Several types of gelatinous zooplankton, including medusae, sometimes occur in extremely high numbers (blooms). The reasons for dramatic population fluctuations are not understood. The scyphomedusa Chrysaora quinquecirrha is unusual in thriving in estuarine waters of as little as 7% salinity. However, its annual population fluctuations may be related to differences in springtime conditions during asexual production of medusae in the spring. This research is designed to test the combined effects of temperature, salinity, and food levels on the production and survival of young medusae. Drs. Purcell and Wright will examine ionic and osmotic regulation in the polyps and medusae in order to determine if they are physiologically limited in low salinities. This project is an effort to understand population fluctuations of a major predator in Chesapeake Bay. The results are important in understanding the formation of blooms in pelagic ecosystems. Responses of bloom organisms to changing environmental conditions are of particular importance now, given the predicted temperature and salinity changes associated with global warming.
