Specific features of the spatial and temporal distribution of the White Sea population of harp seal

Analysis of the data obtained during aerial survey of sea mammals in the 1980s–1990s (White and Barents seas) has revealed that, during all the seasons of the year, harp seals of the White Sea population form two types of aggregations which differ in size and some ecological features. Large herds of seals (tens of thousands of individuals) are able to occupy areas extending tens and even hundreds of kilometers. Harp seals prefer to inhabit the northern part of the population range (Barents Sea), whereas the southern part (White Sea) is mainly used for reproduction and molting. Small herds (several hundred animals) can be scattered over vast territories, but they tend to dwell in the southern part of the area including the White Sea and southern areas of the Barents Sea. The opportunity to distinguish between these two types of aggregations makes it possible to study the biological features of each of them and to specify characteristics of the species biology.     

Changes in trace metal concentrations in the tissues of the White Sea mussel <Emphasis Type="Italic">Mytilus edulis</Emphasis> over the reproductive cycle

Seasonal changes in the concentrations and total amounts (contents) of Cd, Zn, and Cu in the mussel Mytilus edulis cultivated in the White Sea were studied over the reproductive cycle (prespawning, spawning, and postspawning stages). The results, when compared with published data on the closely related species M. trossulus from the Sea of Japan, suggest that the seasonal dynamics of trace element contents in mussel tissues are related to specific geochemical conditions, as well as to the dynamics of changes in soft tissue weight over the reproductive cycle. The contents of Cd and Cu in the mussels before, during, and after spawning changed similarly in the mollusks from the White Sea and the Sea of Japan. Changes in the Zn content at different stages of the reproductive cycle of the White Sea mussels were similar to those in mussels from the Sea of Japan but had smaller amplitude. The concentration of Zn in the White Sea mussels was before spawning the highest, but still lower than in mussels from the Sea of Japan. After the spawning, the Zn concentration in the White Sea mussels, in contrast to the Pacific mussels, decreased because of the redistribution of this element during the prespawning period from the somatic tissue into the gonad.     

On the distribution of larvae and localization of spawning stocks of White Sea herring <Emphasis Type="Italic">Clupea pallasii marisalbi</Emphasis>

On the basis of ichthyoplankton surveys made in June 2004–2005 and 2007, June–July 2010, and July 2011 in these bays and beyond them (in open waters of the White Sea Basin and adjacent areas of the Gorlo) larvae of White Sea herring were absent. Principal aggregations of larvae are found in the Kandalaksha Bay in June 2004–2005 and 2007. In the Onega Bay and in the Dvina Bay surveyed in June 2007 abundance of larvae was ratter low and in June–July 2010 and July 2011 in these bays and beyond them (in open waters of the White Sea Basin and adjacent areas of the Gorlo) larvae of White Sea herring were absent. Within the Kandalasksha Bay, from year to year, there were two disconnected aggregations of larvae. The space between them was situated in the open part of the bay along the transect of the Chupa Estuary and the Umba Estuary. One of the aggregations of larvae occupied the tail of the bay, and the second aggregation occupied the ante-mouth and mouth areas of the Chupa Estuary. It is supposed that these aggregations result from spawning of two independent spawning groups of the White Sea herring spawning in isolated regions of the Kandalaksha Bay. Presence of the bulk of larvae of the White Sea herring within the limits of the Kandakaksha Bay and their almost complete absence at the boundary of the bay with the White Sea Basin and at the boundaries between the Onega Bay and the Dvina Bay and the Basin support the hypothesis on the absence of an exchange with larvae between stocks of the White Sea herring spawning in large bays of the White Sea. The larvae are retained within shallow waters of the Kandalaksha Bay by the system of two-layer water circulation in the areas of spawning of herring in bays and gulfs of the estuarine type. Their drift outside of the Onega Bay and the Dvina Bay may be delimited by frontal divides at their boundaries with the Basin.     

