Impact of seasonal anoxic events on phytoplankton dynamics over the Western Indian shelf: An intra- and inter-annual study.

Coastal deoxygenation impacts phytoplankton communities crucial for marine productivity. The inter- and intra-annual variability in phytoplankton communities at a shallow (27 m) station over the Western Indian Shelf (CaTS site, off Goa) during deoxygenation events of the late southwest monsoon (LSWM September-October) were studied from 2020 to 2023. The water column (0-27 m depth) experienced seasonal hypoxia/anoxia at subsurface depths (0-1.

Suboxic waters of the eastern Arabian Sea shelter secondary chlorophyll maximum dominated by heterotrophic dinoflagellate Pronoctiluca spp. (order Noctilucales).

In the present study, we investigated the dinoflagellate assemblages in the upper water column (< 150-m depth), focusing on the suboxic waters of the eastern Arabian Sea (EAS) along 68°E from 8°N to 21°N during the southwest monsoon 2020 (SWM-2020). Dinoflagellate abundance was higher in the upper water column (0-80-m depth, mean ± SD = 411 ± 903 cells L) compared to deeper waters (80-150-m depth, mean ± SD = 128 ± 216 cells L). Among 11 identified taxonomic dinoflagellate orders, Peridinales were predominant in the upper waters column (71%, mean ± SD = 285 ± 858 cells L).

Dynamics of subsurface chlorophyll maxima in the northern Indian Ocean.

Subsurface chlorophyll maxima (SCM) significantly contributes to oceanic primary productivity, emphasizing the need to study its dynamics and governing mechanisms. We used datasets from various platforms to investigate relationships between the SCM characteristics (SCM depth (Z), SCM magnitude (Chl), SCM thickness (T)) and environmental variables modulated by various physical processes in the Northern Indian Ocean (NIO). In the Arabian Sea (western NIO), seasonal processes like convective mixing and upwelling, primarily regulated the SCM characteristics.

Daylight driven vertical migration of mesozooplankton in the Arabian sea and the Bay of Bengal.

Diurnal vertical migration (DVM) of mesozooplankton in the Deep Scattering Layer (DSL) of the Indian seas is poorly studied. This cyclical vertical migration substantially controls the carbon sequestration in the ocean. The present research is a comprehensive examination to analyse the factors affecting the DVM pattern of the zooplankton community in the Arabian Sea (AS) and the Bay of Bengal (BoB).