Variations of nutrients and chlorophyll-a in the coastal area of Baltalimani (Bosphorus-Turkey)

Abstract

This study was carried out in the coastal area of the Bosphorus. Sea water samples were collected at 1 m above bottom, once a week, from November 2003 to May 2004. Primary hydrogoraphic conditions, such as salinity (16.11-23.55 psu), temperature (5.5-14 degrees C) and dissolved oxygen (6.56-10.58 mg/L) were recorded on sampling stations. The lowest and highest concentrations of NO3+NO2-N, PO4-P, SiO4-Si and chlorophyll-a were 1.03-13.70 mu M, 0.28-1.36 mu M, 3.94-11.70 mu M and 0.44-3.94 mu g/L, respectively. The mean atomic ratio of N/P was lower than the Redfield ratio of 16 for ocean phytoplankton, and N was the limiting nutrient. The ratio of nitrogen to phosphorus varied C from 3.6 to 12.5. Si/P ratios were low, except in May. Silicate was likely the limiting factor for the growth of especially diatoms, and the region examined is oligotrophic in nature.