Centre for Sustainable Technologies,Centre for infrastructure, Sustainable Transportation and Urban Planning,
Energy and Wetlands Research Group, Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560 012, India
Bivalves (Clams and oysters) contribute to the livelihoods of many people in India. Shell and sand mining in the molluscan beds, over-exploitation of bivalves, and sustained freshwater flows from the hydroelectric projects are expected to have adverse consequences on estuarine bivalve resources. The present study was conducted in the four major estuaries of Uttara Kannada District (Kali, Gangavali, Aghanashini, and Sharavathi), to see the diversity of edible bivalves and their distribution. The study was conducted in 2011-2012 period in these estuaries. The status of edible bivalves of the estuaries was assessed through primary observations and interviews with local fisher folks. Past studies were also referred to gather such information. Anadara granosa, Meretrix casta, M. meretrix, Paphia malabarica, Polymesoda erosa, Villorita cyprinoides and oysters were present in the Uttara Kannada estuaries. In Sharavathi estuary only Polymesoda erosa and oysters were found. The distribution zones of edible bivalves, and thereby their abundance, in the Kali estuary was less than the Aghanashini and Gangavali estuaries. The reasons for such disparity between the neighboring estuaries could be attributed to major human intervention in the form of construction of hydroelectric projects upstream that caused low salinity conditions in the downstream causing depletion of most estuarine bivalves, as is glaringly evident in the Sharavathi estuary.
Keywords: Bivalves, estuary, Uttara Kannada, Impact of dams.