THE INFLUENCE OF DIFFERENT PHOSPHATE AND NITRATE CONCENTRATIONS ON GROWTH, PROTEIN AND CHLOROPHYLL A CONTENT OF Scenedesmus obliquus

The growth, chlorophyll a and protein production with Scenedesmus obliquus was performed in modified Johnson's medium at initial phosphorus and nitrogen concentrations of 0.1, 0.3, 0.5, 0.7 (P) and 8, 12, 16 20 mM (N). Initial concentrations of both nutrients had a significant effect (p>0.01) on growth and contents. The highest yield (15.5 +/- 0.176 x 10(6) cell mL(-1)), chlorophyll a (10.3 +/- 0.157 mg L(-1)), and protein yields (32.3 +/- 0.323 ma L(-1)) were obtained with concentrations of 0.3 mM phosphate and 12 mM nitrate. Cell number showed significant correlations with amount of chlorophyll a (p<0.01, r = 0.97) and protein (p<0.01, r = 0.83). The medium with a 40:1 N/P ratio favored S. obliquus growth. Specific growth rates varied from 0.28 to 0.40 cell divisions d(-1)

Assessment of phytoplankton and environmental variables for water quality and trophic state classification in the Gemlik Gulf, Marmara Sea (Turkey)

Phytoplankton assemblages related to environmental factors and ecological status of the Gemlik Gulf were investigated between June 2010 and May 2011. A total 155 phytoplankton species were detected and 6 taxa (Amphisolenia laticincta, Archaeperidinium minutum, Cochlodinium sp., Gynogonadinium aequatoriale, Heterocapsa rotundata and Metaphalacroma sp.) were new records for the Turkish Seas. The lowest and highest total phytoplankton abundance among the sampling units (depths) was recorded in April 2011 (7.4 x 10(3) cells L-1) and July 2010 (251.8 x 10(3) cells L-1). Local small patches of visible red tide events were detected especially in the gulf, although a phytoplankton bloom was not observed. The water column was well stratified in the early autumn and well mixed in the early spring according to stratification index values. Surface nutrient concentrations increased especially at stations located inside of the gulf. The limiting effect of silicate was observed in early, midsummer and early winter periods while the nitrogen was the limiting nutrient in the gulf during the whole sampling period. In the Gulf, low water quality-high mesotrophic and bad water quality-eutrophic status, high quality and low trophic level were generally detected according to Chl a, dissolved oxygen and trophic index. However, indices developed to determine the trophic level and water quality of the Mediterranean Sea can give unexpected results about the current environmental quality status when it is applied to the Marmara Sea which has limited photic zone by the halocline-pycnocline and thermocline. (C) 2016 Elsevier Ltd. All rights reserved

SEASONAL VARIATIONS OF NUTRIENTS AND CHLOROPHYLL A IN THE COASTAL WATERS OF THE EDREMIT BAY AND THE TROPHIC INDEX (TRIX) VALUES OF THE ENVIRONMENT

This first comprehensive study was carried out on current ecological quality status of Edremit bay between the years of 2003 and 2004. The samples were seasonally collected from 5 different depths (0.5-20 m) at 3 stations determined from shore to offshore. During the study, temperature, salinity and dissolved oxygen levels of the seawater ranged between 13.0-26.5 degrees C, 35.9-38.8 ppt, and 2.69-11.2 mg L(-1), respectively. Nitrate+nitrite-N (0.05-2.63 mu g-at L(-1)), phosphate-P (0.19-0.66 mu g-at L(-1)) and silicate-Si (0.49-4.92 mu g-at L(-1)) concentrations were measured, and also chlorophyll a values ranged between 0.1-2.2 mu g L(-1). The lowest and highest level of N:P ratio were obtained to be 0.16 and 11.32, respectively, and also this ratio was recorded lower than Redfield ratio (16:1). This result indicates that the studied region is oligotrophic in nature. Trophic Index (TRIX) values, which were calculated in the study to describe water quality, were between 0.86 and 2.98, reflecting high quality of water (range of 0-4). According to the Trophic Index, this region has the lowest trophic level but the highest quality status