessment endpoints (GEAEs): summary of the policy support for
their use and their practicality 9
4-1. Potential GEAEs 24
LIST OF FIGURES
1-1. Application of generic ecological assessment endpoints (GEAEs) in risk assessment
IV
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PREFACE
Ecological risk assessment is a process for evaluating the likelihood that adverse
ecological effects may occur or are occurring as a result of exposure to one or more stressors. A
critical early step in conducting an ecological risk assessment is deciding which aspects of the
environment will be selected for evaluation. This step is often challenging because of the
remarkable diversity of species, ecological communities, and ecological functions from which to
choose and because of statutory ambiguity regarding what is to be protected. The purpose of this
document is to build on existing EPA guidance and experience to assist those who are involved
in ecological risk assessments in carrying out this step, which in the parlance of ecological risk
assessment is termed "selecting assessment endpoints." The document describes a set of
endpoints, known as generic ecological assessment endpoints (GEAEs), that can be considered
and adapted for specific ecological risk assessments.
This document was prepared by a Technical Panel under the auspices of EPA's Risk
Assessment Forum. The Risk Assessment Forum was established to promote scientific
consensus on risk assessment issues and to incorporate this consensus into appropriate risk
assessment guidance. To accomplish this, the Forum assembles experts from throughout EPA in
a formal process to study and report on these issues from an Agency-wide perspective. The
document reflects the Forum's long-standing commitment to advancing ecological risk
assessment and is intended to supplement the use of the Forum's Guidelines for Ecological Risk
Assessment (U.S. EPA, 1998a). Following the publication of the guidelines, the Forum surveyed
ecological risk assessors from across the Agency to prioritize and select risk assessment topics
for further development. Additional guidance on assessment endpoints emerged as one of the
highest-priority topics. A subsequent EPA colloquium sponsored by the Forum to consider high
priorities from the survey identified a need for Agency-wide generic ecological assessment
endpoints and directly led to the development of this document.
The primary goal of this document is to enhance the application of ecological risk
assessment at EPA, thereby improving the scientific basis for ecological risk management
decisions. However, the document is not a regulation, nor is it intended to substitute for federal
regulations. It describes general principles and is not prescriptive. Rather, it is intended to be a
useful starting point that is flexible enough to be applied to many different types of ecological
risk assessments. Risk assessors and risk managers at EPA are the primary audience; the
document also may be useful to others outside the Agency.
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AUTHORS, CONTRIBUTORS, AND REVIEWERS
This report was prepared by a Technical Panel of EPA scientists under the auspices of
EPA's Risk Assessment Forum.
Technical Panel
Glenn W. Suter II (Chair)
National Center for Environmental
Assessment
Office of Research and Development
U.S. EPA
Cincinnati, OH 45268
Thomas Gardner
Office of Science and Technology
Office of Water
U.S. EPA
Washington, DC 20460
Donald J. Rodier
Office of Pollution Prevention and Toxics
Office of Prevention, Pesticides, and
Toxic Substances
U.S. EPA
Washington, DC 20460
Michael E. Troyer
National Center for Environmental
Assessment
Office of Research and Development
U.S. EPA
Cincinnati, OH 45268
Patti Lynne Tyler
Office of Technical and Management
Services
Region 8
U.S. EPA
Denver, CO 80202
Office of Pesticide Programs
Office of Prevention, Pesticides, and
Toxic Substances
U.S. EPA
Washington, DC 20460
Marjorie C. Wellman
Office of Science and Technology
Office of Water
U.S. EPA
Washington, DC 20460
Steven Wharton
Office of Partnerships and Regulatory
Assistance
Region 8
U.S. EPA
Denver, CO 80202
James White
Office of Air Quality Planning and
Standards
Office of Air and Radiation
U.S. EPA
Research Triangle Park, NC 27711
Risk Assessment Forum Staff
Scott Schwenk
National Center for Environmental
Assessment
Office of Research and Development
U.S. EPA
Washington, DC 20460
Douglas J. Urban
VI
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AUTHORS, CONTRIBUTORS, AND REVIEWERS (continued)
EPA REVIEWERS
Jim Carleton
Office of Pesticide Programs
Office of Prevention, Pesticides, and
Toxic Substances
U.S. EPA
Washington, DC 20460
Bruce Duncan
Office of Environmental Assessment
Region 10
U.S. EPA
Seattle, WA 98101
Anne Fairbrother
Western Ecology Division
National Health and Environmental
Effects Research Laboratory
Office of Research and Development
U.S. EPA
Corvallis, OR 97333
Gina Ferreira
Division of Environmental Planning and
Protection
Region 2
U.S. EPA
New York, NY 10007-1866
Laura Gabanski
Office of Wetlands, Oceans, and Watersheds
Office of Water
U.S. EPA
Washington, DC 20460
Jim Goodyear
Office of Pesticide Programs
Office of Prevention, Pesticides, and
Toxic Substances
U.S. EPA
Washington, DC 20460
Amuel Kennedy
Office of Pollution Prevention and Toxics
Office of Prevention, Pesticides, and
Toxic Substances
U.S. EPA
Washington, DC 20460
Wayne Munns
National Health and Environmental
Effects Research Laboratory
Office of Research and Development
U.S. EPA
Narragansett, RI 02882
Deirdre Murphy
Office of Air Quality Planning and
Standards
Office of Air and Radiation
U.S. EPA
Research Triangle Park, NC 27711
J. Vincent Nabholz
Office of Pollution Prevention and Toxics
Office of Prevention, Pesticides, and
Toxic Substances
U.S. EPA
Washington, DC 20460
Vicki Sandiford
Office of Air Quality Planning and
Standards
Office of Air and Radiation
U.S. EPA
Research Triangle Park, NC 27711
Mike Slimak
National Center for Environmental
Assessment
Office of Research and Development
U.S. EPA
Washington, DC 20460
vn
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Barbara M. Smith
Policy and Management Division
Region 9
U.S. EPA
San Francisco, CA 94105
Sharon Thorns
Waste Management Division
Region 4
U.S. EPA
Atlanta, GA 30303-8960
Amy Vasu
Office of Air Quality Planning and
Standards
Office of Air and Radiation
U.S. EPA
Research Triangle Park, NC 27711
Randall S. Wentsel
Office of Science Policy
Office of Research and Development
U.S. EPA
Washington, DC 20460
Jordan M. West
National Center for Environmental
Assessment
Office of Research and Development
U.S. EPA
Washington, DC 20460
Molly R. Whitworth
Office of Science Policy
Office of Research and Development
U.S. EPA
Washington, DC 20460
EXTERNAL PEER REVIEWERS
William J. Adams
Rio Tinto HSE
Lawrence W. Barnthouse
LWB Environmental Services, Inc.
Peter M. Chapman
EVS Environment Consultants
Peter L. deFur
Center for Environmental Studies
Virginia Commonwealth University
John H. Gentile
Harwell Gentile & Associates, LC
Bruce K. Hope
Land Quality Division
Oregon Department of Environmental
Quality
Lawrence A. Kapustka
ecological planning and toxicology, inc.
Charles A. Menzie
Menzie-Cura & Associates, Inc.
Donald Norman
Norman Wildlife Consulting
James M. Polisini
Department of Toxic Substances Control
California EPA
Ralph G. Stahl, Jr.
DuPont Company
Kent. W. Thornton
FTN Associates, Ltd.
Vlll
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1. INTRODUCTION: PURPOSE OF THIS DOCUMENT
In the practice of ecological risk
assessment, assessment endpoints are the valued
attributes of ecological entities upon which risk
management actions are focused (U.S. EPA,
1998a). Because not all organisms or ecosystem
features can be studied, regulatory agencies and
other risk managers must choose from among
many candidate endpoints. A recommendation
for improving ecological risk assessment and
management within the U.S. Environmental
Protection Agency (EPA, or the Agency) has
been to develop a set of generic assessment
endpoints that are based on environmental
legislation and EPA's policies and precedents and
that cover EPA's range of concerns for the
protection of ecological entities and functions.
In response to that recommendation, this
document presents a set of generic ecological
assessment endpoints (GEAEs) that provides
examples of endpoints applicable to a wide
variety of assessment scenarios. It also provides
guidance for using these GEAEs to develop
robust, assessment-specific endpoints. The role
of assessment endpoints within the ecological
risk assessment is shown in the text box. The
application of GEAEs to the process of
generating and using assessment endpoints in ecolog
1-1.
The role of assessment endpoints in
EPA's framework for ecological
risk assessment
Ecological risk assessments are
preceded by a planning phase in which
risk managers, risk assessors, and, as
appropriate, interested parties define the
management goals. The goals are broad
statements of desired conditions such as
"restore the wetlands" or "sustain the
trout population."
The planning phase is followed by the
problem formulation phase, in which the
assessors define the assessment
endpoints based on the management
goals. The assessment endpoints are
specific entities and their attributes that
are at risk and that are expressions of a
management goal.
The analysis and risk characterization
phases of the risk assessment are devoted
to estimating the nature and likelihood of
effects on those endpoints.
Finally, risk communication involves
conveying those results and associated
uncertainties as well as explaining their
implications. These processes are
explained in Guidelines for Ecological
Risk Assessment (U.S. EPA, 1998a).
;ical risk assessments is illustrated in Figure
1.1. Definitions of Assessment Endpoints
An assessment endpoint is defined in Guidelines for Ecological Risk Assessment (U.S.
EPA, 1998a) as "an explicit expression of the environmental value to be protected, operationally
defined as an ecological entity and its attributes." An ecological entity for example, might be an
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Planning
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and scientifically defensible environmental
decisions.
GEAEs are assessment endpoints that are
applicable to a wide range of ecological risk
assessments (ERAs) because they reflect the
programmatic goals of the Agency, they are
applicable to a wide array of environmental
issues, and they may be estimated using existing
assessment tools. GEAEs do not comprise a
complete list of what is or, by exclusion, what is
not protected by EPA. They are not specifically
defined for every conceivable case, and some ad
hoc elaboration by users is expected (Section
3.3). Furthermore, they are not goals or
objectives, but they should be related to goals or
objectives when such are known. For example, a
generic endpoint could be created for endangered
species, but the specific species of concern
would be defined during problem formulation,
and attributes of the species could be selected to
fulfill the goals of the Endangered Species Act,
the recovery plan for the species, and the objectives of the particular assessment.
Published generic endpoints are available for regional assessments (Suter, 1990),
population assessments (Suter and Donker, 1993), assessments of hazardous waste combustors
(U.S. EPA, 1999a), and assessments of contaminated sites in Alaska (Alaska Department of
Environmental Conservation, 2000). In addition, examples of ecological assessment endpoints
evaluated within certain EPA programs have been highlighted in prior EPA documents (U.S.
EPA, 1994, 1997a, c, 1998a). These examples are presented, as appropriate, in Appendix A.
The relationship of measures of effects
with assessment endpoints
Measures of effects (also known as
measurement endpoints) are the results of
tests or observational studies that are used
to estimate the effects on an assessment
endpoint of exposure to a stressor. For
example, a conventional measure of effect
from an acute lethality test is the median
lethal concentration (LC50), which might
be used to estimate the risk of a fish kill
(an assessment endpoint) from exposure
to a spill of the tested chemical.
Measures of effect and assessment
endpoints may be expressed at the same
level of organization (organism level in
this case). However, the same measure of
effect may be used, with considerably
greater uncertainty, to estimate risks to a
population-level assessment endpoint
(abundance of a fish species) or a
community-level endpoint (number of
species).
1.2. Potential Uses for Generic Assessment Endpoints
The set of generic assessment endpoints proposed in Section 2 of this document should
be useful for risk assessors and managers involved in planning and performing ecological risk
assessments within various EPA programs and offices. In particular, this document can be
consulted during the problem formulation stage of ecological risk assessments to assist in
developing assessment endpoints that are useful in EPA's decision-making process, practical to
measure, and well defined. In addition, the specific environmental laws, precedents, and other
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polices presented in Appendix A, which provide the supporting information for this initial set of
generic endpoints of this document, should be equally useful in supporting assessment-specific
endpoints.
Individual programs may have specific uses for these generic endpoints beyond
ecological risk assessments. For example, water quality management programs may want to
consider using this information during the process of refining designated aquatic life uses in state
and tribal water quality standards, when re-evaluating or developing guidance for consistent and
environmentally relevant monitoring programs, and in interpreting and implementing narrative
water quality standards. In particular, this set of generic endpoints may be useful within the
context of a total maximum daily load for a water body that has been listed for nonsupport of
aquatic life, but where there are no numeric biocriteria in the state's water quality standards.
This set of generic endpoints could be used to assist in the selection of appropriate ecological
response variables or to judge the effectiveness of the pollutant reductions.
Ultimately, generic assessment endpoints could have several other uses within the
Agency, such as in
• Giving risk managers a basis for action similar to commonly employed human health
endpoints;
• Providing a threshold for prevention of environmental degradation by ensuring that
certain values are at least considered for assessment;
• Complying with legal requirements;
• Improving the consistency of ecological risk assessment and management;
Serving as models for site-, action-, or region-specific endpoints;
• Performing screening ecological risk assessments where endpoints may need to be
developed rapidly with little input from risk managers;
• Providing clear direction for the development of methods and models;
• Facilitating communication with stakeholders by creating a set of familiar and clear
generic endpoints; and
• Reducing the time and effort required to conduct assessments.
These uses are described more fully in Suter (2000).
It is important to emphasize that the generic assessment endpoints are not mandatory or
applicable to all assessments. These particular generic endpoints should be used only when and
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where they are relevant. In many cases, it is likely that the endpoints derived from the generic
assessment endpoints will be supplemented by other assessment endpoints that are relevant to
the specific stressor or ecosystem. Over time, EPA anticipates that this initial set of generic
ecological assessment endpoints will be periodically reviewed, modified, and supplemented as
experience is gained in applying and interpreting them in a variety of natural conditions and
regulatory contexts (see Section 4).
1.3. Criteria for GEAEs
Like assessment endpoints developed for specific risk assessments, the GEAEs presented
in this report are intended to be useful in EPA decision making and to have a sound basis in
ecological theory. The following criteria are used in this report for evaluating potential GEAEs;
they are independent of specific assessment situations and in that way differ from the criteria that
should be used in developing assessment-specific endpoints (see the text box in Chapter 3).
