The Seabed That Feeds the Barents Sea
Invasive Paralithodes camtschaticus (red king crab) on the seafloor of Dalnezelenetsky Bay. Source: Wikimedia Commons, Yury Zuyev, NOAA, Public Domain.
In our previous post, we discussed plankton communities—organisms that live in the water column and respond to changes in the surface layers, such as rising air temperatures and shifts in the ice regime of Arctic seas. Now, it is time to talk about the benthos, or the inhabitants of the seabed.
THE CHANGING BARENTS SEASeries · 2 posts
- Atlantification Reshapes the Barents and Kara Seas
- The Seabed That Feeds the Barents Sea
Like plankton, the benthos forms the foundation of the marine food web. Many commercially valuable species—such as cod and red king crab—feed on benthic organisms, including mollusks, worms, and other bottom-dwelling animals. Walruses, one of the iconic symbols of the Arctic, also feed on the benthos. All these species compete for food resources, and their well-being depends on the health of benthic ecosystems.
The Barents Sea is one of the world’s most important regions for cod fishing. It is home to a population of Atlantic cod considered to be the largest in the world (as the cod population near Newfoundland was almost entirely wiped out). Cod are not only delicious but also grow to be quite large—some individuals reach up to 1.5 meters in length! Among the fish in the Barents Sea, cod occupy the top of the food chain. While juveniles feed primarily on zooplankton, adults consume capelin, young herring, and benthic organisms. Capelin are particularly important, though their numbers fluctuate significantly from year to year. When capelin are abundant, cod grow rapidly and build up fat reserves. When capelin are scarce, cod switch to other prey—sometimes even consuming the young of their own species. Consequently, fluctuations in the cod population affect the state of the entire Barents Sea ecosystem.
Invasive crab species also inhabit the Barents Sea. Between 1961 and 1969, a special program was implemented to introduce red king crabs from the Far East into the Barents Sea, primarily in the area of the Kola Bay. The goal of this experiment was to establish a new, valuable commercial resource in the European North of the USSR. Over the course of the relocation effort, several thousand adult crabs, ten thousand juveniles, and 1.5 million larvae were released into the sea. The introduced crabs successfully adapted and began to reproduce.
The red king crab (Paralithodes camtschaticus), also called Kamchatka crab or Alaskan king crab, showing mouth parts. Kodiak Island. Source: iStock, Gerald Corsi.
Subsequently, the red king crab spread along the coast of the Kola Peninsula, entered Norwegian waters, and expanded eastward across the Barents Sea. Another invasive crab species, the snow crab (Chionoecetes opilio), was first discovered in the Barents Sea in 1996.
The snow crab, Chionoecetes opilio. Source: iNaturalist, Georgy Vinogradov, CC BY 4.0.
It was initially hypothesized that its larvae had arrived accidentally via the ballast water of ships traveling from the North Atlantic, where the species is found off the coasts of Canada and Greenland. A more recent theory suggests that these crabs may have reached the Barents Sea from the northern Pacific Ocean.
Despite their enormous size—reaching up to 3 meters in length and weighing as much as 1.5 tons—and their formidable appearance (featuring impressive, saber-toothed-tiger-like tusks), walruses feed primarily on small bottom-dwelling animals.
They dive to depths of several tens of meters and use their sensitive whiskers (vibrissae) to forage along the seabed for mollusks. They employ their giant tusks to dig the mollusks out of the silt, subsequently sucking the soft tissue from their shells. Consequently, walruses prefer to inhabit shallow marine areas, where there is an abundant food supply on the seafloor, as well as suitable locations for resting on the shore or on sea ice. The future of walruses in the Barents Sea will depend not only on the state of the sea ice but also on the productivity of benthic (seafloor) ecosystems. As apex predators, walruses serve as a vital indicator of the health of Arctic seas, helping to assess the consequences of warming for the entire marine ecosystem.
Conditions on the seafloor change much more slowly than those at the surface, as atmospheric shifts occur far more rapidly than changes within the ocean. Fluctuations in air temperature, wind, solar radiation, and the formation or melting of ice primarily affect the sea’s surface layer; the impact of these changes only reaches the seabed after a time lag. Consequently, benthic communities are accustomed to highly stable environmental conditions. Nevertheless, contemporary climate change is eventually reaching them as well. Investigating these processes is one of the objectives of the Floating University expedition.
