uncertainty for use by managers who must on many occasions, make decisions based on the 
limited data that may be available. This is of particular concern for the protection of certain 
endangered species which cannot be tested or other species that are not feasible to test. 
Most species sensitivity comparisons have been made on individual chemicals, and modes of 
action have been used for certain extrapolations for individual species. However, there is little 
understanding of the relationships and uncertainty between chemical classes and the sensitivity of 
taxonomic groups of species to these chemical classes. A particular mode of action (chemical 
class) may pose greater or lesser jeopardy to certain families/populations of organisms than 
others, allowing one to better assess what will occur ecologically (diversity). This concept will 
be evaluated in extrapolating chemical toxicity data across species and taxonomic groupings. 
The present research specifically covers five major modes of action (see second item below), but 
will add others from existing data bases, further supporting chemical modes of action/structure- 
activity research being addressed by NHEERL/WED. 
Effects on native fish and invertebrate populations are important indicators of changes in surface 
waters due to human-related impacts such as the damming of rivers, lowering of aquifers, 
addition of pollutants, and introduction of non-native species. The planned research to determine 
the utility of using surrogate species in hazard evaluations to estimate the potential for toxic 
chemicals to affect other aquatic species has the following objectives: 
1. Assess the rainbow trout, fathead minnow, and sheepshead minnow as appropriate surrogate 
test species for endangered fishes and other species. 
2. Determine differences in acute sensitivity to chemicals with differing modes of action 
(carbaryl, copper, 4-nonylphenol, pentachlorophenol, and permethrin) between surrogate test 
species and selected endangered organisms. 
3. Develop interspecies correlations between surrogate test species and endangered fishes and 
other aquatic species using 48-h EC50/96-h LC50 data for the above five chemicals. 
4. Develop user manual and software for interspecies correlations of acute toxicity data for 
aquatic species using data bases from Mayer and Ellersieck (1986), Mayer (1987), OPP, and 
AQUatic toxicity Information REetrieval (AQUIRE). 
5. Perfomi acute toxicity tests to fill data gaps identified in item 4 where performance of specific 
tests would significantly enhance the number of data sets available for use in developing 
interspecies correlations (e.g., additional modes of action in item 2). 
6. Enhance utility of ACE (acute-to-chronic endpoint) model to predict chronic toxicity to 
endangered and other species on a population basis. 
This research will further develop project N1 by addressing the importance of untested species 
and endpoints and providing methodology for assessing limited data sets and filling data gaps. In 
addition, models for estimating chronic toxicity from acute toxicity data will concentrate on 
population-level assessments. 
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