Picophytoplankton biogeography, community structure, and carbon biomass in the Eastern Indian Ocean during the spring inter-monsoon season
Date
2026Author
Chaudhari, G.
Mitbavkar, S.
Paul, P.
Patil, J.S.
Damare, S.
Metadata
Show full item recordAbstract
Picophytoplankton are globally ubiquitous and play essential roles in marine food webs and biogeochemical cycles, yet the Eastern Indian Ocean remains comparatively understudied. To address this gap, we investigated picophytoplankton biogeography, community structure, and carbon biomass across the Bay of Bengal (BoB), Equatorial Indian Ocean (EqIO), and South Tropical Indian Ocean (STIO), spanning the 90°E Ridge (20°N − 30°S) during the spring inter-monsoon of 2021. The EqIO exhibited the warmest waters, followed by the BoB and STIO, while salinity increased progressively from the BoB to the STIO. Flow-cytometric analyses revealed a decreasing trend in picophytoplankton abundance and carbon biomass from the BoB to the STIO. Synechococcus populations were highest above the subsurface chlorophyll maxima layer (SCML), whereas Prochlorococcus and picoeukaryotes dominated within the SCML. Depth-integrated abundances and biomass of Synechococcus and Prochlorococcus were highest in the BoB, followed by the STIO and EqIO, while picoeukaryotes, though contributing the least, aligned with Synechococcus in the STIO. The presence of Synechococcus and Prochlorococcus in the BoB Oxygen Minimum Zone (130 m) suggests potential heterotrophic or mixotrophic capabilities. Picophytoplankton abundance and carbon biomass were elevated in the westward-flowing, nutrient-rich, stratified South Equatorial Current (Indonesian Throughflow), and lower in the reverse-flowing, deeply-mixed waters of the Equatorial Under Current. The Generalized Additive Model revealed a non-linear predictor-response relationship across the study region. The RCbray analyses showed that the picophytoplankton community assembly across all regions was overwhelmingly governed by stochastic processes, with the majority of samples falling within the ecological drift range. The insights gained from this study provide valuable inputs for improving predictive models of microbial responses to environmental variability and for refining biomass estimations in the Eastern Indian Ocean.
Collections
- Scholarly literature [9282]

