Stevenson, R. University of Louisville, stevenson@louisville.edu
Sweets, P. University of Louisville, prswee01@homer.louisville.edu
Pan, Y. Portland State University, pany1@sbii.sb2.pdx.edu

 
MULTI-LEVEL COMPARISON OF THE SENSITIVITY AND PRECISION OF ALGAL INDICES OF ECOLOGICAL CONDITIONS
 
The objective of our research was to develop quantitative methods for assessing ecological risk with characteristics of periphytic algal assemblages. We hypothesized that bioassessment metrics based on relative abundances of specific species would relate more sensitively and precisely to changes in environmental conditions than metrics based on changes in functional group and assemblage-level characteristics. This hypothesis was tested with results from several studies in wetlands and streams. Changes in indices based on species relative abundances and autecologies were more highly correlated to changes in environmental conditions (e.g., trophic status) than changes in species diversity and biomass of algal assemblages. In addition, indices of trophic status (e.g., long-term average TP concentration) based on species composition and species autecologies were more precise than assessments based on algal biomass or one-time measurement of TP in the water. Shifts in functional groups (e.g., diatom dominated to blue-green or green dominated communities) were also poorly correlated to environmental gradients. These results indicate that different species have adapted to all but severe environmental conditions such that species replacement can often maintain community-level stability. Finally, these results are incorporated into a risk assessment framework by linking them to hazard assessment, exposure assessment, and risk management.
 
Day: Friday, Feb. 5
Time: 11:15 - 11:30am
Location: Hilton of Santa Fe
 
Code: SS11FR1115H