River systems Seasons Species Rupsha-Pashur Monsoon Thalassiosira oestrupii, Thalassiosira ecentrica, Thalassiosira decipens, Coscinodiscus centralis, Coscinodiscus concinus,  Coscinodiscus spiniferus, Cyclotella striata,  Roperia tesselata, Nitzschia lorenziana Winter Thalassiosira wongii, Coscinodiscus granii, Cyclotella stylorum, Chaetoceros affinis, Chaetoceros debile, Skeletonema costatum, Thalassionema nitzschioides, Synedra ulna, Pleurosigma angulatum, Cylindrotheca fusiformis, Ankistrodesmus falcatus Summer Ditylum brightwelli, Anabaena cf. flos-aquae and Spirulina platens Khalpatua-Arpangachia Monsoon Thalassiosira ecentrica, Thalassiosira oestrupii, Thalassiosira decipens, Thalassiosira angulata, Coscinodiscus centralis, Coscinodiscus spiniferus, Coscinodiscus angsti, Coscinodiscus concinus, Cyclotella striata, Cyclotella striata, Pleurosigma angulatum, Pleurosigma directum, Pleurosigma cf. elongatum, Cerataulina bicornis, Thalassionema nitzschioides, Ceratium fusus winter Thalassiosira wongii, Thalassiosira punctigera, Thalassiosira pseudonona, Thalassiosira anguste-lineata, Coscinodiscus marginatus, Coscinodiscus wailesii, Coscinodiscus radiatus, Coscinodiscus pavillardi, Actinocyclus anulatus, Actinocyclus Pruniosus  , Cylindrotheca closterium, Pleurosigma normani, Navicula meninscus, Ditylum brightwelli, Odontella sinensis, Odontella mobiliensis, Bacillaria paxillifera, Surirella gemma, Entomoneis sulcata, Entomoneis paludosa, Leptocylindrus minimus, Cladopyxis hemibrachiata, Protoperidinium biconicum, Protoperidinium subinerme, Protoperidinium claudicans, Protoperidinium leonis, Ceratium furca, Eudorina elegans, Netrium oblongum Summer Not available Bhola-Baleswar Monsoon Thalassiosira ecentrica, Thalassiosira oestrupii, Thalassiosira decipens, Coscinodiscus centralis, Coscinodiscus spiniferus, Nitzschia behrei, Roperia tesselata, Cerataulina dentate, Eudorina elegans, Hydroductyon etc. Winter Thalassiosira lundiana, Thalassiosira wongii, Coscinodiscus angsti, Skeletonema costatum, Cylindrotheca fusiformis, Fragilaria sp., Entomoneis sulcata, Entomoneis paludosa, Chaetoceros affinis, Actinocyclus anulatus, Pleurosigma estuarii, Odontella mobiliensis, Cladopyxis hemibrachiata, Ceratium furca, Protoperidinium punctulatum, Protoperidinium subinerme, Netrium oblongum, Pediastrum simplex, Pediastrum duplex etc. Summer Anabaena cf. flos-aquae, Microcystis sp, Spirulina platens, Anacystis aeruginosa etc

Table 3: List of the most abundant phytoplankton genera found in the Sundarbans river-systems at different seasons.