R/P-50

Description:

We propose experiments and modeling to test the hypothesis that low dissolved oxygen (DO) in bottom waters of Chesapeake Bay and its tributaries favors increased importance, and perhaps abundance, of gelatinous zooplankton. Our objectives for this 2-year project are: 1) to determine how low DO affects growth rates of sea nettles (Chrysaorra quinquecirrha) and ctenophores (Mnemiopsis leidyi), and egg production by ctenophores, under a range of prey densities; and 2) to predict whether, how much, and where bottom layer oxygen depletion favors increased growth rates of sea nettles and ctenophores, and egg production by ctenophores, relative to in water columns with high DO throughout. Low DO resulting from excess anthropogenic nutrient loadings to stratified coastal systems is a major threat to the ecology and fisheries of estuaries and other coastal waters worldwide, and has been a major focus of management efforts in Chesapeake Bay. However, we currently have very little understanding of how low oxygen affects the Chesapeake Bay food web, or what changes to expect if DO conditions improve or worsen.