Level II
estimate the effect or impact of pollutants on single or multiple species. Bioassays
are a very systematic means of determining the effect of a chemical concentration
or physiology of an organism or group of organisms. When the findings of the
work have
meaning to management objectives, the resul
be very useful
thebasisforcleardirectionforsettinggoalsandevenregulation.
The benefits of extending the findings from bioassay from one species to another
or interpreting confounding influences are less obvious.
and Calow (1989)
reviewed the application of bioassays and found that the responses observed in
particular systems were not transferable or relevant to others, and that the
mechanism of the response should be part of the theoretical framework for
designing the bioassay.
Habitat Variables
Macroinvertebrate and fish habitat assessment for streams and lakes, and their
riparian and shoreline areas, are discussed below. More direct measurements and
fewer ratings are suggested for level
Stream Macroinvertebrate Habitat. The physical and chemical quality of the
Stream Macroinvertebrate Habitat
stream and its substrate are the major features of macroinvertebrate habitat.
Initially monitoring hydrologic properties and substrate quality are priority
habitat variables. Some protocols also
organic matter and interstitial water
chemistry. Wiederholm (1984) discusses lake and stream macroinvertebrate
response to various pollutants.
Hydrologic Parameters. The stability of an
is dependent
upon the presence, discharge, and velocity of water. Both low flows (e.g., low
precipitation, low water table, or withdrawals) and major runoff events should be
tracked. Water velocity (distance moved per unit time) and depth may have an
important influence on the structure of benthic communities (Osborne and
Hendricks 1983). The lnstream Flow Incremental Methodology
is a
technique for recommending flows for stream management. The
was
developed by the US Fish and Wildlife Service with the primary objective of
assessing the changes in fish-standing crop and species composition due to
changes in streamflow (Bovee 1978). Some
studies have been applied to
benthic organisms (Gore and Judy 1981).
(1984) discusses stream hydrologic habitat assessment and identifies
potentially important variables to consider.
substrate consists of parent material, human trash, and
organic matter such as leaves, branches, logs, grass,
algae, moss, etc.
Macroinvertebrates live on the substrate and are especially adapted for clinging
and attaching to it. The substrate functions as a place for burrowing, escapement,
protection from current, or a place to construct a case or deposit eggs. Minshall
(1984) provides a list of potentially useful substrate variables for evaluating
macroinvertebrate habitat. Chapman and
(1987) provide a detailed
literature review of the importance and measurement of substrate variables.
Sediments should also be disturbed to determine and document the presence and
extent of odors, oils, and deposits (Plafkin et al. 1989). Sewage, petroleum, and
chemical odors or anaerobic conditions should also be documented. Past
3.20
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