Effects of Climate Change on Arctic Marine Mammals
30.04.2008 - Other
Published in the Ecological Applications of the Ecological Society of America, a new study entitled "Arctic Marine Mammals and Climate Change" estimates hooded seals, polar bears and narwhals to be the most at-risk mammals of the Arctic.
Using nine different parameters, including population size, habitat uniqueness, diet diversity and ability to cope with sea ice change, scientists estimated the effects of climate change on the health of 11 sea mammals living in the Arctic year-round. In order to quantify the sensitivity of Arctic marine mammals to habitat change, the study developed an index of sensitivity based on:
- narrowness of distribution and specialisation of feeding habits
- seasonal dependence on ice
- reliance on sea ice as a structure for access to prey or predator avoidance
The vulnerability of the three most sensitive Arctic marine mammal species (hooded seal, polar bear and narwhal) is essentially due to their reliance on sea ice and to their specialised feeding habits. Based on the above index, scientists also concluded that the two least sensitive species were the ringed seal and bearded seal, due to their large circumpolar distributions, large population sizes and flexible habitat requirements.
Although the polar bear has become an icon of global warming vulnerability, the narwhal, a whale with a long spiral tusk having inspired the myth of the unicorn, is just as vulnerable to the changing climate, and even more so according to Stanford University biologist Terry Root, who was not part of this study. Polar bears live all over the circumpolar Arctic. This means their habitat is unlikely to melt all at once and gives them time to potentially shift their habitat range.
Having evolved specifically to live within small cracks of the Arctic, where there is 99 percent heavy ice, its survival is at stake as the Arctic sea ice melts and lets predators, such as the killer whale, inside the narwhal's habitat. Furthermore, the species' restricted migration route and food availability also puts the species at high risk should anything happen to their food supply.
