of the Copepoda Community in Sevastopol Bay (1976
1996)
A. D. Gubanova, I. G. Polikarpov, M. A. Saburova, and I. Yu. Prusova
Kovalevskii Institute of Biology of the Southern Seas, National Academy of Sciences, Sevastopol, Ukraine
Received July 16, 2001; in final form, July 16, 2001
Abstract—The results of the regular year-round studies of mesozooplankton in Sevastopol Bay carried out in
1976, 1979–1980, 1989–1990, and from 1995 to 1996 are presented. The emphasis is put on the Copepoda
community. It is shown that a pronounced transformation of the Copepoda species composition took place as
early as in 1976. During the 1980s, the abundance of eutrophic species increased and the Copepoda community
became more unstable. During the period from 1989 to 1990, the sharpest and the most essential changes in the
community and in the individual populations of copepods proceeded. The number of species decreased almost
two times, and the forms that dominated before, namely, Acartia clausi (the small form) and Oithona nana, dis-
appeared, whereas A. clausi and Pseudocalanus elongatus became the dominant species. In addition, the total
abundance of the Copepoda community decreased by more than one order of magnitude and their share in the
total mesozooplankton abundance dropped from 62 to 15%. During that period, pronounced changes in the
principal characteristics that determine the community structure took place. The changes in the structure of the
Copepoda community and in the seasonal dynamics over the twenty-year-long period are considered. The pos-
sible reasons for the community degradation are discussed, namely, deterioration of the environmental quality
for marine organisms due to the anthropogenic activity, the long-term climatic fluctuations, and the impact of
the invader ctenophore Mnemiopsis leidyi.
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