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This study presents the results of lithological, diatom, geochemical analyses and radiocarbon chronology of the bottom lake sediments and peat bogs in the central part of the Onega Peninsula (the southern coast of the White Sea): Lake Maloye Murakanskoye (11.0 m a.s.l.), Lake Zhirovskoye (9.5 m a.s.l.), Lake Murakanskoye (7 m a.s.l.), and the Gorbovatiy Mokh bog (6.5 m a.s.l.). The bottom topography and sediments of Lake Murakanskoye were examined using sonar and ground penetration radar (GPR) survey, whereas in the other locations only the water depth was measured. Then, the digital models of the lake bottom topography were created. As an additional indicator of the relative sea-level (RSL) position, we used data on the altitude of the coastal terraces. Evidences of two transgressions in the White Sea (late glacial and Middle Holocene) are revealed. The transgressions were interrupted by two regressions (Early and Late Holocene). Our studies do not allow us to make a clear conclusion about the time and maximum level of the late glacial transgression. However, we may suggest that its level was above 11 m a.s.l. The regression of the Early Holocene started before 10.6–10.2 ka cal BP when the water level in the study area dropped below the altitude of 11m. At 9.4–9.1 ka cal BP the RSL was at an altitude of ca 7m. The Middle Holocene transgression (Tapes) started after 8.4 ka cal BP. The maximum level was reached before 7.4 ka cal BP and did not exceed an altitude of 9.5 m. The RSL stabilized at an altitude about 8.5–8 m during 7.4–6.0 ka cal BP. During 6.0–3.9 ka cal BP RSL very slowly decreased or fluctuated by the level of 8–7 m. RSL began to fall from the 7 m altitude about 4.0–3.9 ka cal BP and by 2.7–2.3 ka cal BP the sea-level reached 4.5 m. After that RSL dropped to its modern position. During the last 4.0 ka cal BP the rate of RSL fall was approximately 0.17–0.18 cm/year. [ABSTRACT FROM AUTHOR]

Fiard coasts are common on the periphery of the areas previously covered by ice sheets. The conditions in such areas are favorable for separation of bays and straits from the sea. As a result of the glacial isostatic adjustment of the area the fiards would be transformed into coastal lakes. To discover the regularities of evolution of such water bodies, we studied topography, sea and lake sediments, hydrology and diatom associations of meromictic Lake Kislo-Sladkoe at the Karelian Coast of the Kandalaksha Bay, the White Sea, Russia (66°32′54″N, 33°08′05″E). Detailed geomorphological, geodetic, bathymetric, and aerial imagery field works have been completed on the coastal area. We built a Digital Elevation Model (DEM) of the coast and seabed. Radioisotope dating (210Pb, 14С), grain size distribution, loss on ignition, C org /N org ratio and diatom analysis have been completed for the entire 1.5-m sequence of the Lake's sediments. Currently, the Lake Kislo-Sladkoe communicates with the sea through a rising sill. We have established that the water body is meromictic due to its upper water layer being of variable salinity, middle layer comprising of aerated salty water, and the near-bottom water layer being anaerobic. However, several-year-long periods of water stratification alternate there with occasional late-autumn or early-winter flushes. The water body evolution falls into four stages: (1) a strait with an active hydrodynamic environment (prior to 1500–1560s), (2) a strait with a variable hydrodynamic environment (1500–1560s to 1850–1890s), (3) a semi-isolated lagoon with a quiet hydrodynamic environment (1850–1890s to early 1950s), and (4) a meromictic lake at an early stage of separation from the sea (early 1950s to present). We show how coastal processes on fiard coasts change the mode and duration of isolation of coastal water bodies from the sea. Based on the assessment of the rate of the post-glacial rebound and hydrological conditions of the coastal area we propose an approach to estimating the duration of transitional phase between a marine bay or strait and freshwater lake, including its meromictic stage. We predict that the meromictic stage of the lake will be completed no earlier than c. 100–200 years after the sill rises above the tidal zone. [ABSTRACT FROM AUTHOR]

