Phytoplankton characteristics and species assemblage patterns in northwest Bay of Bengal

Abstract

Qualitative and quantitative composition of phytoplankton of surface waters showed 109 species, represented by blue-green algae, diatoms and dinoflagellates. Among these, Trichodesmium thiebautii (29.34%), T. erythraeum (27.97%), Nitzschia seriata (10.06%), Rhizosolenia cylindrus (4.64%), Thallassiothrix longissima (2.05%), Dinophysis sp. (0.78%), Noctiluca scintillans (0.75%) and Ceratium sp. (0.6%) constituted the most important species. Miscellaneous species made up 23.8% to the total population. In general, there was a decrease in the overall abundance of phytoplankton offshore and increase in species diversity. Based on principal component analysis (PCA) it was possible to identify 5 assemblages of phytoplankton as determined by the prevailing hydrographical conditions.