This awakening triggers activity throughout the food chain from zooplankton up to fish, birds and marine mammals, from the first days of spring till the late-summer onset of the Arctic night. In the NSR seas, polar bear, walrus, seal and whale famously occupy the apex of the food chain.
Data on marine life in the NSR indicate substantial variance according to the area investigated, and from season to season and year to year. Moreover, the distribution of habitats, breeding patterns and characteristics of the flora and fauna in this region remains poorly understood; many questions will simply have to wait for further survey efforts. For the present purposes, we will select three species of mammal and provide an overview of the distribution of their habitats.
The polar bear population is estimated at 20,000-30,000, and their active range is confined to a small area. Living close to the ice fields, their movement mirrors the seasonal expansion and contraction of the Arctic ice. When the ice melts, polar bears live on the nearby coasts. In the NSR region, many polar bears can be seen in March throughout a wide swath of territory from Novaya Zemlya through the Kara Sea coast, the east coast of Severnaya Zemlya and the north shores of the Novosibirskiye Islands to Wrangel Island and the Chukchi Sea. In August they are concentrated in Severnaya Zemlya and Wrangel Island.
About 250,000 walrus are estimated to exist, living mostly in a band from the Chukchi Sea to the Bering Sea. In the NSR region, some 5,000 inhabit the Laptev Sea and near the north coast of the Novosibirskiye Islands.
Estimates of the worldwide seal population run into the millions, though their number in the Arctic is not known with certainty. Seals, generally found in the entire NSR region, tend to cluster near the coast during the summer and move to the rim of fast ice during the winter. When the seas are covered in ice, the seals breathe through crevices, leads and fractures; they are also known to maintain their own breathing holes even in the growing sea ice. With one breath a seal can typically stay underwater for seven to eight minutes, and sometimes as long as 20 minutes. If the Arctic Ocean were ever polluted by an oil spill, the seal population would be among the most seriously affected of all Arctic fauna.
Many gaps in knowledge and points of controversy remain regarding surveys and data on the Arctic ecosystem and its food chain from phytoplankton to the mammals at its apex. More detailed studies and forecasts are needed at this point for use in reliable environmental impact assessment on the implementation of NSR shipping.