Sources of Domestic Sewage Effluent Pollution and its Impact on Seawater Quality in the Coastal Waters of Northern Gulf of Mannar and Palk Bay, India

The seawater quality in the northern Gulf of Mannar and Palk Bay, southeast coast of India has been increased by the uncontrolled release of untreated sewage effluents from coastal villages and towns, seepage of diesel oils and related products from mechanized boats and other human activities. The Gulf of Mannar and Palk Bay regions harbor diverse coral reefs and associated fauna of commercial and economic importance. The untreated sewage discharges badly affect the coral reefs and its partner ecosystems such as seaweed and seagrass. Therefore the present study was identified the sources of sewage inputs, vulnerable zones and probable remedial measures for impacted coastal and coral reef ecosystems of northern Gulf of Mannar between Rameswaram and Chinna Erwadi as well as Palk Bay regions between Rameswaram and Veedhalai. The coastal water quality and pathogenic microbial distribution were assessed for three years (2019-2012) at intervals of 3 months. This study reveals that mainly BOD, COD, turbidity and nutrient levels reached notably at higher levels where the sewage effluent discharged directly into the coastal waters. Further, the abundance of pathogenic indicator microbes in Rameswaram and Keezhakkarai Coastal regions aggravates the situations worsen due to release of untreated domestic sewage effluents. Mostly Rameswaram and Keezhakkarai coastal waters showed highest pathogenic bacterial count. To protect the coastal and coral reef environment of Gulf of Mannar and Palk Bay, India from the uncontrolled release of sewage outfalls, it is necessary to design and construct separate sewer treatment and disposal facility before releasing into coastal waters and also to monitor the coastal water quality along with pathogenic microbes at regular intervals to protect fragile coral reef ecosystems.