One of the main impacts of urban sprawl in rapidly growing countries has been contamination of coastal environments by waterborne pathogens, posing a critical risk to ecosystem and human health. Microbial source tracking (MST) has been a robust tool to identify the origin of these pathogens globally. This study compared the occurrence of a human‐associated Bacteroides marker (BT‐α) with faecal indicator bacteria (FIB) in an urban estuary (Golden Horn, Istanbul, Turkey). Faecal coliform (culture method), enterococci (both culture and qPCR method) concentrations and physicochemical variables were compared with the BT‐α concentrations in monthly collected samples for a year (n=108). Enterococci concentrations detected by culture and qPCR were positively correlated (r = 0.86, p < 0.01) suggesting that qPCR can be an alternative method for monitoring. BT‐α marker was positive for 30% of the samples and positively correlated with enterococci (r = 0.61 and r = 0.64 for culture and qPCR methods respectively, p < 0.01). Rainfall had a moderate positive correlation with all faecal/MST indicators suggesting combined sewer overflows also severely impacted estuarine water quality. The high FIB and BT‐α concentrations at upper estuary suggested that faecal pollution mainly originated from the peri‐urban settlements around two creeks entering the estuary.

This paper represents the results of a case study of the interaction between sea level rise (SLR), subsidence and the consequences of this phenomenon on fresh water resources that may be subject to exacerbated salt-water intrusion. The possible reasons for rapid SLR at the permanent tide gauge station located on the southern coast of the Marmara Sea have been investigated based on time series data recorded since 1984. The population in the region relies mainly on groundwater resources for urban, tourism and agricultural water use, which represents a severe risk with regard to the replenishment of the coastal aquifer. Based on the findings, appropriate methods of assessing the coastal vulnerability to future SLR and recommendations for coastal zone management with emphasis on the protection of water resources are discussed.