Because marine mammals are large, homeothermic animals, they can cope with significant ranges of water and air temperatures. So, marine mammals residing in, and those that currently migrate seasonally into, the Barents Region are not likely to be directly physiologically challenged by the predicted increases in air and water temperatures. Physical changes in the marine environment are likely to have impacts first and foremost on the animals that depend on sea-ice (e.g. Kovacs and Lydersen, 2008; Kovacs et al., 2009).
Changes in the geographic extent of sea ice and in the seasonal period of coverage of the sea ice are likely to impact on the distribution and abundance of most, if not all ice-dependent marine mammal species in the Barents Region, including polar bears, ringed seals, bearded seals, harp and hooded seals, bowhead whales, narwhal and belugas. Polar bears depend on sea ice as a hunting platform for much of the year to access ice-dependent seals, which are their primary prey. The ice dependent seals depend on sea ice as a resting platform and a breeding substrate. The cetacean link is somewhat less direct, but, it is thought that the three resident arctic cetaceans feed on ice-associated prey and also benefit from sea-ice providing protection from predators, in particular killer whales. Sea ice coverage is likely to affect range expansions for pelagic marine mammal species that migrate into the region from temperate areas on a seasonal basis.