1. Generally useful in EPA's decision-making process. Usefulness may be indicated
by the language found in statutes, treaties, and regulations that the Agency implements or with
which it must comply. Judicial decisions also indicate how the values defined by statutes may
be translated into generically useful endpoints. In addition, Agency guidance, guidelines,
protocols, and official memoranda indicate potentially useful endpoints. Finally, various actions
of the Agency that were based on ecological protection (i.e., Agency precedents) provide
evidence of general utility for GEAEs. These various sources of environmental policy are
summarized in U.S. EPA (1994, 1997a). Additional sources are referenced in Appendix A.
Note that the reliance on available policy and precedent in this document should not suggest a
similar restraint on risk assessors and managers in practice. EPA has a broad mandate to protect
the environment that can support the use of novel endpoints in individual assessments (see
Sections 3 and 4).
2. Practical. Methods used to estimate risks to the endpoint entity and attribute should
be available and reasonably practicable in various assessment contexts. This requires methods
that directly measure or observe the endpoint's attributes or that estimate them using a
combination of measurements and models. However, this does not require that a GEAE be
useful for all situations. Some GEAEs will not be implementable for some taxa or ecosystems,
but they should be practical in many situations.
3. Well defined. At a minimum, a GEAE must include an entity and an attribute of that
entity (U.S. EPA, 1998a). The entity and attribute should be clearly explained, so that they are
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understandable by the public and decisionmakers without appearing ambiguous to environmental
scientists. A definition should be supported by a clear explanation of the endpoint's relationship
with the Agency's management goals and programmatic applications.
Support for the first two criteria (usefulness and practicality) is presented in Appendix A
and summarized in Table 2-2. The third criterion (that GEAEs be well defined) is supported by
the definitions in Section 2.1 and supplemented by the background in Appendix A.
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2. EPA's INITIAL SET OF GEAEs
This chapter presents EPA's initial set of GEAEs to be considered for the uses described
in Section 1.2. As stated, these GEAEs are not exhaustive or mandatory but rather are provided
to assist EPA programs and researchers and decisionmakers who are involved in protecting the
nation's ecological resources, as described in Section 3. The entities and properties in the initial
set of GEAEs are presented in Table 2-1. The specific taxa, communities, or ecosystems for
which policy or precedents were identified are listed in the last column of the table. The GEAEs
are defined in Section 2.1, and the basis for the terms "assessment community" and "assessment
population," which are used in the definitions, is
explained in Section 2.2. Information concerning
laws, regulations, and precedents that support the
selection and use of these GEAEs is presented in
Appendix A and summarized in Table 2-2. A
general discussion of the values related to these
GEAEs is presented in Appendix B. Other
potential GEAEs that were promising but did not
fully meet the criteria in Section 1.3 are
discussed in Section 4.
These GEAEs are not always biologically
distinct, but the apparent overlaps are justified in
pragmatic terms. For example, the generic
endpoint "population extirpation" is an extreme
case of the generic endpoint "population
abundance." However, the extirpation of a
population is qualitatively different from a
simple percentage loss of abundance. The
implications of reductions in fish abundance
include a loss of fishing income, but extirpation
means an end to the fishery. In addition, it is typically much easier to establish that extirpation
has occurred (e.g., the fish are no longer caught) or will occur (e.g., the trout stream will be
inundated by a reservoir, or the pH will be far beyond the lethal level) than to establish that some
percentage reduction in abundance has occurred or will occur. This difference in implications
for the assessment and decision-making processes justify treating extirpation and abundance as
different endpoints.
Overlap of GEAEs
GEAEs are not necessarily discrete
or mutually exclusive; therefore, there
may be some redundancy in a set of
GEAEs. For example, the condition of
an ecological entity at one level of
biological organization (e.g., organism)
may influence the condition of other
entities at that level and interdependent
entities at higher levels of organization
(e.g., population or community).
Also, a large change in one attribute
may overlap with another attribute, as in
the case of abundance and extirpation.
Furthermore, GEAEs may relate to more
than one environmental value (see
Appendix B), which may be reflected in
multiple statutes, regulations, public
policies, or public perceptions (see
Appendix A).
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Similarly, kills of organisms have short-term effects on population abundance but do not
necessarily have a significant or long-term effect on abundance. The methods for determining
Table 2-1. Generic ecological assessment endpoints"
Entity
Attribute
Identified EPA precedents
Organism-level endpoints
Organisms (in an assessment
population or community)
Kills (mass mortality, conspicuous
mortality)
Gross anomalies
Survival, fecundity, growth
Vertebrates
Vertebrates
Shellfish
Plants
Endangered species
Migratory birds
Marine mammals
Bald and golden eagles
Vertebrates
Invertebrates
Plants
Population-level endpoints
Assessment population
Extirpation
Abundance
Production
Vertebrates
Vertebrates
Shellfish
Vertebrates (game/resource species)
Plants (harvested species)
Community and ecosystem-level endpoints
Assessment communities,
assemblages, and ecosystems
Taxa richness
Abundance
Production
Area
Function
Physical structure
Aquatic communities
Coral reefs
Aquatic communities
Plant assemblages
Wetlands
Coral reefs
Endangered/rare ecosystems
Wetlands
Aquatic ecosystems
Officially designated endpoints
Critical habitat for threatened or
endangered species
Special places
Area
Quality
Ecological properties that relate to
the special or legally protected
status
e.g., National parks, national
wildlife refuges, Great Lakes
aGeneric ecological assessment endpoints for which EPA has identified existing policies and precedents, in
particular the specific entities listed in the third column. Bold indicates protection by federal statute. See Table 4-1
for additional endpoints that could be considered by EPA in the future.
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Table 2-2. Generic ecological assessment endpoints (GEAEs): summary of the policy support for their
use and their practicality3
GEAE# Entity: attribute(s)
Policy support
Practicality
Organism-level endpoints
1
Organisms: kills
(mass mortality,
conspicuous
mortality)
Supported by many EPA programs;
e.g., EPA has restricted the use of
pesticides (e.g., diazinon and
carbofuran) due to incidents of bird
mortality.
Likelihood of kills from chemical
pollutants can be estimated from
toxicity testing. Incidents may be
easy or difficult to observe, but when
seen, they suggest a common
mechanism or stressor exerting a
strong effect.
Organisms: gross
anomalies
Gross anomalies in birds, fish,
shellfish, and other organisms are a
cause for public concern and have
been the basis for EPA regulatory
action and guidance (e.g., assessed
at Superfund sites, incorporated into
biocriteria for water programs).
External gross anomalies are readily
observed and are commonly included
in survey protocols for fish and
forests. They are also reported in
toxicity tests offish, birds, mammals,
and plants.
Organisms: survival
fecundity, growth
Many EPA programs rely on
organism-level attributes of
survival, fecundity, and growth in
assessing ecological risks (e.g.,
water quality criteria, pesticide and
toxic chemical reviews, Superfund
sites). Organism-level species
protection is mandated by the
Endangered Species Act, Marine
Mammal Protection Act, Bald Eagle
Protection Act, and Migratory Bird
Treaty Act.
Results of toxicity tests of the
survival, fecundity, and growth of
organisms are abundant and often
can be extrapolated to endangered
species and other species of concern.
Information on the ranges of listed
endangered species is available
through state and federal
governments.
Population-level endpoints
Assessment
population:
extirpation
EPA has taken action or provided
guidance to prevent extirpation of
local populations (e.g., assessment
of likelihood of extirpation of fish
populations due to acid rain). See
also the description for Assessment
population: abundance.
Extirpation can be predicted using
population viability analysis.
Demonstrating extirpation may be
easy or difficult, depending on the
conspicuousness of a species. See
also the description for Assessment
population: abundance.
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Table 2-2. Generic ecological assessment endpoints (GEAEs): summary of
the policy support for their use and their practicality" (continued)
GEAE#
Entity: attribute(s)
Policy support
Practicality
Assessment
population:
abundance
Major environmental statutes
mandate protection of animals,
plants, aquatic life, and living things
generally, which can be inferred to
entail protection of populations.
EPA policies for pesticides, toxic
chemicals, hazardous wastes, and
air and water pollutants are intended
to protect assessment populations of
organisms. Mammals, birds, fish,
aquatic invertebrates, and plants are
typically assessed.
Changes in abundance may be
predicted using conventional toxicity
data with statistical extrapolation
models and population models.
OPPT evaluated a population model
to explore effects of chloroparaffms
on fish populations. Measurement of
abundance in the field may be easy
or difficult, depending on the
species.
Assessment
population:
production
See description for Assessment
population: abundance.
Additionally, a number of laws are
intended to maintain production of
various economically valuable
species. EPA water programs (e.g.,
National Estuary Program) and air
programs (e.g., criteria pollutant
standards) have involved protecting
production of resource species
populations.
Changes in production may be
predicted using conventional toxicity
data as well as population-based
approaches. For resource species
such as tree or fish species,
production changes may be
measurable in the field but may
require long periods of observation.
Community and ecosystem-level endpoints
7
Assessment
communities,
assemblages, and
ecosystems: taxa
richness
EPA water quality biocriteria
frequently incorporate measures of
community taxa richness.
Additionally, EPA testing for
pesticides, toxic chemicals, and
water pollutants is intended to
assess impacts to communities as
well as populations and organisms.
Fish, aquatic invertebrates, and
aquatic plant assemblages are often
assessed.
Changes in communities can be
inferred or modeled from
conventional toxicity data.
Measuring taxa richness and
abundance of aquatic communities,
at least for fish and
macroinvertebrate communities, is
practical and well established.
Ecosystem models that assess effects
of toxicants on community properties
are available and can use data
acquired from organism-level
laboratory testing, but they have not
been routinely applied to date.
Assessment
communities,
assemblages, and
ecosystems:
abundance
As in the case of taxa richness,
water quality biocriteria incorporate
measures of community abundance,
and EPA testing protocols are
intended to assess impacts to
communities.
See description above for taxa
richness within assessment
communities.
10
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Table 2-2. Generic ecological assessment endpoints (GEAEs): summary of
the policy support for their use and their practicality" (continued)
GEAE#
Entity: attribute(s)
Policy support
Practicality
Assessment
communities,
assemblages, and
ecosystems: plant
production
EPA water quality policies address
overproduction of aquatic plants
(and concomitant eutrophication)
due to excess input of nutrients.
EPA policies for pesticides, toxic
chemicals, water pollutants, and air
pollutants (as in the case of ozone
and acid rain) also target decreases
in production of forests or other
plant communities.
Methods for measuring plant
production are well developed for
both terrestrial and aquatic
communities. Methods for
predicting effects of nutrient addition
are relatively well developed.
Protocols for testing plant toxicity
are available and include production
metrics.
10
Assessment
communities,
assemblages, and
ecosystems: area
Policy support exists for
considering the area of wetlands,
coral reefs, and endangered/rare
ecosystems. Among the supports
for wetlands protection are the
Clean Water Act, the National
Environmental Policy Act (NEPA),
the Coastal Zone Management Act,
Executive Order 11990, and the
federal wetlands delineation
manual.b Policies for protection of
coral reefs are established by
Executive Order 13089; additional
support may be found in the Coastal
Zone Management Act and the
Marine Protection, Research, and
Sanctuaries Act. Many U.S. coral
reefs are protected by state or
federal government. Fewer EPA
precedents exist for endangered/
rare ecosystems, but a variety of
EPA programs have considered
them, e.g., Superfund and NEPA.
Assessing the area of communities is
generally straightforward, although
when clear boundaries between
communities are absent, defining
areas may be somewhat difficult.
Methods for delineating wetlands are
well established, and changes in
wetland area are therefore relatively
easy to measure and monitor over
time. The area of coral reefs is also
relatively easy to determine. In the
case of endangered and rare
ecosystem types, a ready data source
is NatureServe0, which maintains
data on all known U.S. ecological
communities, ranked from critically
imperiled to secure. Prediction of
change from one community or
ecosystem type to another may be
difficult.
11
Assessment
communities,
assemblages, and
ecosystems: function
Policy support for ecosystem
function is primarily limited to
wetlands. The support for wetland
protection cited above for
community/ecosystem area
generally applies to wetland
function as well.
Loss of wetland function can be
inferred from loss of wetland area.
However, losses of function
independent of area loss generally
are not readily observable or
predictable.
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Table 2-2. Generic ecological assessment endpoints (GEAEs): summary of
the policy support for their use and their practicality" (continued)
GEAE#
Entity: attribute(s)
Policy support
Practicality
12
Assessment
communities,
assemblages, and
ecosystems: physical
structure
The primary policy support for this
endpoint derives from the Clean
Water Act, which applies to aquatic
ecosystems. Restoring and
maintaining the physical integrity
(along with the chemical and
biological integrity) of the nation's
waters is the primary goal of the
Clean Water Act. EPA policies and
monitoring guidance under the Act
include measures of physical
structure.
Protocols exist for measuring many
of the physical characteristics of
aquatic ecosystems. The impacts of
many actions (e.g., channelization,
dam construction) on the physical
structure of water bodies can be
readily predicted. Other effects
(such as hydrology changes due to
land use changes) are more difficult,
but still possible, to model.
Officially designated endpoints
13
Critical habitat for
threatened and
endangered species:
area
The Endangered Species Act
specifically mandates the protection
of critical habitat for endangered
species in addition to the species
themselves. The area (quantity) of
available habitat is commonly used
in assessing risks to these species.
Information on habitat used by listed
species is available from state and
federal agencies, although critical
habitat has not been officially
designated for most listed species.
Generally it is practical to determine
effects on habitat area.
14
Critical habitat for
threatened and
endangered species:
quality
Legal protection of critical habitat
extends to the quality (suitability) of
the habitat to endangered species, in
addition to its extent.
Assuming that critical habitat can be
identified (even if not officially
designated), it generally should be
practical to determine whether it has
been or will be adversely modified.
15
Special places:
ecological properties
that make them
special or legally
protected
The Clean Air Act, NEPA, and
other statutes require protection of
special places such as national
parks, wilderness areas, and wildlife
refuges, and this is reflected in EPA
policies. The Clean Water Act
gives EPA a role in designating
national estuaries and outstanding
national resource waters, which
receive additional protection.
Special places and their important
ecological properties usually can be
defined readily. The ability to predict
or detect impacts to these properties
will depend on the nature of the
properties and whether impacts are
direct or indirect.
aSee Appendix A for details and references.
