ABSTRACT: The copepod community of the Pomeranian Bay, in the outer part of the Oder Estuary (Southern Baltic Sea), is dominated by Acartia bifilosa Giesbrecht in winter and spring and by A. tonsa Dana in autumn. During summer both species co-occur. The egg production of these species was studied in 1994/1995. Rates (eggs female^-1 d^-1) were found to vary both seasonally and spatially. In winter, egg production rates of A. bifilosa were low, but showed a positive response to increasing chlorophyll a concentrations. During the late phase of the spring bloom (dominated by the diatom Skeletonema costatum), egg production of A. bifilosa was clearly higher than in winter, while water temperature remained at a low level. Phytoplankton concentrations during the spring bloom varied, but egg production rates were uniform all over the bay, suggesting production was not food limited. Length-specific weight and lipid content indicate that females were in good physiological condition. During summer and autumn, both high and very low egg production rates were observed for both species. The relation between egg production rate and chlorophyll a concentration was negative. The analysis of the phytoplankton composition in summer suggested that a high proportion of dinoflagellates was beneficial for egg production whereas high proportions of cyanobacterial colonies and filaments had negative effects. Except during the spring bloom period, the egg production of Acartia spp. in the Pomeranian Bay was limited by the amount and quality of phytoplankton.

KEY WORDS: Acartia spp. · Egg production · Phytoplankton · Food quality · Pomeranian Bay

Published in MEPS Vol. 174 (1998) on November 26
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1998