Biotic components - Articles

Microbes. Photo: U:S. Department of health and human services

Microbes

Expected increased temperatures related to climate change will likely affect growth rates and other biological processes.  This may cause competitive conditions to change between cold-adapted bacteria and bacteria adapted to warmer waters (Børsheim and Drinkwater 2014). Consequently, the species composition of bacterial communities may also change as temperatures change.

Plankton sampling. Photo: Norwegian Polar Institute

Phytoplankton

Among phytoplankton species in the Barents Sea, there tends to be large inter-annual and geographical variation in patterns of distribution and abundance.  However, the overall annual pattern of succession is quite stable, despite variability between years for abiotic factors such as temperature.  Formation of the spring bloom varies between years, and is largely determined by the degree of stabilization in upper layers of the water column.

Jellyfish

Zooplankton

Estimated abundance of large gelatinous zooplankton was higher in 2013 than in 2012. The center of distribution and highest abundance was located in the central to south-western part of the Barents Sea in 2013; a quite typical pattern consistent with observations from 2008 until present. During this period, occurrence of “jellyfish” has overlapped significantly with regions of low mesozooplankton biomass.

Calanus glaciale. Photo: Norsk Polarinstitutt

Zooplankton

Samples were collected by PINRO in the Barents Sea during the 2011-2012 autumn bottom-trawl survey to estimate pre-winter euphausiid assemblages.   During 2012, further decrease in the abundance of euphausiids was recorded in some areas; at the same time their abundance increased in other areas.  However, euphausiid abundance generally remained above the long-term mean in all areas of the Barents Sea (Figure 4.3.7).

Calanus glaciale - nauplius stages N2 to N4. Photo: Norwegian Polar Institute

Zooplankton

Horizontal distribution of mesozooplankton biomass in 2013 is shown in Figure 4.3.2. Patterns of distribution have been similar between years, even though the area of survey coverage may vary. Particularly low biomass was observed in central parts of the Barents Sea. In westernmost areas southeast of Bear Island, slightly higher zooplankton biomass was observed — somewhat similar to what was observed in 2009 and 2010. Another area with high mesozooplankton biomass was observed in the Russian sector of the Barents Sea, west of Novaja Zemlja and east of 25°E.

Gammarus wilkitzkii. Photo: Norwegian Polar Institute

Benthos

More than 3,050 invertebrates species inhabit the Barents Sea benthos (Sirenko, 2001) and boreal-arctic species dominate in terms of biomass. Benthic areas with low abundance (less than 1,000 individuals/ m2) and biomass (less than 10-25 g/m2) are usually restricted to bottom depressions such as the western deep-water areas in the Bear Island Channel (Bjørnøyrenna) and Hopen Deep (Hopendypet) (Figure 4.3.11), deep-water areas between Franz Josef Land and shallow waters of the Novaya Zemlya Bank and deep-water areas in the Eastern Basin (Øst bassenget sør, Figure 4.3.11).

Trawling activity. Photo: Norwegian Polar Institute

Benthos

The Barents Sea is subjected to a number of pressures (Figure 4.3.23) which are expected to have an effect on the megabenthos. These pressures include: 1) the non-indigenous snow crab, which may become a dominant species in a continuously spreading zone; 2) the influx of warm Atlantic waters into southwestern and possibly northwestern regions which may change the

Sea star. Photo: Norwegian Polar Institute

Benthos

Zoobenthic monitoring in the Kola section is one of the most published and extensive monitoring programs in the Russian Arctic. Data collection was initiated in the early 20th century by the Marine Biological Station, in Alexander Harbor of the Kola Bay. Modern benthic investigations in the Kola Section have been conducted by the Murmansk Marine Biological Institute (MMBI) since 1995. PINRO joined the monitoring program in 2003 using methods comparable to the existing long-term monitoring series. Since 2010, PINRO and MMBI have collaborated to ensure increased sampling regularity, greater speed in data processing, and more accurate taxonomic identification.

Three species of wolfish — Atlantic wolffish (Anarhichas lupus), Spotted wolffish (Anarhichas minor), and Northern wolffish (Anarhichas denticulatus) — live in the Barents Sea.  The abundance and biomass of all three species is relatively low (Figure 4.3.48), but they are all widely distributed throughout the Sea. The stock size of Atlantic wolffish and spotted wolffish, as measured by area-swept-clear estimates, has been relatively stable since 2004; the Northern wolffish has varied between 35,000

During the recent warming period (1998-2012), distinct trends were observed in abundance of fish species from different zoogeographic groups (Figure 4.3.54).  The abundance of coldwater fish species (Arctic, mainly Arctic, and Arcto-boreal) decreased during the period between 2000 and 2010. However, a trend of slight increase has been observed since 2010 in the abundance of mainly arctic and Arcto-boreal groups.

Based on the most recent estimates of fishing mortality and SSB, ICES classifies the stock as having full reproductive capacity and being harvested sustainably. SSB increased to a historic high in 2003, and then decreased; there is evidence, however, that SSB is now increasing again. Blue whiting is not fished in the Barents Sea; however a TAC is set for the entire Northeast Atlantic region. Total landings in 2012 were estimated at 384,000 tonnes.

