Spatial distribution of epifaunal communities in the Hudson Bay system

Marie Pierrejean,Philippe Archambault,Frédéric Maps,David G Babb,Christian Nozais

doi:10.1525/elementa.00044

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.

Highlights

The spatial distribution of benthic community structure is predominantly related to variables such as water depth, salinity, substrate type, and food supply (Piepenburg, 2005; Grebmeier et al, 2006a; Cusson et al, 2007; Witman et al, 2008; Roy et al, 2014)
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
Unlike previous studies, which have concluded that the Hudson Bay (HB) was a less productive ecosystem than other Arctic regions, our results demonstrate that present values of epibenthic characteristics are comparable to other Arctic regions (Grebmeier et al, 2006a; Piepenburg et al, 2011; Roy et al, 2015)

Summary

Introduction

The spatial distribution of benthic community structure is predominantly related to variables such as water depth, salinity, substrate type, and food supply (Piepenburg, 2005; Grebmeier et al, 2006a; Cusson et al, 2007; Witman et al, 2008; Roy et al, 2014). In Arctic waters, sea ice cover is an additional variable that influences primary production and the efficiency of pelagic-benthic coupling (Piepenburg, 2005; Renaud et al, 2007; Boetius et al, 2013; Roy et al, 2015; Olivier et al, 2020). ArcticNet, Québec Océan, Takuvik, Département de biologie, Université Laval, Québec, Canada. Arctic marine ecosystems are currently responding to climate-induced changes to environmental and ecological variables, such as changing precipitation, river discharge, sea ice cover, and marine biota (Déry et al, 2016; Bring et al, 2017; Osborne et al, 2018; Derksen et al, 2019). Arctic regions is still limited, preventing accurate predictions of how species richness and distribution will respond to climate change (Piepenburg et al, 2011). The HBS sea ice season has already grown shorter (Andrews et al, 2018) and is Downloaded from http://online.ucpress.edu/elementa/article-pdf/8/1/00044/465302/elementa.00044.pdf by guest on 18 January 2022

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