Geethu Mohan^1,, R. Aravind², P. Anjaneyan¹, S.M. Raffi³, K.S. Swathy¹, S. Athul¹, T.M. Sreenath¹

Phytoplankton, the primary producers in all aquatic systems, play an important key role in biogeochemical processes that are linked to higher trophic levels and climate variability. The spatio temporal composition and abundance of micro phytoplankton species was examined in relation to physical and chemical surface water variables (i.e., Salinity, temperature and nutrients). The primary objectives of the study were to observe the variations in phytoplankton species assemblages as a response to environmental variables. Hierarchiel cluster analysis and non-metric multidimensional scaling were used to find out distinct seasonal groups based on the composition of phytoplankton. The results indicate that several key environmental factors like temperature, salinity and nutrients like nitrate, nitrite, phosphate and silicate influenced seasonal phytoplankton assemblages within the lagoon waters. The distribution of phytoplankton population showed main groups where the blue green algae populations favored the warmer conditions of pre-monsoon period, whereas the diatom population primarily flourished in the post monsoon and monsoon period. The present study deals with the phytoplankton community structure in the Indian Ocean, Lakshadweep Archipelago, Minicoy Island, particularly in the surface water with respect to environmental variables to understand the region-specific dominant community and its governing environmental settings.

phytoplankton, lagoon, nutrients, seasons, environmental factors