Rachel Rosen, Harvard University

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Abstract:

During the summer months from May to October, a shift in the size classes of Chrysaora quinquecirrha is observed. The gelatinous zooplankton in the early to mid summer consist of three classes, a small, medium and a large size class. By the end of August, a more moderate sized plankter has replaced these extremes of size previously seen. The question that this study hopes to address is: are there two distinct populations of C. quinquecirrha in the Bay at the beginning and end of the summer or only one population which undergoes degrowth during the summer. The hypothesis is that the larger sized sea nettles are undergoing a period of starvation. When the jellyfish starve, the medusa diameter is reduced. This catabolism could account for the lack of large size classes late in the summer. The delta 15N values should confirm that starvation is occurring; an increase in the delta 15N values should be observed. The definition of the C. quinquecirrha population as one distinct population rather than two calls for reevaluation of the food web of the Chesapeake Bay and a closer examination of nutrient cycling within the Bay.