Biodiversity of benthic assemblages on the Arctic continental shelf: historical data from Canada

This study describes patterns of abundance, diversity, and assemblages of benthic macrofauna within the Canadian Arctic Archipelago. A review of data reports and the published literature yielded 219 stations and 947 taxa from 7 sources in various regions of the Canadian Arctic Archipelago (i.e. Beaufort Sea and Mackenzie Shelf, Victoria Island, Hudson and James Bays, Frobisher Bay, Ungava Bay, and Southern Davis Strait). In general, we observed that eastern regions of the Canadian Arctic Archipelago showed greater values of species richness (or a diversity) than the western and central regions, whereas no specific patterns were observed for Shannon-Wiener's diversity (H') and Pielou's evenness (J') indices. The Beaufort Sea and Mackenzie Shelf region exhibited high values of taxonomic distinctness (Delta(+)), whereas Hudson Bay showed low values. However, the Hudson Bay region showed high values of turnover (beta(W)) diversity. A non-metric multi-dimensional scaling plot of similarity (Bray-Curtis index) and analysis of similarity revealed that species composition differed among regions, even those located in close proximity to one another. These investigations were conducted at different levels of taxonomic resolution (Species, Order, Class and Phyla) and the results demonstrated that most patterns were maintained up to the Order and Class level. A relatively small number of taxa, mainly annelids, were responsible for most of the dissimilarity among regions. Bottom salinity and temperature were the most important environmental variables (among depth of site, bottom temperature, salinity, physical and chemical sediment characteristics) for determining these assemblage patterns. Multiple regression analyses also demonstrated that variance in species richness and diversity (H') was best explained by variance in salinity (55 and 43% respectively). The analysis of a time series from Frobisher Bay revealed that the temporal (mo/yr-scale) variability of assemblages was of the same order as the spatial (km-scale) variability among sites.