Picophytoplankton community characteristics at the subsurface chlorophyll maxima in the Northern Indian Ocean.

Autotrophic picoplankton are integral to marine ecosystems, contributing nearly half of oceanic primary productivity, particularly in warm, oligotrophic regions. Given that subsurface chlorophyll maxima (SCM) account for over 80 % of depth-integrated primary production, this study aimed to explore the variations in picophytoplankton community composition at the SCM under dynamic environmental conditions in the Northern Indian Ocean, using flow cytometry and chemotaxonomy. We found that picophytoplankton dominated the SCM (∼60 %), with picochlorophytes being the most prevalent group (∼50 %).