A Net-Plankton Study in the Bosphorus Junction of the Sea of Marmara

Authors: Zahit UYSAL

Abstract: A 16-month study of diatoms (>55 micrometers) and certain groups of zooplankton was carried out at 21 stations in the Bosphorus junction of the Sea Marmara on board the R/V ÒBilimÓ. The maximum diatom bloom was observed in January 1986, followed by a less frequent secondary flowering in summer. Both the diatom and zooplankton maxima were observed at 10 m. The lowest levels were attained below the halocline at a depth of 30 m. Remarkable variations, both in the species composition and abundance of diatoms, were observed with depth throughout the research. Both the species richness D and species diversity HÕ were found to be relatively high in March (2.30-3.06) and October 1986 (2.23-2.97) as well as the proportional representation JÕ (0.96-0.91). In the distribution of diatom species at different depths, higher degrees of similarity were achieved in October, the maximum being 0.8 (Jacc. coeff.) between the surface and 10 m. Among the physico-chemical factors affecting the distribution of zooplankton with depth were temperature, salinity, dissolved oxygen, phosphate and nitrate+nitrite , which showed significant correlations.

Keywords: Net-Plankton, Diatoms, Sea of Marmara