Soft Bottom Communities in Marine Lakes Sisjajarvi and Linjalampi (Barents Sea)

Based on the data of benthic surveys of 2010–2012, three benthic communities: a shallow-water community with the dominance of Scoloplos spp., Nucula tennuis, and Scalibregma inflatum; a deep-water community with the dominance of Chaetosone sp.; and a community of mixed sediments, have been distinguished in soft sediments in marine lakes Sisjajarvi and Linjalampi. These communities are typically marine and similar to other communities in shallow areas of the Barents Sea. They mostly differ in a high abundance of the polychaete Scalibregma inflatum and a small number of echinoderms from the communities in other bays of the Barents Sea. The abundance of the polychaete S. inflatum indicates indirectly possible cases of anoxia in Lake Sisjajarvi.     

Mitochondrial DNA polymorphism of atlantic cod of the Barents and White seas

High level of intraspecific polymorphism of the mtDNA cytochrome b gene in the Atlantic cod Gadus morhua L. from the northeastern part of the species range (Barents and White seas) is detected. The absence of genetic differentiation between the samples from different areas of the Norwegian and Barents seas is shown, and the fact that these samples belong to the same population of Northeast Arctic cod is confirmed. Significant differences in the frequences of mitochondrial DNA haplotypes between the cod from the Barents and White seas, as well as from the northwestern part of the range, are found. The cod Gadus morhua kildinensis Derjugin, 1920 from Mogilnoye Lake and Gadus morhua marisalbi Derjugin, 1920 from the White Sea were revealed to have common haplotypes with the cod from the Barents Sea, confirming the recent origin of these forms from the Atlantic cod G. morhua.     

New Data on the Distribution of Lamprey <Emphasis Type="Italic">Petromyzon marinus</Emphasis> and <Emphasis Type="Italic">Lethenteron camtschaticum</Emphasis> (Petromyzontidae) in Barents and White Seas

Information about the sites of catches of the sea lamprey Petromyzon marinus in the western Barents Sea and Arctic lamprey Lethenteron camtschaticum in the Barents and White seas is presented based on the data of trawl surveys performed in 2004?2016. It is demonstrated that sea lamprey is occasionally encountered in the western Barents Sea; nine specimens have been recorded during the entire period of surveys. The northernmost point of a capture of sea lamprey is located near 76° N and the easternmost point is at 31°15′ E. Arctic lamprey is not numerous in the Barents and White seas; a total of 66 and 17 specimens have been caught, respectively. Its local aggregations are found in the southeastern part of the Barents Sea and in Dvina Bay in the White Sea. Arctic lamprey penetrates to the north to 76° N and into the central part of the Barents Sea.     

The ecological and parasitological characteristics of the golden redfish, <Emphasis Type="Italic">Sebastes norvegicus</Emphasis> (Ascanius, 1772) (Teleostei: Scorpaenidae) that inhabit the Arctic Ocean Seas

An ecological, faunistic, and zoogeographical analysis of the parasite fauna of the golden redfish Sebastes norvegicus (Ascanius, 1772) that inhabit the Barents, Norwegian, and Greenland seas, has been performed. The specifics of formation of the parasite fauna in this species have been studied.     

Population structure and variability of Pacific herring (<Emphasis Type="Italic">Clupea pallasii</Emphasis>) in the White Sea,Barents and Kara Seas revealed by microsatellite DNA analyses

Pacific herring, Clupea pallasii, have recently colonised the northeast Atlantic and Arctic Oceans in the early Holocene. In a relatively short evolutionary time, the herring formed a community with a complex population structure. Previous genetic studies based on morphological, allozyme and mitochondrial DNA data have supported the existence of two herring subspecies from the White Sea and eastern Barents and Kara Seas (C. p. marisalbi and C. p. suworowi, respectively). However, the population structure of the White Sea herring has long been debated and remains controversial. The analyses of morphological and allozyme data have previously identified local spawning groups of herring in the White Sea, whereas mtDNA markers have not revealed any differentiation. We conducted one of the first studies of microsatellite variation for the purpose of investigating the genetic structure and relationship of Pacific herring among ten localities in the White Sea, the Barents Sea and the Kara Sea. Using classical genetic variance-based methods (hierarchical AMOVA, overall and pairwise F _ST comparisons), as well as the Bayesian clustering, we infer considerable genetic diversity and population structure in herring at ten microsatellite loci. Genetic differentiation was the most pronounced between the White Sea (C. p. marisalbi) versus the Barents and Kara seas (Chesha–Pechora herring, C. p. suworowi). While microsatellite variation in all C. pallasii was considerable, genetic diversity was significantly lower in C. p. suworowi, than in C. p. marisalbi. Also, tests of genetic differentiation were indicating significant differentiation within the White Sea herring between sympatric summer- and spring-spawning groups, in comparison with genetic homogeneity of the Chesha–Pechora herring.     

