Red king crab (<Emphasis Type="Italic">Paralithodes camtschaticus</Emphasis>) in the Barents Sea: A comparative study of introduced and native populations

Red king crab (Paralithodes camtschaticus) was introduced into the Barents Sea in the 1960–1970s. At present, it occurs along the coast from Hammerfest (Northern Norway) to the (northeastern coast of Kola Peninsula). We studied the polymorphism of a mitochondrial gene encoding cytochrome oxidase (COI) and five nuclear microsatellite loci in four samples from the Barents Sea and two donor populations from the Western Kamchatka and Primorye (Russian Pacifics). No decrease in the genetic diversity of the introduced populations was observed. The results of PCA103 locusanalysis but some samples from the Barents Sea significantly differed from the Pacific populations according to the test for population differentiation demonstrated that the sample from Varrangerfjord was highly significantly different from the other five populations. As no significant differences between the other samples were found at this locus. We consider it to be a marker for Varangerfjord population differentiation. Possible reasons of this phenomenon are discussed.     

Evidence for Two Highly Differentiated Herring Groups at Goose Bank in the Barents Sea and the Genetic Relationship to Pacific Herring, Clupea pallasi

Genetic studies on Atlantic herring, Clupea harengus, have generally revealed a low level of genetic variation over large geographic areas. Genetically distinct herring populations in some of the Norwegian fjords are exceptions, and juvenile herring from the large oceanic herring, Norwegian Spring Spawners (NSS), are often found in mixture with local fjord populations as well as widely distributed in the Barents Sea. Research surveys in the eastern Barents Sea (Goose Bank) in 1993, 1994 and 2001 included collection of herring samples for allozyme analyses. As expected the results identified juveniles from NSS stock, but an additional unique group of herring (low vertebrae number), being almost fixed for alternative alleles at several allozyme loci, was detected. In some cases, the two groups of herring were taken in the same trawl catches as documented by highly significant departure from Hardy—Weinberg expectation with large excess of homozygotes providing evidence for population mixing. Large genetic differences (Nei's genetic distance = 1.53; F_ST = 0.754) were detected in pairwise comparisons based on five allozyme loci. The two herring groups were also compared with reference samples of Pacific herring, Clupea pallasi, including one sample from Japan Sea and three Alaskan samples. UPGMA dendrogram based on five allozyme loci revealed a close genetic relationship between the low vertebrae herring in the Barents Sea and the group of samples of Pacific herring. Although significant different in allele frequencies, one of the herring samples clustered together with the reference sample from Bering Sea with genetic distance of 0.008 and F_ST value of 0.032. The close genetic relationship found in this paper, suggest a re-evaluation of the taxonomic status of the Barents Sea herring populations investigated.     

East Greenland and Barents Sea polar bears (Ursus maritimus): adaptive variation between two populations using skull morphometrics as an indicator of environmental and genetic differences

A morphometric study was conducted on four skull traits of 37 male and 18 female adult East Greenland polar bears (Ursus maritimus) collected 1892-1968, and on 54 male and 44 female adult Barents Sea polar bears collected 1950-1969. The aim was to compare differences in size and shape of the bear skulls using a multivariate approach, characterizing the variation between the two populations using morphometric traits as an indicator of environmental and genetic differences. Mixture analysis testing for geographic differentiation within each population revealed three clusters for Barents Sea males and three clusters for Barents Sea females. East Greenland consisted of one female and one male cluster. A principal component analysis (PCA) conducted on the clusters defined by the mixture analysis, showed that East Greenland and Barents Sea polar bear populations overlapped to a large degree, especially with regards to females. Multivariate analyses of variance (MANOVA) showed no significant differences in morphometric means between the two populations, but differences were detected between clusters from each respective geographic locality. To estimate the importance of genetics and environment in the morphometric differences between the bears, a PCA was performed on the covariance matrix derived from the skull measurements. Skull trait size (PC1) explained approx. 80% of the morphometric variation, whereas shape (PC2) defined approx. 15%, indicating some genetic differentiation. Hence, both environmental and genetic factors seem to have contributed to the observed skull differences between the two populations. Overall, results indicate that many Barents Sea polar bears are morphometrically similar to the East Greenland ones, suggesting an exchange of individuals between the two populations. Furthermore, a subpopulation structure in the Barents Sea population was also indicated from the present analyses, which should be considered with regards to future management decisions.     

