9412304 Patterson This project investigates the balance between heterotrophy and symbiotic autotrophy in sponges, a topic that we know very little about. Through a series of laboratory experiments the investigators will determine the effects of ecosystem (freshwater vs. marine), sponge morphology, and energy regime on the extent of sponge heterotrophy and autotrophy. The techniques employed are novel and include flow cytometry and DNA to RNA ratios. This study will result in new fundamental understanding of the biology of sponges and their role in ecosystems. The results of this study can be applied to ecosystem management, especially for those ecosystems in which sponges are important, including such diverse systems as Lake Baikal and the Florida Keys.