Temporal variability of phytoplankters in Vellar Estuary

Abstract

Seasonal variation in the numerical abundance of 42 spp of phytoplankters (18 centric, 20 pennate diatoms, 3 dinoflagellates and 1 <i>Trichodesmium</i>) at the mouth of the Vellar Estuary, Tamil Nadu, India has been followed for 3 yr. Quantitative distribution of diatoms follows trimodal annual patterns. Negative correlations exist between diatom density and blooms of dinoflagellates and <i>Trichodesmium</i>. Variations in quantity and settling volume correspond to changes in ambient salinity. Shannon-Wiener indices are linearly related to number of species, phytoplankton density and settling volume. Temporal variations in the community largely depend on the salinity and to a lesser extent on the ambient surface water temperature. The correlation matrix reveals the presence of atleast 5 diverse components in the phytoplankton community.