Kara Sea ecosystem

• Category: Marine and Oceanic Biomes.
• Geographic Location: Arctic Ocean.
• Summary: A low-productivity ecosystem covered by seasonal ice for much of the year, the Kara Sea is characterized by a variety of habitats.

A marginal sea in the Arctic Ocean, the Kara Sea is north of the Siberian coast, with the Barents Sea to its west and the Laptev Sea to its east. The Kara Strait and the Novaya Zemlya archipelago separate it from the Barents Sea, while the Severnaya Zemlya archipelago divides the sea from the Laptev. Though the Barents is warmed by Atlantic currents, the Kara Sea has more in common with the Laptev. Very cold year round, it is frozen about nine months of the year, and has low salinity that varies seasonally with the freshwater inputs from the Ob, Yenisei, Pyasina, and Taimyra rivers. The water exchange with the Arctic Ocean and periodic river inputs contribute to providing a range of marine habitats, despite the ecosystem’s low productivity.

Much of the Kara Sea lies on the Arctic shelf, and while it is deeper than the East Siberian Sea or much of the Laptev, the average depth is still only 328 feet (100 meters). This has contributed to the prevalence of ice cover, and until modern ice-breaking technology, the sea was considered to be non-navigable except in summer.

While the other marginal seas of the Arctic have few islands except along their coasts, the Kara is an exception. Its islands include Uedineniya, or Lonely Island; Vize; and Voronina, which is located in the open sea. The Nordenskjold Archipelago consists of more than 90 islands, including five subgroups.

Biodiversity

Unlike the Laptev, the Kara is an important fishing ground despite the sea’s mostly ice-bound condition, but it is not as commercially developed as the warmer Barents. Common fish include flatfish, smelt, scorpionfish, and Arctic cod.

The inland tundra serves as breeding grounds and nesting colonies for as many as 16 million migrating seabirds. Local bird species include the little auk (Alle alle), barnacle goose (Branta leucopsis), pink-footed goose (Answer brachyrhynchus), Sabine’s gull (Xema sabini), and white-billed diver (Gavia adamsii). Also, 16 whale and seven seal species, respectively, have been recorded in the Kara. Polar bear, walrus, and narwhal also are common in great numbers; they use the coastal areas as breeding grounds. Polar bears roam the frozen edges of the sea, foraging, fishing, and hunting seals.

Ice algal activity accounts for 50 percent of total primary productivity in the Kara Sea, as in the Laptev and East Siberian, and is depended on by other Arctic biomes through sedimentation and life cycles. Especially abundant are protozoan and metazoan ice meiofauna, such as nematodes, crustaceans, rotifers (wheel animals), and turbellarians (flatworms).

The larvae and juveniles of benthic, or bottom-dwelling, animals such as mollusks and polychaetes (a class of marine worms) migrate into the ice matrix to feed on ice algae in Kara’s shallow waters, forming a sophisticated and diverse ice invertebrate community.

Some species of shrimplike crustaceans here are nearly endemic (found nowhere else) to the Arctic marginal seas; they live on the underside of ice floes. They occur seasonally and transport particulate organic matter from sea ice to the water column through their feces. Pelagic fish such as the Arctic cod feed under and near sea ice, depending on ice crustaceans and other small fauna. The decreased sea ice due to warming waters threatens these communities and the other elements of the food chain that depend upon it. This is an aspect of climate change that may also open the door to the large-scale encroachment by exotic species here.

Environmental Threats

Whitefish have declined significantly, especially in the west, where numbers dropped by half from the 1980s to the 1990s. Overfishing is a growing concern, and coastal dumping of radioactive material from nuclear power plants and submarines has put millions of fish, shellfish, starfish, and marine mammals in jeopardy. Unlike the Laptev and East Siberian Seas, the Kara Sea is fairly close to the Russian industrial centers, which are the most polluting in the Arctic region. From the 1960s to the 1990s, the Kara Sea was a dumping ground for high-level nuclear wastes from nuclear-powered submarines as a routine part of their refueling operations. Nuclear reactors suffering malfunctions also were discarded in the sea. At least 16 reactors (10 power-generation and six submarine reactors) were dumped on the sea bottom, and there is a good chance that more have gone unreported.

The petroleum and natural gas reserves detected and surveyed here present an extension of the West Siberian oil basin, but they have not been developed. The reserves are believed to be vast enough that development is inevitable as oil demand increases. If peak-oil models prove valid, the development will have a major impact on terrestrial and marine ecosystems here and in adjoining seas. While the area is not developed, projects are underway to develop the area. In 2023, the Gazprom Nedra company completed the construction of a prospecting and appraisal well in the sea. The platform was demobilized that same year to a winter mooring site.

As one of the seas on the Arctic shelf, the Kara is expected to be among the Earth’s first areas to feel the effects of climate change. Warming surface temperatures, changes in the mixed layer, and reduction of sea ice will greatly impact the distribution and timing of ice-related pelagic production and the deposition of carbon. In time, these changes will affect the deeper waters of the Arctic Ocean since they receive their carbon from the shelf.

Warmer waters and a reduction of ice will affect the life cycle of plankton, microflora, and microfauna, which will have a cascading effect on higher trophic levels such as seabirds and marine mammals. Eventually, climate change will shake up the whole ecosystem. Migration will be affected, too, as longer summers or more plentiful polynyas (expanses of free water surrounded by ice) will encourage more wildlife to remain in place to feed, rather than traveling south.

Protected Areas

The region’s Franz-Josef-Land nature reserve is one of the largest marine protected areas in the Northern Hemisphere, and home to diverse habitats. The former Soviet Union had restricted the rights of indigenous peoples to use much of their traditional reindeer-pasturing land around the coasts here, while allowing nonindigenous arrivals to exploit the area for oil and mineral reserves. The collapse of the Soviet Union, however, has made it more difficult for the indigenous people to collectivize and strengthen their political autonomy. Without controls implemented by the former Soviet Union, the chief factor preventing environmental deterioration of the Kara Sea region is its remoteness.

Bibliography

Akulichev, Viktor Anatol’evich. Far Eastern Seas of Russia. Moscow: Nauka Press, 2007.

Butler, William. Northeast Arctic Passage. New York: Sijthoff & Noordhoff, 1978.

“Gazprom Nedra has Completed the Construction of a Prospecting and Appraisal Well in the Kara Sea.” ROGTEC, 3 Nov. 2023, www.rogtecmagazine.com/gazprom-nedra-has-completed-the-construction-of-a-prospecting-and-appraisal-well-in-the-kara-sea/. Accessed 2 Dec. 2024.

Heileman, S. and I. Belkin. Large Marine Ecosystems of the World: Kara Sea. Washington, DC: National Oceanic and Atmospheric Administration, 2009.

Nilsen, Thomas. "Expedition Finds Reactors 56 Years After Dumping." The Barents Observer, 2 Sept. 2021, thebarentsobserver.com/en/nuclear-safety/2021/09/expedition-found-exact-location-dumped-reactor. Accessed 2 Dec. 2024.