Feeding of Greenland halibut <Emphasis Type="Italic">Reinhardtius hippoglossoides</Emphasis> (Pleuronectidae) in the Kara Sea

Feeding of Greenland halibut Reinhardtius hippoglossoides in the northern Kara Sea was studied based on data collected in summer–autumn 2007–2013. The main food of all size groups of halibut were fish—up to 98% of weight of the food bolus. Larger individuals had lower intensity of feeding as compared to juveniles, which was probably owing to the lack of suitable food for large fish and, along with gonad maturation process, could be one of the reasons of their migration to the Barents Sea. The northern part of the Kara Sea, as well as the adjacent areas of Barents Sea, can be considered as an important area of habitation of juvenile Greenland halibut of the Norwegian–Barents Sea population.     

A new deep-sea hydroid (Cnidaria: Hydrozoa) from the Bering Sea Basin reveals high genetic relevance to Arctic and adjacent shallow-water species

The marine benthic fauna in Arctic shallow-water is reported to be a relatively young assemblage by species of either Pacific or Atlantic affinity. Whether current deep-sea Pacific species are included in the affinity or not is unknown. Combining morphological comparisons and genetic analyses, a new deep-sea hydroid to science, Sertularia xuelongi sp. nov. (Cnidaria: Hydrozoa: Sertulariidae), is described from the northern margin of the Bering Sea Basin at depths of 800–1570 m collected in 2010. It is characterized by slender and zigzag-shaped hydrocauli, alternately arranged hydrothecae and the absence of distal-lateral horns in fully matured female gonothecae. Its distribution, currently known only from Bering Sea Basin, suggests that it could not be an Arctic species with Pacific affinity. However, phylogenetic analyses based on the mitochondrial 16S rRNA gene show that it is clustered into a distinctive clade with four closely related species recorded from shallow-water of Northwest France, Iceland, Chukchi Sea and/or Bering Sea. In addition, its sequence similarity is highly relevant to these four species: Sertularia argentea (98.6 %), S. cupressina (98.8 %), S. plumosa (98.8 %) and S. robusta (99.4 %). All these provide a new insight into the relevance of North Pacific deep-sea species to the benthic fauna in Arctic and adjacent shallow-water. The taxonomic restriction of the genus Sertularia and the re-validation of the genus Polyserias are discussed. Future researches on more deep-sea species from Pacific and/or Atlantic are required to understand the evolution and speciation pattern involved in polar relevance.     

Enhancement of local species richness in tundra by seed dispersal through guts of muskox and barnacle goose

The potential contribution of vertebrate-mediated seed rain to the maintenance of plant community richness in a High Arctic ecosystem was investigated. We analyzed viable seed content in dung of the four numerically most important terrestrial vertebrates in Northeast Greenland – muskox (Ovibos moschatus), barnacle goose (Branta leucopsis), Arctic fox (Alopex lagopus) and Arctic hare (Lepus arcticus). High numbers of plant propagules were found in the dung of muskox and barnacle goose. Seeds of many plant species were found in the faeces of one vertebrate species only. Propagule composition in barnacle goose droppings was relatively uniform over samples, with a high abundance of the nutritious bulbils of Polygonum viviparum (Bistorta vivipara), suggesting that geese have a narrow habitat preference and feed selectively. Propagule composition in muskox dung was diverse and heterogeneous among samples, suggesting a generalist approach in terms of food selection and the haphazard ingestion of plant propagules with foliage. The species composition of plant propagules in dung samples was different from that of the receiving plant communities (in terms of the Sørensen and Czekanowski dissimilarity indices), and dung deposition, especially by muskox, often brought new species to the receiving community. The results suggest that endozoochorous propagule dispersal in the Arctic has a great potential in the generation and maintenance of local species richness, albeit being little specialized. It is further suggested that endozoochory is an important means of long-distance dispersal and, thereby, of plant migration in response to climate change.     

Ecology of Arctic cod <Emphasis Type="Italic">Boreogadus saida</Emphasis> (Gadiformes,Gadidae) and its fishery potential in Kara Sea

According to the bottom trawl-survey data, 97% of the ichthyomass in the southwestern region of the Kara Sea are composed of the Arctic cod Boreogadus saida; its stock is significantly higher than the previously registered resources. The Arctic cod is most unevenly distributed across the water area and capable to form the high-density aggregations, which can be caught by the targeted trawls. A wide range of the age composition (0+?6+), the size-age composition, and the growth rates of the Arctic cod in the trawl catches in the Kara Sea, which are different from those in the fish in the adjacent Barents Sea, can indicate their assignment of the Arctic cod in these seas to different populations.     