This paper discusses the results of siliceous microfossils studies performed in a "staircase" of four isolation basins (33.7 m–2.9 m a.s.l.) on Big Solovetskiy Island (Solovki Archipelago, the White Sea). Diatoms were used as a primary group for paleoinferences, while chrysophyte cysts and sponge spicules also demonstrated high indicative potential. In all study lakes, the siliceous microfossils stratigraphy revealed three main stages of their evolution, i.e. large-basin, transitional and small-lake stages, each characterized by certain composition of the diatom assemblages and floristic diversity, relative abundances of chrysophyte cysts and sponge spicules, and siliceous microfossils concentrations. In the uppermost lake, glaciolacustrine environments unfavorable for aquatic biota existed during the large-basin stage. The proglacial lake stage terminated prior to ca. 10.4 cal ka BP, followed by a (semi)terrestrial episode before the transition to small-lake environments. In the other three lakes, marine environments were inferred at the earlier stage, characterized by the predominance of marine and brackish-marine diatoms, increased proportions of sponge spicules and low "cysts to diatoms" ratio. At the transitional marine-freshwater stage, mass growth of small fragilarioid diatoms and decreased abundances of spicules indicated unstable environments, while increased proportions of cysts pointed to progressive freshening of the basins. The duration of the marine-freshwater transition expectedly prolonged from ca. 200 yr in the upper basin (16.6 m a.s.l) to ca. 500 yr in the lowermost lake (2.9 m a.s.l.). The isolation from the sea took place between ca. 6.3 and 1.4 cal ka BP. At the small-lake stage, siliceous microfossils stratigraphies reflected local specifics of the basins and their catchments. We argue that besides traditionally used diatom data, relative and absolute abundances of siliceous microfossils also possess high indicative value for isolation basin studies. Our study demonstrated that marine waters on Big Solovetskiy Island never reached ca. 34 m a.s.l. during the Holocene, unlike the western coast of the Onega Bay where the Preboreal marine intrusion was recorded even at higher elevated localities. Different rates and amplitudes of shoreline displacement are thus suggested for the inner and outer parts of the Onega Bay. During the mid-Holocene Tapes transgression, before ca. 6.3 cal ka BP, the relative sea level on Big Solovetskiy Island exceeded 17 m a.s.l. The average estimated rates of the shoreline retreat during the second half of the Holocene gradually decreased from 0.28 cm year−1 to 0.2 cm year−1, indicating slowed isostatic uplift. [ABSTRACT FROM AUTHOR]

The White Sea is a semi-enclosed Arctic marginal sea receiving a significant loading of freshwater (225–231 km 3 yr −1 equaling an annual runoff yield of 2.5 m) and dissolved organic matter (DOM) from river run-off. We report discharge weighed values of stable oxygen isotope ratios (δ 18 O) of −14.0‰ in Northern Dvina river for the period 10 May–12 October 2012. We found a significant linear relationship between salinity (S) and δ 18 O (δ 18 O=−17.66±0.58+0.52±0.02×S; R 2 =0.96, N=162), which indicates a dominant contribution of river water to the freshwater budget and little influence of sea ice formation or melt. No apparent brine additions from sea-ice formation is evident in the White Sea deep waters as seen from a joint analysis of temperature (T), S, δ 18 O and a CDOM (350) data, confirming previous suggestions about strong tidal induced vertical mixing in winter being the likely source of the deep waters. We investigated properties and distribution of colored dissolved organic matter (CDOM) and dissolved organic carbon (DOC) in the White Sea basin and coastal areas in summer. We found contrasting DOM properties in the inflowing Barents Sea waters and White Sea waters influenced by terrestrial runoff. Values of absorption by CDOM at 350 nm ( a CDOM (350)) and DOC (exceeding 10 m −1 and 550 µmol l −1 , respectively) in surface waters of the White Sea basin are higher compared to other river-influenced coastal Arctic domains. Linear relationship between S and CDOM absorption, and S and DOC (DOC=959.21±52.99–25.80±1.79×S; R 2 =0.85; N=154) concentrations suggests conservative mixing of DOM in the White Sea. The strongest linear correlation between CDOM absorption and DOC was found in the ultraviolet (DOC=56.31±2.76+9.13±0.15×a CDOM (254); R 2 =0.99; N=155), which provides an easy and robust tool to trace DOC using CDOM absorption measurements as well as remote sensing algorithms. Deviations from this linear relationship in surface waters likely indicate contribution from different rivers along the coast of the White Sea. Characteristics of CDOM further indicate that there is limited removal or change in the DOM pool before it exits to the Barents Sea. [ABSTRACT FROM AUTHOR]

