A study carried out to monitor the seasonal variations in physicochemical properties of the Kalpakkam coastal waters for a period of one year (February 2006 to January 2007) showed that the coastal water was influenced by freshwater input during northeast (NE) monsoon and post-monsoon periods. Concentration of all the nutrients and dissolved oxygen (DO) was relatively higher, whereas, salinity and chlorophyll-a (chl-a) concentration were low during monsoon. Phytoplankton production peak was observed in summer. nitrate, phosphate, silicate and turbidity were significantly high (1.5-8 times), but DO and chl-a were relatively low when compared to studies carried out 15 years ago along this coast. A notable indication from this study is that though nutrient concentration in the coastal waters had increased significantly, the increase in turbidity has affected the phytoplankton production adversely. Significant changes in water quality could be due to increased anthropogenic activities along the coast in the recent past, which has a potential to alter the chemical properties and biological community in the nearshore waters.

Physicochemical properties, seasonal variations, coastal waters, southeast coast of India