Global Outlook for Ice & Snow

Weddell seals. Photo:MichaelHambrey,Swiss­ Educ (www.swisseduc.ch) and Glaciers online (www.glaciers- online.net)

increased predation rates from killer whales (Orcas); increased risks from disease and parasites; greater potential for exposure to increased pollution loads due to long range transport of pollutants such as PCBs and mercury; and, impacts via increased human traffic and development in previously inaccessible, ice-covered areas. Predicted changes in sea ice in combination with oth- er climate change impacts on Arctic ecosystems, and resultant changes in human activity patterns, will un- doubtedly affect the abundance and distribution pat- terns of species within polar marine mammal com- munities. The full-time, ice-associated residents of the Arctic and Antarctic are likely going to be negatively im- pacted, while the seasonal and summer migrants will likely increase in abundance and extend their ranges in a warmer Arctic that is ice-free in summer.

Seals Many polar seal species depend on sea ice as a birthing, moulting and resting platform, and some seals also do much of their foraging on ice-associated prey 64 , 68 – 72 . Ross seals, crabeater seals and leopard seals in the Antarctic and harp seals, hooded seals, ribbon seals, and spotted seals in the Arctic all breed in drifting pack-ice. Arctic bearded seals breed in areas of shal- low water along coast-lines on small pieces of ice that break away from the annually-formed land-fast ice in the late spring. Ringed seals in the Arctic and Weddell seals in the Antarctic breed on land-fast ice. These two species occupy extensive areas of ice that form along coastlines because they are able to maintain breathing holes, even in sea ice that can reach 1 to 2 metres in thickness (see box on ringed seals). All of the ice-as- sociated seals require temporally predictable, extensive areas of sea ice. Current projections suggested for the

CHAPTER 5

ICE IN THE SEA

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