During 2009–2012 stocks of the bivalve Arctica islandica (Linnaeus, 1767) (Ocean quahog) in Kandalaksha Bay (the White Sea) has been assessed using a side-scan sonar, grab sampling and underwater photo imaging. Structurally uniform localities were highlighted on the basis of side-scan signal. Each type of a signal reflects combination of sediment type, microtopography and structural characteristics of benthic community. The distribution of A. islandica was the predominant factor in determining community structure. Seabed attributes considered most significant were defined for each type of substrate type. Relations of sonar signal and sediment type were used for landscape mapping based on sonar data. Community characteristics at known localities were reliably interpolated to the area of survey using statistical processing of geophysical data. A method of integrated sonar and sampling data interpretation for high-resolution mapping of A. islandica by biomass groups, benthic faunal groups and associated habitats was developed. [ABSTRACT FROM AUTHOR]

A number of layers with macroscopic imprints have been discovered in the Ediacaran deposits in the southeastern White Sea region during 40years of the study. Two fossil assemblages of the Flinders-style preservation are the most abundant and well studied. Comparison of the taxonomic and quantitative composition of biota as well as the characteristics of the microbial surfaces, assumed as the habitation substrate of these Ediacaran organisms, was assessed for these two fossil assemblages. Analysis of size-frequency distribution using a statistical data manipulation program R allows recognition of different size modes, reflecting different stages of sea floor colonization by benthos. On the basis of the received data, the community structure of such fossil assemblages was reconstructed for the White Sea Basin for the first time. The fossil assemblages display the variations of development of similar communities of the benthic Ediacaran organisms, reflecting seasonal colonization of the sea bottom by larvae of mobile and sessile benthos, immigration of the adult individuals of mobile benthos and seasonal conditions of microbial mats associated with these communities. [ABSTRACT FROM AUTHOR]

Abstract: Coastal environments of Kandalaksha Gulf in the White Sea (Russia) despite nature conservation efforts are heavily influenced by human activities. Biological effects of complex environmental pollution, including organic substances, heavy metals, and oil hydrocarbons, were assessed in widely distributed marine invertebrates, Gammarus duebeni (Crustacea, Amphipoda) and Mytilus edulis (Mollusca, Bivalvia), collected from a series of anthropogenically-impacted areas and distanced reference sites in Kandalaksha Gulf. The parameters of intracellular protein degradation pathways such as cytosol calpain system and lysosomal cathepsins B (CatB) and cathepsin D (CatD) were studied. The response reactions observed in invertebrates vary in specificity and ranged from adaptive to destructive depending on the total contaminant level and the nature of predominant pollutant. The ecological relevance of studied parameters as biomarkers was confirmed by their ability to indicate both expose to pollutants and adverse effects at the organism level. [Copyright &y& Elsevier]

The mineral ikaite (CaCO 3 ·6H 2 O) and its pseudomorphs (glendonite) are considered as important paleoclimate indicators in the geological record. Here we examine the youngest known glendonites, their host concretions, and bivalve shells fossilized within these host concretions from the White Sea, north-western Russia. We applied mineralogical, geochemical and isotopic methods to shed new light on the paleogeographic and geochemical environments during ikaite precipitation and ikaite-calcite transformation. We show that White Sea glendonites are so far the youngest known glendonites in the world (4.1 ± 0.4 cal thousand years before present). Ikaite precipitation occurred during the cold winter months, accompanied by the formation of extensive sea ice and presence of decaying organic matter, which resulted in a small negative Ce anomaly and negative δ13C values. Increasing temperature led to ikaite dehydration and subsequent cementation with aragonite or amorphous calcium carbonate, containing elevated concentrations of Ba and Sr. Needle-like cements within glendonites display small negative Ce anomalies and precipitated from pore waters derived from seawater. The high‑magnesium calcite forming the host concretion precipitated in the sulfate-reduction zone from pore waters derived from seawater. The geochemistry of these pore waters was modified by interaction with clastic components of the host sediments, resulting in δ18O values comparable to those of dissolved inorganic carbon (DIC) and almost flat Post Archean Australian Shale (PAAS)-normalized rare earth element patterns. Therefore, we show that glendonites can be used as a proxy for near-freezing bottom water temperatures at least seasonally during the cold winter months. Changes in the geochemical composition of carbonate phases within the glendonites and host concretions can be used to determine successive changes in the geochemical environment during their formation. • Values of δ18O in glendonite and shell is attributed to precipitation in different seasons and Holocen Periods. • Th U dating of glendonites revealed formation during the Subboreal Holocene Period. • The chemical composition of different carbonate types depends on its mineralogical composition. • Results of microprobe analyses indicate changes in geochemical environment of precipitation and diagenesis. [ABSTRACT FROM AUTHOR]

