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A B C
D E F
G H I J K
L M N
O P Q R
S T U
V W V Y
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Adverse
ecological effects — Changes considered undesirable because
they alter valued structural or functional characteristics of ecosystems
or their components.
Assessment endpoint — An
explicit expression of the environmental value that is to be protected,
operationally defined by an ecological entity and its attributes.
For example, salmon are valued ecological entities; reproduction
and age class structure are some of their important attributes.
Together “salmon reproduction and age class structure” form an assessment
endpoint.
Attribute — A quality
or characteristic of an ecological entity.
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Characterization
of ecological effects — — A portion of the analysis
phase of ecological risk assessment that evaluates the ability of
a stressor(s) to cause adverse effects under a particular set of
circumstances.
Characterization of exposure — A
portion of the analysis phase of ecological risk assessment that
evaluates the interaction (either by actual contact or co-occurrence)
of the stressor with one or more ecological entities.
Community — An assemblage
of populations of different species within a specified location
in space and time.
Conceptual model — A
conceptual model in problem formulation is a written description
and visual representation of predicted relationships between ecological
entities and the stressors to which they may be exposed.
Cumulative distribution function
(CDF) — Cumulative distribution functions are particularly
useful for describing the likelihood that a variable will fall within
different ranges of x. F(x) (i.e., the value of y
at x in a CDF plot) is the probability that a variable will
have a value less than or equal to x (figure B-1).
Figure B-1. Plots of cumulative distribution function (CDF).
Cumulative ecological risk assessment — A
process that involves consideration of the aggregate ecological
risk to the target entity caused by the accumulation of risk from
multiple stressors.
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Disturbance — Any
event that disrupts ecosystem, community, or population structure
and changes resources, substrate availability, or the physical environment
(modified from White and Pickett, 1985).
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EC50 — A
concentration expected to cause an effect in 50% of a group of test
organisms.
Ecological entity — A
general term that may refer to a species, a group of species, an
ecosystem function or characteristic, or a specific habitat.
Ecological relevance — One
of the three criteria for assessment endpoint selection. Ecologically
relevant endpoints reflect important characteristics of the system
and are functionally related to other endpoints.
Ecological risk assessment — The
process that evaluates the likelihood that adverse ecological effects
may occur as a result of exposure to a stressor.
Ecosystem — The biotic
community and abiotic environment within a specified location in
space and time.
Exposure — The contact
or co-occurrence of a stressor with a receptor.
Exposure profile — A
summary of the magnitude and spatial and temporal patterns of exposure
for the scenarios described in the conceptual model.
Exposure scenario — A
set of assumptions concerning how an exposure may take place, including
exposure setting, stressor characteristics, and activities that
may lead to exposure.
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LC50 — A
concentration expected to be lethal to 50% of a group of test organisms.
Lines of evidence — Information
derived from different sources or by different techniques that can
be used to describe and interpret risk estimates. Unlike the term
“weight of evidence,” it does not necessarily assign quantitative
weights to information.
Lowest-observed-adverse-effect
level (LOAEL) — The lowest level of a stressor evaluated
in a test that causes statistically significant differences from
the controls.
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Management goal — A
goal is a general statement of the desired outcome for the overall
decision that would solve the problem or take maximum advantage
of the opportunity, etc., for example, "Reestablish and maintain
water quality and habitat conditions in Waquoit Bay and associated
wetlands, freshwater rivers, and ponds."
Management objective — An
objective is a more specific statement of the desired outcome.
It should be specific enough to allow scientists to develop measures
from them for a risk assessment. Objectives for Waquoit Bay included:
"Restore and maintain self-sustaining native fish populations
and their habitat." Objectives include an entity (native fish
in this case), some attribute (population), and a desired state
or direction of change (self-sustainability). Note that assessments
endpoints are similar in that they include an entity and an attribute,
but do not include a desired state or direction of change.
Measure of ecosystem and receptor
characteristics — Measures that influence the behavior
and location of organisms of interest, stressor distribution, and
organismal life-history characteristics that may affect exposure
or response to the stressor.
Measure of effect — Describes
change assessment endpoint (or surrogate) attributes in response
to a stressor to which it is exposed. Dose-response data are an
example.
Measure of exposure — Describes
stressor existence and behavior in the environment and its contact
or co-occurrence with the assessment endpoint.
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No-observed-adverse-effect
level (NOAEL) — The highest level of a stressor evaluated
in a test that does not cause statistically significant differences
from the controls.
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Population — An
aggregate of individuals of a species within a specified location
in space and time.
Primary effect — An
effect where the stressor acts on the ecological component of interest
itself, not through effects on other components of the ecosystem
(synonymous with direct effect; compare with definition for secondary
effect).
Probability density function
(PDF) — Probability density functions are particularly
useful in describing the relative likelihood that a variable will
have different particular values of x. The probability that
a variable will have a value within a small interval around x
can be approximated by multiplying f(x) (i.e., the value
of y at x in a PDF plot) by the width of the interval
(figure B-2).
Figure B-2. Plots of probability density functions (PDF).
Prospective risk assessment — An
evaluation of the future risks of a stressor not yet released into
the environment or of future conditions resulting from an existing
stressor.
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Receptor — The
ecological entity exposed to the stressor.
Recovery — The rate
and extent of return of a population or community to some aspect
of its previous condition.
Retrospective risk assessment — An
evaluation of the causal linkages between observed ecological effects
and a stressor in the environment.
Risk characterization — Integrates
exposure and stressor-response to evaluate the likelihood of adverse
ecological effects associated with exposure to a stressor.
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Secondary effect — An
effect where the stressor acts on one component of the ecosystem,
which in turn has an effect on the component of interest (synonymous
with indirect effects; compare with definition for primary effect).
Source — An entity
or action that releases a stressor to the environment (or imposes
a stressor on the environment).
Stressor — Any physical,
chemical, or biological entity that can induce an adverse response.
Stressor-response profile — A
summary of data on the effects of a stressor and the relationship
of the data to the assessment endpoint.
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Trophic levels — A
functional classification of taxa within a community that is based
on feeding relationships (e.g., aquatic and terrestrial green plants
make up the first trophic level and herbivores make up the second).
Outside Resources: Other
Glossaries
US EPA Terms of Environment (http://www.epa.gov/ocepa111/OCEPAterms/)
US EPA Terminology Reference System (http://www.epa.gov/trs/index.htm)
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