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The absence of quantitative comparisons of sediment trap-collected zooplankton (TCZ) and plankton net-collected zooplankton (NCZ) prevents the effective use of TCZ for ecological studies. We compared 24 TCZ time-series at 200 m with 19 vertical NCZ casts and recorded various environmental variables in Franklin Bay, Canadian Arctic during 2003-2004. While 30 taxonomic groups were commonly found in both the TCZ and NCZ assemblages, their taxonomic composition and seasonal variation differed. Based on the multiple regression analysis, we divided zooplankton taxa into three groups; Group 1: it was significantly correlated with NCZ abundance, Group 2: it was significantly correlated with environmental variables but not with NCZ abundance, and Group 3: no significant correlations were found. Pteropods (mostly Limacina helicina) and two copepods ( Heterorhabdus norvegicus and Metridia longa) were found in Group 1, suggesting that their entrapment activity were relatively constant throughout the year, and therefore their NCZ abundance can be estimated from that of TCZ using the trap settings in this study. Conversely, in Group 2, Calanus hyperboreus had no significant relationship with the NCZ abundance ( C. hyperboreus). This is likely the result of a winter peak in TCZ abundance during their reproductive season; the co-occurrence of high suspended particulate organic matter with low C/ N ratio around the trap probably indicated the presence of C. hyperboreus eggs and nauplii. Therefore, monitoring interannual changes in C. hyperboreus reproductive succession by TCZ abundance might be possible in the future studies. In conclusion, Group 1 taxa are potential candidates for ecological monitoring using TCZs. [ABSTRACT FROM AUTHOR]

Regional variability in the annual fluxes of particulate organic carbon (POC) and biogenic silica (Si) at the periphery of the Mackenzie Shelf (Beaufort Sea) was investigated using eight long-term sediment traps moored at ~100-m depth. Relatively high autochthonous POC and Si fluxes were recorded in the Mackenzie Trough (4.1 and 8.9 g m year respectively) and off Cape Bathurst (6.6 and 79 g m year), two areas where upwelling events are frequently observed. Diatomaceous new production was minimum on the mid-slope of the Mackenzie Shelf (2.8 g C m year), moderate in the Mackenzie Trough (14.5 g C m year), and highest off Cape Bathurst (128.7 g C m year). High annual autochthonous POC flux corresponded to high diatom production. Among sites, the vertical attenuation of the POC flux increased with diatomaceous new production. Hence, the retention of autochthonous POC in the surface layer (<100 m) was highest (95%) at the highly productive site off Cape Bathurst, intermediate (72%) in the moderately productive Mackenzie Trough, and low (4%) at the unproductive mid-slope of the shelf. Our results indicate that, on Arctic shelves, upwelling and the production of diatoms increase the fraction of the POC which is retained in the surface layer and diverted to the pelagic food web. In the relatively unproductive waters of the Arctic Ocean, biological hot spots such as the one identified off Cape Bathurst where the food web promotes retention rather than vertical export could be disproportionately important as feeding grounds for higher trophic levels. [ABSTRACT FROM AUTHOR]

Time-series sediment traps were deployed at six mooring sites in the southeastern Beaufort Sea from October 2003 to August 2004 during the cruise of the Canadian research vessel Amundsen within the framework of the Canadian Arctic Shelf Exchange Study (CASES). Trap-collected zooplankton (TCZ) at around 200 m water depth was dominated by copepods accounting for 74–93% of the total abundance throughout the year with increase in abundance at all sites during the fall. Seven distinct TCZ groups were identified through cluster analysis. Two marked seasonal shifts in TCZ composition from late fall to early winter and from spring to early summer were revealed at five sites at 200 m depth. The zooplankton was dominated by Oncaea spp., pteropods, and copepod nauplii in the late fall cluster and in the winter cluster, and by copepod nauplii in the summer cluster. A significant change in water temperature, salinity, and sea ice concentration was observed only with the spring–summer shift. The cluster analysis also revealed that TCZ composition at 200 m at a station located in the Cape Bathurst Polynya was markedly different from those at other sites through the study period by being characterized by the dominance of various copepodite stages of Metridia longa. This was probably due to a less prolonged period of sea ice cover, which provides favorable food conditions for the zooplankton community. [ABSTRACT FROM AUTHOR]

A variable fraction of fecal pellets produced in the epipelagic layer is intercepted and retained before reaching the bottom. We assessed fecal pellet retention in the ice-covered Beaufort Sea in early February by comparing the shape and size-frequency distribution of pellets collected by a sediment trap moored at 210 m to that produced in vitro. Appendicularian ellipsoidal and copepod cylindrical pellets made up 75 and 24% of the flux (165 μg C m−2 day−1). In contrast, production (135 μg C m−2 day−1) was dominated by cylindrical pellets (93%). The vertical flux of cylindrical pellets at 210 m was attenuated by 70%. Pellets >120 μm in width, represented 42% of the production, but were not detected in the trap. Retention most likely resulted from coprorhexic feeding by copepods such as Metridia longa. Our observations suggest that the detritivore food web prevailing under the ice of the Arctic Ocean in winter is dominated by appendicularians feeding on pellets fragmented by copepods. [ABSTRACT FROM AUTHOR]