9304219 SULLIVAN While the importance of scyphomedusae as predators in planktonic communities has ben amply demonstrated, we are not presently able to clearly predict which components of planktonic populations will be affected by scyphomedusan predation. Conventional methodologies such as laboratory "black box" feeding studies or gut contents from field samples have been valuable but insufficient approaches to resolve this issue because they do not reveal how the feeding interactions occur. The how is necessary to predict which prey will be consumed in novel situations. A new approach will be developed in this project that combines the separate expertise of two investigators specializing in video and conventional methods for the study of prey selection. First, laboratory work will quantify relationships between medusan body plan, fluid motions and prey capture. Second, field studies of prey selection by gut analyses will determine congruence of an evolving model with in situ selection patterns. Third, mesocosm studies with controlled predator-prey conditions will critically evaluate the model via hypothesis testing. The research will center on the ephyral through young adult transition period of two abundant and cosmopolitan scyphomedusae, Auerlia aurita and Cyanea capillata. While sharing similar ephyral morphologies, the adult forms diverge widely in body plan. The results of this work will contribute to our understanding of these specific predators, the ephyral form shared by most scyphomedusae and, ultimately, to the mechanics of predator-prey interactions in planktonic communities.
