SEASONAL VARIATIONS IN THE ENVIRONMENTAL PARAMETERS AND WATER QUALITY STATUS OF THE GULF OF GEMLIK IN THE MARMARA SEA (TURKEY)

Abstract

This study was implemented to determine the seasonal variations in the nutrient concentration and water quality of the Gulf of Gemlik. Samples were collected seasonally at totally 11 stations at 7 different depths (0.5-50 m) between July 2010 and April 2011. 6 of these stations were littoral stations and 5 were offshore stations. During the study, temperature, salinity and dissolved oxygen levels of the seawater ranged between 8.7-28.3 degrees C, 14.98-36.59 ppt and 2.63-17.18 mg l(-1), respectively. Nitrate+nitrite-N (0.01-21.14 mu g-at l(-1)), ammonium-N (0.02-1.93 mu g-at l(-1)), phosphate-P (0.1-5.1 mu g-at l(-1)) and silicate-Si (0.08-33.06 mu g-at l(-1)) concentrations were measured. Also chlorophyll a values ranged between 0.00-10.64 mu g l(-1). The lowest and highest level of N:P ratio were obtained to be 0.16 and 28.92. Trophic Index (TRIX) values, which were calculated to describe water quality, were between 0.91 and 4.92. According to Bray-Curtis similarity index, the stations which had vertical depths had a similarity of 94%, while littoral stations were approximately 85% similar to each other. Trophic Index values indicated that this region has the lowest trophic level but the highest quality status.