Seasonal and spatial variability in the flux of biogenic particles in the North Water, 1997–1998

Major biogenic fluxes (of phytoplankton and fecal pellets) were measured using moored sediment traps to identify factors that control spatial and temporal variations in biological production in the North Water, a polynya located in northern Baffin Bay. Time-series sediment traps were deployed at ca. 200 m below the sea surface and 50 m above the bottom at five stations, located north and south (75 and 78°N) and along a central east–west transect (72–78°W) in the polynya, from September 1997 through June 1998. Fluxes of phytoplankton cells and fecal pellets showed marked seasonal variations in the study area. While the highest fluxes of phytoplankton cells were observed in spring 1998 (mid-May–June) at all stations, fecal pellet fluxes at the transect stations showed marked increases in fall 1997 (September–mid-November) that exceeded those in spring. Fluxes of these biogenic components generally coincided with those of particulate organic matter and particulate organic carbon (POC) at all stations. The averaged POC flux at transect stations during the productive period was greater than those reported previously at ice-covered locations and in other Arctic polynyas. POC fluxes at about 200 m, estimated using the empirical formula of Martin et al. (Deep-Sea Research, Part I 34 (1987) 267), were compared with the observed fluxes at the transect stations in spring 1998. The differences indicated that a marked loss of sinking particles had occurred within the surface 200 m. During the productive period, we suggest that surface-produced sinking particles were broken into small-sized particles, including phytoplankton remains, which were subjected to pelagic remineralization processes and widely dispersed throughout the North Water by water advection.