Journal of Marine Biology & OceanographyISSN: 2324-8661

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Anthropogenic hypoxia in estuaries and seawater quality along north-west coast of India

Anirudh Ram S Jaiswar, Jiyalal Ram M Jaiswar, Divya Majithiya, Ajay Yadav, Shailesh Salvi, Vaibhav Joshilkar, M A Rokade, P S Rakesh, B R Thorat and S N Gajbhiye

CSIR-National Institute of Oceanography, India

: J Mar Biol Oceanogr


I ncreased population density and increased industrialization along the north-west coast of India resulted in discharge of domestic and industrial wastes which have increased the level of contaminants and organic load such an extent that most of the estuaries, creeks, bays and fishing harbours i.e. Ratnagiri, Veraval and Porbandar, Mahim Bay, Versova Creek, Ulhas, Kolak, Mindola, Tapi and Sabarmati Estuaries, which consequently open into sea exhibit hypoxic (DO<2.0 mg/l)/anoxic (DO<0.2 mg/l) conditions especially during ebb. The sparse information on the ecological status of these creeks and estuaries necessitated the present study. For understanding the prevailing status of these water bodies, the studies on water quality and phytoplankton pigments were carried out during different years between 1997-2014. The results showed hypoxic/anoxic conditions with elevated concentration of nutrients in terms of NO2 - -N (ND-22.8 µM), NH4 +-N (194.2-1241.8 µM) and (PO4 )3 - -P (3.8-41.4 µM) in Veraval harbour, and NH4 +-N (19.7-62.5 µM), (PO4 )3--P (2.3-8.6 µM) in Porbandar harbour. The release of waste water resulting in anoxic condition with augmented level of NH4 +-N, NO2 - -N, NO3 - -N and (PO4 )3 - -P have caused frequent fish kill in Tapi and Mindola estuaries. Similarly Ulhas Estuary remains hypoxic for most of the time. The decreased ratios of chlorophyll a/phaeophytin (<1.0) in these water bodies were indicative of an unhealthy condition of phytoplankton. The presence of certain species belonging to genera of phytoplankton such as Tetraspora, Bacteriastrum, Skeletonema and Thalassiosira in anoxic waters of Veraval and Porbandar harbours suggested their hardy nature. The water quality of northwest coast of India, beyond 25 km from shore was grossly unaffected by the anthropogenic sources since nutrients in terms of NO3 - -N (4.0-12.8 µM), NO2 - -N (0.1-2.5 µM), NH4 +-N (0.1-2.2 µM) and (PO4 )3--P (0.1-3.0 µM) were relatively lower showing efficient utilization/dilution in the nearshore region. Seasonal hypoxia in the near shore coastal waters off Mumbai and Veraval has been recorded in recent years. However, seawater quality beyond 25 km from the mouth of Gulf of Cambay showed riverine and terrestrial influx in terms of nutrients (NO3 - -N: 4.0-39.4 µM; NH4 +-N: 0.2-3.4 µM; (PO4 )3--P: 0.2-10.0 µM), suspended particulate matter (SPM:47-635 mg/l) and salinity (32.3-36.1 psu).


Anirudh Ram S Jaiswar is a scientist at the Regional Centre, CSIR-National Institute of Oceanography, Mumbai. He received his PhD from University of Mumbai in Inorganic Chemistry. His research interest is marine ecological assessment and studies for sustainable developments in the coastal and shelf areas. He has participated in 16 Research Cruises to study the extent of pollution in the coastal water of north-west coast of India. He has participated in study and preparation of more than 300 technical reports related to marine environmental impact assessment (MEIA) and pollution monitoring. He has published more than 15 papers in various national and international journals and presented papers in National and International conferences.

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