Environmental-driven dynamics of phytoplankton assemblages in the Bay of Bengal, Southeast coast of India

A study conducted from January to December 2018 examined seasonal variations in horizontal phytoplankton communities. A total of 93 species were identified, including 63 Coscinodiscophyceae, 4 Fragilariophyceae, 7 Bacillariophyceae, 15 Dinophyceae, and 4 Cyanophyceae. The highest species diversity and abundance occurred during the postmonsoon and premonsoon periods. Environmental parameters (viz., temperature, salinity, dissolved oxygen, pH, ammonia, nitrite, silicate, total suspended solids) were all statistically significant except for nitrite (p > .05). Multivariate statistical analyses (PCA and CCA) revealed that in the postmonsoon period, silicate and nitrate were responsible for the proliferation of phytoplankton abundance, species composition and density, while in the premonsoon period, temperature, salinity, and pH significantly influenced and favored specific phytoplankton groups (such as Chaetocerotaceae) in terms of species composition and abundance.