Diatoms as indicators of water quality deterioration in the estuaries of Dakshina Kannada and Udupi Districts of Karnataka

The seasonal variation in physicochemical properties and distribution of diatom species was studied at estuaries of Dakshina Kannada and Udupi Districts for a period of one year (October 2009 to September 2010). The study revealed that the estuarine zone was significantly influenced by pollution due to anthropogenic and organic wastes, industrial effluent discharges and improper sanitation measures. Habitat destruction due to sand mining and urbanization was noticed. The nutrient level showed a significant raise during monsoon in all the study areas. Distribution of members of diatom species was studied which revealed that percentage of different species showed abrupt changes with the variations in the water quality. Diatom species like Achnanthus brevipes, Gomphonema parvulum, Cymbella tumida, Melosira sp., Cyclotella sp., play an important role in the indication of deterioration of water quality and act as bioindicatiors in the aquatic pollution. Estuaries are an irreplaceable natural resource that must be managed carefully for ecological sustenance. Using bioindicators as an early warning of deterioration of an ecosystem can help sustain critical resources.