^Environmental Laboratory (1987)
TSTatureServe's web address is .
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that a kill has occurred are much simpler than the methods for determining that the abundance of
a population has changed. In addition, the effects on the public of a kill (such as concerns over
odor and disease) are not necessarily related to effects on the populations involved. For
example, public response to a fish kill may not be related to the ability of the fish populations
involved to recover rapidly. Therefore, kills are distinct from both population abundance and
extirpation in terms of assessment approaches and management implications.
2.1. Definitions of the GEAEs Organisms
Organisms are the most distinct units of ecology, and attributes of organisms have been
the focus of EPA's efforts to protect the environment. However, the use of organisms as
endpoints does not necessarily imply that each individual is protected. Rather, "organisms" is a
level of biological organization with certain attributes that may be the basis of management
decisions. Although organisms of any species may be chosen as assessment endpoint entities,
some species are protected at the organism level by statute, including (a) endangered and
threatened species (those listed by the U.S. Fish and Wildlife Service or the National Marine
Fisheries Service as in danger of extinction under the Endangered Species Act), (b) marine
mammals that are protected by the Marine Mammal Protection Act (whales and porpoises, seals,
sea lions, and walruses, polar bears, sea otters, and manatees), (c) bald eagles and golden eagles,
which are protected by the Bald Eagle Protection Act, and (d) nearly all birds in the U.S.,
including their eggs and nests, which are protected by the Migratory Bird Treaty Act.
1. Kills: an event or multiple events involving numerous mortalities of organisms
within an assessment population or community. Kills may also be referred to as mass
mortality or conspicuous mortality. These events may be repeated and wide-spread, as in
bird kills due to pesticide applications; repeated at a location, as in fish kills due to
repeated treatment failures; or a single event, as in a seabird kill due to an oil spill. They
may involve one or more species. Precedents for this GEAE have involved vertebrates.
2. Gross anomalies: deformities, lesions, or tumors in animals; death or necrosis of
plant leaves; or other overt physical injuries of organisms within an assessment
population or community. The occurrence of these injuries may involve one or more
species. Precedents for this GEAE have involved vertebrates, shellfish, and terrestrial
plants.
3. Survival, fecundity, or growth: survival (which may be reduced by direct lethality
or by sublethal effects that diminish survival probabilities), fecundity (the production of
viable young), and growth (increased mass or length) of some proportion of the animals
or plants in an assessment population or community are the basic attributes of concern for
nonhuman organisms. In addition to the specific legal protections at the organism level
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for the groups discussed above, there are precedents for using these attributes for
vertebrates, invertebrates and plants.
Assessment population. An assessment population is a group of conspecific organisms
occupying an area that has been defined as relevant to an ecological risk assessment.
4. Extirpation: depletion of an assessment population to the point that it is no longer a
viable resource or is unlikely to fulfill its function in the ecosystem. Precedents for this
GEAE have involved vertebrates.
5. Abundance: numbers or density of individuals in an assessment population. Total
abundance or abundances by age or size classes may be used. Precedents have involved
vertebrates and shellfish.
6. Production: the generation of biomass or individuals in an assessment population
due to survival, fecundity, or growth. Precedents have involved vertebrates (primarily
game and resource species) and plants (primarily harvested species).
Assessment community, assemblage, or ecosystem A community is a multispecies
group of organisms occupying an area that has been defined as relevant to an ecological risk
assessment. Groups that are limited to organisms in a taxon (a plant community or bird
community) or that are in certain size classes within a taxon (macroinvertebrates or zooplankton)
are termed assemblages. Ecosystems are equivalent to communities but include the physical and
chemical features of the environment.
7. Taxa Richness: the number of native species or other taxa in an assessment
community or assemblage. Precedents have involved aquatic communities and policies
protecting coral reefs.
8. Abundance: the number of individuals in an assessment community or assemblage.
Total abundance or relative abundances of individual species, other taxa, trophic groups,
or other ecologically defined groups may be used. Precedents have involved aquatic
communities.
9. Production: the generation of biomass or individuals in an assessment community or
assemblage. Precedents for this GEAE have involved plant assemblages. The
assemblage may include all plants in an area or water body, in a taxon (e.g., flowering
plants), or in another definition (e.g., phytoplankton or above-ground herbs).
10. Area: the area of an ecosystem may be defined as extent of a particular type (e.g.,
Atlantic white cedar bog) or a particular category (e.g., palustrine wetlands). Area is a
protected attribute of wetlands and coral reefs. There are precedents for protecting the
14
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areal extent of endangered or rare ecosystem types, which are ecosystems that are at high
risk of extinction because they are rare or significantly declining due to destruction or
transformation to another type. The ecosystem may be generic (e.g., old growth or
virgin forests in the conterminous U.S.) or geographically specific (e.g., Hempstead
Plains grasslands on Long Island, NY). The National Biological Survey (Noss et al.,
1995) and the Association for Biodiversity Information, among others, have compiled
information on rare and endangered ecosystem types.
11. Function: processes performed by ecosystems that are services to humans or other
ecological entities. Function is a protected attribute of wetlands. Functional attributes of
wetlands may include water storage, maintenance of high water tables, nutrient retention
and cycling, sediment retention, accumulation of organic matter, and maintenance of
habitats for wetland-dependent plants and animals.
12. Physical structure: precedents are limited to aquatic ecosystems. Physical
structure encompasses the physical attributes or characteristics of water bodies, including
hydrological characteristics, bathymetry, bank form, sinuosity, pool and riffle structure,
bank and channel vegetation, and substrate type and composition. This endpoint includes
the aesthetic and other values of aquatic ecosystem structure, not simply habitat quality
for aquatic organisms.
Critical habitat for threatened and endangered species. Critical habitat is the specific
area within the geographical area occupied by an endangered or threatened species on which are
found physical or biological features essential to the conservation of the species and that may
require special management considerations and protections (16 U.S.C. 1532(5)). Critical
habitats, legally defined and specified by the U.S. Secretary of Interior, are listed in 50 CFR, Ch.
1, Sections 17.94-76. However, habitats that are critical to a threatened or endangered species
should be protected when identified even if they are not listed.
13. Area of critical habitat for threatened and endangered species: the land
coverage or equivalent aquatic extent (e.g., stream kilometers) that potentially supports
the endangered or threatened species.
14. Quality of critical habitat for threatened and endangered species: the suitability
of the habitat to support the endangered or threatened species.
15. Properties of Special Places. Special places are public and private areas of
ecological or cultural significance that are not necessarily endangered or threatened but whose
unique character or natural heritage is important—as revealed by laws or other actions that set
them aside. Examples include World Heritage sites, national parks and natural landmarks,
wilderness areas, national wildlife refuges, national conservation areas, wild and scenic rivers,
estuarine and marine sanctuaries, private nature preserves (e.g., Nature Conservancy preserves
15
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and National Audubon Society sanctuaries), and state and local parks. For a more
comprehensive list, see U.S. EPA (199la). The ecological properties to be protected are those
that make the place special, including those that are an important part of the historical or cultural
heritage of a place (e.g., shortgrass prairie at Little Bighorn National Monument). Hence, this
GEAE is relevant only to special places with ecological properties that are important to their
designation. We would not, for example, apply this GEAE to a renovation of Grant's Tomb.
2.2. Assessment Populations and Communities
Because the conventional ecological meaning of "populations" and "communities"
presents problems in practice, this document introduces the terms "assessment population" and
"assessment community" (defined above). Although ecological assessment endpoints inevitably
include population properties, such as abundance and production, and community properties,
such as species richness, it is difficult to delineate populations and communities in the field.
Classically defined populations are discrete and interbreeding. Classically defined communities
are discrete and their constituent species are relatively consistent and interact in predictable
ways. Although these classical definitions have been important to the development of genetics,
evolution, and ecology (e.g., Hardy-Weinberg equilibrium and the competitive exclusion
principle), they have always had manifest limitations in practice.
More recently, ecology has become more focused on temporal dynamics, spatial patterns
and processes, and stochasticity that belie the notion of static, independent populations. One
example of this is metapopulation analysis, which reveals that population dynamics are
significantly determined by exchange of individuals among habitat patches or differential
movement across a landscape that continuously varies in suitability (Hanski, 1999).
Communities are subject to the same dynamics. For example, the species diversity of Pacific
coral reefs is apparently determined by the availability of recruits from other reefs within 600 km
(Bellwood and Hughes, 2001). If the composition of coral reefs, which would appear to be
classic discrete communities, is in fact determined by regional dynamics, there is little chance of
delimiting discrete communities in general.
Populations may be readily delimited if they are physically isolated within a broader
species range (e.g., a sunfish population in a farm pond) or if the species consists of only one
spatially discrete population (e.g., the endangered Florida panther, whose current range is
restricted almost exclusively to southwest Florida). Otherwise, population boundaries are
difficult to define because they are typically structured on multiple scales. Genetic analyses,
which are needed to define discontinuities in interbreeding frequencies and thus to delimit
populations, are not a practical option for most ecological risk assessments.
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The practical problems are even greater for communities. Although the members of a
population consist of a single species, it is not always clear whether a particular group of
organisms constitutes an instance of a particular community type. This is because the species
composition of communities varies over space and time.
To protect properties such as population production or community species richness, it is
necessary to develop a pragmatic solution to these problems. An example of such a solution is
the approach taken by the Nature Conservancy and NatureServe (formerly the Association for
Biodiversity Information) to inventory and map biodiversity (Stein et al., 2000). Because it is
not feasible to define discrete populations or communities, these organizations inventory and
map occurrences of conservation elements, which may be defined at various scales, depending
on the elements and circumstances. For example, a plant community occurrence may be "a stand
or patch, or a cluster of stands or patches." However, an occurrence of a bird species would be
defined quite differently.
We propose a similar approach for GEAEs. For individual assessments, the population
or community entities to be protected must be defined during the problem formulation stage of
risk assessment. These assessment populations and assessment communities should be defined
in a way that is biologically reasonable, supportive of the decision, and pragmatic with respect to
policy and legal considerations. For example, it would not be reasonable to define the belted
kingfishers in a 20 m steam reach as an assessment population if that reach cannot fully support
one belted kingfisher pair. On the other hand, even though the kingfisher's range is effectively
continuous, it would not be reasonable to define the entire species as the assessment population,
given that it ranges across nearly all of North America. Rather, it may be reasonable to define
the kingfishers on a watershed or a lake as an assessment population.
Assessment populations may be defined by nonbiological considerations as well. For
example, for Superfund ecological risk assessments on the U.S. Department of Energy's Oak
Ridge Reservation, populations of large terrestrial vertebrates were delimited by the borders of
the reservation (Suter et al., 1994). This definition was reasonable not only because the
Superfund site was defined as the entire reservation, but also because the reservation was large
enough to sustain viable populations of deer, wild turkey, and bobcat, among others. Although
the reservation is more forested than are the surrounding agricultural and residential lands, its
borders are not impenetrable and are not ecologically distinct at all points. However, the
pragmatic definition proved useful and acceptable to the parties. For similarly practical reasons,
one might define an assessment community of benthic invertebrates in the first fully mixed reach
of a stream receiving an effluent.
The selection of a scale to define an assessment population or community involves a
tradeoff. If the area is large relative to the extent of the stressor, the effects of that stressor will
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be diluted. However, if the area is small, the assessment population or community may be
significantly affected but may seem too insignificant to prompt stakeholder concern or action by
the decisionmaker. Hence, appropriate spatial scales should be determined during the problem
formulation stage for individual risk assessments, taking into consideration both the ecological
and policy aspects of the problem; it must not be manipulated during the analysis to achieve a
desired result.
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3. HOW TO USE THE GEAEs
In a risk assessment for a specific site,
effluent, stressor, or action, it will be necessary to
determine whether any of the GEAEs are
applicable to the assessment and sufficient for the
case, and if so, how they can be made specific to
the case. These activities are performed as part of
the problem formulation phase of risk assessment
(U.S. EPA, 1998a).
3.1. Using GEAEs in Assessment Endpoint
Selection
The set of GEAEs is intended to be
helpful for identifying and specifically defining
assessment endpoints for particular assessments.
During problem formulation, risk assessors,
scientists, risk managers, and any stakeholders
identify endpoints that are relevant to the
assessment, that are of sufficient importance to
potentially influence the decision, and that reflect
any goals that may have been set prior to the
problem formulation (U.S. EPA, 1998a). The
assessment-specific criteria for selecting
assessment endpoints from the guidelines for
ERA are used in that process (see text box).
The process of developing assessment
endpoints for an ecological risk assessment may be thought of as bringing together five types of
information and answering questions related to each, as shown below. Together, the questions
address the criteria for ecological assessment endpoints. The GEAEs constitute one type of
information that answers one question. In addition, the table of GEAEs can be consulted while
answering the other questions as a means of ensuring that commonly considered types of entities
and attributes are considered.
Criteria for selection of
assessment endpoints
EPA has provided criteria for
developing assessment-specific
assessment endpoints: ecological
relevance, susceptibility, and relevance
to management goals (U.S. EPA, 1998a,
Section 3.3.2).
Ecological relevance pertains to the
role of the endpoint entity in the
ecosystem and therefore depends on the
ecological context.
Susceptibility pertains to the
sensitivity of the endpoint to the stressor
relative to its potential exposure and
therefore depends on the identity of the
stressor and the mode of exposure.
Relevance to management goals
pertains to the goals set by the risk
manager and therefore depends on the
societal, legal, and regulatory context of
the risk management decision as well as
the preferences of the individual risk
manager and stakeholders.
These situation-specific criteria
should be applied whenever GEAEs are
converted to assessment endpoints in
individual assessments.
1. Stressor characteristics. What is susceptible to the stressor? For well-understood
stressors, this question is straightforward. Benthic invertebrates are susceptible to
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dredging, birds are susceptible to granular pesticides, wetlands are susceptible to filling,
and so on.
2. Ecosystem and receptor characteristics. What is present and ecologically relevant?
For site-specific assessments, this is the species, communities, or ecosystems at the site.
For other assessments, the scenario should define the types of species communities and
ecosystems that are likely to be exposed. For example, an assessment of a new pesticide
for corn would consider the species likely to be found in or adjacent to corn fields in the
midwestern U.S. In the absence of specific information about the particular importance
of an entity, those that are present may be assumed to be ecologically relevant.