Winter distribution and migrations of beluga whales (<Emphasis Type="Italic">Delphinapterus leucas</Emphasis>) in the White Sea based on satellite tracking data

Based on satellite tracking of eight beluga whale males in the White Sea, their habitats in the autumn, winter, and spring periods have been identified. A correlation between the distribution of beluga whales, ice dynamics, and migration of Atlantic salmon has been revealed. It has been found than beluga whale males do not leave the White Sea during the entire ice period. The results obtained confirm the hypothesis that the White Sea population of beluga whales is isolated.     

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.     

Larvae of Barnacles (Cirripedia: Thoracica) in the White Sea Plankton

The barnacle fauna of the White Sea is briefly described. The morphology of barnacle larvae in this water body is comparatively analyzed. The characters important for the larvae identification are given particular attention. A classification key for the naupliar and cyprid larvae of White Sea barnacles is proposed.     

Comparative analysis of genetic variability of white sea cod (Gadus morhua marisalbi) at allozyme and microsatellite markers

Variability of cod spawning and feeding schools from Kandalaksha Bay of the White Sea, was examined at six allozyme and eight microsatellite loci. The degree of genetic differentiation at allozyme loci constituted θ = 0.36% [95% bootstrap interval 0.0458; 0.6743]. The differentiation estimates obtained using microsatellite markers were higher, θ = 1.33% [0.057; 3.11]. It was demonstrated that the level of genetic diversity in the White Sea cod was lower than that established for the Atlantic cod from Barents Sea using the same set of allozyme and microsatellite markers. The genetic data obtained support the opinion that the White Sea cod is a reproductively independent group formed as a result of the Holocene dispersal of Atlantic cod.     

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.     

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.     

New data on the longevity of coastal cod Gadus morhua Linnaeus, 1758 in the White Sea

The cod, Gadus morhua, is a common and abundant demersal fish in the White Sea coastal zone. The published data on the maximum age of White Sea cod still requires additional documentation, because some authors have noted difficulties in age determination by otoliths of large specimens. To obtain accurate data on the longevity of this species in the White Sea, an image analysis of thin‐sections of otoliths was made for age estimation. Research surveys in the Chupa Inlet and adjacent waters of the Kandalaksha Bay were conducted in June to August from 2007 to 2013. The five largest specimens of a total of 3564 captured fish were selected for age determination. Age of these largest individuals ranged between 7 and 12 years, total length and weight varied from 60.2 to 77.0 cm and from 2.4 to 6.1 kg, respectively. According to the data, maximal White Sea cod longevity is greater than in previously published data, and demonstrates similar longevity to conspecifics from the Baltic and North seas, whereas its life cycle is much shorter than cod from the Northeast Arctic, Iceland, Greenland, Newfoundland and Labrador stocks.     

Distribution of the Harp Seal Whelping Grounds in the White Sea 1960s–1990s

Analysis of air survey data has shown that from the 1960s to the 1990s the whelping grounds of the harp seal Phoca groenlandica formed at the end of February through the first days of March in two regions of the White Sea: in the eastern part of Bassein and in Gorlo. The areas of the whelping grounds varied depending on the current ice conditions. It was recorded that, despite ice conditions unfavorable for the pups' survival that developed in some years, in general the ice regime of the White Sea was favorable for reproduction of the White Sea population of the harp seal.     

The biogeochemical background and trace metal accumulation by brown algae of the genus <Emphasis Type="Italic">Fucus</Emphasis> in coastal waters of the Sea of Japan,the Sea of Okhotsk,and the White Sea

The ranges of background concentrations of Fe, Mn, Zn, Cu, and Cd in Fucus algae from the Sea of Japan, the Sea of Okhotsk, and the White Sea were determined. The lower background threshold of element concentration was calculated as Me₁₅–2MAD₁₅, the upper background threshold was determined as Me+2MAD. The upper background threshold of the metal contents in Fucus algae can be used as the maximum permissible regional concentration in assessing pollution levels of marine habitats. Comparison of the Me₁₅–2MAD₁₅ values showed that Fucus algae of the White Sea had increased Mn and decreased Cd concentrations compared to those in Pacific algae. The concentrations of Zn were higher in Fucus algae of the Sea of Japan than in macrophytes from the White Sea and the Sea of Okhotsk. The background concentration range of Fe in Fucus algae of the Sea of Japan was much narrower compared to that in their counterparts from the White Sea and the Sea of Okhotsk. The background metal concentrations in Fucus algae are specific to a sea region; their variations are connected not only with the trace element contents in abiotic components of the environment, but also with the functioning of coastal ecosystems.     

