Date of Award

Fall 1983

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ocean & Earth Sciences

Program/Concentration

Oceanography

Committee Director

David L. Feigenbaum

Committee Member

Anthonly J. Provenzano

Committee Member

John R. McConaugha

Call Number for Print

Special Collections LD4331.O35K45

Abstract

The significance of sea nettle abundance on lower levels of the Chesapeake Bay food chain was examined in a field study and by the analysis of medusa gut contents. In the field study, the abundance of four levels of the food chain (Chlorophyll (a), copepods, the ctenophore Mnemiopsis leidyi, and the Schyphomedusa Chrysaora guinguecirrha) were monitored twice weekly at four stations from May 10 through September 30, 1982. The copepod standing stock declined sharply in late May when M. leidyi appeared, but rebounded a month later when C. guinguecirrha medusae reduced the ctenophore population. Despite the additional presence of Aurelia aurita (Scyphomedusa) from July onward, herbivore abundance remained at moderate levels through the remainder of the study period. Phytoplankton abundance did not appear to be limiting for the copepods.

A total of 241 medusae were examined for the gut content analysis. The average number of prey per sea nettle was 17.7. Using digestion times (mean= 2.69 hours) available from previous work, feeding rates were obtained and it was estimated that 22.5% of the copepod standing stock in the Lafayette River was consumed daily by this species.

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DOI

10.25777/gce7-me63

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