Quantifying the Sensitivity of Arctic Marine Mammals to Climate-Induced Habitat Change

Abstract

Abstract. We review seven Arctic and four subarctic marine mammal species, their habitat requirements, and evidence for biological and demographic responses to climate change. We then describe a pan-Arctic quantitative index of species sensitivity to climate change based on population size, geographic range, habitat specificity, diet diversity, migration, site fidelity, sensitivity to changes in sea ice, sensitivity to changes in the trophic web, and maximum population growth potential (R max ). The index suggests three types of sensitivity based on: (1) narrowness of distribution and specialization in feeding, (2) seasonal dependence on ice, and (3) reliance on sea ice as a structure for access to prey and predator avoidance. Based on the index, the hooded seal, the polar bear, and the narwhal appear to be the three most sensitive Arctic marine mammal species, primarily due to reliance on sea ice and specialized feeding. The least sensitive species were the ringed seal and bearded seal, primarily due to large circumpolar distributions, large population sizes, and flexible habitat requirements. The index provides an objective framework for ranking species and focusing future research on the effects of climate change on Arctic marine mammals. Finally, we distinguish between highly sensitive species and good indicator species and discuss regional variation and species-specific ecology that confounds Arctic-wide generalization regarding the effects of climate change.

Marine birds and mammals foraging in the rapidly deglaciating Arctic fjord - numbers, distribution and habitat preferences

“…Marine bird and mammal sensitivity to the loss of sea ice habitat will depend partially on current population sizes and distributions, which will need to be monitored in order to identify species at risk and to employ appropriate conservation strategies (Gaston et al 2005;Laidre et al 2008Laidre et al , 2015Moe et al 2009;Hoegh-Guldberg and Bruno 2010;Lydersen et al 2014). Widely recorded sea ice shrinking and rapid glacier retreating may have different ecological consequences on coastal trophic seabird and mammal foraging communities.…”

Site fidelity of Svalbard polar bears revealed by mark-recapture positions

“…Although polar bears are highly mobile animals (Mauritzen et al 2003a), site fidelity may be an important strategy in a largely heterogeneous and variable sea ice habitat that nonetheless has certain predictable features. Organisms that are strongly tied to a specific location or habitat may be particularly vulnerable in the face of changing resources and habitat availability (Laidre et al 2008). For polar bears, such changes could take the form of large interannual variability in sea ice conditions or long term reduction in summer sea ice cover due to a warming climate (Serreze et al 2007, Moline et al 2008).…”

Drivers and hotspots of extinction risk in marine mammals

“…Predictive, spatially explicit models that can identify which species are most likely to be at risk are urgently needed to address the rapid changes impacting marine mammal biodiversity (13,14). Such quantitative models have been developed for terrestrial mammals (14)(15)(16)(17) and for some marine species (16,18), but are lacking for marine mammals as a whole at the global scale.…”