Depth-Distribution of Holoplankton Functional Traits and Vertical Carbon Export in the Arctic Ocean

The biological carbon pump (BCP) is a fundamental process of the global carbon cycle, transferring organic carbon from surface waters to the deep ocean. Zooplankton regulate BCP efficiently through their functional traits such as body size, feeding behaviour, and trophic modes, which affect the production and consumption of sinking particles. Despite the Arctic Ocean’s importance in global carbon cycling, the functional diversity of its zooplankton communities and their contributions to carbon fluxes remain poorly characterised.We investigated a transect from the Barents Sea to the Central Arctic Ocean, with a focus on holoplanktonic communities. High-resolution sampling with multiple mesh sizes enabled detailed taxonomic identification of life stages across five depth layers. Short-term sediment traps deployed at seven depths at each station provided carbon flux measurements, which were used to calculate carbon attenuation. By linking the distribution of holoplankton traits to carbon attenuation, we aim to elucidate the relationship between the zooplankton functional community structure and carbon flux in this remote region.Despite low biomass, Arctic zooplankton communities play a critical role in modulating the strength and efficiency of the BCP. This study provides novel evidence that functional traits drive carbon export in the Arctic, moving beyond traditional taxonomic approaches to emphasise functional diversity. These insights enhance our understanding of the Arctic Ocean’s role in global carbon cycling and offer valuable contributions to improving models of carbon fluxes in this extreme and understudied ecosystem.