Single species toxicity tests are widely used to assess the potential effects of a toxicant on
aquatic life. Increasingly, it is necessary to understand how the results of these tests relate to
toxicant effects in natural communities. This dissertation presents the methodology and
validation for a community level toxicity test that bridges the gap between single species tests
and natutal community responses. The research involved control of environmental parameters,
improvement of feeding regimes and testing of the final community. The results are presented
as four separate papers.
The first paper addresses the development and validation of a standardized reconstituted water
for culturing and toxicity testing of algae, cladocerans, a rotifer and two fish species. The next
two papers address the substitution of the food source currently used in the fathead minnow
survival-growth impairment test (Artemia) with a freshwater food source (the rotiter, Brachionus
calyciflorus). Along with the alga Chlorella vulgaris (producer), B. calyciflorus (primary
consumer) and the fathead minnow larvae (secondary consumer) comprise a three level food
chain that was used to address trophic level interactions (feeding reduction and growth
impairment) in the final phase of this research. The end result is an experimental procedure in
which environmental parameters (water quality, temperature, etc.) and trophic structure
parameters (Le. producer and primary consumer density) can be controled we" enough to
insure that any shifts in community structure can be attributed to toxicant related effects.
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