CHANGES IN PHYTOPLANKTON COMMUNITY STRUCTURE IN THE GULF OF BANDIRMA, MARMARA SEA IN 2006-2008

Abstract

Phytoplankton composition and some ecological variables were investigated seasonally between November 2006 and August 2008 in the Gulf of Bandirma. From the analysis of phytoplankton community composition, 99 species of 5 different algal groups were identified: 56 dinoflagellates (56.6%), 38 diatoms (38.4%), 3 dictyochophyceans (3%), 1 euglenophycean (1%) and 1 prasinophycean (1%). Amphidinium sphenoides was reported for the first time in the Turkish coastal waters. Diatoms and dinoflagellates were the most dominant groups in terms of species number at 3 sampling stations. The maximum total phytoplankton abundance (640 x 10(3) cells L-1) was observed in the surface water of Station 2 in August 2008, with Cerataulina pelagica being the most dominant species of that month (600 x 10(3) cells L-1). During the sampling period, water temperature ranged between 6.5 and 26.0 degrees C, salinity between 21.4 and 38.5 ppt, dissolved oxygen between 3.50 and 15.62 mg L-1 the amount of NO2+NO3-N between 0.08 and 6.25 mu g-at N L-1 PO4-P 0.18-8.60 mu g-at P L-1, SiO4-Si 0.05-20.37 mu g-at Si L-1 and chlorophyll-a values between 0.22 and 14.70 mu g L-1. All through the study, the increase in depth caused an increase in the amount of nitrogen and silica, and a decrease in the amount of phosphorus.