Projected Polar Bear Sea Ice Habitat in the Canadian Arctic Archipelago

Abstract

BackgroundSea ice across the Arctic is declining and altering physical characteristics of marine ecosystems. Polar bears (Ursus maritimus) have been identified as vulnerable to changes in sea ice conditions. We use sea ice projections for the Canadian Arctic Archipelago from 2006 – 2100 to gain insight into the conservation challenges for polar bears with respect to habitat loss using metrics developed from polar bear energetics modeling.Principal FindingsShifts away from multiyear ice to annual ice cover throughout the region, as well as lengthening ice-free periods, may become critical for polar bears before the end of the 21st century with projected warming. Each polar bear population in the Archipelago may undergo 2–5 months of ice-free conditions, where no such conditions exist presently. We identify spatially and temporally explicit ice-free periods that extend beyond what polar bears require for nutritional and reproductive demands.Conclusions/SignificanceUnder business-as-usual climate projections, polar bears may face starvation and reproductive failure across the entire Archipelago by the year 2100.

High genetic variability of vagrant polar bears illustrates importance of population connectivity in fragmented sea ice habitats

“…These observations show that climate-related changes in Arctic habitats can isolate polar bear populations from their conspecifics. Large-scale reductions in summer sea ice extent have been projected, fragmenting the remaining habitat into one or several regions by the late 21st century (Amstrup et al, 2008;Durner et al, 2009;Hamilton et al, 2014). Until that time, polar bears will face intermediate levels of habitat fragmentation (Durner et al, 2009;Peacock et al, 2015), likely with regional differences: Amstrup et al (2008) projected the convergent and Archipelago ecoregions to maintain polar bear habitat the longest, similar to projections by Durner et al (2009), that, however, suggest local deviations from this large-scale pattern.…”

“…Even under scenarios where polar bears eventually may be restricted to one remaining refugium (Amstrup et al, 2008;Durner et al, 2009;Hamilton et al, 2014), preservation of genetic diversity will be an important long-term management goal to safeguard evolutionary potential (Reed & Frankham, 2003). Hence, albeit not surprising from a theoretical standpoint, our results highlight an aspect that has not received much attention in polar bear management , possibly because it is difficult to influence (Crooks & Sanjayan, 2006): that factors contributing to maintained connectivity in fragmented habitats should receive conservation attention (Heller & Zavaleta, 2009).…”

“…Recent sea ice projections for the Canadian Arctic Archipelago have confirmed that its northern-most regions Figure 1 Map of all 19 polar bear subpopulations recognized by the IUCN/SSC Polar Bear Specialist Group , showing the numbers of analyzed samples per subpopulation and marker system (mtDNA|Y chromosome|autosomal microsatellites). Dark and light colors: sampled and unsampled subpopulations/ ecoregions as defined by Amstrup et al (2008) will retain polar bear habitat the longest (Hamilton et al, 2014). Should suitable habitat eventually indeed contract into one single region, range-wide fragmentation would still occur on intermediate time scales (Durner et al, 2009;Peacock et al, 2015).…”

Advection in polar and sub-polar environments: Impacts on high latitude marine ecosystems

“…With reductions in sea ice, the sea-ice habitat will shrink substantially and the numbers of both polar bears and ice-dependent seals are expected to decline (Loeng et al, 2005;Durner et al, 2009;Rode et al, 2014;Laidre et al, 2015). Polar bears may have to retreat to land, which will likely lead to increased starvation for lack of appropriate food and declines in abundance (Hamilton et al, 2014).…”

Arctic 2.0: What happens after all the ice goes?

“…Research 6 suggests that many will starve if the ice-free season gets too long in much of the Arctic. "Basically, you can write off most of the southern populations, " says Andrew Derocher, a biologist at the University of Alberta in Edmonton, Canada.…”