Fate of sinking particles, especially fecal pellets, within the epipelagic zone in the North Water (NOW) polynya of northern Baffin Bay

Moored time-programmed sediment traps were deployed from late August 1997 through late July 1999 in the North Water (NOW) polynya to determine the fate of sinking particles in the upper 200 m water column (epipelagic zone). The contribution of phytoplankton carbon (PPC), fecal pellet carbon (FPC), and other unidentified particulate carbon (UPC) to total particulate organic carbon (TPOC) collected in sediment traps varied over the 2 yr. UPC fluxes contributed significantly to TPOC fluxes (ca. 37 to 96%) during the sampling period. FPC fluxes (ca. 20 to 33 mgC m–2d–1) dominated the TPOC fluxes (ca. 45 to 62%) between July and August 1998, when the highest TPOC fluxes occurred. However, during the period of highest primary production (June) more than 99% of the total fecal pellets produced in the epipelagic zone (ca. 74 to 122 mgC m–2d–1) did not reach 200 m. No marked decreases in fecal pellet production in the upper 50 m and flux at 200 m were observed in July. The changing proportion of FPC flux between June and July suggests that losses of fecal pellets due to fragmentation by coprophagy and/or coprorhexy by zooplankton equivalent to ca. 73–121 mg C m–2d–1occurred in the upper mesopelagic layer in June. The fate of sinking particles represented by these fecal pellets can be influenced by the retention processes mediated by coprophagous feeding behavior of zooplankton within the epipelagic layers of the NOW.