The Influence of Sea Ice Cover and Atlantic Water Advection on Annual Particle Export North of Svalbard

The Arctic Ocean north of Svalbard has recently experienced large sea ice losses and the increasing prominence of Atlantic water (AW) advection. To investigate the impact of these ongoing changes on annual particle export, two moorings with sequential sediment traps were deployed in ice-free and seasonally ice-covered waters on the shelf north (NSv) and east (ESv) of Svalbard, collecting sinking particles nearly continuously from October 2017 to October 2018. Vertical export of particulate organic carbon (POC), total particulate matter (TPM), planktonic protists, chlorophyll a, and zooplankton fecal pellets were measured, and swimmers were quantified and identified. Combined with sensor data from the moorings, these time-series measurements provided a first assessment of the factors influencing particle export in this region of the Arctic Ocean. Higher annual TPM and POC fluxes at the ice-free NSv site were primarily driven by the advection of AW, higher grazing by large copepods, and a wind-induced mixing event during winter. Higher diatom fluxes were observed during spring in the presence of sea ice at the ESv site. Along with sea ice cover, regional differences in AW advection and the seasonal presence of grazers played a prominent role in the biological carbon pump along the continental shelf off Svalbard.

Automated summary

This study investigated the impact of ongoing changes in the Arctic Ocean on annual particle export. It found that advection of Atlantic water and grazing by large copepods were the main factors driving higher total particulate matter and particulate organic carbon fluxes at the ice-free NSv site. In contrast, higher diatom fluxes were observed during spring in the presence of sea ice at the ESv site. Sea ice cover, regional differences in Atlantic water advection, and the seasonal presence of grazers played important roles in the biological carbon pump off the continental shelf of Svalbard.