Red king crab (<Emphasis Type="Italic">Paralithodes camtschaticus</Emphasis>) fisheries in Russian waters: historical review and present status

The red king crab (Paralithodes camtschaticus) is a highly valued delicacy on the international market and currently contributes significantly to the income from fisheries in the regions where it is harvested. Russian income from red king crab export is $200–250 million per year. We review both the biology and fishery of the two largest populations of this species in Russia, i.e., in western Kamchatka (Sea of Okhotsk) and in the Barents Sea. The latter was established in the mid-1990s after introduction of red king crab to the area in the 1960s. The Barents Sea crabs are larger, grow faster and mature earlier than the crabs from the Sea of Okhotsk owing to more favorable temperature conditions in the Barents Sea. Additionally, we provide fishery information for the Prymorie population of red king crab (Sea of Japan) that remains depressed and closed for commercial fishery at present. Although the fishery period of red king crab in western Kamchatka is much longer than in the Barents Sea (1930–present time vs. 2004–present time), similar patterns were observed for the exploited king crab populations. High annual landings led to a pronounced decrease in population density and total abundance that, in turn, led to closures or some limitations of fisheries. Subsequent rehabilitations of the populations provided an opportunity for reopening of the fisheries and further exploration of red king crab populations under sustainable management. The main reason explaining a decline in red king crab populations both in the North Pacific and in the Barents Sea is high, mainly illegal, fishing pressure. Sustainable harvest strategies for the fisheries could prevent negative scenarios (overfishing) in the future.     

Regional and local spatial genetic structure of Siberian primrose populations in Northern Europe

We have investigated the local and regional scale genetic structure of Siberian primrose (Primula nutans) populations in Northern Europe. The genetic diversity and structure of fifteen populations sampled from the Bothnian Bay in Finland, the Barents Sea in Norway and the White Sea in Russia were assessed using eleven microsatellite markers. We investigated the distribution of genetic variation within and between populations, and studied the local genetic structure using spatial autocorrelation analysis. We found very low genetic and allelic diversity in the Bothnian Bay and Barents Sea populations, and only slightly higher in the White Sea population. The level of genetic differentiation between the regions was very high, whereas differentiation between the populations within the regions was moderate. We found no spatial structuring of populations in any region suggesting efficient dispersal on a local scale. Clonal reproduction seemed to have no effect on genetic structure.     

The genetic variability of the red king crab, <Emphasis Type="Italic">Paralithodes camtschatica</Emphasis> (Tilesius, 1815) (Anomura,Lithodidae) introduced into the Barents Sea compared with samples from the Bering Sea and Kamchatka region using eleven microsatellite loci

The intentional introduction of red king crab, Paralithodes camtschatica (Tilesius, 1815) in the Barents Sea represent one of a few successful cases and one that now supports a commercial fishery. Introductions of alien species into new environments are often associated with genetic bottlenecks, which cause a reduction in the genetic variation, and this could be important for the spreading potential of the species in the Atlantic Ocean. Red king crab samples collected in the Varangerfjord located on the Barents Sea (northern Norway) were compared with reference crab samples collected from the Bering Sea and Kamchatka regions in the Pacific Ocean. All samples were screened for eleven microsatellite loci, based on the development of species-specific primers. The observed number of alleles per locus was similar, and no reduction in genetic variation, including gene diversity and allelic richness, was detected between the Varangerfjord sample and the reference sample from Okhotsk Sea near Kamchatka, indicating no genetic bottlenecking at least for the microsatellite loci investigated. The same results were found in comparison with the sample from Bering Sea. The level of genetic differentiation among the samples, measured as overall F _ST across all loci, was relatively low (0.0238) with a range of 0.0035–0.1000 for the various loci investigated. The largest pairwise F _ST values were found between the Bering Sea and Varangerfjord/Barents Sea samples, with a value of 0.0194 across all loci tested. The lowest value (0.0101) was found between the Varangerfjord and Kamchatka samples. Genetic differentiation based on exact tests on allele frequencies revealed highly significant differences between all pairwise comparisons. The high level of genetic variation found in the Varangerfjord/Barents Sea sample could be of significance with respect to further spreading of the species to other regions in the North Atlantic Ocean.     