3. Management goals. What is relevant to the management goals? Statements of
management goals should suggest the changes in attributes of ecological entities that
would preclude achieving the goal.
4. Input by interested parties. What is of concern? If interested parties are consulted or
make their preferences known, their concerns about particular ecological effects should
be considered. Although societal values at a national scale are reflected in the GEAEs,
values that are specific to a locale or resource are expressed by interested parties.
5. GEAEs and new policies or precedents. What is supported by policy or precedent?
The GEAEs defined in this report provide a set of entities and attributes that meet this
criterion, which is an expression of national goals and values at the time of publication.
The answers to each of these questions would be a list of potential assessment-specific
endpoints. None of the questions imply absolute requirements. For example, susceptibility to a
novel stressor may be unknown, and the concerns of interested parties are often unknown and
often do not include important potential endpoints.
No particular procedure is prescribed for this process of answering the questions or for
using the GEAE set. If consistency with policy and precedent is particularly important, one
might go through the GEAE set and ask the other four questions with respect to each generic
endpoint. Alternatively, the questions might each be answered and the lists then integrated. In
that case, the endpoints for a specific assessment may simply be those that are represented on
most of the lists.
3.2. Making the Generic Endpoints Specific
To convert a GEAE into an assessment endpoint for a specific assessment, it is necessary
to define the specific entity and attribute and the spatial and temporal context of the entity. This
specificity is needed to make the endpoint relevant to the assessment and to determine which
measurements and models are needed to estimate it.
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Consider the first GEAE, kills of organisms, as an example. The generic entity is
organisms. For a specific assessment endpoint, we must specify whether the endpoint entity
corresponds to members of a specific taxon such as fish or birds, an assemblage such as
macroinvertebrates, or a specific species such as sea otters. The generic attribute is kills, which
should be defined more specifically and in terms that are appropriate to the assessment. For
example, the definition of a kill would differ for a well-monitored experimental use of a
pesticide versus public reports of mortalities, for oil spills versus lawn treatments, and for
modeling studies versus observational studies. Possible definitions could include the number of
organisms that must die during an episode for it to be considered a kill, the proportion of
organisms visiting a site that would be expected to die, or the frequency of public reports of dead
organisms associated with the stressor. Finally, the spatial and temporal contexts should be
defined. For an effluent, the contexts may be the downstream reach within which mixing occurs
and the period of a permit. For a pesticide, they may be the region within which the pesticide is
used on a particular crop and the number of applications per year over the period of use. For an
oil spill, they may refer to the area encompassed by the plume and the time until the plume is
dispersed or degraded to the point that it no longer oils marine birds or mammals. Hence, an
assessment endpoint derived from this GEAE might be episodic mortality of at least 10 fish of
any species occurring in the 1 km reach downstream of the effluent release point.
The answers to the first four questions in Section 3.1 provide the basis for specific
endpoint definitions; that is, they determine which specific organisms, populations, or
ecosystems are susceptible and potentially exposed and which are of concern, the spatial and
temporal scales that are relevant to management goals, and other relevant considerations.
More than one assessment endpoint may be derived from a GEAE for a particular
assessment. For example, the GEAE population abundance may be used to generate assessment
endpoints for each of several populations of concern, and the change in abundance and spatial
context may be different for each. On the other hand, a site-specific concern may relate to more
than one GEAE. In the example of the wetland discussed in the previous chapter, the site-
specific problem formulation must determine whether the management concern and the evidence
of wetland susceptibility are related to the area of the wetland, a functional attribute of the
wetland, such as nitrogen retention, or both.
3.3. Other Ecological Assessment Endpoints
The GEAEs presented in this document are those that are thought to be currently
genetically useful in EPA and do not preclude the use of other endpoints. Other endpoints may
be chosen because they reflect some particular environmental value associated with a site or held
by a particular stakeholder or for some other reason they are particularly appropriate for a
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particular assessment (see Section 3.1). In addition, some endpoints that are not generically
practical may be practical in a particular case because of peculiarities of the stressor or receptor,
data availability, or availability of a model of the receiving system or because time and resources
are available to assess a difficult endpoint. These additional assessment endpoints must meet the
criteria in the EPA's guidelines.
3.4. Completing a List of Assessment Endpoints for a Specific Assessment
When a list of potential assessment endpoints has been developed, it may be necessary to
review the list and reduce it to those that are important to the decision. Because of the
limitations of time and resources, it is often advisable to limit the list of assessment endpoints to
those that are most relevant and susceptible. There is likely to be some redundancy in the
endpoints. Kills of organisms imply immediate changes in population abundance that may
influence community abundances. If population or community properties are important to the
decisionmaker, they should be retained. However, if kills are sufficient to warrant action, the
extrapolations to higher levels of biological organization may be unnecessary and those
endpoints may be dropped as unnecessarily redundant.
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4. RECOMMENDATIONS FOR FURTHER PROGRESS
The main purpose of this report is to improve ecological considerations within EPA by
developing an initial set of generically useful ecological assessment endpoints (see Table 2-1).
However, these initial assessment endpoints are based on existing policy and practice rather than
on an evaluation of all the potentially useful ecological assessment endpoints that may exist for
the Agency now or in the future. Therefore, readers of this report are encouraged to (1) develop
and maintain a continual, open process for reviewing, amending, and creating new GEAEs and
(2) establish a means of keeping track of the many rationales and precedents used for making
ecological risk-based decisions throughout EPA. In particular, as the GEAEs are applied to
ecological risk assessments, the experiences should be documented and published as case
studies. The remainder of this chapter provides more discussion about these two
recommendations and concludes with a method of how you, the reader, can contribute to EPA's
progress in this area by suggesting other useful assessment endpoints. Table 4-1 presents
potential GEAEs for more immediate consideration by EPA.
4.1. Develop and Support a Continual, Open Process for Reviewing, Amending, and
Creating New GEAEs
The initial GEAEs presented in this report include important ecological attributes to
consider when conducting ecological assessments throughout EPA. However, the Agency
should not remain static or constrain itself to these particular GEAEs. EPA should establish and
maintain an adaptive and open process for reviewing and amending ecological assessment
endpoints over time, as science and Agency experience evolve. Care must be taken so that new
GEAEs are consistent with this document and the Agency's ecological risk assessment
guidelines. The process and frequency of these updates or reviews must be approved by Agency
management.
Both the technical panel and external peer reviewers of this document suggested that
regular reviews of EPA's generic ecological assessment endpoints are important and that five-
year intervals would be appropriate for updating them. There is consensus that broad
participation is also vital. Members of future review panels should represent as many
programmatic, regional, and support offices of EPA as possible, and they should consider
external input from other government agencies, nongovernment organizations, academia, the
general public, and the private sector.
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Table 4-1. Potential GEAEs
Entity
Attribute
Organism-level endpoints
Organisms (in an assessment
population or community)
Physiological status (in addition to growth)
Disease or debilitation (in additions to gross anomalies)
Avoidance behavior
Courtship behavior (e.g., birds)
Migratory behavior (e.g., birds and salmonids)
Nurturing and rearing behavior (e.g., nest abandonment)
Population-level endpoints
Assessment population
Genetic diversity
Community and ecosystem-level endpoints
Assessment communities,
assemblages, and ecosystems
Trophic structure
Energy flow
Nutrient cycling (ecosystems in addition to wetlands)
Nutrient retention
Decomposition rates
Sediment and material transport
Area or function of estuaries and riparian ecosystems
Resilience
Vertical structure of plant communities
Attributes that influence public health
Landscape-level endpoints
Assessment landscapes (of multiple
populations, communities, assemblages, and
ecosystems)
Spatial pattern (random, clustered or uniform; dominance;
contagion; contiguity or fragmentation; juxtaposition)
4.2. Develop a Database to Document and Keep Track of New Rationales, Precedents, and
Assessment Endpoints
A readily accessible and searchable database of existing and new ecological assessment
endpoints should be established and supported on a continual basis. This database could be for
internal (and perhaps external) use and provide rationales and precedents (or histories) of how
these ecological assessment endpoints have been used by EPA. For example, when a program or
regional office finds scientific or societal justification for an ecological assessment endpoint, that
office should consider it again in future assessments and share this knowledge with other offices
throughout the Agency. Useful information could include how the ecological assessment
endpoint affected decision making, whether some endpoints carry more weight than others, or
whether they were ignored or too difficult to interpret or use. The technical panel recommends
creating a centralized, web-based database for facilitating this process.
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4.3. Potential GEAEs for Future Consideration
EPA is responsible for stating its mandates as clearly understood goals and assessment
endpoints for ecological protection. As different stressors challenge our environment and our
scientific understanding of ecosystems improves, new ecological assessment endpoints will need
to be considered and incorporated into EPA's mission.
In Table 2-1, the technical panel
recommends assessment endpoints that have
some existing precedent or legal or regulatory
basis for use within EPA. Such precedents, as
presented in Appendix A, include treaties,
statutes, regulations, judicial decisions, official
memoranda, guidance or procedures, and other
documentation. However, the technical panel
remains concerned about otherwise valid and
important ecological assessment endpoints being
excluded from Table 2-1 and encourages users of
this guidance to continually strive for further
progress and innovation within the Agency to
advance new and improved GEAEs. Therefore,
on the basis of comments received from peer
reviewers of this report as well as suggestions
found in recent Agency publications (e.g., U.S.
EPA 2002a), the technical panel also
recommends the potential GEAEs presented in
Table 4-1 for consideration by EPA scientists and
managers. Note that some of these potential
assessment endpoints are not entirely new, but
rather are extensions the of the GEAEs listed in
Table 2-1, and some may not yet satisfy the
criterion of practicality, as defined in Section 1.3.
We encourage EPA's program and
regional offices to regularly consider the GEAEs
in Tables 2-1 and 4-1 and other potentially
relevant assessment endpoints for purpose of
guiding EPA's evolving ecological mission.
However, in order to keep GEAEs meaningful,
Developing new assessment endpoints
One suggestion for developing new
assessment endpoints is to consider the
following dimensions associated with
ecological systems and whether they are
addressed in Agency risk assessment
activities:
1. Levels of biological organization
(e.g., potentially ranging from DNA to
biomes).
2. Spatial scale (e.g., ranging from
local to global boundaries).
3. Temporal scale (e.g.,
considerations of the timing, duration
and/or frequency of biological activities
or events).
4. Magnitude (e.g., the total number
of ecological entities present, impacted,
or remaining with respect to a known
baseline or presumption of what should
be there).
5. Taxonomic groups (i.e., beyond
mammals, fish, and birds to other taxa
such as amphibians, reptiles,
invertebrates, bacteria, fungi, and
flowering and nonflowering plants.
6. Range of ecological properties
(e.g., resiliency in ecosystems).
The initial GEAEs presented in
Table 2-1 incorporate or touch upon
many of these dimensions, yet many
other assessment endpoints could
potentially be derived by increasing the
range of just one of these dimensions or
by integrating two or more of these
dimensions in a new way.
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the Agency should consider maintaining a conservative approach toward adding new ones. This
can be done by consistently applying the criteria established in this guidance and by paying close
attention to the distinction between assessment endpoints and measures of effect (i.e.,
measurement endpoints).
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5. CONCLUSION
The development of this document revealed that the laws, policies, and precedents for
protecting attributes of ecological entities are numerous and diverse. They provide a strong basis
for defining assessment endpoints at the organism, population, and community/ecosystem levels
of organization. They are defined and organized in a consistent fashion in this report as GEAEs.
GEAEs are widely applicable to various assessment scenarios and can provide a
foundation for the development of endpoints for specific assessments during problem
formulation. This set of GEAEs can be used by risk assessors and risk managers with the
confidence that they are supported by established policies and precedents and thus will improve
the scientific basis for ecological risk management decisions.
Risk assessors and risk managers throughout the Agency are encouraged to track the
rationales for making ecological risk-based decisions, thereby providing a basis for reviewing
and updating these GEAEs in the future.
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APPENDIX A. SUPPORTING INFORMATION
This appendix serves as a reference for those who need to know the basis for a particular
GEAE defined in Section 2. The GEAEs have been divided into three categories of biological
organization—organism, population, and community/assemblage/ecosystem—and a fourth
category containing endpoints (critical habitats and special places) that are most easily described
separately. Each category is introduced by general information about how the GEAEs in that
category have been used by the Agency. Additional supporting information divided into two
sections, is then provided for each GEAE. The first section is Laws, Regulations, and
Precedents, which discusses the authorities that support the use of each GEAE by EPA and gives
examples of Agency actions that provide a further basis for their use. The second section is
Practicality, which discusses the availability of methods to estimate risks to the endpoint and
their applicability in various risk assessment contexts. Because assessment endpoints are
defined as valued properties of the environment (U.S. EPA, 1998a), public values associated
with the GEAEs are discussed in broad terms in Appendix B.
It should be noted that the specific laws and other policies cited below are not the only
support for ecological endpoints. The many federal environmental laws and their implementing
regulations provide a general mandate for environmental protection that goes far beyond the
specific instances presented in this appendix. In particular, the National Environmental Policy
Act of 1970 creates a broad mandate for federal agencies to protect and prevent degradation of
the environment. Although nearly all environmental statutes refer to the environment as an
entity to be protected, and many refer to more specific ecological entities such as fish, wildlife,
and estuaries, few indicate an attribute to be protected or even the nature of the entity. In
addition, terms are not necessarily used in a technical way. For example, the Clean Water Act
refers repeatedly to "a balanced indigenous population offish, shellfish and invertebrates."
Clearly, the phrase does not refer to a biological population, which is formed of members of one
species. Further, when referring to fish, does the act mean fish at the level of organism,
population, or assemblage or as a taxon? Given these ambiguities, the wording of the statutes
must be interpreted to define endpoints. The primary source of support for the following
interpretations is precedent.
The precedents and other expressions of policy discussed below are a sample of those
that have been used in assessments, guidance, protocols, and other Agency actions over the
years. Although they are derived from particular laws and regulatory contexts, they may be
interpreted as examples of what Congress and the Agency have meant by protecting the
environment. For example, the Clean Air Act calls for specific protection of "national parks,
national wilderness areas, national monuments, national seashores, and other areas of special
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national or regional natural, recreational, scenic, or historic value." This requirement can be
interpreted as a mandate to the Agency to protect those special areas from pollution, not just
from the threats from air pollution that were brought to the attention of Congress.
