Zooplankton biomass in the Saronikos Gulf, winter 1972-1973

Abstract

       The Saronikos Gulf can be divided into three major areas based on the eutrophication. The areas include the outer Saronikos Gulf with a zoo­plankton biomass from 0.5 to 2.9 mg/m³; the Saronikos proper with zoo­biomass from 3.0 to 17.2 mg/m³ and Elefsis bay with zooplankton biomass from 25.0 to 96.1 mg/m³.

       The zooplankton concentrations at the surface or at deeper layers varied from one place to another and depended mainly on the circulation of the water masses.

       The zooplanktonic community appeared extremely monospecific in Elefsis. Bay and consisted of Acartia clausi only. In the Saronikos proper all the Aegean Sea species were present but A. clausi was the most abundant, roughly comprising 30 percent of the total population. A. clausi in the Saronikos Gulf may have originated in the Elefsis Bay.

       It was apparent that the eutrophic waters had a higher zooplanktonic biomass and altered the species composition. In the extreme case of Elefsis, a mono-specific population of very high biomass was found. In the less eutrop­hic waters of Saronikos proper a predominance of certain species (A. clausi and N. miliaris) and intermediate biomass values were found.