Determination of limited nutrients in the Turkish coastal waters of the Mediterranean and Aegean Seas
Vildan Tüfekçi, Ersan Kuzyaka, Hüseyin Tüfekçi, Gülsen Avaz, Aslı Süha Günay, Süleyman Tuğrul
TÜBİTAK- Marmara Research Center, Institute of Environment, Gebze-Kocaeli, TURKEY
Institute of Marine Sciences, METU, Erdemli-Mersin, TURKEY
Increased human activities, rapid and uncontrolled industrial development, intensive urbanization have polluted and hence drastically modified the Turkish coastal water ecosystem of North East (NE) Mediterranean and Aegean Seas. Assessments of nutrient budgets and limiting nutrients in aquatic systems are of wide interest because of their fundamental importance in understanding carbon fixation, coastal eutrophication and wastewater management. In this study, the relative importance of nitrogen and phosphorus as potential limiting factors for primary producers during spring and summer seasons of 2009 was investigated in the near surface water along the Turkish coasts of the NE Mediterranean and Aegean Seas by using the 14C bioassay technique. The results of bioassays and nutrient concentrations (DIN, PO4, Si) indicate that phosphorus is primarily limiting factor in the less contaminated, nutrient-depleted coastal waters of NE Mediterranean (including the Aegean Sea). However, nitrogen appears to be potential limiting element in heavily polluted semi-closed coastal zones (Izmir and Edremit Bays of the Aegean Sea) due to large organic and nutrient loads from industrial and domestic sources in the last decades and consequent occurrence of intense denitrification in the elongated Izmir Bay, reducing the N/P ratio in the shallow water column.
Keywords: Eutrophication, nutrients, limiting nutrient, phytoplankton.