PINRO conducted specialized trawl surveys to assess the stock level of northern shrimp in the Barents Sea Svalbard area from 1982 to 2003. Since 2004, the stock has been assessed using the joined Russian-Norwegian ecosystem survey. During this 1982-2013 survey period, shrimp biomass has peaked at approximately 7–8 year intervals which were observed in 1983–84, 1991–92, 1998, 2006, and 2010 (Figure 4.3.36).

Since 1990, the Russian fishery for Icelandic scallop has been conducted near Svatoy Nos in the Barents Sea, and on scallop banks in the White Sea Funnel (Figure 4.3.33). Due to harsh fishing conditions in the Funnel area — related to strong currents and, stiff bottom substrate — most scallops were traditionally fished in the Svyatoy Nos colony area.  A sharp decline in condition of the Svyatoy Nos scallop colony — following multi-year fishing activities — lead to termination of the fishery in this area

Ecosystem surveys have shown exceptionally rapid growth of the snow crab – especially in the waters adjacent to the northern island of the Novaya Zemlya archipelago   – and the expansion of its range in the north-east direction (Figure 4.3.30).

Harp seals are migratory and have a much wider distribution range than ringed seals, bearded seals, and walruses; they also have a more pelagic life history (Lavigne and Kovacs, 1988; Haug et al., 1994a). Three different populations inhabit the North Atlantic: the Northwest Atlantic population off Canada’s east coast; the Greenland Sea (West-Ice) population which breeds and moults just north of Jan Mayen; and the East-Ice population which congregate in the White Sea to breed. 

Hooded seals form one stock in the Northwest Atlantic and another in the Northeast Atlantic; although, recent genetic studies suggest no biological distinction between the groups (Coltman et al., 2007). In the Northeast Atlantic, whelping takes place in mid-late March in the West Ice, not far from where the West-Ice harp seals give birth. Between breeding and the moult, hooded seals carry out feeding excursions to the continental shelf edge off the Faroe Islands and Northern Ireland and to areas in the Norwegian Sea. 

Among the toothed whales, the long-finned pilot whale, sperm whale, the northern bottlenose whale, and killer whales are summer visitors to the Barents Sea. The Northeast Atlantic population of long-finned pilot whales number some 780,000 individuals (NAMMCO 1998), but only a very small (and unknown) part of this population enters the Barents Sea. Few sightings have been made in areas covered by IMR surveys; these sightings are insufficient to estimate

Numbers of seabirds breeding in the Barents Sea Region have changed dramatically over the last 50 years. A recent assessment of population status and trends has been conducted, based on monitoring and census date for several species breeding in the western part of the Barents Sea (i.e., Norwegian mainland and Svalbard) (Fauchald et al., 2015). Resulting analyses indicate that breeding populations of subarctic pelagic auk species (common guillemot Uria aalge, razorbill

Future higher temperatures in the Norwegian Arctic, including the Barents Sea, will likely cause several pathogens (parasites, bacteria, viruses) to extend their distributions northward (Tryland et al., 2009). The prevalence and abundance of pathogens may also change. Such a change in distribution of pathogens may have several consequences for both wild and domesticated animals, which are difficult to predict due to a lack of data.

Several seabird populations in the Barents Sea region are of international importance. The most numerous species are: Brünnich´s guillemot (Uria lomvia); little auk (Alle alle); Atlantic puffin (Fratercula arctica); black-legged kittiwake (Rissa tridactyla), northern fulmar (Fulmarus glacialis); and common eider (Somateria mollissima). An important part of the global breeding population of the rare ivory gull (Pagophila eburnea) is found within the northern part of the region — in Svalbard and Franz Josef Land.

The Barents Sea is inhabited by 21 species of sea mammals. Among these, 11 species are threatened according to the IUCN Red List, 13 are included in the Red Book of the Russian Federation (2001) and 8 extant species are on the endangered species list of Norway (Table 4.3.6) (plus the recently extinct northern right whale stock). Anthropogenic factors thought to be most harmful for marine mammals are fisheries interactions, pollution, and climate warming; the

The Barents Sea region is inhabited by 28 fish species which are either on the Global Red List (8 species) or on the Norwegian Red List (25 species) (Table 4.3.6). Among these, 13 are data deficient (DD) species, i.e. the species would likely appear on the red list if adequate information were available. When considering the lists of rare and threatened marine fish species, 3 main groups of impact factors may be considered: 1) fisheries (catch and by-catch); 2) environmental

Marine algae Codium fragile introduced in the southern Barents Sea. Photo: seaweedinsustry.com

Introduced species

During the last half century, 2 major crab species were introduced to the Barents Sea: red king crab Paralithodes camtschaticus in the 1960s; and snow crab Chionoecetes opilio in the 1990s. Early this century(2000), species from the southern boreal areas have expanded northward to appear in the Barents Sea, including the snake pipefish Entelurus aequoreus, snail ray Dipturus linteus, whiting Merlangius merlangus, grey gurnard Eutrigla gurnardus, and megrim Lepidorhombus whiffiagonis.

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