The following abbreviations and acronyms are used in this appendix:
CAA Clean Air Act
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
CFR Code of Federal Regulations
CITES Convention on International Trade in Endangered Species
CWA Clean Water Act
ESA Endangered Species Act
FIFRA Federal Insecticide, Fungicide, and Rodenticide Act
FR Federal Register
LC50 Median lethal concentration
LD50 Median lethal dose
NCP National Contingency Plan
NEPA National Environmental Policy Act
OSWER Office of Solid Waste and Emergency Response
PCB Polychlorinated biphenyl
RCRA Resource Conservation and Recovery Act
SSD Species sensitivity distribution
TSCA Toxic Substances Control Act
A.I. Organism-Level Endpoints
Major EPA statutes such as the CAA, CWA, CERCLA, FIFRA, TSCA, and RCRA
require that EPA consider and protect organism-level attributes or various taxa of organisms,
including fish, birds, and plants and, more generally, animals, wildlife, aquatic life, and living
things. The toxicity information that is available to EPA in administering these statutes is
dominated by organism-level attributes such as mortality. Organism-level attributes tend to be
more practical to measure or predict than attributes at higher levels of organization for most EPA
assessments. Consequently, EPA's ecological assessments historically have focused on
organism-level endpoints. Note that these endpoints do not normally imply protection of each
individual organism, but rather the protection of these critical attributes of organisms within
assessment populations or communities. As will be described, however, certain special
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categories of organisms, such as endangered species
protection on an individual basis.
In ecological assessments, EPA considers
organism-level effects in a variety of taxa. For
example, tests required for pesticide regulation
can include effects on survival, growth, and
reproduction (GEAE #3) of aquatic
invertebrates, fish, birds, mammals, and both
terrestrial and aquatic plants. Effects on a
similar range of taxa are considered under TSCA
(Lynch et al., 1994; Zeeman et al., 1999) and in
deriving water quality criteria under the CWA.
Less commonly, other taxa, such as earthworms
(e.g., at certain Superfund sites), honeybees (e.g.,
for certain pesticides), and reptiles and
amphibians are considered .
A.1.1. GEAE#1. Kills of Organisms
Laws, Regulations, and Precedents: Kills
The regulation of chemicals to prevent
kills of organisms, in the absence of effects on
populations or communities, has been sustained
by federal courts. For example, the use of the
pesticide diazinon on golf courses and sod farms
was prohibited after documentation of
widespread and repeated bird kills (U.S. EPA,
1988a). Subsequently, EPA cited continuing
bird kills as a factor in the agreement with
pesticide manufacturers to phase out all outdoor
residential uses of diazinon (U.S. EPA, 2001a).
Bird kills were also the basis for phasing out
most uses of another pesticide, granular
carbofuran (U.S. EPA, 1991b; Houseknecht,
1993). Kills of birds and other wildlife in oil
pits are considered evidence of "imminent and
substantial endangerment to the environment" under
and marine mammals, have been afforded
Connections between organism and
higher-level endpoints
Not only are organism attributes
potentially important in themselves, but
they are also important because they are
protective of higher-level attributes. That
is, we commonly assume that if we
protect important attributes of organisms
in a population or community, the
population and community attributes will
be protected as well. EPA's principles for
ecological risk assessment and risk
management at Superfund sites (U.S.
EPA, 1999b) illustrate a common usage
of organism-level endpoints at EPA:
"Except at a few very large sites,
Superfund ERAs [ecological risk
assessments] typically do not address
effects on entire ecosystems, but rather
normally gather effects data on
individuals in order to predict or postulate
potential effects on local wildlife, fish,
invertebrate, and plant populations and
communities that occur or that could
occur in specific habitats at sites....
Levels [of chemicals] that are expected to
protect local populations and communities
can be estimated by extrapolating from
effects on individuals and groups of
individuals using a lines-of-evidence
approach."
When organism-level information is
not sufficient, it may be necessary to
assess higher-level attributes directly, by
employing population or community
models or measurements.
RCRA §7003 (U.S. EPA, 2003a). Fish kills
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have also been considered a concern by EPA; for example, Region 5 considers fish kills and
other excess mortality to be obvious impacts under RCRA (U.S. EPA, 1994).
Under FIFRA reporting requirements for adverse effects of pesticides (40 CFR Part 159),
EPA categorizes kills (and other adverse incidents) involving multiple organisms as more severe
events than single organism incidents and imposes additional reporting requirements on pesticide
registrants for such events. More severe wildlife incidents are defined as those involving at least
1000 individuals of a schooling fish species or 50 individuals of a nonschooling species; 200
individuals of a flocking bird species, 50 individuals of a songbird species, or 5 individuals of a
predatory species; or, for mammals, reptiles, and amphibians, 50 individuals of a relatively
common or herding species or 5 individuals of a rare or solitary species. (Note that incidents
involving numbers of organisms below these thresholds still must be reported, but the
requirements are different than those for more severe incidents. Also note that these criteria do
not apply outside FIFRA.)
Practicality: Kills
The likelihood of kills is relatively readily estimated using the common acute lethality
tests that generate LCSOs and LDSOs. The number of species involved in kills may be estimated
from SSDs of LCSOs or LDSOs, as in the calculation of the acute National Ambient Water
Quality Criteria (U.S. EPA, 1985a; Posthuma et al., 2002). The occurrence of kills in the field
may be readily observed in the cases of conspicuous organisms and open habitats, but in other
cases, such as with small birds in crops or fence rows, kills may be unobserved and difficult to
document. Recently, a model has been developed to predict the probability of bird kills for a
particular use of a cholinesterase-inhibiting pesticide using SSDs of LDSOs and field studies
(Mineau, 2002).
A.1.2. GEAE #2. Gross Anomalies of Organisms
Laws, Regulations, and Precedents: Gross Anomalies
Gross anomalies in birds, fish, shellfish, and other organisms are cause for public concern
and have been the basis for EPA regulatory action and guidance. For example, crossed bills and
other deformities in piscivorous birds are a basis for the proposed remediation of the PCB-
contaminated sediments at the Fox River/Green Bay Superfund site (Wisconsin Department of
Natural Resources, 2001; U.S. EPA, 1998b) and were a basis for the designation of the system as
an Area of Concern by the Great Lakes National Program Office (U.S. EPA, 2001b). EPA
actions to restrict the use of tributyltin as an antifoulant on boats (U.S. EPA, 1988b), as well as
the restrictions imposed by the Organotin Antifouling Paint Control Act of 1988, were triggered
by the observed induction of gross deformities in mollusks that threatened the marketability of
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oysters, reduced the fecundity of the deformed organisms, and suggested the potential for other
effects.
Natural resource damage regulations for CERCLA, the CWA, and the Oil Pollution Act
include gross anomalies among the designated injuries (43 CFR §11.62(f)), and deformities,
erosion, lesions and tumors in fish (BELT anomalies) are used in the biocriteria of many state
water quality standards and in Agency guidance (Yoder and Rankin, 1995; U.S. EPA, 1996).
Changes in development, which can be manifested in physical anomalies, have been identified as
an environmental effect of regulatory concern under TSCA (U.S. EPA, 1983).
Anomalies in plants and plant injuries have also been the basis for EPA action. For
example, EPA established a secondary ambient air quality standard for ground-level ozone partly
on the basis of visible foliar injury to commercial crops and natural vegetation, stating that
"foliar injury is occurring on native vegetation in national parks, forests, and wilderness areas,
and may be degrading the aesthetic quality of the natural landscape, a resource important to
public welfare" (U.S. EPA, 1997b). EPA has also used visible injury of plants as a basis for
regulating air emissions of aluminum reduction plants and sulfuric acid production units (U.S.
EPA, 1994).
Practicality: Gross Anomalies
External gross anomalies are readily observed, as are some internal anomalies with
external manifestations such as severe scoliosis or large tumors. Gross anomalies are commonly
included in biological survey protocols for fish and in forest health surveys. They are also
included as endpoint responses in some chronic tests offish and birds.
A.1.3. GEAE #3. Survival, Fecundity, and Growth of Organisms
As discussed in Section A.I., EPA's ecological assessments have considered effects on
survival, fecundity, and growth in a variety of taxa. Although actions based on survival may be
the most common, EPA has also made regulatory decisions on the basis of effects on fecundity
and growth of organisms identified in ecological risk assessments. For example, the pesticide
chlorofenapyr was not approved by EPA on the basis of Agency concerns over reproductive
risks to birds. Additionally, federal statutes and other precedents confer special status on
particular kinds of organisms: endangered and threatened species, marine mammals, bald and
golden eagles, and migratory birds. The remainder of this section concentrates on the basis for
the special status of these organisms within the organism-level endpoints.
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Laws, Regulations, and Precedents: Survival, Fecundity, and Growth
Endangered and threatened species. The ESA protects threatened or endangered
species from taking, which is defined as "to harass, harm, pursue, hunt, shoot, wound, kill, trap,
capture, or collect, or to attempt to engage in any such conduct" (16 US Code, §1532, and 50
CFR, parts 14, 17, and 23). Under the act, the term "species" includes "any subspecies offish or
wildlife or plants and any distinct population segment of any species of vertebrate fish or
wildlife which interbreeds when mature." The ESA states that it is "to be the policy of Congress
that all Federal departments and agencies shall seek to conserve endangered species and
threatened species" and that "Federal agencies shall cooperate with State and local agencies to
resolve water resource issues in concert with conservation of endangered species" (16 US Code,
§1531). Hence, the provisions of the ESA are applicable to EPA actions, and both the
prohibition against harming individual members of threatened or endangered species and the
affirmative obligation to conserve those species would seem to include toxic effects.
Additionally, the CAA (§112) specifically requires EPA to prevent adverse effects to endangered
species in regulating hazardous air pollutants.
Like other federal agencies, EPA has published regulations and taken actions to protect
endangered species. For example, EPA has consulted with the U.S. Fish and Wildlife Service
and the National Marine Fisheries Service to prevent jeopardy to endangered species, as required
by the ESA, for actions such as setting water quality standards and regulating pesticides. In
these consultations, the attributes of concern have generally been survival, fecundity, and
growth, although other attributes may be important in specific cases. The NCP specifies that the
ESA is a federal "applicable or relevant and appropriate requirement" with which Superfund
remedial actions should comply under CERCLA §121(d)(2)(A), and examples of Superfund
ecological risk assessments that used endangered species as endpoints include the Asarco
Tacoma site (chinook salmon and bull trout) (Hillman and Rochlin, 2001), the Metal Bank of
America site (shortnose sturgeon) (Wentsel et al., 1999), and the Montrose, Iron Mountain Mine,
Fort Ord and Monterey Marine Sanctuary, Camp Pendleton-Santa Margarita River, and Pearl
Harbor sites (U.S. EPA, 1994).
Marine mammals. The Marine Mammal Protection Act protects marine mammals from
taking, which is defined as
to harass, hunt, capture, or kill, or attempt to harass, hunt, capture, or kill any marine
mammal... .The term 'harassment' means any act of pursuit, torment, or annoyance which
(I) has the potential to injure a marine mammal or marine mammal stock in the wild; or
(ii) has the potential to disturb a marine mammal or marine mammal stock in the wild by
causing disruption of behavioral patterns, including, but not limited to, migration,
breathing, nursing, breeding, feeding, or sheltering. (US Code, §1362)
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Although the act does not specifically address toxic effects on marine mammals, the
special protection afforded these species by the act implies a particular concern for their well-
being. Also, the law clearly protects properties of marine mammals at the organism level.
As with threatened and endangered species, the NCP specifies that the Marine Mammal
Protection Act is a federal "applicable or relevant and appropriate requirement" with which
Superfund remedial actions should comply under CERCLA, §121(d)(2)(A), and it cites marine
mammals as examples of specific natural resources to be protected under CERCLA, Part 101,
§16.
Bald and golden eagles. Prohibited actions under the Bald and Golden Eagle Protection
Act include to "take, possess, sell, purchase, barter, offer to sell, purchase or barter, transport,
export or import, at any time or in any manner any bald eagle commonly known as the American
eagle or any golden eagle, alive or dead, or any part, nest, or egg thereof of the foregoing
eagles..." (16 US Code, §668). To take, as defined by regulation, includes "to pursue, hunt,
shoot, wound, kill, trap, capture, or collect, or attempt to pursue, hunt, shoot, wound, kill, trap,
capture, or collect" bald eagles or golden eagles, including any "part, nest, or egg of such
bird[s]"(50CFR§10.12).
Deaths of bald eagles due to secondary poisoning were an endpoint in EPA's assessment
of granular carbofuran (U.S. EPA, 1991b), which led to the phaseout of most uses of this
pesticide. Also, EPA's ecological risk assessment for PCBs in the Hudson River included
survival, growth, and reproduction of piscivorous birds as an assessment endpoint, with the bald
eagle selected as one of the representative species of piscivorous birds (U.S. EPA, 2000).
Birds. The Migratory Bird Treaty Act of 1918 prohibits or regulates a number of
activities, including pursuing, taking, hunting, capturing, killing, possessing, selling,
transporting, or purchasing migratory birds, including their eggs and nests (16 US Code, §703).
This act, based originally on a treaty between the United States and Great Britain (including
Canada), has since been extended by migratory bird conventions with Mexico, Japan, and the
Soviet Union. Because nearly all species of birds native to the United States are protected by the
act (U.S. Fish and Wildlife Service, 2001), the endpoint may be assumed to apply to native birds
in general. Although the Migratory Bird Treaty Act does not specifically address toxic effects
on birds, the special protection afforded these species by the act implies a particular concern for
their well-being. Also, the law clearly protects birds at the organism level. Furthermore, by
Executive Order 13186, all federal agencies are required to "support the conservation intent of
the migratory birds conventions by integrating bird conservation principles, measures, and
practices into agency activities and by avoiding or minimizing, to the extent practicable, adverse
impacts on migratory bird resources when conducting agency actions" and to "prevent or abate
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the pollution or detrimental alteration of the environment for the benefit of migratory birds, as
practicable" (Clinton, 2001).
