Assessment of seasonal and spatial variation of surface water quality: Recognition of environmental variables and fecal indicator bacteria of the coastal zones of Izmir Bay, Eastern Aegean

Abstract Izmir Bay coasts are likely to face increasing pressures and growth of demand for infrastructures, e.g. port, marinas, transport and waste-water treatment facilities since 1970s. This study reflects characteristic features of coastal regions in Izmir Bay and the impacts of human activities between 2015 and 2017. The eutrophication status of coastal zones was assessed using different tools such as the trophic index, eutrophication index, Turkish legislation about eutrophication and Redfield ratios. Low anthropogenic impact is detected from the high DIN:P, Si:P and low DIN:Si ratios in Urla and Guzelbahce indicating that P-limited areas. Nutrient loadings cause to the increase of DIN:Si ratio and decrease of Si:P ratio, thus the ecosystem can be defined as Si limited coasts in Sahilevleri, Inciralt i , Goztepe, Karatas, Pasaport, Bayrakl i , Kars i yaka. Mavisehir was characterized with high eutrophication problem due to surplus of P and Si. Additionally, maximum E. coli were found in Goztepe, Bayrakl i , Kars i yaka while the highest Intestinal enterococci were obtained in Goztepe, Sahilevleri, Kars i yaka.