Abundance and biomass of phytoplankton and chlorophyll concentration tn eastern Mediterranean in late summer period

The data on taxonomic composition, abundance, and biomass of phytoplankton and chlorophyll a concentration in the eastern part of the Mediterranean Se a during late summer period are given in the paper. Different methods of me asurements of the chlorophyll a concentration are compared. All the quantit ative characteristics of phytoplankton manifest the oligotrophic level of w ater productivity during the period under study. The spatial distribution o f the abundance and biomass of phytoplankton and chlorophyll a concentratio n are significantly influenced by the mesoscale eddies of typical size 10-5 0 miles. The quantitative characteristics of phytoplankton in the coastal z one were usually higher, as compared with the open sea regions. As for vert ical distribution of micro- and nanophytoplankton, the maximum cell concent rations occurred within the upper homogenous layer and in the layer of pycn ocline. The vertical profiles of phytoplankton and chlorophyll a were compa red with the profiles of fluorescence; the maximum of fluorescence correspo nded to the maximum of chlorophyll a concentration and seemed to result fro m high concentration of picophytoplankton. The maximum of fluorescence also manifested itself in the cases when the cell densities in the layers of ma ximum if micro- and nanophytoplankton exceeded 10(4) cells per liter.