Geography

Monitoring export fluxes to detect seasonal and interannual changes in the pelagic ecosystem of the northern Bering Sea

Document Type

Article

Abstract

The considerable loss of sea ice and warmer waters recently observed in the northern Bering Sea significantly affected the seasonal development and composition of algal blooms and zooplankton, with cascading effects on the quantity and quality of material exported to the seafloor. In this context of rapid environmental change, a moored sediment trap was deployed from October 2020 to August 2022 to quantify the magnitude, timing and composition of particles exported and to monitor the influence of sea ice cover duration on the seasonal development of the pelagic ecosystem in the region. Export fluxes showed that an early sea ice breakup followed by a few weeks of sea ice drifting in the region in 2022 led to higher fluxes of chlorophyll a, diatoms, biomarkers, and particulate organic carbon compared to 2021. The composition of the diatom fluxes also changed, with a majority of diatoms exported without chloroplasts in 2022. In addition to large fluxes of ice-associated diatoms, larger fluxes of pelagic diatoms were observed in 2022. Low numbers of zooplankton and meroplankton collected in 2022 possibly reflected reduced food supply associated with the dominance of diatoms without chloroplasts. Whereas low numbers of large copepods have previously been observed under reduced sea ice in the northern Bering Sea, the coincident low abundance of small copepods was unexpected. Further monitoring is necessary to determine if rapid nitrate depletion and the apparent collapse of the zooplankton population are recurrent events. As early sea ice breakup has recently become more frequent and may significantly alter the composition and phenology of the marine ecosystem in the northern Bering Sea, the deployment of moored sediment traps has proven valuable for monitoring these continuing changes. © 2026 Elsevier Ltd

Publication Title

Deep-Sea Research Part II: Topical Studies in Oceanography

Publication Date

4-2026

Volume

226

ISSN

0967-0645

DOI

10.1016/j.dsr2.2026.105611

Keywords

Algae, Bering Sea, Particulate Organic Carbon, sediment trap, zooplankton

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