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)

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 22 ) was the second highest flux during the study period (the highest was in Jul; 1015 mg C m 22 ) 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.

Zooplankton respiration and the export of carbon at depth in the Amundsen Gulf (Arctic Ocean)

“…Based on the above, mean active vertical carbon transport by Calanu s was estimated at 3.1 ± 2.1 and 2.5 ± 1.7 g C m −2 below 100 m and 200 m respectively for the period 24 October–17 April in regions of Amundsen Gulf deeper than 250 m. Active transport of carbon beyond 100 m represented approximately 85% of the POC passive flux at 100 m recorded from 24 October to 28 July at Station CA‐08 (M. Sampei, unpublished data, 2010) and 132% of the passive flux for the same period at Station CA‐16 [ Sampei et al , 2012]. Our estimate of active transport of carbon beyond 100 m by Calanus is close to the lower limit of the range of annual gravitational POC fluxes (3.3–6.0 g C m −2 yr −1 ) at Station CA‐08 for 2004, 2005 and 2006 [ Forest et al , 2010].…”

Review: Potential catastrophic reduction of sea ice in the western Arctic Ocean: Its impact on biogeochemical cycles and marine ecosystems

“…In the Amundsen Gulf in the southeastern Beaufort Sea, sinking dead copepods accounted for 87-91% of the export flux during the winter (January-February), 2003-2004, when the large copepods C. hyperboreus and P. glacialis were present (Sampei et al, 2009(Sampei et al, , 2012. The spawning of C. hyperboreus generally peaks at some point during the winter; as a result, the senescence and mortality of most adult stages occurs in winter.…”

“…The spawning of C. hyperboreus generally peaks at some point during the winter; as a result, the senescence and mortality of most adult stages occurs in winter. Thus, sinking dead copepods in winter may contribute importantly to the annual TMF (Sampei et al, 2012). The development time of copepods from egg to hatching is such that the relatively high abundance of copepod nauplii collected in March would reflect the eggs laid between December and March (Sampei et al, 2012).…”

Dead heat: copepod carcass occurrence along the Japanese coasts and implications for a warming ocean

“…Some recent studies have shown that zooplankton carcasses can make up a major fraction (up to 91%) of the carbon sinking flux, especially outside of the phytoplankton bloom periods (Frangoulis et al, 2011;Sampei et al, 2009Sampei et al, , 2012.…”