This project was one of a small number of proposals funded under the first joint solicitation of the EPA/NSF Watershed Initiative. It employs both laboratory experiments, and large-scale surveys in several ecoregions, to address basic issues in the ecology of the lower trophic levels of stream ecosystems. Specifically, this research examines the structural response of algal and invertebrate communities to site level variations in nutrient availability and disturbance regime. Key questions being addressed include (1) Are responses to nutrients in the organization structure of lower trophic levels more or less continuous, or are there thresholds where small changes result in large structural responses in the lower trophic levels? (2) how and why do algal communities escape the control of grazing macroinvertebrates? (3) Are there levels of nutrient loading, or of hydrologic disturbance, which will guarantee algal escape?
Public benefit: Non-point source and point source nutrient additions continue to be the most pervasive form of stream pollution. In contrast to the situation we find in lakes, we have little ability at present to predict the biological response of streams to nutrient increments. This project explores some of the basic science necessary to understand the practical implications of human alterations of stream nutrient budgets. The ultimate resolution of these issues will have important regulatory implications.
Collaborators: Dr. J. Stevenson (Univ. of Louisville), and Dr. J. Holomuski (Ohio State University), Mike Wiley (SNRE).