Hydrodynamic Control of Late Summer Species Composition and Abundance of Zooplankton in Hudson Bay and Hudson Strait (Canada)

• Published in: Journal of Plankton Research
• Main Authors: Harvey, Michel, Therriault, Jean-Claude, Simard, Nathalie
• Format: Text
• Language: English
• Published: Oxford University Press 2001
• Subjects: ORIGINAL ARTICLES; Arctic; Hudson Bay; Canada; Hudson; Hudson Strait; Belcher; Ungava Bay; Phytoplankton; Subarctic; Zooplankton; Copepods; James Bay
• Online Access: http://plankt.oxfordjournals.org/cgi/content/short/23/5/481; https://doi.org/10.1093/plankt/23.5.481

The spatial variation in zooplankton biomass, abundance and species composition in relation to hydrography and chlorophyll a (Chl a) was studied in the subarctic waters of Hudson Bay and Hudson Strait. Sampling was carried out in early September 1993 at 21 stations arranged along a transect following the Québec coast from James Bay, in Hudson Bay, to the vicinity of Ungava Bay in Hudson Strait. Both the biomass and the abundance of total zooplankton were low along the lower part of Hudson Bay (averaging 1.6 g DM m–2 and 9432 ind. m–2) and increased sharply toward the upper end of the Bay and in Hudson Strait (averaging 6.0 g DM m–2 and 40 583 ind. m–2). A total of 80 zooplankton taxa was identified in the samples. Copepods were clearly numerically dominant at all sampling stations, accounting for more than 85% and 93% of the zooplankton community in the Bay and the Strait, respectively. Clustering samples by their relative species composition revealed four groups distributed along well defined environmental gradients characterizing the distribution of physical variables and Chl a. The first group, located in the most southern region of Hudson Bay and farther offshore, northwest of the Belcher and Sleeper Islands, was strongly influenced by freshwater run-off from James Bay and other major rivers around the Bay, and was characterized by the presence of two euryhaline copepod species (Acartia longiremis and Centropages hamatus). The second and the third groups occupied the largest region along the sampling transect, from the middle of Hudson Bay to the western region of Hudson Strait, and were characterized by a typical arctic zooplankton fauna related to the cyclonic circulation in central Hudson Bay. The fourth group was located in the easternmost part of the sampling transect in Hudson Strait where the highest phytoplankton biomass values were observed (Chl a ~220 mg m–2). The zooplankton assemblage there showed an important increase in the abundance of the large herbivorous copepod Calanus ...