Variability of export flux in polynya regions of the Canadian Arctic coastal waters

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Regional and temporal variability of downward particle flux using time-series sediment traps were observed in waters of the Mackenzie Shelf slope and the Amundsen Gulf during the CASES (Canadian Arctic Shelf Transport Study) Project in 2003-2004. Objectives Of the present study are; 1. To know the contribution of both autochthonous and allochthonous organic particles and the decadal change through a comparison between 1987-1988 and 2003-2004. 2. To know how to vary biogenic fluxes regionally and seasonally and what are the major flux-mediating processes. 3. To find indicator organisms of food web, change through a comparison of collected swimmer compositions between 1987-1988 and 2003-2004. Results obtained were; 1. Contribution of annual terrigenous POC flux ranged from 4 to 49% of total POC flux through a year of 2003-2004, which was approximately the same as that in 1987-1988. 2. The biogenic flux varied regionally and seasonally, and the fluxes could be mediated by the food web str … More ucture associated with sea ice concentration. 3. Large microphagous aminals, such as pteropods, may be indicative of food web change in response to the decrease of sea ice concentration (global warming?).As for the seasonal variation of compositions and abundances of zooplankton swimmers (>1mm in total length), copepods were the dominant component numerically, and Amphipoda, Ostracoda and Polychaeta were the less abundant zooplankton taxa. Among the copepods, Metridia longa and Calanus hyperboreus were usually much abundant and Pereuchaeta glacialis was relatively abundant in summer ZooplanIcton taxonomic composition varied temporally and spatially. Agglomerative hierarchical cluster analysis using time-averaged abundance and compositions of swimmers showed that compositions at all stations in summer were different from those in other seasons, and similar to that at CAI8 (400m) in winter, suggesting the seasonal vertical and horizontal migration of zooplankton community around this sea areas.Among small-sized zooplankton (copepod nauplii, Oncaea spp, Oithona spp and Metridia spp,), copepod nauplii occurred predominantly and varied seasonally. Their body length of the nauplii collected in early spring were about 190 um in three stations. If these trap-collected copepod nauplii were really inhabited in and around the trap depth, they stayed at about 200m layer in early spring after their hatching, and then migrated upward to the surface layers as they grew in spring to summer. Less