Seasonal Variations in Vertical Flux of particulate matter and composition in the Northern Barents Sea

Abstract

The Barents Sea is an inflow shelf sea in the Arctic Ocean which experiences climate change consequently reduction in the sea ice extent thereby significantly impacting its ecological importance. This study investigates seasonal variations in the vertical flux of particulate matter including both particulate organic matter (chl a) and particulate inorganic matterin the form of CaCO3 contributed by planktonic marine calcifiers, and explores the implications of seasonality on the vertical flux of particulate matter (TPM) and composition (PIM and POM). Long term sediment traps were deployed at the Nansen Legacy M1 mooring station (79°34.975N; 28°04.38E) during 2019-2020. The study parameters include total particulate matter (organic and inorganic matter), chlorophyll a, and role of planktonic marine calcifiers (foraminifers and pteropods). The annual vertical flux of TPM has been found ~5.96 g m-2 year-1. The PIM contributes ~ 4.29 g m-2 year-1 and POM contributes ~1.67 g m-2 year-1 to the TPM. The annual vertical flux of chl a has been found ~ 0.16 g m-2 year-1 and calcifiers contribute ~ 0.42 g m-2 year-1 to PIM as CaCO3. Notably, the total particulate matter flux exhibited peaks during polar night, particularly in December, with dominant contributions from particulate inorganic matter during winter, contrasting with higher particulate organic matter flux in productive and summer periods. Chlorophyll a demonstrated unexpected high flux during December, suggesting aged and degraded organic materials influenced by water advection and resuspension processes as supported by low chlorophyll a/phaeo-pigments ratios. Seasonal trends in the contribution of planktonic marine calcifiers highlighted lower fluxes during winter and higher contributions during summer, showcasing varying deposition patterns and shell sizes among different species. This study emphasizes the connections between environmental conditions, seasonal changes, and CaCO3 flux to the vertical flux of total particulate matter in the Barents Sea, and offering key insights for future exploration of its seasonal dynamics.