Interlinking diatom frustule diversity from the abyss of the central Arabian Sea to surface processes: physical forcing and oxygen minimum zone

Pandey, Medhavi; Biswas, Haimanti; Chowdhury, Mintu

doi:10.1007/s10661-022-10749-7

Cited by 1 publication

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“…(in 2018) (Chowdhury et al., 2021) could escape grazing (Jansen, 2008; Löder et al., 2011) due to larger body size (Hansen et al., 1994) and can be exported to the lower mesopelagic. In another study, we analyzed the distribution and diversity of diatom frustules using 5 short sediment core top samples from the central Arabian Sea (Pandey et al., 2023). It was revealed that the NFJ and AFJ stations were dominated by large diatoms like Coscinodiscus and Rhizosolenia .…”

Section: Discussionmentioning

confidence: 99%

Spatiotemporal Variability in Phytoplankton Size Class Modulated by Summer Monsoon Wind Forcing in the Central Arabian Sea

Chowdhury,

Biswas,

Silori

et al. 2023

JGR Oceans

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The Arabian Sea is an area of intense ocean‐atmospheric coupling that impacts its physicochemical, and biological processes. During the summer monsoon (June‐September), in the central Arabian Sea, a low‐level atmospheric jet blows parallel to the Arabian Peninsula causing open ocean upwelling in the north and downwelling in the south of the jet axis. High wind speeds are witnessed in the jet axis which advect nutrients from the Somali coast. Consequently, hydrography and physicochemical parameters show high spatial variability. In this dynamic region, phytoplankton size class distribution, directly controlled by nutrient supply, can be modulated by monsoon wind variability via upwelling, advection, and entrainment, however, has not been investigated recently. We studied phytoplankton size class related to atmospheric forcing, hydrography, and nutrient stoichiometry in August 2017 and 2018 along 64°E (11°N–21°N). Chemical taxonomy‐based analysis (CHEMTAX and manual) revealed that in the north, upwelling‐driven nutrient enrichment supported microphytoplankton, mostly diatoms contributing ∼50% to phytoplankton biomass. A stronger upwelling due to higher wind forcing in 2018 compared to 2017 resulted in an enhanced nutrient supply as well as an increased contribution of diatoms. Prymnesiophytic nanophytoplankton distribution was linked to mixed layer depths with insignificant spatial variability (20%–30%). Conversely, in the nutrient‐poor southern region, zeaxanthin and DV‐Chla containing picocyanobacteria and prochlorophytes contributed >50% to the total phytoplankton biomass and were associated with high temperatures. Likely, increasing warming and related changes in monsoon intensity might directly influence phytoplankton size classes impacting trophic transfer and carbon cycling.

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