Satellite Monitoring Of Surface Phytoplankton Functional Types In The Northern Indian Ocean Over A Decade (2014-23)

This study examines the spatio-temporal variability of phytoplankton functional types (PFT) in the Northern Indian Ocean (2014-2023) using satellite data from the Copernicus Marine Service. Parameters include chlorophyll-a, phytoplankton size classes (pico, nano, and microplankton), and specific PFTs like Prochlorococcus, haptophytes, diatoms, and dinoflagellates. In the Arabian Sea, nanoplankton showed a shift from negative to positive anomalies post-2018, influenced by El Niño. Prochlorococcus and prokaryotes exhibited positive anomalies during post-monsoon seasons post-2016 due to rising sea temperatures. In the Bay of Bengal, chlorophyll-a anomalies shifted positive during the 2018 north-east monsoon, driven by Cyclone Ockhi. Spatial analysis revealed higher chlorophyll-a in the Western Bay. Microplankton trends were consistent across regions, while nanoplankton showed a positive decade-long increase, with pronounced peaks in the Western Bay. Overall, the study underscores the sensitivity of phytoplankton communities to climate variability, particularly ENSO events and cyclones, highlighting the role of remote sensing in tracking marine ecosystem changes.