Phytoplankton bloom in the Hooghly estuary

Abstract

The characteristic species of diatoms in bloom proportions during postmonsoon and early premonsoon period were Coscinodiscus excentricus, Coscinodiscus radiatus, Rhizosolenia alata, Biddulphia sinensis, Dityllum brightwelli and Pleurosigma elongatum. The overall cell counts varied from 1720 to 7080 cells. l-1. Total surface area of phytoplankton varied from 1.19-7.24 x 10(7) mu-m2. l-1. Variations in salinity, transparency and nutrients were the major factors causing blooms, in addition to the increase in size and the shape of phytoplankton specific cells.