Changes in the diet of the coastal cod <Emphasis Type="Italic">Gadus morhua marisalbi</Emphasis> in the Kandalaksha Gulf of the White Sea under conditions of increased abundance of three-spined stickleback <Emphasis Type="Italic">Gasterosteus aculeatus</Emphasis>

The data on feeding of coastal cod Gadus morhua marisalbi in the area of the Chupa Bay (Kandalaksha Gulf of the White Sea) are presented. In the food spectrum of cod, over 25 cm long fish and their eggs dominated (77.5% by frequency of occurrence and 91.7% by weight). Other groups of food organisms occupied a secondary place. Among fish, three-spined stickleback Gasterosteus aculeatus was the most prominent food item in the diet of cod (48.3% by weight). The published data on long-term changes of the diet of cod are considered, which are mostly related to considerable fluctuations of the abundance of three-spined stickleback in the White Sea. It is shown that, at present, three-spined stickleback again plays an important role in the diet of the White Sea cod     

Quantitative Phylogenomics of Within-Species Mitogenome Variation: Monte Carlo and Non-Parametric Analysis of Phylogeographic Structure among Discrete Transatlantic Breeding Areas of Harp Seals (Pagophilus groenlandicus)

Phylogenomic analysis of highly-resolved intraspecific phylogenies obtained from complete mitochondrial DNA genomes has had great success in clarifying relationships within and among human populations, but has found limited application in other wild species. Analytical challenges include assessment of random versus non-random phylogeographic distributions, and quantification of differences in tree topologies among populations. Harp Seals (Pagophilus groenlandicus Erxleben, 1777) have a biogeographic distribution based on four discrete trans-Atlantic breeding and whelping populations located on “fast ice” attached to land in the White Sea, Greenland Sea, the Labrador ice Front, and Southern Gulf of St Lawrence. This East to West distribution provides a set of a priori phylogeographic hypotheses. Outstanding biogeographic questions include the degree of genetic distinctiveness among these populations, in particular between the Greenland Sea and White Sea grounds. We obtained complete coding-region DNA sequences (15,825 bp) for 53 seals. Each seal has a unique mtDNA genome sequence, which differ by 6 ~ 107 substitutions. Six major clades / groups are detectable by parsimony, neighbor-joining, and Bayesian methods, all of which are found in breeding populations on either side of the Atlantic. The species coalescent is at 180 KYA; the most recent clade, which accounts for 66% of the diversity, reflects an expansion during the mid-Wisconsinan glaciation 40 ~ 60 KYA. F_ST is significant only between the White Sea and Greenland Sea or Ice Front populations. Hierarchal AMOVA of 2-, 3-, or 4-island models identifies small but significant Φ_SC among populations within groups, but not among groups. A novel Monte-Carlo simulation indicates that the observed distribution of individuals within breeding populations over the phylogenetic tree requires significantly fewer dispersal events than random expectation, consistent with island or a priori East to West 2- or 3-stepping-stone biogeographic models, but not a simple 1-step trans-Atlantic model. Plots of the cumulative pairwise sequence difference curves among seals in each of the four populations provide continuous proxies for phylogenetic diversification within each. Non-parametric Kolmogorov-Smirnov (K-S) tests of maximum pairwise differences between these curves indicates that the Greenland Sea population has a markedly younger phylogenetic structure than either the White Sea population or the two Northwest Atlantic populations, which are of intermediate age and homogeneous structure. The Monte Carlo and K-S assessments provide sensitive quantitative tests of within-species mitogenomic phylogeography. This is the first study to indicate that the White Sea and Greenland Sea populations have different population genetic histories. The analysis supports the hypothesis that Harp Seals comprises three genetically distinguishable breeding populations, in the White Sea, Greenland Sea, and Northwest Atlantic. Implications for an ice-dependent species during ongoing climate change are discussed.     

