Diverse taxa of freshwater zooplankton can use chemical cues to discriminate between particles which differ in food value. Thus, many planktonic grazers may be more specialized in theirdiets than previously suspected. This research will use foodselection experiments, gut analysis, and field enclosureexperiments to investigate patterns and strategies of chemically.mediated selection, and to evaluate the importance of thisphenomenon in a natural community. Foraging theory predicts that decision-based selection behavior should be sensitive to nutritional quality, the abundance of alternative foods, and hunger. These predictions will be tested with copepods feeding in natural seston. Enclosure experiments will be used to test for differences between taste-sensitive (Diaptomus) and nondiscriminating (Daphnia) grazers in their impacts on natural phytoplankton, bacteria, and detritus. In addition to these basic research objectives, undergraduate involvement through the Crooked Lake Biological Station is a major asset of the project.