Diets and body condition of polar cod (<Emphasis Type="Italic">Boreogadus saida</Emphasis>) in the northern Bering Sea and Chukchi Sea

To understand trophic responses of polar cod Boreogadus saida (a key species in Arctic food webs) to changes in zooplankton and benthic invertebrate communities (prey), we compared its stomach contents and body condition between three regions with different environments: the northern Bering Sea (NB), southern Chukchi Sea (SC), and central Chukchi Sea (CC). Polar cod were sampled using a bottom trawl, and their potential prey species in the environment were sampled using a plankton net and a surface sediment sampler. Polar cod fed mainly on appendicularians in the NB and SC where copepods were the most abundant in the environment, while they fed on copepods, euphausiids, and gammarids in the CC where barnacle larvae were the most abundant species in plankton samples on average. The stomach fullness index of polar cod was higher in the NB and SC than CC, while their body condition index did not differ between these regions. The lower lipid content of appendicularians compared to other prey species is the most plausible explanation for this inconsistency.     

Spatial analysis of marine categorical information using indicator kriging applied to georeferenced video mosaics of the deep-sea Håkon Mosby Mud Volcano

The exact area calculation of irregularly distributed data is in the focus of all territorial geochemical balancing methods or definition of protection zones. Especially in the deep-sea environment the interpolation of measurements into surfaces represents an important gain of information, because of cost- and time-intensive data acquisition. The geostatistical interpolation method indicator kriging therefore is applied for an accurate mapping of the spatial distribution of benthic communities following a categorical classification scheme at the deep-sea submarine Håkon Mosby Mud Volcano. Georeferenced video mosaics were obtained during several dives by the Remotely Operated Vehicle Victor6000 in a water depth of 1260 m. Mud volcanoes are considered as significant source locations for methane indicated by unique chemoautotrophic communities as Beggiatoa mats and pogonophoran tube worms. For the detection and quantification of their spatial distribution 2840 georeferenced video mosaics were analysed by visual inspection. Polygons, digitised on the georeferenced images within a GIS, build the data basis for geostatistically interpolated mono-parametric surface maps. Indicator kriging is applied to the centroids of the polygons calculating surface maps. The quality assessment of the surface maps is conducted by leave-one-out cross-validation evaluating the fit of the indicator kriging variograms by using statistical mean values. Furthermore, the estimate was evaluated by a validation dataset of the visual inspection of 530 video mosaics not included within the interpolation, thus, proving the interpolated surfaces independently. With regard to both validating mechanisms, we attained satisfying results and we provided each category applied for the identification of biogeochemical habitats with a percentage probability value of occurrence.     

Intraspecies structure of beaked redfish <Emphasis Type="Italic">Sebastes mentella</Emphasis> of the Atlantic and Arctic oceans

On the basis of the results of complex interdisciplinary investigations of the population composition and structure of the beaked redfish Sebastes mentella of the Atlantic and Arctic oceans, its three populations are discerned relatively isolated from each other by the system of permanent marine currents—North Atlantic, Flemish-Cape, and Norway-Barents Sea. The population structure of the species in the southern part of its area corresponds to the model of a local stock. Interaction of the North Atlantic and the Norway-Barents Sea populations well correspond to the model of fluctuating stocks. Redfish aggregations in different biotopes (mesobenthal and mesopelagial) are intrapopulational epigenetic groups. In the period of warm and anomalously warm years, a part of mature specimens from the pelagial of the North Irminger Sea make an irreversible migration to the southern part of the Norwegian Sea and form there mixed aggregations of fish from the North Atlantic and Norway-Barents Sea populations. With consideration of the effect of climatic–oceanological processes, a principally new scheme is elaborated describing the process of seasonal migrations of redfish in the mesobenthal and mesopelagial. The previous views on direction of return migrations of redfish of the Norway-Barents Sea population are reconsidered. Juveniles from the western part of the Barents Sea and Spitsbergen not only supplement the demersal aggregations but also migrate to the pelagial of the Norwegian Sea.     

Unusual abundance of macrobenthos and biological invasions in the Chukchi Sea

The data from the expedition of the program RUSALCA conducted in 2004 showed unexpectedly high quantitative indices of macrobenthos in the southeastern Chukchi Sea. Extensive areas of the bottom northwest of the Bering Strait were dominated by the bivalve Macoma calcarea. The greatest biomass of benthos in Macoma-dominated areas was 4232 g/m² with an average of 1382 g/m² for the investigated region. Such a high biomass of soft-bottom communities, which is extremely uncommon even in the temperature regions of the oceans, is reported for the Arctic for the first time. The long-term existence (more than 70 years) of highly productive benthic communities dominated by Macoma calcarea in one and the same area of the Chukchi Sea can most likely be attributed to gyres, which constantly arise in the region northwest of the Bering Strait. These cyclonic gyres carry nutrient-rich bottom water to the surface and hinder larval transport away from mother populations. They also keep and concentrate major food sources of benthos (live and dead phyto-and zooplankton and fecal pellets) over the benthic community locations. Most likely, a significant proportion of the primary production in the southeastern Chukchi Sea is used by benthos within the investigated Macoma community. Findings of three relatively large warm-water Pacific species near Point Hope in the Chukchi Sea are probably indicative of the progressive climate warming during the last century.     

