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

Chih‐Lin Wei,Ricardo A Scrosati,Peter Lawton,Heike Link,Tanya Brown,Philippe Archambault,Evan Edinger,Brenda J Burd,Paul V R Snelgrove,Kent Gilkinson,Renald Belley,Patricia A Ramey‐Balci,Ellen Kenchington,Mathieu Cusson,K C Burns

doi:10.1111/ddi.13013

Abstract

AbstractAimWe examined the relationships between bathymetry, latitude and energy and the diversity of marine benthic invertebrates across wide environmental ranges of Canada's three oceans.LocationCanadian Pacific, Arctic and Atlantic Oceans from the intertidal zone to upper bathyal depths, encompassing 13 marine ecoregions.MethodsWe 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.ResultsThe 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 hump‐shaped 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 ConclusionsWe 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, 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.

Highlights

Canada has the longest coastline of any country in the world (243,791 km), encompassing more territorial waters (2,687,667 km2 within 12 nautical miles) than all European countries and the United States of America combined
As a signatory to the United Nations (UN) Convention on Biological Diversity (CBD) and under its own Oceans Act (1996), Canada is responsible for the “management of estuarine, coastal and marine ecosystems” including implementation of marine protected areas (MPAs) for “the conservation and protection of marine areas of high biodiversity or biological productivity.”
We found no statistical relationship between latitude and any of the three species diversity indices for either of the top three best linear mixed-effects (LME) models (Table 1a) or the average model (Table 2)

Summary

| INTRODUCTION

Canada has the longest coastline of any country in the world (243,791 km), encompassing more territorial waters (2,687,667 km within 12 nautical miles) than all European countries and the United States of America combined. We extended the previous effort (Archambault et al, 2010) by using additional quantitative, taxonomically standardized and spatially/temporally referenced community data to infer the underlying mechanism(s) driving seafloor biodiversity patterns This more comprehensive database for Canada's three oceans of benthic biodiversity (TOBB database) provides a more robust baseline from which to evaluate the effectiveness of ecosystem-based management approaches, including the establishment of conservation goals and monitoring programmes for MPA networks and in assessing concomitant impacts of economic development and climate changes on benthic biodiversity within Canada's territorial waters

| METHODS

Findings

| DISCUSSION