Egg Size and Formation of the Geographical Range in <Emphasis Type="Italic">Thysanoessa inermis</Emphasis> (Kroyer, 1846) (Crustacea: Euphausiacea) in the Norwegian and Barents Seas

Using materials on the euphausiacean Thysanoessa inermis collected in the Norwegian and Barents seas (from 60°N to 73°N) we studied the variability of size characteristics in the eggs (diameter of embryos and egg capsules and the width of the perivitelline space) and their correlations with water temperature and salinity. The size of embryos showed almost no variability irrespective of the location of the sampling site and the water temperature and salinity; the perivitelline space performs a protective function, and its width showed a tendency to decrease with increasing water temperature and salinity. The similarities in the size of embryos in T. inermis populations thousands of kilometers away from each other might be explained, first, by the relatively small age of the populations (the age of the population from the Barents Sea did not exceed 6000–7000 years) and second, by movement of the crustaceans with currents from the Norwegian Sea to the Barents Sea.     

Occurrence of viral haemorrhagic septicaemia virus (VHSV) in wild marine fish species in the coastal regions of Norway

This study was aimed at determining the occurrence of viral haemorrhagic septicaemia virus (VHSV) in selected stocks of wild fish species in the coastal regions of Norway. Six cruises were undertaken covering areas which included the coastal regions of northern Norway, the Norwegian Sea, the Barents Sea, and the Skagerrak area down to the Danish border. Collected, pooled samples of internal organs (kidney, spleen and heart) from 8395 fish were examined for the presence of VHSV by inoculation on BF-2 cells. Identification of virus was performed by a standard ELISA procedure with monoclonal antibody IP5B11, which is specific for the VHSV nucleocapsid protein (N-protein). VHSV was isolated from blue whiting and Norway pout in Skagerrak. No positive samples were detected in the northern coastal regions of Norway, the Norwegian Sea, or the Barents Sea. The findings indicate a very low occurrence of VHSV in the coastal regions of Norway. Geographically, the only positive samples were obtained from fish collected in areas where VHSV has previously been found in different species of fish.     

Fungi in bottom sediments of the barents and Kara seas

The mycobiota of bottom sediments at depths of 128?472 m was investigated in Barents and Kara sea areas remote from the shore. The species composition and fungal abundance, that is, the number of fungal colony-forming units (CFUs), were determined in 5 samples from the Kara Sea and in 14 samples of the Barents Sea. For the first time for the Arctic seas, the fungal biomass was determined in 12 samples of the bottom sediments from the Barents Sea. It was found that fungal abundance in the bottom sediments of the both seas did not exceed 13 CFUs per 1 g of dry substrate weight. In total, only 58 colonies of filamentous fungi belonging to 22 morphotypes, 8 of which were sterile, were isolated from all the samples. No more than six morphotypes were contained in 1 g of dried substrate; they were mostly species of the genus Cladosporium and sterile isolates. The study of the fungal biomass detected both spores and fungal mycelium in the bottom sediments. The total biomass was extremely low and ranged from 0.1 to 0.620 mg/g of the studied substrate. Small spores (with a diameter less than 3 μm) absolutely predominated (from 88 to 99.7% of the biomass).     

Status,number, and monitoring of the common eider (<Emphasis Type="Italic">Somateria mollissima</Emphasis>) population in the barents sea and the White Sea

The breeding, molting, and wintering ranges of the common eider (Somateria mollissima) were mapped and described in the southern part of the Barents Sea region, including the White Sea population in the western White Sea and the Murmansk population in the northwestern White Sea and the southeastern Barents Sea. The present-day abundance was determined for both populations: since the 1950s, it was the highest in the 2000s for the entire period of ornithological monitoring in the region. Aerial survey from a helicopter is considered to be the only reliable method for estimation of the total population number. The best season for surveying the White Sea population is March–early April (wintering); the most favorable period for surveying the Murmansk population is August (postbreeding/molting). The population status of the common eider in the northern and eastern parts of the Barents Sea has not yet been evaluated. On Franz-Josef Land, the common eider is distributed sporadically, and its number was assessed using expert estimates. The current abundance of the common eider on Novaya Zemlya is unknown. Helicopter-based aerial survey performed in late summer during the postbreeding season is the only relevant method to obtain reliable estimates for the population of the common eider inhabiting Franz-Josef Land and Novaya Zemlya.     

Do Norwegian Atlantic salmon feed in the northern Barents Sea? Tag recoveries from 70 to 78° N

Three tagged Atlantic salmon Salmo salar were recaptured as subadults or adults (1·4–3 kg) between 70·5 and 78° N in the western Barents Sea, two of which originated from the Alta Fjord region in northern Norway and one from the Drammen River, south-eastern Norway. An additional tag was recovered from the stomach of a Greenland halibut Reinhardtius hippoglossoides captured south-west of Bear Island at >600 m depth; this tag was from a smolt released in the River Alta 1 month earlier. These are the northernmost tag recoveries reported for Atlantic salmon, and indicate that Norwegian Atlantic salmon, especially the fish from northern populations, may use the northern Barents Sea as a feeding area during part of their life cycle.     