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.     

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.     

Macrozoobenthos in saline rivers in the Lake Elton basin: Spatial and temporal dynamics

The data on seasonal and interannual changes in the taxonomic, structural, and quantitative characteristics of macrozoobenthos communities in rivers with a high salinity gradient are given. A total of 91 benthic invertebrate taxa have been revealed, which were dominated by Cricotopus salinophilus, Chironomus salinarius, C. aprilinus, Tanytarsus kharaensis, Microchironomus deribae, Glyptotendipes salinus (Diptera: Chironomidae), Culicoides (M.) riethi, Palpomyia schmidti (Diptera: Ceratopogonidae), Paranais simplex (Oligochaeta), and Ephydra sp. (Ephydridae) in different years. The fauna of benthic communities is mainly represented by eurybiontic halotolerant species with different ranges of resistance to salinity. The taxonomic composition and diversity of macrozoobenthos communities are closely correlated with water salinity in the range from 4 to 41 g/L; the complex of hydrological and hydrophysical factors (depth, overgrowing, water temperature, pH, etc.) control the distribution and abundance of species.     

Under-ice distribution of polar cod <Emphasis Type="Italic">Boreogadus saida</Emphasis> in the central Arctic Ocean and their association with sea-ice habitat properties

In the Arctic Ocean, sea-ice habitats are undergoing rapid environmental change. Polar cod (Boreogadus saida) is the most abundant fish known to reside under the pack-ice. The under-ice distribution, association with sea-ice habitat properties and origins of polar cod in the central Arctic Ocean, however, are largely unknown. During the RV Polarstern expedition ARK XXVII/3 in the Eurasian Basin in 2012, we used for the first time in Arctic waters a Surface and Under Ice Trawl with an integrated bio-environmental sensor array. Polar cod was ubiquitous throughout the Eurasian Basin with a median abundance of 5000 ind. km^?2. The under-ice population consisted of young specimens with a total length between 52 and 140 mm, dominated by 1-year-old fish. Higher fish abundance was associated with thicker ice, higher ice coverage and lower surface salinity, or with higher densities of the ice-amphipod Apherusa glacialis. The fish were in good condition and well fed according to various indices. Back-tracking of the sea-ice indicated that sea-ice sampled in the Amundsen Basin originated from the Laptev Sea coast, while sea-ice sampled in the Nansen Basin originated from the Kara Sea. Assuming that fish were following the ice drift, this suggests that under-ice polar cod distribution in the Eurasian Basin is dependent on the coastal populations where the sea-ice originates. The omnipresence of polar cod in the Eurasian Basin, in a good body condition, suggests that the central Arctic under-ice habitats may constitute a favourable environment for this species survival, a potential vector of genetic exchange and a recruitment source for coastal populations around the Arctic Ocean.     

An analysis of allozyme variation in herring <Emphasis Type="Italic">Clupea pallasii</Emphasis> from the White and Barents Seas

An analysis of genetic variation is made according to four allozyme loci of reproductive (spawning) groups of oligovertebrate herring Clupea pallasii collected in various bays of the White Sea and the south-eastern part of the Barents Sea in 1995–2002. The temporal stability of genetic characteristics during several years is shown. The analysis of genetic variation revealed a significant difference between herring from the south-eastern part of the Barents Sea and spring-spawning and summer-spawning herring from inner bays of the White Sea. The analysis of geographic variation of genetic characteristics of spawning aggregations revealed the change in frequencies of alleles of loci LDH-2* and MDH-4* from the north-east to the south-west along the coast.     

Subtidal Underwater Rock Communities of the White Sea: Structure and Interaction with Bottom Flow

The taxonomic composition and quantitative characteristics of typical subtidal rock communities of the White Sea (biocenosis of Laminaria and biocenosis of Lithothamnion and the sponges Polymastia arctica) were studied. The hydrodynamic activity of the near-bottom water layer within and beyond the communities was estimated using the plaster structures technique. A comparative analysis of our results and the literature data revealed three main types of interactions between the benthic community and the water flow: turbulation of the water flow (mussel banks), smoothing of turbulent pulsations (Laminaria community), and an insignificant effect on the water flow (community of Lithothamnion and sponges).