TAXON-SPECIFIC INGESTION RATES OF NATURAL PHYTOPLANKTON BY CALANOID-COPEPODS IN AN ESTUARINE ENVIRONMENT (POMERANIAN-BIGHT, BALTIC SEA) DETERMINED BY CELL COUNTS AND HPLC-ANALYSES OF MARKER PIGMENTS

This paper provides information on the application of marker pigment a nalyses for estimation of phytoplankton biomass as well as qualitative and quantitative estimates of food uptake by calanoid copepods Acarti a bifilosa, Giesbrecht in early summer (27 June to 2 July 1994) in the Oder estuary (Pomeranian Eight, southern Baltic Sea). The marker pigm ent concentrations were converted into C-equivalents for comparison wi th data obtained by the classical Utermohl method. Both data sets were generally in good agreement, although differences were found at the t axon-specific level, which could be explained largely by Limitations o f the Utermohl method. The ingestion rates estimated from cell counts and marker pigment concentrations were within a comparable range (0.31 to 0.84 mu gC ind.d(-1) and 0.50 to 1.04 mu gC ind.(-1) d(-1) respect ively). A. bifilosa showed a positive food selection for dino- and cry ptophytes and an avoidance of cyanobacteria and chlorophytes. Diatoms were ingested according to their abundance. Marker pigment detection h as been shown to be a useful tool for estimation of taxon-specific gra zing activity in estuarine environments.