Limnic Biota Freshwater fish include whitefish, lake trout, and the Arctic char. Freshwater located far from sources of pollutants can become contaminated due to deposition from the atmosphere. The char, a member of the salmon family, spends most of its life in freshwater, venturing into the sea for only a few weeks each summer. Char, an important food source of northern peoples, is exposed to both terrestrial and coastal pollutants. According to Muir et al.
Ice algae are small plants attached to sea ice.
Pollutants then are transferred up the food chain when the algae are consumed. Arctic cod are a major food source for the ringed seal, beluga, narwhal, and some seabirds. Polar bears, at the fifth trophic level, feed mostly on ringed seals. Seals, belugas, narwhals, and polar bears will be influenced by contaminants in the ocean water as well as by contaminants entering the surface ocean from the atmosphere or sea ice melt, and from river runoff in coastal areas. Because they feed at a lower trophic level than seals and other marine mammals, the effects of biomagnification are not as extreme in walrus.