This first comprehensive study was carried out on current ecological quality status of the Kapidag Peninsula between the years of 2011 and 2012. The samples were collected seasonally from 5 different depths (0.5-30 m) at 3 stations determined from shore to offshore. During the study, temperature, salinity and dissolved oxygen levels of the seawater ranged between 7.5-26.0 °C, 18.06-35.06 ppt and 2.77-10.33 mg L -1 , respectively. Nitrate+nitrite-N (0.01-5.39 μg-at N L -1), ammonium-N (0.01-0.79 μg-at N L -1), phosphate-P (0.01-1.48 μg-at P L -1) and silicate-Si (0.52-21.18 μg-at L -1) concentrations were measured, and also chlorophyll-a (chl-a) values ranged between 0.02-4.21 μg L -1 . The chl-a concentration is an important bioge-ochemical quantity monitored a present pigment in all phytoplankton species and, for this purpose commonly used as an index of biomass. In addition, the spatial and tem-poral patterns of chl-a concentration seawater temperature and nutrients are important oceanographic characteristics with important implications for sustainable management of fisheries and aquaculture. In autumn-winter months, high chl-a concentration was found along the station 3, and lower values were observed in summer. This high chl-a concentration could be related to the nutrients input from land through rivers discharge and anthropogenic effects.