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“…The observed higher nitrate concentrations may possible due to the nitrification processes which reported from earlier studies (Yilmaz et al, 1998, 2006, Yayla et al, 2001. Phosphate concentrations were less variable in the coastal station.…”

“…The importance of Chl-a for different regions of the southern Black Sea is well documented by different research groups (Yilmaz et al, 1998;CobanYildiz et al, 2000;Yayla et al, 2001). In the seasonally stratified surface waters of the Black Sea, Chl-a profiles display a sub-surface maximum at the base of the euphotic zone (Coban-Yildiz et al, 2000).…”

“…The variations in nutrient concentration are mainly due to sub-surface nutricline and mixing process (Besiktepe et al, 2000;Yayla et al, 2001). In the spring-autumn period of 1995-1996, average concentrations in the euphotic zone ranged regionally and seasonally from 0.16 to 1.5 μM for TNOx (mainly NO 3 ) and from 0.03 to 0.35 μM for phosphate (Yilmaz et al, 1998). In another study, concentrations in the euphotic zone were determined as <0.35 μM for PO 4 , <0.5 μM for NO 3 +NO 2 and 5 μM for reactive silicate during July 1997-September 1998 period in the southern Black Sea.…”

“…Overall, PP in the Black Sea displays two phytoplankton peaks throughout the year; the major bloom of mainly diatoms occur in early spring while a secondary bloom of mainly coccolithophores appear during autumn in both the coastal and open waters (Sorokin, 1983;Vedernikov and Demidov, 1997). Recently, additional summer blooms of dinoflagellates and coccolithophorids (mainly Emiliana huxleyi) have frequently been reported (Hay et al, 1990;Sur et al, 1996;Yilmaz et al, 1998;Yayla et al, 2001). The most important changes in the Black Sea ecosystem recorded over the last decade are changing of the ratio of major phytoplankton groups (Bat et al, 2011;BSC 2008;Feyzioglu and Seyhan, 2007) resulted from the deterioration of the Black Sea ecosystem (Kideys, 2002;Kopelevich et al, 2002).…”

“…Despite the significant roles of phytoplankton, earlier studies conducted in the Black Sea mainly focused on several distinct areas (e.g. NW shelf); however, information about PP and Chl-a for the southern Black Sea has been remained poorly studied (Yilmaz et al, 1998(Yilmaz et al, , 2006Yayla et al, 2001).…”