Phytoplankton samples collected from ten stations in the Kadalundi estuary during July 2018 to June 2019 were studied. A total of 87 species of phytoplankton belonging to 60 genera, 46 Families, 33 Orders, 8 Classes and 5 Phyla were recorded. Among them, 43 species belonged to the Phylum Bacillariophyta (Diatoms), followed by 24 species under Miozoa (Dinoflagellates), 9 species under Charophyta (green algae), 6 species under Chlorophyta (green algae) and 5 species under Cyanobacteria (Blue-green algae). Among the species, Tripos furca contributed maximum with 7%, followed by Trieres chinensis (6%), Skeletonema costatum and Tripos muelleri (5% each) and the rest of the species contributed less than 5% each. An average density of 25130 cells/m3 was recorded from the study area with a maximum of 25% in September and a minimum of 1.7% in July. Station wise concentration varied from 9% to 11%. In all the stations, diatoms dominated and it varied from 51% at station 7 to 66% each at stations 3 and 10. Diversity studies were carried out using PRIMER software. The Pielou’s evenness index, ShannonWiener’s index and Simpson index did not show significant variation between months. The taxonomic diversity index and average taxonomic distinctness were the highest in July and lowest in March. In the dendrogram, the highest similarity in species composition and abundance were recorded between November and December and the similarity was low between July and September.

Phytoplankton, species distribution, abundance, diversity, Kadalundi