Seasonal variation in diatoms in response to physico-chemical characteristics of coastal waters of Uttara Kannada district, West Coast of India

The present study was undertaken to know the diatom distribution in different seasons in response to physico-chemical properties of Arabian Sea water in the Uttara Kannada District, Karnataka over a period of one year from November 2009-0ctober 2010. The study revealed the presence of 55 species of diatoms, highest number was recorded in post-monsoon and the least in monsoon season. The major genera belong to Amphora, Chaetoceros, Coscinodiscus, Navicula, Pleurosigma, Achnanthes, Cymbella, Mastogloia, Nitzschia, Biddulphia, Diploneis and Licmophora. Bloom of Asterionella japonica was observed during early monsoon season. The physico-chemical parameters studied showed noticeable seasonal variations, which may be attributed to the local climatic conditions and water exchange mechanisms. The physicochemical parameters like temperature, salinity, conductivity and nutrients were found to influence the occurrence of diatoms.