Ever since the early evidence of sea-ice melting due to climate change, scientists have been predicting how it will affect polar wildlife.
Until recently hard evidence of wildlife responses due to environmental change has been frustratingly hard to come by. However, there is now empirical evidence of changes in both movement patterns and foraging behaviour in the arctic ringed seal (Ursus maritimus) due to melting sea ice.
Ringed seals are both common and widespread, occupying an arctic and sub-arctic distribution, but don’t let this lull you into a false sense of security. Ringed seals are a keystone species, meaning they play numerous key roles within their ecosystem and are the species that holds the arctic food web together. Their circumpolar distribution and high numbers mean that a number of other animals rely on them to survive. They are the primary source of food for polar bears, are a valuable resource to native human populations and have a strong controlling effect on fish populations. Arctic foxes, killer whales, Greenland sharks, glaucous gulls and Atlantic walruses also rely on them for food throughout the the year.
The changes in seal activity were recorded after a major sea ice collapse in Svalbard, Norway, which shifted the summer position of the marginal ice zone northward, to the deep Arctic Ocean Basin. Since this change, young ringed seals swam greater distances, showed less area restricted behaviour, dived for longer periods, had shorter intervals between dives, rested less on sea ice and did less diving beneath sea ice. This all means that they have to expend far more energy to find food which can have a huge number of knock-on effects, such as reduced reproductive potential.
Ringed seals rely hugely on the quickly melting sea ice for much of their lives. They find and use sea ice for giving birth on, for resting, and for moulting. In years on low sea ice, their reproductive success is greatly reduced.
The fact that they play such a vital role within their ecosystem means that many other species will surely be affected by the seals’ changing behaviour. Polar bears, for example will have much more difficulty trying to find and catch the seals now that they are foraging less under sea ice. The increased rate of climate change will continue to have a greater detrimental effects on the seals. It will continue to effect the arctic ecosystems right at its very centre. This once again highlights the urgent need for us to take action against global warming. It is affecting our wildlife directly, right now. It is time we did more to stop it.
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