Assessment of the water quality of the Aegean sea by macrophyte biotic index

Ecological Evaluation Index (EEI) is used to assess ecological status of coastal and transitional waters. This index was intercalibrated by the Mediterrenean Geographic Intercalibration Group (MEDGIG), that is based on macrophytes (macroalgae and angiosperms). In this study, the ecological status of the Aegean coastal waters were assessed by using the Ecological Evaluation Index. Sampling was performed at 13 stations [Saros Bay, Yeniköy, Ayvalık, Çandarlı, Bostanlı, Urla, Ildır Bay, Küçük Menderes, Didim, Güllük, Bodrum, Akyaka, Datça] in August 2017. Macrophyte samples were collected from upper-infralittoral region by using a quadrat of 20x20 cm (400 cm2). The physico-chemical parameters [pH, temperature(°C), oxygen (mg/L), turbidity (mg/L), conductivity (μS), salinity (‰), phosphate (mg/L), ammonium nitrogen (mg/L)] were measured. According to EEI, macrophyte samples were divided into two ecological state groups (ESG I and ESG II). The absolute abudance of ESG I and ESG II, the average percent coverage of macrophyte samples and EEI values were calculated. The EEI values have been transformed into ecological quality ratio from 0 to 1 specified by the EU Water Frame Directive. Each of sampling areas were classified into five ecological status. As a result, the ecological status of ten stations [Saros Bay (1 EEIeqr), Yeniköy (0.74 EEIeqr), Ayvalık (0.98 EEIeqr), Çandarlı (0.77 EEIeqr), Urla (0.81 EEIeqr), Ildır Bay (0.76 EEIeqr), Didim (0.86 EEIeqr), Bodrum (0.84 EEIeqr), Datça (0.97 EEIeqr), Güllük (0.72 EEIeqr)] are "High", the ecological status of two stations [Küçük Menderes (0.57 EEIeqr), Akyaka (0.58 EEIeqr)] are "Good" and the ecological status of Bostanlı (0 EEIeqr) is "Bad". Phosphate and ammonium nitrogen which are nutritional elements that provide the development of opportunistic species, were found to be highest in Bostanlı station.