EPA policies and precedents affirm the use of survival, growth, and reproduction of birds
in ecological assessments. The NCP specifies that the Migratory Bird Treaty Act is a federal
"applicable or relevant and appropriate requirement" with which Superfund remedial actions
should comply under CERCLA §121(d)(2)(A), and examples of Superfund ecological risk
assessments that used birds as endpoints include the Baird and McGuire site (survival and
reproduction of songbirds) (Menzie et al., 1992) and the United Heckathorn site (reproductive
effects on birds) (Wentsel et al., 1999). EPA's ecological risk assessment for PCBs in the
Hudson River included survival, growth, and reproduction of insectivorous birds, waterfowl, and
piscivorous birds as assessment endpoints (U.S. EPA, 2000). EPA regulations authorize the
Agency to require pesticide registrants to submit tests on avian mortality and impaired avian
reproduction caused by pesticides. Results from these tests, in conjunction with other available
information, are used by EPA in making pesticide registration decisions. Also, EPA's
involvement in bird conservation initiatives such as Partners in Flight and the North American
Bird Conservation Initiative provides further support for using birds in assessment endpoints
(U.S. EPA, 2002b).
Practicality: Survival, Fecundity, and Growth
Because the vast majority of standard toxicity tests determine effects on the survival,
fecundity, and growth of organisms, direct toxic effects on this endpoint are readily predicted. In
addition, extrapolation models are available that can estimate effects on this endpoint for
particular organisms and exposure routes of concern on the basis of tests conducted on other
species, life stages, or exposure durations or routes.
It is rarely possible to obtain toxicity data for threatened and endangered species, but
SSDs, intertaxa regressions, or other interspecies extrapolation models should serve to estimate
effects of these species (Suter, 1998; Posthuma et al., 2002). EPA research has confirmed that
endangered species are not inherently more sensitive than other species to toxic effects
(Sappington et al., 2001), although, from a population standpoint, they may be at greater risk due
to their low abundance.
Effects on marine mammals are relatively difficult to observe in the field. However, die-
offs of pinnipeds and cetaceans are readily observed when their conspicuous carcasses appear on
beaches. The toxicology of marine mammals is poorly known, and, for obvious reasons, marine
mammals are not included in routine toxicity testing. However, effects on all mammals are
routinely estimated from tests performed with rodents. Exposure of marine mammals is also
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poorly known and is not routinely estimated, even though these mammals can accumulate high
levels of persistent pollutants.
Eagles are highly conspicuous, and dead or debilitated eagles are more likely to be
reported by the public than are most birds. In addition, federal, state, and private organizations
monitor eagles at various scales. Toxic effects on eagles may be predicted from standard avian
toxicity tests or, more confidently, from tests with kestrels, with avian allometric models used to
extrapolate toxicity results to eagles.
In general, the biology of birds is well known, and well-developed methods exist for
surveying bird populations and communities. Both acute and chronic test protocols for birds are
available, and avian toxicity data are available for most pesticides and many other chemicals.
However, because birds are highly mobile, often migratory, and often territorial, it is usually
difficult to demonstrate chronic effects on these organisms in the field.
A.2. Population-Level Endpoints
As described in Section A.I., most environmental statutes authorizing EPA activities call
for protection of a diverse array of organisms. These statutes generally can be inferred to protect
population-level endpoints in addition to organism-level endpoints, even if populations are not
specifically cited by law. EPA's principles for ecological risk assessment and risk management
at Superfund sites exemplify EPA's concern about population-level endpoints: "Superfund's
goal is to reduce ecological risks to levels that will result in the recovery and maintenance of
healthy local populations and communities of biota" (U.S. EPA, 1999b).
Predicting population-level impacts generally is not as straightforward as estimating
organism-level effects and, as a result, explicit estimates of population effects are less common
in EPA ecological assessments. Adverse effects on organisms are often inferred to indicate risk
to populations and hence a cause for concern under certain EPA programs, such as Superfund.
Similar inferences are made for chemical reviews under TSCA. In examining environmental
effects of concern under TSCA, an EPA position paper reviewed a number of statutes spanning
the period of 1785 to 1978 to determine society's environmental values (U.S. EPA, 1983). EPA
concluded that such laws were passed to prevent any reduction, degradation, or loss in the
quality, quantity, or utility of a resource that is valued by the public. It also concluded that
chemicals could adversely affect these resources by causing an undesirable change in the
population structure of a species by affecting rates of mortality, reproduction, or growth and
development. Thus, organism-level attributes such as mortality can be inferred to affect
population-level attributes valued by society. Less commonly, EPA prepares quantitative
estimates of population effects based on organism-level effects or other information.
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Population-level endpoints have been assessed at EPA for commercially or recreationally
valuable species such as fish, birds, and shellfish.
A.2.1. GEAE #4. Extirpation of an Assessment Population
Extirpation can be viewed as an extreme case of a change in abundance or production of
an assessment population, and thus its selection is supported by the factors cited in Section
A.2.2. Additionally, extirpation of an assessment population may have qualitatively more
significant impacts on ecological function and environmental values than just reduction in the
size of the assessment population, as reflected in an alternative term for this population attribute:
functional extinction.
Laws, Regulations, and Precedents: Extirpation
Several EPA precedents exist for assessing population extirpation. For example, EPA
examined the likelihood of extirpation offish populations in northeastern lakes under the acid
deposition program and vetoed a permit for a dam and reservoir project under Section 404 of the
CWA, in part on the basis of the projected extirpation of populations of birds of special interest
(U.S. EPA, 1994). Absence of a species normally occurring in the habitat has been used as
evidence of ecological risk at Superfund sites. Where designated aquatic life uses have been
specified in state water quality standards, extirpation of a naturally occurring species may be
considered as evidence that the waterbody is not attaining its designated uses.
Practicality: Extirpation
Field observations to determine whether a species is present usually are not difficult to
conduct, but ease of observation depends upon the species, and care must be taken in interpreting
results. Failure to observe a species that is expected to occur in low numbers even in the absence
of stressors, that is subject to substantial natural fluctuations in abundance, or that is
inconspicuous may not be indicative of extirpation. Demonstrating extirpation at a site also
requires evidence that the species was formerly present.
In some cases, risk of extirpation can be inferred from toxicity data. Very high exposure
in the field in comparison to exposures where toxic effects have been observed in laboratory
tests suggests a high likelihood of extirpation and, conversely, very low exposure implies that
extirpation is unlikely. Population modeling (such as population viability analysis) or ecosystem
modeling may be required to estimate the likelihood of extirpation in cases where exposure is
lethal to only a portion of individuals, where effects on reproduction are expected but limited, or
where effects are indirect. Population modeling typically requires species-specific data on
parameters not routinely available in ecological risk assessment, such as age-specific
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reproduction rates. However, population models are available and well developed and have been
used to predict extirpation, particularly of fisheries (Barnthouse, 1993; Pastorok et al., 2002).
See also Section A.2.2.
A.2.2. GEAE #5. Abundance of an Assessment Population
Laws, Regulations, and Precedents: Abundance
Abundance is the most common population-level endpoint considered by EPA. On
occasion, EPA evaluated population models to explore effects on abundance by chemicals
regulated under TSCA. For example, EPA explored the risks of chloroparaffins to a rainbow
trout population using a projection matrix model (U.S. EPA, 1993a). Maintenance of
populations of piscivorous birds and mammals was the ecological assessment endpoint for the
Mercury Report to Congress (U.S. EPA, 1995).
Additionally, more than 25 estuaries have been selected as national estuaries by EPA, as
authorized by the CWA. Restoring or protecting populations and production offish and shellfish
for commercial and recreational use typically is among the goals of individual national estuary
programs. Similarly, a goal of the Chesapeake Bay Program (a partnership among EPA and the
states adjoining the bay) is restoring, protecting, and enhancing fish and shellfish, with measures
including populations of oysters and priority migratory fish species such as striped bass.
Practicality: Abundance
Changes in population abundance may be predicted using conventional toxicity data with
statistical extrapolation models and population models (Suter, 1993; Pastorok et al., 2002). This
approach can produce reasonable results, and has been validated in controlled conditions. For
example, Kuhn et al. (2001) compared a mysid shrimp population prediction from a stage-based
projection matrix model with a 55-day laboratory population study involving shrimp exposed to
p-nonylphenol. The population model was able to project within a few micrograms per liter the
concentration where population-level effects would begin to occur (16 |ig/L projected from the
model vs. 19 |ig/L measured from the assay). Although such projection matrix models are
practical, they require more effort than is normally applied to routine ecological risk
assessments.
Population abundance may also be estimated using individual-based population models
or, as discussed in Section A.3, ecosystem models. Measurement of population abundance in the
field may be easy (e.g., for flowering plants) or difficult (e.g., for pelagic cetaceans). However,
even when measurement is easy, distinguishing changes in abundance may be quite difficult due
to temporal variance, and distinguishing differences from reference populations may be difficult
due to differences in habitat quality as well as stochastic variance. The literature in ecology
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concerning the measurement and monitoring of various plant and animal populations is
voluminous.
A.2.3. GEAE #6. Production of an Assessment Population
Laws, Regulations, and Precedents: Production
Much of the support for GEAE #5, abundance of an assessment population, also applies
to this endpoint. For example, the CWA sets a national goal of "protection and propagation of
fish, shellfish, and wildlife," which implies both abundance and production, and efforts under the
National Estuary and Chesapeake Bay programs to protect resource species involve both
abundance and production. Additionally, numerous federal laws and treaties have the purpose of
maintaining or increasing the production of game birds and mammals, commercial fish, and
timber species. Examples include the Migratory Bird Hunting Stamp Act (48 Stat. 451),
Wildlife Restoration Act (50 Stat. 917), Fish Restoration and Management Act (64 Stat. 430),
Convention on Great Lakes Fisheries (6 UST 2836), and Fish and Wildlife Act of 1956 (70 Stat.
1119). Relevant provisions include requirements to "develop measures for maximum
sustainable production offish" (70 Stat. 1119) and "make possible the maximum sustained
productivity of Great Lakes fisheries" (6 UST 2836).
Prevention of adverse effects to public welfare, including (but not limited to) effects on
soils, water, crops, vegetation, animals, and wildlife is mandated under Section 108 (§109) of the
CAA (National Ambient Air Quality Standards). EPA has included production of an assessment
population, among other endpoints, as an indicator of public welfare. For example, EPA revised
the secondary ozone standard to provide increased protection against ozone-induced effects on
vegetation, such as agricultural crop loss and damage to forests (U.S. EPA, 1997b). Also, EPA
regulations authorize the Agency to require pesticide registrants to submit tests on pesticide
effects on plant mortality and plant growth inhibition. Results from these tests, in conjunction
with other available information, are used by EPA in making pesticide registration decisions.
Changes in production of specific legume species were endpoints in a TSCA assessment of
release of recombinant rhizobia (McClung and Sayer, 1994; Orr et al., 1999).
Practicality: Production
Plant production is relatively easily and commonly measured in the field. Production of
animals is more difficult to measure in the field, but well-developed techniques exist and are
commonly employed for fisheries, game species, and pest insects. Toxic effects on production
may be estimated from chronic tests that include survival, fecundity, and growth. The combined
effects on population production of these organismal responses may be estimated using
population or ecosystem models.
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Example of support of community/
ecosystem-level endpoints: Superfund
EPA's principles for ecological risk
assessment and risk management at
Superfund sites state that"Superfund's
goal is to reduce ecological risks to levels
that will result in the recovery and
maintenance of healthy local populations
and communities of biota." Community
effects can either be measured directly
(e.g., as in benthic species diversity) or
estimated indirectly (e.g., from toxicity
tests on individual species) (U.S. EPA,
1999b).
A.3. Community and Ecosystem-Level Endpoints
Abundant statutory and regulatory
support exists for environmental protection at
levels above the organism and population levels.
This support stems both from the recognition that
maintaining particular organisms of concern
involves their preserving surrounding
environment and from appreciation for the
ecosystem as a whole. In the case of direct
assessment of community-level endpoints, taxa
richness (GEAE #7) and abundance (GEAE #8)
are the two most commonly addressed attributes.
Production (GEAE #9) of plant communities (as
with production of plant populations, GEAE #6)
has also been considered by EPA in some cases.
Perhaps the simplest and most widely used ecosystem-level endpoint is the area (extent)
of an ecosystem (GEAE #10). Physical structure (GEAE # 12) is also commonly used as an
endpoint in assessing aquatic ecosystems. The authors found little precedent at EPA for using
attributes based on ecosystem function, such as primary production, energy flow, total biomass,
and nutrient cycling, except in the case of wetland ecosystems (GEAE #11). Such endpoints
may have limited use to date, because they are somewhat abstract and not as directly linked to
management values as other endpoints. Several such endpoints are listed in Table 4-1 as
potential GEAEs for future EPA consideration.
Further details about the support for community- and ecosystem-level endpoints are
presented in this section in two ways. First, support spanning multiple attributes of
community/ecosystem-level GEAEs is described for four general categories of ecosystems for
which significant precedent exists: aquatic ecosystems, wetlands, coral reefs, and
endangered/rare ecosystem types. Next, supporting information is presented for each of the six
community/ecosystem-level GEAEs.
Aquatic Ecosystems
To date, the most common application of community- and assemblage-level endpoints at
EPA has been to aquatic communities, particularly fish and macroinvertebrates. Section
101(a)(2) of the CWA calls for an interim goal of water quality that provides for the protection
and propagation offish, shellfish, and wildlife. Section 304(a) of the Water Quality Act of 1987
directs EPA to develop and publish water quality criteria and information on
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methods—including biological monitoring and assessment methods—that assess the effects of
pollutants on the aquatic community. Aquatic community components and attributes addressed
include "biological community diversity" and "productivity." Taxa richness (GEAE #7) and
abundance (GEAE #8) of species or trophic groups offish and macroinvertebrate communities
are used in the biocriteria of many states and in Agency guidance (Yoder and Rankin, 1995; U.S.
EPA, 1996, 1999c).
Potential community-level impacts also have been inferred and considered a basis of
concern by EPA programs, based on organism-level responses. The U.S. Ambient Water
Quality Criteria for Protection of Aquatic Life are based on SSDs, with the criteria set at the fifth
percentile (U.S. EPA, 1985a); hence, they can be interpreted as protecting at least 95% of the
species in a community. The assessment community is also commonly used in EPA programs
under TSCA. The Quotient Method is typically applied to the most sensitive organismal
response, as well as uncertainty factors, to infer effects on a community. Organisms are chosen
to represent a variety of taxonomic groups.
