Bivalves are notorious for their ability to bioconcentrate contaminants and
hence they can be used as effective indicators for monitoring trace toxic
contaminants in coastal waters due to their wide distribution, sessile life style,
euryhaline nature, resistance to stress and high accumulation of wide range of
chemicals and ease of sampling. Bivalve resources of Kerala State mainly include
different species of clams, oysters and mussels. During 2005- 2006 period, the total
bivalve landing was about 61280 tones, of which 75% was contributed by a single
species, Villorita cyprinoides (black clam). More than 90% of the total black clam
production of the state is supported by Vembanad Lake system