The book is aimed to serve as a repository of data generated during the tenure of my doctoral study and comprises the very significant experimental data procured from studies on one of the globally important well mixed estuaries in the vicinity of the Indian Sundarban and should be adequate enough in intriguing researchers aspiring to work on the same or relevant ecological aspects of planktonic diatoms. The thetical book ought to serve as a valuable reference to those who wish to study the ecological intricacies of the mangrove dominated, yet anthropogenically perturbed deltaic ecosystems of the northern coastal Bay of Bengal. The true success of the present venture lies in its eventual servitude to aspiring researchers and scholars in offering them a template to construct their hypotheses upon.