Cheung, Zeller & Pauly
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Projected species shifts due to climate change in the Canadian Marine Ecoregions The Pew Charitable Trusts Projected species shifts due to climate change in the Canadian Marine Ecoregions A report to Environment Canada prepared by William W. L. Cheung1, Dirk Zeller2, Daniel Pauly2 1 School of Environmental Sciences, University of East Anglia, Norwich, U.K., NR4 7TJ 2 Sea Around Us Project, University of British Columbia, Vancouver, B.C., Canada. V6T1Z4 Table of Contents Abstract ........................................................................................................................................... 2 Introduction ..................................................................................................................................... 3 Methods .......................................................................................................................................... 7 Sample of species and their current distributions ...................................................................... 7 Projecting future distributions under climate change ................................................................ 7 Results ........................................................................................................................................... 11 Discussion ...................................................................................................................................... 18 Conclusion ..................................................................................................................................... 23 References ..................................................................................................................................... 24 Appendix I: Species list .................................................................................................................. 28 Appendix II: Seabirds in Canadian marine ecoregions .................................................................. 41 Abstract ..................................................................................................................................... 41 Part I: Seabird abundance in Canadian ecoregions ................................................................... 41 Part II: Seabird occurrence in Canadian ecoregions .................................................................. 45 1 Cheung, Zeller & Pauly 2011 Abstract Anthropogenic climate change is expected to alter oceanographic conditions in the next decades, and also affect marine biodiversity, notably by affecting the distribution of marine species. Such changes will affect the effectiveness of existing conservation and ecosystem management measures. The Department of Fisheries and Oceans classified the Canadian Exclusive Economic Zones into a system of ‘marine ecoregions’ based on the biophysical characteristics of each area, allowing for region-specific integrated ecosystem management. However, the potential effects of climate change on the biotic characteristics in these ecoregions have so far not been considered. Such information would be important to assess the current and future ecosystem management and conservation planning in these ecoregions. This study aims to assess the potential changes in composition of marine fishes and invertebrates in the Canadian marine ecoregions likely to result from climate change-induced shifts in species distributions. Using a published dynamic bioclimate envelope model, we simulated shifts in distribution of 475 marine fishes and invertebrates that are currently occurring or potentially moving into the marine ecoregions from 2000 to 2050 under the IPCC’s Special Report on Emission Scenario A1B and B1, with an emission pathway of approximately tripling and doubling the atmospheric CO2 concentration, respectively, by 2100 relative to pre-industrial level, which may be considered conservative under current trends of greenhouse gas emissions. The model projected high rates of species gain in the Arctic marine ecoregions, and patches of high rates of species loss occurred throughout the Pacific, Atlantic and Arctic marine ecoregions. The pattern of species turnover (gain + loss relative to current) is dominated by species gain, and the overall patterns of rates of species gain, loss and turnover were similar between the two climate change scenarios, although the magnitude was greater under the SRES A1B scenario. Projections from this study provide spatially-explicit hypotheses of potential effects of climate change on the distributions and biodiversity of marine fishes and invertebrates in the Canadian marine ecoregions by 2050. Biodiversity and ecosystem structure in the Arctic ecoregions are likely to be particular hotspots of climate change impacts. However, the potential ecological risk of climate change impacts at lower latitudes should not be overlooked, given their high number of species and turnover. Although the fine-scale projections remain uncertain, the broad-scale changes projected from the model are likely to be robust. Also included in the present report is a summary of available data on the occurrence and abundance of Canadian seabirds by ecoregion. Although climate change impacts on seabird populations were not modelled here, the data presented by ecoregion can serve as a baseline for future comparison of changes in seabird occurrence and abundance in Canada. The results from this study should be useful in adapting and designing integrated ecosystem management and inform ecoregional planning for networks of marine protected areas. 2 Cheung, Zeller & Pauly 2011 Introduction Fisheries and Oceans Canada (DFO) defines 12 marine ecoregions 1 in the Canadian Exclusive Economic Zone (EEZ), based on the geographical, physical and biological properties of these regions (Figure 1) (Powles et al. 2004; Fisheries and Oceans Canada, 2009). These ecoregions are defined as continental shelf-scale areas that are characterized by regional variations in salinity, marine flora and fauna, and productivity (Harper et al. 1993; Fisheries and Oceans Canada, 2009). An application of the ecoregion classification is to set more region-specific integrated ecosystem management objectives. Thus, there is a need to develop scenarios of how climate change may affect the faunal characteristics in these ecoregions, to assess the need to adjust current integrated ecosystem management objectives. Such need is recognized in a recent review on climate change and adaptation in relation to protected areas in Canada that highlights the importance in developing strategies to consider the changing climate in protected area design (Lemieux et al. 2010), and in recent analyses for terrestrial conservation areas (Lindsay et al. 2011). Figure 1. Canadian marine ecoregions (source: Fisheries and Oceans Canada 2009) 1 The term “ecoregion” is used in the reports documenting the development of this bioregionalization approach (Powles et al. 2004; Fisheries and Oceans Canada, 2009). However, “bioregion” is used in a document for the National Framework for Canada’s Network of Marine Protected Areas (2010). This report follows the original terminology of “ecoregion”. 3 Cheung, Zeller & Pauly 2011 In the National Framework for Canada’s Network of Marine Protected Areas (Fisheries and Oceans Canada 2010), mitigation and adaptation of climate change is stated explicitly as a goal of Marine Protected Areas (MPAs) in Canada. Specifically, the Framework states that, as an environmental benefit, a network of Marine Protected Areas in Canada should contribute to climate change mitigation and adaptation by, amongst various contributions, “provision of refuge for marine species displaced by habitat change (i.e., access to similar habitat in new areas)”. Moreover, ecoregions are adopted as a framework to develop Canada’s MPAs. Anthropogenic climate change is causing alterations in ocean conditions occurring at rates much higher than those that occurred previously under natural conditions (Brierley and Kingsford 2009; Hoegh-Guldberg and Bruno 2010). These changes include physical (e.g., temperature, ocean current patterns) and chemical (e.g., acidity, oxygen content) modifications in oceanographic conditions. In waters adjacent to the Canadian coast, sea surface temperature (SST) generally increased by 0.2 – 2o C between the 1960s (average 1950-1969) and 2000s (1988-2007) (Figure 2). Figure 2. Changes in sea surface temperature (SST) between the 1960s (average 1950-1969) and 2000s (1988-2007), with Canadian marine ecoregions outlined (Rayner et al. 2006; source: Met. Office Hadley Centre; http://hadobs.metoffice.com/hadsst2/data/download.html). 4 Cheung, Zeller & Pauly 2011 Long-term changes in environmental conditions affect distributions of marine species and community structure (e.g., Perry et al. 2005; Hiddink and Hofstede 2007; Dulvy et al. 2008; Nye et al. 2009). Amongst these changes, shifts in distributions of marine fishes and invertebrates are the most commonly observed features that are related to long-term oceanographic changes. For example, off the coast of North America, Nye et al. (2009) showed that 26 (of 36) fish stocks significantly shifted the centres of their biomass distribution poleward and increased their mean depths of occurrence in the Northeast United States continental shelf from 1968 to 2007, due to changes in oceanographic conditions in the region. The invasion of the Humboldt squid (Dosidicus gigas) along the west coast of North America from Central and