Comparative chemical composition of the Barents Sea brown algae

Comparative study of phytochemical compositions of the most widespread brown algae species (one laminarian and four fucoid algae) from Barents Sea has been performed. A modified technique for mannitol determination in brown algae is proposed. It was revealed that fucus algae (fam. Fucaceae) contain 3% (of total dry weight) less mannitol than laminaria (Laminaria saccharina). The contents of alginic acid and laminaran in the Barents Sea fucoids are more than 10% less compared to laminaria. The alga L. saccharina contains almost two times more iodine than the species of fam. Fucaceae. The amounts of fucoidan and sum lipids in the Barents Sea fucoid algae is higher than in Laminaria saccharina (4-7% and 1-3%, respectively). In terms of contents of main biologically active compounds, fucus and laminarian algae from Barents Sea are inferior to none of the Far-Eastern species. The Barents Sea algae may become an important source of biologically active compounds.     

Long-term changes in Krill biomass and distribution in the Barents Sea: are the changes mainly related to capelin stock size and temperature conditions?

Krill plays a significant role in the Barents Sea ecosystem, providing energy transport between different trophic levels. The current paper presents the results of a long-term study (1980–2009) based on pelagic trawl catches from August to September. Our investigations show that the krill species were distributed widely in the Barents Sea and that the largest krill concentrations were restricted to the west-central and eastern parts of the Barents Sea. The current paper presents the relative biomass indices, and the estimates must be interpreted as minimum biomass. The mean annual krill biomass was estimated to be 22 million tonnes in wet weight, with the highest values being as much as 48 million tonnes. Capelin is the largest pelagic stock, and in some years, their biomass can amount to 4–7 million tonnes, which can impose high predation pressure on krill. When their biomass is high, capelin may consume close to 26 million tonnes annually. The predation from pelagic (herring and blue whiting) and bottom (cod and haddock) fish species was much lower, being 9 and 1 million tonnes, respectively. A negative relationship between krill biomass and capelin stock size above 74°N was observed during the study period. However, during the last decade, the krill biomass has increased despite heavy predation from capelin in some years. A positive significant linear relationship between the mean annual Kola temperature and the krill biomass seems to indicate that the recent warming conditions have favourable impacts on the krill populations in the Barents Sea.     

The mortality of the planktonic copepod <Emphasis Type="Italic">Oithona similis</Emphasis> Claus, 1866 (Copepoda: Cyclopoida) in the Barents and White Seas

The mortality rates of the copepodite IV-copepodite V and copepodite V-adult individuals pairs in the populations of one of the most common species of planktonic copepod, Oithona similis, were estimated for the first time in the Barents and White seas. The average parameters were 0.060 and 0.082/day, respectively, in the Barents Sea and 0.166 and 0.120/day in the White Sea. In the Barents Sea, the mortality rates of O. similis significantly increased with an increase in water temperature and in the White Sea a significant decrease occurred with an increase in salinity. It was concluded that the mortality rate of this species is determined first by abiotic factors and that biotic factors are of secondary significance.     

Combined effect of environmental temperature and trematodes on fatty acids composition of lipids of Littorina saxatilis (Olivi 1792) (Gastropoda, Prosobranchia)

An effect of environmental temperatures and invasion by helminthes larvae on fatty acids composition of digestive gland lipids of marine littoral gastropod Littorina saxatilis from White Sea and Barents Sea was investigated. We have compared gastropods from boreal and subarctic populations. It was found that gastropods from waters of lower temperature have increased omega3/omega6 fatty acids ratio. However, saturation index of individual membrane phospholipids was not affected. Also, content of eicosenoic acid (20:1) in individual phospholipids was not affected by temperature. Invasion increases the omega3/omega6 ratio of common lipids but not the omega3/omega6 ratio of common and individual phospholipids with the exception of phosphatidilcholine of cold water mollusks from Barents Sea that had this ratio doubled. In contrast to temperature, invasion affects the content of eicosenoic acid that was increased in the investigated organs. Adaptability of these effects is discussed regarding parasite-host system.     

