Seafloor biodiversity of Canada's three oceans: Patterns, hotspots and potential drivers

Abstract

Aim:We examined the relationships between bathymetry, latitude and energy and the diversity of marine benthic invertebrates across wide environmental ranges of Canada's three oceans.Location: Canadian Pacific, Arctic and Atlantic Oceans from the intertidal zone to upper bathyal depths, encompassing 13 marine ecoregions. Methods:We compiled 35 benthic datasets that encompass 3,337 taxa (70% identified to species and 21% to genus) from 13,172 samples spanning 6,117 sites.Partitioning the analyses by different gear types, ecoregions or sites, we used Hill numbers to examine spatial patterns in α-diversity. We used resampling and extrapolation to standardized sampling effort and examined the effects of depth, latitude, chemical energy (export particulate organic carbon [POC] flux), thermal energy (bottom temperature) and seasonality of primary production on the benthic biodiversity. Results:The Canadian Arctic harboured the highest benthic diversity (e.g. epifauna and common and dominant infauna species), whereas the lowest diversity was found in the Atlantic. The Puget Trough (Pacific), Beaufort Sea, Arctic Archipelago, Hudson Bay, Northern Labrador and Southern Grand Bank (Atlantic) were the "hotspots" of diversity among the ecoregions. The infauna and epifauna both exhibited humpshaped diversity-depth relationships, with peak diversity near shelf breaks; latitude (positively) predicted infaunal diversity, albeit weakly. Food supply, as inferred from primary production and depth, was more important than thermal energy in controlling diversity patterns. Limitations with respect to calculating POC flux in coastal (e.g. terrestrial runoff) and ice-covered regions or biological interactions may explain the negative POC flux-infaunal diversity relationship. Main Conclusions: We show previously unreported diversity hotspots in the Canadian Arctic and in other ecoregions. Our analyses reveal potential controlling mechanisms of large-scale benthic biodiversity patterns in Canada's three oceans, | 227 WEI Et al.G7H 2B1, Canada.Editor: K. C. Burns which are inconsistent with the prevailing view of seafloor energy-diversity relationships. These results provide insightful information for conservation that can help to implement further MPA networks. K E Y W O R D Salpha diversity, Arctic Ocean, Atlantic Ocean, benthic invertebrates, biodiversity conservation, energy-diversity relationship, marine protected area, Pacific Ocean, productivity-diversity relationship, seafloor biodiversity

Spatial distribution of epifaunal communities in the Hudson Bay system

“…However, little is known about the environmental drivers of benthic communities in the HBS compared to other Arctic regions, such as the Canadian Arctic Archipelago. To date, most of our knowledge on benthic communities comes from relatively old or low spatial resolution diversity data and is based mainly on grab sampling Wacasey, 1989a, 1989b;Cusson et al, 2007;Kenchington et al, 2011;Piepenburg et al, 2011;Jørgensen et al, 2016;Roy and Gagnon, 2016;Pierrejean et al, 2019;Wei et al, 2019). Most of these studies focused on infaunal organisms, and none related benthic community structure to environmental drivers.…”

Description and Spatial Modelling of Benthic Communities Distribution in the Canadian Arctic Archipelago

“…Additionnaly, sampling effort should be increased in the whole area to have a maximal validation resolution. This was suggested by Wei et al (2020), where future research activities must fill these knowledge gaps to improve the accuracy and resolution of pattern predictions. Furthermore, we must be careful with predictions of habitat suitability for communities around coastal areas, since we do not actually have any infauna or epifauna data shallower than 34 meters.…”

The MALINA oceanographic expedition: how do changes in ice cover, permafrost and UV radiation impact biodiversity and biogeochemical fluxes in the Arctic Ocean?

“…Because the organic matter delivered by the river is highly humic and colored, the absorption at 254 nm was approximately 15 times higher at the southern shelf stations for both transects compared to the northern stations (620 and 320). Likewise, the specific UV absorbance of dissolved organic carbon at 254 nm (SUVA 254 ), a metric commonly used as a proxy for assessing both chemical (Weishaar et al, 2003;Westerhoff et al, 2004) and biological reactivity (Berggren et al, 2009;Asmala et al, 2013) of the dissolved organic matter (DOM) pool in natural aquatic ecosystems, decreased rapidly along the south-north gradient in both transects 600 and 300 (Fig. 7c).…”