Intraspecific variability in the “vowel”‐like sounds of beluga whales (Delphinapterus leucas): Intra‐ and interpopulation comparisons

The beluga whale (Delphinapterus leucas) has a rich and complicated vocal repertoire. However, different populations use similar and common types of signals. We studied physical features of one of these types, “vowels,” in three Russian populations: the White Sea population (European North), the Chukotka population (the Bering Sea, Chukotka), and the Okhotsk Sea population (Russian Far East) as well as in four summer aggregations of the White Sea belugas over several years in duration. The pulse repetition rate (PRR) at half of the duration of the signal was measured. We found that the PRR of “vowels” collected in the same summer aggregation during different years is stable in time but varies between locations. The degree of variation corresponds with the geographic distance between different locations. Significant differences were discovered between populations separated by thousands of kilometers, and to a lesser extent, between summer aggregations inhabiting different bays of the White Sea. The variation in PRR between the locations can be caused by the divergence of signals owing to the accumulation of random errors during transmission of these signals from generation to generation, which progressed independently in different summer aggregations and populations.     

Species composition and distribution of ichthyoplankton in the White Sea in July 2003

On the basis of an ichthyoplankton survey made in July 2003 in Kandalaskha Gulf, the Basin, the Gorlo Strait, and the Voronka the species composition and distribution of fish eggs and larvae are investigated. The ichtyoplankton comprises 17 fish species, of which the majority (11) were boreal forms. Other fish were represented by arctic species (2) and arctic-boreal species (4). The traits of distribution of abundantly caught species are considered in detail: larvae of the White Sea oligovertebrate herring Clupea pallasii marisabli, eggs of the dab Limanda limanda, larvae of the northern sand lance Ammodytes marinus, and of the capelin Mallotus villosus villosus. The presence of all larvae of White Sea herring only within Kandalaskha Gulf is considered to be evidence supporting the hypothesis suggested by Dmitriev (1946) on the absence of their drift beyond large gulfs of the White Sea. The natural barrier for mutual exchange with early developmental stages of fish between the White Sea and the Barents Sea in summer may be a developed hydrologic front in the boundary area of the Basin and Gorlo Strait, discovered in the course of the survey. This front causes their death by thermohaline shock in the abrupt gradient zone.     

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.     

Temperature induced anaerobiosis in two populations of the polychaete worm Arenicola marina (L.)

Temperature dependent changes in the mode of energy metabolism and in acid-base status were studied in the range from −1.7 to 26 °C in two populations of Arenicola marina collected in summer as well as in winter from intertidal flats of the North Sea (boreal) and the White Sea (subpolar). Extreme temperatures led to an accumulation of anaerobic end products, indicating the existence of both a low and a high critical temperature, beyond which anaerobic metabolism becomes involved in energy production. In summer animals from the North Sea the high critical temperature was found at temperatures above 20 °C, and the low critical temperature below 5 °C. Latitudinal or seasonal cold adaptation lead to a more or less parallel shift of both high and low critical temperature values to lower values. Between critical temperatures intracellular pH declined with rising temperature. Slopes varied between −0.012 and −0.022 pH- units/°C. In summer animals from the North Sea, the slope was slightly less than in White Sea animals, but differences appeared independent of the season. However, slopes were no longer linear beyond critical temperatures. A drop in intracellular pH at low temperatures coincided with the accumulation of volatile fatty acids in the body wall tissue of North Sea animals. A failure of active pH_i adjustment is held responsible for the reduced ΔpH_i/ΔT at temperatures above the high critical temperature. Extracellular pH was kept constant over the whole temperature range investigated. The ability of North Sea animals to adapt to temperatures beyond the critical temperature is poor compared to White Sea specimens. The larger range of temperature fluctuations at the White Sea is seen as a reason for the higher adaptational capacity of the subpolar animals. A hypothesis is proposed that among other mechanisms critical temperature values are set by an adjustment of mitochondrial density and thus, aerobic capacity. Accepted: 20 August 1996