Seasonal distribution of phytoplankton in the Vellar Estuary, east coast of India

Abstract

Forty-seven species of diatoms belonging to 36 genera were observed at the mouth of the Vellar Estuary during January 1966 to December 1968. Of these, species belonging to the genera Chaetoceros, Rhizosolenia and Coscinodiscus occurred almost throughout the year, while the rest occurred sporadically during different months. The only blue green alga represented was Trichodesmium erythraeum (Ehr.), abundant during March. Noctiluca miliaris (Suriray) was the only dominant species among dinoflagellates. A double mode of distribution of phytoplankton was observed in all the 3 years. However, shifting of the primary and secondary peaks of abundance was observed during the period of investigation. Thus, the two peaks appeared in March and August 1966, May and March 1967 and in June and May 1968. The north-east monsoon period recorded a depletion in the phytoplankton abundance.