Ecosystem models are particularly useful for assessing secondary (indirect) effects of
toxicants on community properties (Bartell et al., 1992; Pastorok et al., 2002). Models have
been used to explore community-level effects, as in the case of evaluating the primary and
secondary effects of chloroparaffins to top predator fish (Bartell, 1990; U.S. EPA, 1993a).
Although there are relatively few examples of application of ecosystem models to the regulation
of chemicals, generic models such as AQUATOX can serve to illustrate how direct and indirect
effects propagate through ecosystems (U.S. EPA, 2003b).
Wetlands
The CWA forms the primary statutory basis for protection of wetlands and, thereby, the
area (GEAE #10) and function (GEAE #11) of wetland communities/ecosystems. In meeting the
CWA's objective of restoring and maintaining the integrity of the nation's waters, under Section
404 of the act, wetlands are considered waters of the United States and are protected from
discharge of dredged and fill material through a permit program jointly administered by the U.S.
Army Corps of Engineers and EPA. Wetlands are defined for regulatory purposes as areas that
are inundated or saturated by surface or ground water at a frequency and duration sufficient to
support—and that under normal circumstances do support—a prevalence of vegetation typically
adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs,
and similar areas (33 CFR §328.3 [b]). The CWA provides authority for the Corps to require
permit applications to avoid and minimize wetlands impacts and requires EPA to develop, in
coordination with the Corps, the criteria used for Section 404 permit decisions. When damages
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to wetlands are unavoidable, the Corps can require permitees to provide compensatory
mitigation.
Additionally, Executive Order 11990, Protection of Wetlands, states that "Each agency
shall provide leadership and shall take action to prevent the destruction, loss or degradation of
wetlands and to preserve and enhance natural and beneficial values of wetlands in carrying out
the agency's responsibilities" (Carter, 1977). As an extension of this order, President George H.
W. Bush in 1989 and succeeding presidents have adopted a national policy of no net loss of
wetlands in recognition of the significance of wetland areas and their ecological functions. The
1972 Coastal Zone Management Act also calls for the protection of coastal wetlands.
EPA has prepared various regulations and guidance documents supporting the wetlands
protection goals of the CWA and Executive Order 11990. For example, "Guidelines for
Specification of Disposal Sites for Dredged or Fill Material" (40 CFR, Part 230, Subpart E)
recommends consideration of potential impacts on special aquatic sites, including wetlands,
referencing changes that result in loss of wetland status due to permanent flooding or conversion
to dry land as well as loss of functions of water purification, water storage, and provision of
wetland habitat.
The large number of Superfund sites located in or adjacent to wetlands has lead EPA's
policy and emphasis toward a greater concern regarding the impact of contamination from these
sites on the extent and ecological functions of wetlands. OSWER highlights the importance of
wetlands protection in the directive, "Policy on Floodplain and Wetland Assessment for
CERCLA Action" (U.S. EPA, 1985b). Under this policy, Superfund action should meet the
substantive requirements of Executive Order 11990 as well as the those of the Floodplain
Management Executive Order (E.O. 11988). Section 404 of the CWA is also considered a
federal "applicable or relevant and appropriate requirement" with which Superfund remedial
actions should comply under CERCLA Section 121(d)(2)(A). Other Superfund policies that
involve consideration or protection of wetlands include the Hazard Ranking System (U.S. EPA,
1990a, 1992a), the Superfund removal process guidance (U.S. EPA, 1992b), a Memorandum of
Agreement between EPA and the U.S. Department of Army (U.S. EPA, 1990b), and the OSWER
directive, "Controlling the Impacts of Remediation Activities In or Around Wetlands" (U.S.
EPA, 1993c).
EPA's "Procedures for Implementing the Requirements of the Council on Environmental
Quality on the National Environmental Policy Act" (40 CFR §6.108) singles out wetlands by
stating that "if the proposed action may have significant adverse effects on wetlands" an
environmental impact statement is required. EPA's regulations for State and Local Assistance
(40 CFR, Part 35, Appendix A to Subpart H) require that project proposals demonstrate
compliance with Executive Order 11990.
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Coral Reefs
At present, coral reefs have not attained the same legal and regulatory stature under EPA
programs as have wetlands, perhaps in part because few EPA actions involve coral reefs.
However, support for their protection has been increasing in recent years. Taxa richness (GEAE
#7) and area (GEAE #10) are the attributes of coral reef communities/ecosystems most
commonly targeted for assessment and protection. Executive Order 13089 established special
protection for coral reefs (Clinton, 1998). In particular, "All Federal agencies...shall.. .utilize
their programs and authorities to protect and enhance the conditions of such ecosystems." This
Executive Order names the EPA Administrator as a member of the Coral Reef Task Force, which
is responsible for implementing the order. An EPA memorandum to the field specifically applies
the order to EPA's responsibilities under Section 404 of the CWA, Sections 102 and 103 of the
Marine Protection and Sanctuaries Act, and Section 307 of the Coastal Zone Management Act
(Fox and Westphal, 1999). The order is also considered a federal "applicable or relevant and
appropriate requirement" with which Superfund remedial actions should comply under CERCLA
Section 121(d)(2)(A).
"Guidelines for Specification of Disposal Sites for Dredged or Fill Material" (40 CFR,
Part 230, Subpart E) recommend consideration of potential impacts on special aquatic sites,
including coral reefs. The guidelines refer to loss of productive colonies and subsequent loss of
coral-dependent species.
Diversity is the only ecological attribute defined as a value of coral reefs in the National
Action Plan to Conserve Coral Reefs (U.S. Coral Reef Task Force, 2000). A practical
operational definition of that attribute is taxa richness. This document also mentions "shoreline
protection, areas of natural beauty, recreation and tourism, and sources of food, pharmaceuticals,
jobs, and revenues" as services of coral reefs. These services could be protected by preserving
the area and taxa richness of coral reefs.
CITES, to which the United States is a party, restricts international trade in corals and
other reef organisms. All coral reefs in Florida are protected by either the U.S. or the state
government. Other specifically protected reef communities are found in Puerto Rico, Hawaii,
the U.S. Virgin Islands, Guam, Northern Marianas, and American Samoa.
Endangered or Rare Ecosystems Types
Support for the protection of endangered and rare ecosystems (particularly in the case of
terrestrial ecosystems) is less extensive and more indirect than it is for the classes of
communities/ecosystems described above, but it can be identified in a variety of programs. Area
(GEAE #10) is the primary attribute assessed for these ecosystems. Additionally, note that
inherent in the definition of the area of endangered and rare ecosystems may be attributes such as
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taxa richness (GEAE #7) and abundance (GEAE #8), and, consequently, the loss of these
attributes could constitute loss of area of the ecosystem type as it is converted to a different
ecosystem type.
Several lines of support for protecting endangered and rare ecosystems are apparent in
Superfund programs. The NCP specifies that, "evaluations shall be performed to assess threats
to the environment, especially sensitive habitats" (emphasis added) (U.S. EPA, 1989). The
Hazard Ranking System for Superfund (U.S. EPA, 1990a) gives as an example of "sensitive
environments," "particular areas, relatively small in size, important to maintenance of unique
biotic communities." The Superfund removal process guidance (U.S. EPA, 1992b) recommends
that the On-Scene Coordinator undertake special considerations for actions that include sensitive
ecosystems, which may be interpreted as calling for protection of endangered or rare ecosystem
types.
Other EPA programs also consider endangered ecosystems. For example, the protocol
for screening-level ecological risk assessment for hazardous waste combustion facilities calls for
special consideration of areas having unique and/or rare ecological receptors and natural
resources (U.S. EPA, 1999a). EPA Regions 4, 5, 6 and the Great Lakes Program Office are
developing approaches for identifying high-quality areas (critical ecosystems) for enhanced
environmental protection and restoration. EPA Region 4 has been involved in the development
of the Southeastern Ecological Framework as a decision support tool useful in integrating
program resources for protecting and sustaining ecological processes.
EPA Region 5 is also developing an approach for prioritizing and targeting high-quality
areas in the Midwest (Mysz et al., 2000). Two of the criteria for identifying these areas, also
called "critical ecosystems," are (1) the presence of an indigenous ecosystem and biological
community types (used as an indicator of relative ecological diversity), and (2) the numbers and
rarity of native species and natural features (used as indicators of surviving relict native
ecosystems).
In addition, the EPA Great Lakes program, in collaboration with Environment Canada,
has developed Biodiversity Investment Areas as natural areas along the Great Lakes shoreline
whose high ecological value warrant exceptional attention to protect them from degradation.
EPA Region 6 is using a GIS screening tool to assist in prioritizing ecological areas of concern
for programs such as NEPA (Osowski et al., 2001).
In carrying out its responsibilities for reviewing environmental impact statements under
NEPA, EPA has developed guidance that calls for special attention to human activities in
imperiled ecosystems and identifies mitigation measures to reduce adverse impacts (U.S. EPA,
1993b). Approximately a dozen "principal habitats of concern" were identified within each of
six major U.S. habitat types. Ecological concerns raised by EPA to other federal agencies in
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review of NEPA documents have included impacts to endangered or rare ecosystems (U.S. EPA,
1994).
A.3.1. GEAE #7. Taxa Richness of Assessment Communities, Assemblages, and
Ecosystems
Laws, Regulations, and Precedents: Taxa Richness
As described in Section A.3., the most extensive support for use of this endpoint at EPA
comes from measures to assess and protect the taxa richness of aquatic communities as part of
water quality protection programs under the CWA. Use of taxa richness as an attribute can be
inferred by programs under TSCA and other statutes to assess risks to a range of species across
an aquatic community. Aquatic community composition is presented as an example of an
assessment endpoint in Superfund ecological risk assessment guidance (U.S. EPA, 1997c), and
community diversity or species richness is a generic endpoint for ecological risk assessments of
hazardous waste combustors (U.S. EPA, 1999a). Support for taxa richness of coral reef
communities/ecosystems is also described in Section A.3.
EPA regional offices have considered the effects of federal projects on species diversity
in decisions under NEPA, such as in an assessment of the impacts of the loss of bottomland
hardwood forest on species composition of the wildlife community due to levee construction
(U.S. EPA, 1994).
Practicality: Taxa Richness
Species or taxa richness is the simplest, least controversial, and most easily interpreted
expression of community diversity. Changes in taxa richness are readily observed in standard
biological surveys. If it is assumed that significant toxic effects are likely to result in local
extirpation of a species, changes in taxa richness may be predicted using SSDs or regression
models that relate all species of a community or assemblage to a test species. If indirect effects
are expected to result in the loss of species, ecosystem models may be used to predict species
losses.
In the case of coral reefs, the taxa richness of corals are relatively easily determined. The
taxa richness of some other assemblages (e.g., fishes and sessile noncoral invertebrates) is also
practical to determine. Methods for assessing the condition of coral reefs are discussed in
Jameson et al. (1998). Prediction of the effects of pollutants on coral reefs is difficult due to the
paucity of toxicological information for corals.
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A.3.2. GEAE #8. Abundance of Assessment Communities, Assemblages, and Ecosystems
Laws, Regulations, and Precedents: Abundance
This endpoint shares with GEAE #7 the support described in Section A.3 for aquatic
communities. Abundance offish and macroinvertebrate taxa and trophic groups in sampled
communities is used in the water quality biocriteria of many states and in Agency guidance.
Community abundance can be inferred to be an element of ambient water quality standards and
of chemical evaluations under TSCA. Aquatic community composition (including a metric
describing abundance) is presented as an example of an assessment endpoint in Superfund
ecological risk assessment guidance (U.S. EPA, 1997c).
Practicality: Abundance
Abundance of communities or assemblages, as a whole or by species, taxon, or trophic
group, is available from most routine biological surveys. Although one can readily infer from
standard toxicity tests that some changes in abundance are likely to occur, they are difficult to
predict quantitatively. As discussed in Section A.3, community properties may be estimated
from standard toxicity test data using ecosystem models.
A.3.3. GEAE #9. Production of Assessment Communities, Assemblages, and Ecosystems
Laws, Regulations, and Precedents: Production
This endpoint shares a basis in laws, regulations, and precedents with GEAE #6,
production of plant populations, through FIFRA, TSCA, and CAA programs. For example, the
secondary ambient air quality standard established by EPA to protect public welfare for ground-
level ozone (U.S. EPA, 1997b) cites growth and yield reductions in tree seedlings and mature
trees and impacts on forest stands and community structure due to these reductions.
Superfund directives and guidance identify plant production, such as productivity of
wetlands vegetation, as candidate assessment endpoints (Environmental Response Team, 1994a,
b, c, d). Community productivity and, in particular, herbaceous plant productivity, is a generic
endpoint for ecological risk assessments of hazardous waste combustors (U.S. EPA, 1999a).
EPA actions to control acid rain and its precursors have been based on concerns over the damage
to high-elevation forests—among other effects—attributed to acid rain.
As stated in Section A.3., the CWA (§101(a)(2)) calls for an interim goal of water quality
that provides for the protection and propagation offish, shellfish, and wildlife. Section 304(a) of
the act also lists effects of pollutants on plant life and on rates of eutrophication (excessive plant
production due to nutrient pollution) as factors to consider in establishing pollutant limits.
Eutrophi cation has been the basis for many federal and state regulatory actions and voluntary
control programs, including the establishment of total maximum daily loads (TMDLs) for
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nutrients (U.S. EPA, 1999d), controls on nutrient discharges from sources such as publicly
owned treatment works and confined animal feeding operations, and restrictions on phosphorus
in detergents.
Practicality: Production
Eutrophication has long been a major concern of environmental managers, particularly
with respect to sewage outfalls, so the models for predicting effects of nutrient additions are
relatively well developed. Similarly, studies of fertilizer addition to crops, pastures, and
commercial forests are numerous and provide a good basis for predicting the effects of terrestrial
nutrient additions on plant production. In addition, methods for measuring plant production are
well developed for both terrestrial and aquatic communities. Protocols for testing toxic effects
on terrestrial and aquatic plants focus on various measures of production. However, toxicity data
are less abundant for plants than for animals.
