Laptev Sea
Regional setting of the Laptev Sea. Source: Norman Einstein
The Laptev Sea is a saline water body, lodged between the Kara Sea and East Siberian Sea. The chief land boundary of this marginal sea of the Arctic Ocean is the Siberian region of Russia. Salinity variations throughout the Laptev Basin are extreme, with lower surface salinities occurring at the south, due to large inputs from freshwater influx from Siberia. Diurnal tidal fluctuations are relatively small, typically less than 50 centimetres.
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A large ice sheet begins formation at the north of the Laptev Basin as early as September, and melting of this two meter thick layer does not commence until the May/June time period. The sheet becomes a very large continuous formation, with some intervening polynyas (warmer pools within the greater expanse of ice)
Hydrography
Along the entire Russian coastline sea level decline continues deriving from Isostatic Rebound, the process wherein land surfaces rise when pressure from prior overlying glaciers is relieved during interglacials such as the present era. In this coastal region the decline of sea level due to the post glacial rebound greatly exceeds the small rise in sea level over the last 170 years due to glacial melt.
Besides having low diurnal tidal variation, the seasonal variation in Laptev sea level is also minimal; this variation during the entire year is less than 40 centimetres. Freshwater feeds to the Laptev Sea are chiefly constituted by riverine discharge; approximately 515km3per annum arrives via the Lena River. Other chief influxes are from the Khatanga River (above 100km3), Olenyok River (35km3), Yana River (about 30km3) and Anabar River (20km3). All other smaller river inflows amount to approximately 20km3.
Water temperatures are quite low, both at the surface and for the deep water, typically staying at subzero Celsius temperatures year around; however, there is a warmer middle layer, fed from the Atlantic, which stays sandwiched between the surface and deep cold layers.
Marine ecology
See main article: Laptev Sea large marine ecosystem
Pinnipeds, seabirds, walruses, Arctic foxes and Polar bears make up the varied, rich fauna of this region, especially in the summer months when they can be found at the edge of the drift ice and on the backshore. The Laptev Sea large marine ecosystem has many commercial valuable species of fish. Target stocks are generally concentrated in sub-estuarial zones
The Laptev Basin is sensitive to environmental change. Climate, particularly temperature, is the primary force driving the ecosystem of this basin. Climatic conditions have a major influence on the distribution, growth and recruitment of the Laptev’s fish species and other marine organisms. The Laptev is characterized by perennial ice cover over extensive regions, water exchange with the Arctic Ocean, and freshwater input from the Yana, Lena, Olenek, Anabar, Khatanga and Kotuy Rivers. Ice cover for a major portion of the year prevents sunlight from penetrating deep into the water column and thus limits ecological productivity for several months. Increased production occurs after the ice melts in the summer months. The Laptev Sea large marine ecosystem is considered a Class III, low productivity (<150 grams of Carbon per square meter per year) ecosystem .
References
- V.Y.Alexandrov, T.Martin, J.Kolatschek, H.Eicken, M.Kreyscher, A.P.Makshtas. 2000. Sea ice circulation in the Laptev Sea and ice export to the Arctic Ocean: Results from satellite remote sensing and numerical modeling. Journal of Geophysical Research 105 (C5): 17143–17159
- International Hydrographic Organization. 1953. Limits of Oceans and Seas, 3rd edition.
- A.D.Dobrovolskyi and B.S.Zalogin. 1982. Seas of USSR: Laptev Sea, Moscow University
