9320092 Welch This is an award to support research on the role of invertebrates in controlling the proliferation of filamentous nuisance algae in rubble-bed, natural streams that receive nutrients from point and nonpoint sources. Experimental work is planned using laboratory channels and at three sites in nutrient-enriched, natural streams. The laboratory channels will be used to determine the effectiveness of grazing over a range in grazer sizes and their abundance and the extent to which enrichment level affects grazer effectiveness. Grazing rates will be used to modify an existing model that can be used to predict the expected maximum periphyton biomass concentration as a function of reactive phosphorus concentration using assumptions of available light, temperature and current velocity in the receiving stream. The results of this project are expected to provide knowledge that can be applied in determination of the extent to which nutrient removal is necessary to meet acceptable conditions for discharge of effluents from domestic and industrial wastewater treatment plants into flowing streams and addressing the development of nuisance conditions in streams resulting from nonpoint sources of nutrients. The results of this research may be applied in location of treatment plants, approaches to dealing with nonpoint sources of nutrients and in the engineering design of systems for dealing with the flow of nutrients into natural streams. ***
