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

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

Seasonal variations of microphytoplankton assemblages and environmental variables in the coastal zone of Bozcaada Island in the Aegean Sea (NE Mediterranean Sea)

Seasonal changes in the microphytoplankton assemblages were examined in the coastal zone of Bozcaada Island with regard to some major physical and chemical variables. Samples were collected from May 2000 to December 2001 at four stations. A total of 108 dinoflagellates, 102 diatoms, 1 chrysophycean, 3 dictyochophycean, and 1 prasinophycean species were identified and quantified during the study period. Diatoms and dinoflagellates were the most important in terms of species number and abundance. The maximum values of total microphytoplankton were observed at 0.5 m depth (46.2 x 10(3) cells l(-1) at st. 3) in May as this was the month when the diatom Pseudo-nitzschia pungens bloomed. Chlorophyll (chl) a concentration ranged between 0.08 (August) and 0.78 mu g l(-1) (February). May was another important month in which chlorophyll a increased (0.41-0.47 mu g l(-1)). Species diversity values (H'(log2)) ranged from 1.66 bits (June, 20 m) to 4.11 bits (November, 0.5 m). The increase was attributed to a more balanced distribution of abundance among species. The amounts of nitrate + nitrite (0.6-3.7 mu g-at N l(-1)), phosphate (0.2-0.6 mu g-at P l(-1)) and silicate (0.7-2.5 mu g-at Si l(-1)) were recorded on each sampling occasion. Nutrient concentrations and chl a values of the research area were found to be poorer than those of the many other coastal areas in the northeastern Mediterranean. The mean atomic ratio of nitrogen to phosphorus varied from 1.3 (June) to 12.9 (February). This ratio was lower than the Redfield ratio of 16 for ocean phytoplankton, and phytoplankton was potentially limited by nitrogen for most of the months. The result of this study confirms and emphasizes the oligotrophic nature of the eastern Mediterranean

Contributions to the knowledge of marine phytoplankton of Turkey

The present paper report, three species of dinoflagellates viz., Ceratium deflexum (Kofoid) Jorgensen. ceratium longissimum (Schroder) Kofoid, Triposolenia bicornis Kofoid and three Species of diatoms viz., Lyrella lyra (Ehrenberg) Karajeva, Pleurosigma reversum Gregory, Trachyneis aspera (Ehrenberg) Cleve, all belonging to marine phytoplankton for the first time from coastal waters of Turkey. Ceratium deflexum was also new record for the Aegean Sea and Pleurosigma reversum for the Eastern Mediterranean. Original photographs and some ecological and morphological characteristics of six phytoplankton species are given

Seasonal variations in the phytoplankton and nutrient dynamics in the neritic water of Buyukcekmece Bay, Sea of Marmara

The phytoplankton species and seasonal variations of the nutrients were investigated in Buyukcekmece Bay, Sea of Marmara. The samples were collected monthly from different depths at five stations in Buyukcekmece Bay, from April 1998 to March 1999. A total of 125 phytoplankton species belonging to seven classes were identified, three of which were new to Turkish seas. The maximum values of total phytoplankton occurred at 0.5 m depth (292 x 10(3) cells 1(-1)) in March, for it was in this month that the diatom Skeletonema costatum bloomed. Dinoflagellates were present throughout the year and represented the majority of the population (52%), followed by diatoms (40%). The highest cell concentrations of dinoflagellates were recorded in May, and those of diatoms in March. Throughout the year, the amounts of nitrate + nitrite, phosphate and silicate were 0.05-10.79 mug-at N l(-1), 0.16-1.06 mug-at P l(-1) and 1.10-35.23 mug-at Si l(-1), respectively. The highest and lowest N:P ratios were found to be 11 at 30 m in April and 0.17 just below the surface in June, respectively. N:P ratios were below the normal value of 16:1, and N was a limiting nutrient. These findings show that the region examined is oligotrophic in nature

Toxic metal (Pb, Cd and Hg) levels in the nearshore surface sediments from the European and Anotolian Shores of Bosphorus, Turkey

In this study, some toxic metal such as Pb, Cd and Hg analyzes have been done in the nearshore surface sediments. Sediment samples have been collected from five parts from the European and Anotolian Shores of the Bosphorus during 2003-2004. Total Pb, Cd and Hg contents vary between <0.01 mu g g(-1) and 238 mu g g(-1); <0.01 mu g g(-1) and 0.92 mu g g(-1); 0.001 mu g g(-1) and 0.45 mu g g(-1), respectively. Contamination Factor (CF) values of Pb and Cd range between 1 and 3 whilst CF values of Hg are lower than 1 in all the stations. It means that there are no Hg metal enrichment by natural or anthropogenic inputs contrary to moderately contamination for Pb and Cd metals throughout the Bosphorus sediments. (c) 2012 Elsevier Ltd. All rights reserved