Abstract

Picophytoplankton are vital drivers of marine biogeochemical cycles and serve as indicators of ocean productivity, ecosystem health, and climate change. As the smallest single-celled phytoplankton, they play a crucial role in ocean ecosystems, being globally recognized as major primary producers and significant contributors to the oceanic carbon stock. Despite their ecological importance, their role is often underestimated, particularly in the northern Indian Ocean—an oceanic region characterized by high environmental variability and dynamic biogeochemical processes. In this seminar, I will present the results that aimed to quantify the abundance and carbon biomass of picophytoplankton and to assess the influence of regional physicochemical parameters on their spatial distribution and ecological role in the northern Indian Ocean. Our findings demonstrate that the contribution of picophytoplankton carbon biomass to the total particulate organic carbon (POC) pool was substantial in both the Arabian Sea and the Bay of Bengal. This underscores their significant, yet often overlooked, role in supporting the regional biological pump and influencing carbon fluxes.