PREDATION BY GELATINOUS ZOOPLANKTON AND RESOURCE LIMITATION AS POTENTIAL CONTROLS OF ACARTIA-TONSA COPEPOD POPULATIONS IN CHESAPEAKE BAY

Gelatinous zooplankton are conspicuous predators during summer in Chesapeake Bay. Inverse correlations of the abundances of gelatinous predators and their zooplankton prey have led to speculation that these predators may control their prey populations. We measured predation on copepods by hydromedusae, scyphomedusae. and ctenophores in the mesohaline region of the bay in May-October 1987 and 1988. We simultaneously assessed the possibility of food limitation in Acartia tonsa by measuring its phyto- and microzooplankton food resources and rates of adult female egg production. We conclude that A. tonsa populations are not limited by gelatinous zooplankton predation and rarely by food. Other predators (e.g. fish, adult copepods) and environmental limitations (e.g. temperature. hypoxic bottom waters) probably affect A. tonsa abundances in this region.