A substantial export flux of particulate organic carbon linked to sinking dead copepods during winter 2007–2008 in the Amundsen Gulf (southeastern Beaufort Sea, Arctic Ocean)

Makoto Sampei, Hiroshi Sasaki, Alexandre Forest and Louis Fortier

Limnol. Oceanogr., 57(1), 2012, 90-96 | DOI: 10.4319/lo.2012.57.1.0090

ABSTRACT: In the Arctic Ocean, vertical fluxes of particulate organic carbon (POC) remain low during the dark winter period because POC fluxes are derived from photosynthetic production. Passively sinking dead copepods are traditionally excluded from POC fluxes estimated using sediment traps, resulting in the underestimation of the total POC flux. Here, we present the seasonal variability of total POC export flux measured by a sediment trap moored at ∼ 100 m in the Amundsen Gulf (southeastern Beaufort Sea) over October 2007–July 2008. Surprisingly, the integrated total POC flux for February (466 mg m−2) was the second highest flux during the study period (the highest was in Jul; 1015 mg C m−2) due to a contribution of 91% from sinking dead copepods. The total POC flux in February 2008 in the Amundsen Gulf was up to two orders of magnitude higher than the previously reported traditional POC winter fluxes that did not include the contribution of sinking dead copepods. Hence, the POC flux in February only could be equivalent to ∼ 18% of the quasi-annual traditional POC flux. Our observations suggest that a substantial POC export flux occurred during winter 2007–2008 due to zooplankton life cycle.

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