Hopp til hovedteksten
Sea and ocean.jpg
Print friendly version

The Barents Sea Ecosystem

Introduction:

The Barents Sea is relatively shallow, with an average depth of 230 m. The oceanographic conditions are strongly affected by the variable inflow from the Norwegian Sea. Recent water temperatures have been the highest levels observed. Pollution levels in the sea are generally very low, but toxic substances, which are transported into the area by currents, are found to accumulate in some top predators such as birds and mammals.

Zooplankton production is high, but variable. A wide variety of benthic organisms are also an integral component of the ecosystem. Important pelagic fish species are capelin, polar cod, herring, and blue whiting. Capelin is a key species in the ecosystem, and undergoes large fluctuations in abundance (0.1–7.0 million tons). These fluctuations largely are due to recruitment failure caused by the predation of strong herring year classes on capelin larvae.

Cod is the most abundant demersal fish species, while haddock, redfish, Greenland halibut and long rough dab are also abundant. The most important marine mammals in the Barents Sea ecosystem are minke whales and harp seals.

Oceanography and Climate

Temperatures in the Barents Sea reached record high levels in February 2008, but anomalies decreased throughout the year, and by autumn temperatures were colder than during the year before. Considering annual means, temperatures were a bit lower and ice cover a bit more extensive than in 2007. This was primarily due to a strongly reduced inflow of Atlantic water relative to previous years.

Water masses in the Barents Sea have been extraordinary warm since 2000. Temperatures during 2008, however, were slightly cooler than during 2007. This is likely due to strong reductions in the transport of Atlantic water into the Barents Sea. Ice cover in the Barents Sea during 2008 was low.

Contaminants

Although wind and ocean currents transport various contaminants into the Barents Sea, levels observed in marine organisms were generally low. The major exception is observed in top predators, such as polar bears, where contaminants from persistent organic pollutants (POPs) aggregate.

IMR routinely carries out monitoring of contaminant levels in the Barents Sea. This includes sampling sea water, sediments, and marine biota. Substances analyzed include: a range of hydrocarbons; POPs; and radio-nuclides. The 2009 report presents examples of radio-nuclide levels found in seawater, sediments, marine biota, and selected POPs (PCB, DDT, HCH, HCB) in cod liver. These studies indicate that contaminant levels in the Barents Sea are generally low.
 

What is an ecosystem?

Ecosystems are often described in terms of energy transfer between levels of the food chain. Behind the energy transfer, however, a life or death struggle between predators and prey is taking place. This struggle, in which every individual tries to make the most of itself by spreading its genes, results in what we call the “interplay of nature”. This interplay is fascinating, both as a field of study and as a management problem.

More about ecosystem

The North Sea and Skagerrak Ecosystems

Barents Sea Facts

Russian name: Barentsevo More
Size: 1.4 million km2 in surface area (approximately four times as large as Norway).
Depth: Average depth = 230 m, Maximum depth = 500 m
Fisheries: Bottom fish such as cod, haddock, Greenland halibut, long rough dab, and redfish. Other commercially important species include: capelin; northern shrimp; minke whales, and harp seals
Special features:

  • Large annual variations in temperature relative to ice coverage
  • A shallow sea which makes up a portion of the continental shelf around the Arctic Ocean
  • Has one of the largest concentrations of sea birds in the world: approximately 20 million individuals distributed across 40 different species
  • Management of living marine resources in the Barents Sea is carried out through collaboration between Norway and Russia.