Within and between species competition in a seabird community: statistical exploration and modeling of time-series data

In a changing environment, the maintenance of communities is subject to many constraints (phenology, resources, climate, etc.). One such constraint is the relationship between conspecifics and competitors. In mixed colonies, seabirds may have to cope with interspecific and intraspecific competition for both space and food resources. We applied competitive interaction models to data on three seabird breeding populations: black-legged kittiwake (Rissa tridactyla), common guillemot (Uria aalge) and Brünnich's guillemot (Uria lomvia) collected over 27-years at Kharlov Island in the Barents Sea. We found a competitive effect only for the kittiwake breeding population size on the common guillemot breeding population size when kittiwakes were abundant. The timing of kittiwake breeding negatively affected the number of breeding Brünnich's guillemots. The timing of breeding was negatively correlated to biomass of the main pelagic fish in the Barents Sea, the capelin (Mallotus villosus), which suggests an indirect action. The community matrix shows that the community was not stable. The kittiwake population did not decrease as seen in north Norwegian populations. Likewise, the common guillemot population, after a crash in 1985, was recovering at Kharlov while Norwegian populations were decreasing. Only the Brünnich's guillemot showed a decrease at Kharlov until 1999. We suggest that the stability of the kittiwake and common guillemot populations at Kharlov is due to better feeding conditions than in colonies of the Norwegian coast, linked to a possible eastward shift of the capelin population with the temperature increase of the Barents Sea.     

Morphometric differentiation of Pseudocalanus minutus populations in the Barents Sea

Dvoretsky VG. and Dvoretsky AG. 2011. Morphometric differentiation of Pseudocalanus minutus populations in the Barents Sea. —Acta Zoologica (Stockholm) 00 : 1–12. We investigated spatial variations in the morphometric characteristics (total length of body, lengths of cephalothorax, abdomen and antennules, and their relative proportions) of Pseudocalanus minutus, an abundant copepod species across the Barents Sea in August–September 2007. Females were found to have higher values for the measured parameters than males. The average absolute morphometric characters of both sexes increased from the south to the north. In most cases, parameters were similar in the southern, central, and eastern regions delineated by cluster analyses of oceanographic variables. The morphometric characteristics were strongly correlated with environmental variables in both males and females. Multiple regression analysis showed that temperature together with salinity explained 72–85% (in females) and 38–91% (in males) of the total variations in the log₁₀‐transformed morphometric parameters. According to principal component analysis and discriminant function analysis, two distinct groups could be separated in the Barents Sea. The first group included the copepods from the northern region; the other included populations from the southern, central, and eastern regions. The observed morphological variation can be interpreted as geographical variation connected with hydrological variability.     

Brucella sp. antibodies in polar bears from Svalbard and the Barents Sea

A prevalence of 5.4% of anti-Brucella sp. antibodies was found in plasma samples from 297 polar bears (Ursus maritimus) from Svalbard and the Barents Sea. Plasma was tested by the classical brucellosis tests Slow Agglutination of Wright (SAW), EDTA modified SAW and Rose Bengal test, as well as by an indirect Protein A ELISA. Only samples classified as positive in all tests were regarded as containing anti-Brucella sp. antibodies. A significant west to east increase in the proportion of bears with anti-Brucella sp. antibodies was found, with 3.6% (n = 253) at Svalbard (Spitsbergen, Nordaustlandet, Edge?ya, Barents?ya and Hopen), and 15.9% (n = 44) in the central Barents Sea. Anti-Brucella sp. antibodies were previously found in ringed seals (Phoca hispida) and harp seals (Phoca groenlandica) from the same geographical areas. The ringed seal is an important prey species for the Svalbard polar bear population, and may thus be a source of brucellosis for the bears. There are no indications of reproductive disorders caused by Brucella sp. or other infectious agents in our study polar bear population. Potential impacts of Brucella sp. exposure on individuals or the population are unknown.     

Cod, Gadus morhua L., populations identified by mitochondrial DNA

Isozyme and haemoglobin analysis has shown that the cod, Gadus morhua L., in the NE Atlantic can be regarded as two populations: Arctic and coastal cod. One hundred and one individual cod from nine different locations were sampled and restriction fragment analysis uncovered 14 different mtDNA clones. Calculation of sequence divergence between localities displayed large divergence between samples from coastal and Arctic areas (l.77–5.62%), as opposed to the low intrapopulation divergence (∼0.10%) and the divergence between localities along the coast (∼0.17%) and in the Barents Sea (∼ 1.00%).     

The rotifer fauna of arctic sea ice from the Barents Sea,Laptev Sea [2pt] and Greenland Sea

Hydrobiologia - Samples from arctic sea ice were studied for their rotifer fauna. Ice core samples were collected in the northern Barents Sea and the Laptev Sea from August to October 1993 and in...