A.3.4. GEAE #10. Area of Assessment Communities, Assemblages, and Ecosystems
Laws, Regulations, and Precedents: Area
The most extensive support for use of community/ecosystem area as a GEAE at EPA
involves protection of wetlands. As discussed in Section A.3, the CWA affords special
protection to wetlands, and a number of EPA programs reflect this emphasis. Within the
Superfund program, for example, unavoidable impacts to on-site and adjacent wetland resources
from current or potential exposure to hazardous substances and from implementation of select
response actions are addressed within the Record of Decision for that site. Records of Decision
for the New London Submarine Base in New London, Connecticut (U.S. EPA, 1998c), Loring
Air Force Base in Limestone, Maine (U.S. EPA, 1997d), and Pease Air Force Base in
Portsmouth/Newington, New Hampshire (U.S. EPA, 1997e) include remedies involving
compensatory wetland mitigation. Mitigation actions are tracked by long-term monitoring plans
and restoration efforts are monitored over a specified time period to ensure success.
Efforts to assess and to control risks to coral reefs—and to rare/endangered ecosystems
generally—also serve as precedents for the use of area as a GEAE (see Section A.3), although
these programs are not currently as extensive at EPA as are those for wetlands.
Practicality: Area
Wetlands are classified and mapped by the National Wetlands Inventory of the U.S. Fish
and Wildlife Service, but determination of wetland boundaries at a given site may be difficult,
particularly in areas of low topographic relief. The 1987 Corps of Engineers Wetlands
Delineation Manual (Environmental Laboratory, 1987) is the current federal delineation manual
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used in the CWA Section 404 regulatory program for the identification and delineation of
wetlands. Most effects on wetland area are readily predicted or observed, because they occur
due to processes such as dredging, filling, draining, or inundation.
The area of coral reef is relatively easily determined. Methods for assessing the
condition of coral reefs are discussed in Jameson et al. (1998). Prediction of the effects of
pollutants on coral reefs is difficult due to the paucity of toxicological information for corals.
An endangered or rare ecosystem type might be diminished by physical destruction,
which is readily observed and quantified, or by physical conversion to another type of ecosystem
(e.g., due to selective logging or grazing), which can also be readily observed and quantified if
the type is clearly defined. The prediction of loss of an ecosystem type due to extirpation of
many or most of the constituent organisms (e.g., due to an herbicide application or oil spill) is
practical because it would involve severe toxicity. However, loss of a type due to more subtle
effects, such as changes in species composition due to differential susceptibility to a stressor,
could be difficult to predict. Information useful in identifying rare and endangered ecosystem
types is available from NatureServe (http://www.natureserve.org), a nonprofit organization that
works with natural heritage programs throughout the United States and elsewhere in the Western
Hemisphere. NatureServe maintains databases on all known ecological communities in the
United States, ranked from critically imperiled to secure. According to NatureServe, the
completeness of inventory and classification work varies widely among states, provinces, and
regions.
A.3.5. GEAE #11. Function of Assessment Communities, Assemblages, and Ecosystems
Laws, Regulations, and Precedents: Function
Although the importance of ecosystem function is widely recognized, precedent for its
use as an independent endpoint at EPA is limited, except in the case of wetlands. Protection of
functional attributes of wetlands is specifically targeted, for example, in EPA's "Guidelines for
Specification of Disposal Sites for Dredged and Fill Material" (40 CFR, Part 230), implementing
Section 404(b)(l) of the CWA. Commonly recognized functions of wetlands include storage
and filtration of water and maintenance of habitat for fish and wildlife.
Practicality: Function
Losses of wetland functions can be inferred from loss of wetlands area (see GEAE #10,
A.3.4), but they are less readily observed or predicted if not accompanied by the loss of wetland
area. The hydrogeomorphic method (Brinson, 1993) is one approach for assessing wetlands
function. EPA, the Corps, and other federal agencies have agreed to formally adopt this method
to improve the assessment of wetlands function in support of the CWA Section 404 Program (62
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FR 33607, June 20, 1997). Toxic effects on wetland functions or on the type of wetland
community are difficult to predict.
A.3.6. GEAE #12. Physical Structure of Assessment Communities, Assemblages, and
Ecosystems
Laws, Regulations, and Precedents: Physical Structure
Policy support for physical structure of ecosystems as a GEAE stems from the CWA's
goals of protecting aquatic ecosystems. The CWA (§101(a)) states that, "The objective of this
Act is to restore and maintain the chemical, physical [emphasis added], and biological integrity
of the Nation's waters." The importance of physical structure is reflected by EPA regulations
implementing the CWA that note the following conditions of a water body that may preclude
attainment of desired beneficial uses (40 CFR §131.10 (g)):
• "natural, ephemeral, intermittent or low flow conditions of water levels"
• "dams, diversions or other types of hydrologic modifications"
• "physical conditions related to the natural features of the water body, such as the lack
of a proper substrate, cover, flow, depth, pools, riffles, and the like, unrelated to water
quality"
Protocol for Developing Sediment TMDLs (U.S. EPA, 1999e) lists channel modification,
pool filling, filling of substrate with fine sediments, and other effects on physical structure as
sediment issues that can result in loss of designated uses. These changes in stream ecosystems
are themselves changes in the ecosystem attributes that result in the lost recreational/aesthetic or
other uses, not simply stressors that affect biological endpoints.
Physical structure has been a factor in setting the designated use of streams in state water
quality standards. For example, in Ohio, a designated use of Modified Warmwater Habitat
applies to streams with extensive and irretrievable physical habitat modifications.
Practicality: Physical Structure
Physical characteristics often are readily observed or measured at sites being assessed
and are usually recorded in biological surveys. Protocols exist for measuring many aquatic
habitat attributes (e.g., U.S. EPA, 1999c). In addition, most of the actions that modify the
physical structure of waterbodies (e.g., channelization, dam construction and operation, water
withdrawals, and culvert installation) have obvious effects on structure that are readily predicted.
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Other effects, such as changes in hydrology resulting from changes in land use, are more
difficult—but still possible—to model.
A.4. Officially Designated Endpoints
The GEAEs in this section do not fall neatly into the organism-population-community-
ecosystem hierarchy used to organize the other GEAEs, but they are important to EPA
nonetheless. Habitat for endangered species (GEAEs #13 and #14) is highlighted because of the
specific protections it receives under the ESA. Habitat has not been chosen as a GEAE for other
categories of organisms because it is the organisms that are valued directly, whereas by
definition habitat is that which supports organisms and thus is valued indirectly. (Habitat here is
distinguished from communities and ecosystems, which may be valued in their own right, as
discussed in Section A.3.) Ecological properties of special places (GEAE #15) can encompass
attributes from all levels of biological organization. Special places are identified because of the
extensive legal and other support for their protection or because of their ecological importance.
A.4.1. GEAEs #13 and #14. Area and Quality of Habitat for Threatened or Endangered
Species
Laws, Regulations, and Precedents: Area and Quality of Critical Habitat
The obligation to protect endangered and threatened species under the ESA includes
protection of the critical habitats on which they depend. Thus the legal and regulatory basis for
protecting endangered species described under GEAE #3 generally also applies to this endpoint.
For example, the Superfund NCP specifies that, "evaluations shall be performed to assess threats
to the environment, especially sensitive habitats and critical habitats of species protected under
the Endangered Species Act" (emphasis added) (U.S. EPA, 1989). EPA's regulations for State
and Local Assistance (40 CFR, Part 35, Appendix A to Subpart H) require that project proposals
determine whether there would be significant adverse effects on critical habitat of endangered
species.
Practicality: Area and Quality of Critical Habitat
Designated critical habitat is readily identified, and it should be practical to determine
whether it will be destroyed (reduced area) or adversely modified (reduced quality). Although
critical habitat has not been officially designated for many endangered or threatened species,
federal documents such as listing decisions and recovery plans typically discuss the distribution
and ecological requirements of listed species. Toxic effects may be predicted if species or taxa
that are components of critical habitat are identified and their response to pollutants can be
evaluated.
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A.4.2. GEAE #15. Ecological Properties of Special Places
Laws, Regulations, and Precedents: Special Places
The legislative acts establishing national parks and monuments, wildlife refuges,
wilderness areas, wild and scenic rivers, recreation areas, marine sanctuaries, and other special
places establish their status and indicate the properties for which the protected status was
provided. Several statutes either give EPA a role in designating special places or direct EPA to
consider environmental impacts to such places in administering Agency programs. The CWA
directs EPA to administer the National Estuary Program and permits states to designate
waterbodies as Outstanding National Resource Waters, which then receive increased protection
in their water quality standards.
The CAA also has several provisions for special places. Section 160 of the CAA
establishes that a purpose of the act is "to preserve, protect, and enhance the air quality in
national parks, national wilderness areas, national monuments, national seashores, and other
areas of special national or regional natural, recreational, scenic, or historic value." Section 162
designates national (and international) parks, wilderness areas, and memorial parks of a certain
size as "class I" areas, which merit the highest level of protection from air pollution. Other
special places cited in both the CAA and the CWA include the Great Lakes, Chesapeake Bay,
and Lake Champlain.
In the area of EPA regulations and guidance, the NCP cites special places such as
national marine sanctuaries and estuarine research reserves as natural resources to be protected
under CERCLA. Superfund removal process guidance (U.S. EPA, 1992b) recommends that the
On-Scene Coordinator to undertake special considerations for actions that include wild and
scenic rivers. EPA procedures for implementing NEPA (40 CFR §6.108) require an
environmental impact statement to be prepared if "the proposed action may have significant
adverse effects on parklands, preserves, or areas of recognized scenic, recreational,
archeological, or historic value." "Guidelines for Specification of Disposal Sites for Dredged or
Fill Material" (40 CFR, Part 230, Subpart E) recommend consideration of potential impacts on
special aquatic sites, including sanctuaries and refuges. The protocol for screening-level
ecological risk assessment for hazardous waste combustion facilities calls for special
consideration of areas having legislatively conferred protection (U.S. EPA, 1999a).
Practicality: Special Places
Special places and their important ecological properties usually can be defined readily.
Given the diverse set of ecological properties at different places, it is not possible to make
overall statements about the practicality of this endpoint. Potentially, all of the surveying,
testing, and modeling methods discussed in the previous sections could be applicable.
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APPENDIX B. TYPES OF VALUES ASSOCIATED WITH ASSESSMENT ENDPOINTS
EPA's ecological risk assessment guidelines (U.S. EPA, 1998a) define an assessment
endpoint as "an explicit expression of the environmental value that is to be protected,
operationally defined by an ecological entity and its attributes" [emphasis added]. In the context
of the guidelines, an environmental value refers to a component of the environment (or an
ecological entity) that society values, with some examples being endangered species and
commercially or recreationally important species. The literature on environmental valuation
covers a wide range of ecological systems and components; for example, bays (Kahn, 1985),
wetlands (Barbier, 1993), riparian corridors (Lant and Tobin, 1989), deserts (Richer, 1995),
recreation areas (Adamowicz et al., 1994), and wilderness or "unspoiled" natural areas (Hanink,
1995; Kopp and Smith, 1993; Randall and Peterson, 1984). In many of these studies,
ecosystems are conceptualized as having assets or structural components such as energy
resources, minerals, or timber; services or natural functions benefitting society (e.g.,
groundwater recharge, flood control, the absorption or assimilation of pollutants) and/or other
attributes provided by the whole ecosystem, such as biological diversity, cultural uniqueness, or
natural heritage (Westman, 1977; Daily et al., 1997).
Table B-l presents one way of organizing environmental values, drawing on Blomquist
and Whitehead (1995), Daily (2000), Ehrlich and Ehrlich (1981), MacLean (1995), Primack
(1993), and Freeman (1984, 1993). The table is not intended to represent a definitive or
comprehensive list of environmental values, rather it is intended to illustrate the breadth of
values that may be cited in support of a GEAE.
Each of the GEAEs presented in this document relate to one or more of these
environmental values. For example, an "assessment population" and its attributes may be used
to represent a commercially and recreationally valuable fish or wildlife population (consumptive
and recreational values). Such an assessment population could also represent a species
population that is valued as a learning tool (educational value) and protected for cultural and
aesthetic reasons (preservation value). Table B-l provides further examples of how each of the
GEAEs may correspond with these values.
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Table B-l. Some categories of environmental values
Value
Definition and examples of corresponding GEAEs
Consumptive
The value of commodities produced by the environment such as food, energy, timber,
fiber, and pharmaceutical and industrial products.
• Area of ecosystems: timber and fuel production by trees
• Production of an assessment population: commercially valuable fisheries
• Extirpation of an assessment population: commercially valuable furbearers
Informational
The value of natural structures, chemicals, or processes as models for anthropogenic
structures, chemicals, or processes (e.g., Pharmaceuticals, synthetic commodities,
engineering designs). Also see Option value.
• Extirpation of organisms: as sources of model adaptations to extreme
environments
• Taxa richness of communities: highly diverse communities may be valuable
sources of bioactive chemicals as models for Pharmaceuticals
Functional
The value of ecological functions benefitting public health and welfare, such as
pollen and seed dispersal, water retention and purification, detoxification of wastes,
and moderation of weather extremes. In some cases, ecosystems are re-established to
make use of their functional value for remediation.
• Ecosystem function: water retention and purification by wetlands
• Abundance of an assessment community: water and soil retention by forests
• Abundance of an assessment population: pollination by insects
Recreational
The value of recreational opportunities such as fishing, birding, boating, and hiking.
In some cases, this is a passive use of a resource, but in others (e.g., tourism) it is an
economic activity.
• Physical structure of an ecosystem: boating, fishing
• Survival, fecundity, and growth of organisms (migratory birds): birding,
hunting
• Properties of special places: camping, hiking, boating
Educational
The value of academic and nonacademic educational opportunities, including nature
and scientific study.
• Properties of special places: parks and refuges for nature study, research
• Area of ecosystems: environmental education sites
Option
The value to future generations of preserving the option of using the environment at
some future time. Option value also includes human welfare gains or net benefits
associated with delaying a decision when there is uncertainty about the payoffs of
certain alternatives, or when one of the choices involves an irreversible commitment
of resources.
• Area and function of ecosystems
• Properties of special places
• Abundance of assessment populations
Existence
Value ascribed to the existence of ecological systems independent of any direct
services or functions. Aesthetic, moral, cultural, religious, or spiritual grounds may
be cited in support of this type of nonuse value.
• Area and quality of critical habitat for endangered species
• Gross anomalies and kills of organisms
• Properties of special places
53
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