Spatial distribution of epifaunal communities in the Hudson Bay system

Abstract

The seasonal sea ice cover and the massive influx of river runoff into the Hudson Bay System (HBS) of the Canadian Arctic are critical factors influencing biological production and, ultimately, the dynamics and structure of benthic communities in the region. This study provides the most recent survey of epibenthic communities in Hudson Bay and Hudson Strait and explores their relationships with environmental variables, including mean annual primary production and particulate organic carbon in surface water, bottom oceanographic variables, and substrate type. Epibenthic trawl samples were collected at 46 stations, with a total of 380 epibenthic taxa identified, representing 71% of the estimated taxa within the system. Three communities were defined based on biomass and taxonomic composition. Ordination analyses showed them to be associated primarily with substrate type, salinity, and annual primary production. A first community, associated with coarse substrate, was distributed along the coastlines and near the river mouths. This community was characterized by the lowest density and taxonomic richness and the highest biomass of filter and suspension feeders. A second community, composed mostly of deposit feeders and small abundant epibenthic organisms, was associated with soft substrate and distributed in the deepest waters. A third community, associated with mixed substrate and mostly located near polynyas, was characterized by high diversity and biomass, with no clearly dominant taxon. The overall analysis indicated that bottom salinity and surface-water particulate organic carbon content were the main environmental drivers of these epibenthic community patterns. In the face of climate change, projections of increased river inflow and a longer open water season for the HBS could have major impacts on these epibenthic communities, emphasizing a need to continually improve our ability to evaluate and predict shifts in epibenthic richness and distribution.

Biodiversity of coastal epibenthic macrofauna in Eastern Canadian Arctic: Baseline mapping for management and conservation

“…Similar results were observed in a previous study where epibenthic assemblages on the continental shelf of the Canadian Arctic were most dissimilar near the Mackenzie River (Roy et al, 2014). In Hudson Bay, assemblages showed low biodiversity values and high dissimilarity near the Nelson River Estuary (Pierrejean et al, 2020). A metadata analysis by Cusson et al (2007) also identified salinity as one of the most important variables that explained patterns in benthic biodiversity and assemblage composition in the Canadian Arctic.…”

On the Intermittent Formation of an Ice Bridge (Nunniq) across Roes Welcome Sound, Northwestern Hudson Bay, and Its Use to Local Inuit Hunters

“…Most of the scientific knowledge of RWS and the ice bridge arises indirectly from study of the polynya and associated biological communities. The polynya in RWS is commonly associated with the much larger polynya in western Hudson Bay (Landy et al, 2017;Bruneau et al, 2021), which is known to be highly productive (Barbedo et al, 2020;Pierrejean et al, 2020;Matthes et al, 2021). While there are no published in situ observations of productivity in RWS, strong tidal mixing is believed to generate hotspots of nutrient-rich surface waters particularly at the northern end of the sound (C.J.…”

The Great Whale River ecosystem: ecology of a subarctic river and its receiving waters in coastal Hudson Bay, Canada

“…In a more recent study, Piepenburg et al (2011) compiled observations for the same area, giving a total of 463. Furthermore, Pierrejean et al (2020) found a total of 380 epibenthic taxa identified which represents 71% of the estimated taxa within the Hudson Bay. Finally, Wei et al (2020) identified the Hudson Complex (including James Bay) as one of the six hotspots of diversity among the 13 ecoregions around Canada.…”