Abstract: Revised diatom and new dinoflagellate cyst and benthic foraminiferal data from the eastern Baltic Sea have refined our understanding of Eemian (Last Interglacial; 131–119.5 ka) sea-level change on the Russian Karelia, a former seaway linking the Baltic to the White Sea. Results from Peski, eastern Baltic show the initiation of marine conditions just before 131 ka in the latest Saalian, after the opening of a connection to the North Sea. Following the onset of the Eemian marine highstand and the opening of the White Sea connection at around 130.25 ka, near-fully marine conditions persisted in the eastern Baltic area for ca 6 kyr, until ca 124 ka. For most of the Eemian, a strong thermal stratification in the eastern Baltic resulted from an Arctic and possible North Atlantic water component from the White Sea merging with warmer waters from the North Sea. From ca 124 ka, decreasing salinity indicates the end of the marine highstand and a simultaneous closure of the Baltic Sea–White Sea connection, i.e. a duration of ca 6 kyr for this seaway. The main influence of White Sea inflow appears to be restricted to the eastern Baltic area, although a large submerged area in the Russian Karelia associated with temperate Atlantic waters could have assisted in creating a more oceanic climate for Central Europe. [Copyright &y& Elsevier]

Abstract: The composition and distribution of the main unicellular eukaryotic groups (diatom algae, ciliates, dinoflagellates (DF), other phototrophic (PF) and heterotrophic flagellates (HF)) were investigated in sandy sediments at five stations allocated across the tidal sheltered beach of the White Sea. Overall, 75 diatoms, 98 ciliates, 16 DF, 3 PF and 34 HF species were identified; some are new records for the White Sea. Common species for each group are illustrated. Diatoms and ciliates showed high alpha-diversity (species richness per sample), whereas flagellates were characterized by high beta-diversity (species turnover across the intertidal flat). Each group demonstrated its own spatial pattern that was best matched with its own subset of abiotic variables, reflecting group-specific responses to environmental gradients. Species richness increased from the upper intertidal zone seaward for ciliates but decreased for HF, whereas autotrophs showed a relatively uniform pattern with a slight peak at the mid-intertidal zone. Across the littoral zone, all groups showed distinct compositional changes; however, the position of the boundary between “upper” and “lower” intertidal communities varied among groups. Most of the species found at Ryazhkov Island are known from many other regions worldwide, indicating a wide geographic distribution of microbial eukaryotic species. [Copyright &y& Elsevier]

Abstract: The aim was to uncover factors that influence short-term (decade) flora dynamics and species richness of northern marine islets characterized by poor flora and weak anthropogenic pressure. The study used presence–absence data of vascular plant species on 100 small uprising islets of the Kandalaksha Gulf of White Sea (Northern Karelia, Russia). We investigated the influence of islands' attributes on species richness and rates of flora dynamics. Two island types were analyzed separately: younger, stone-like and older, islet-like (which generally are larger and have higher diversity of habitats). Sampled islands were studied via classical biogeographical per island approach and metapopulation per species approach. Stone-like islands had noticeably poorer flora with higher rates of immigration and extinction when compared to those of islet-like islands. The species number for islet-like islands correlated positively with number of habitats, abundance of different habitat types and island area. Species richness of stone-like islands correlated positively only with number of habitat types. Plant species associated with birds, crowberry thickets and coastal rocks were the most stable, and the species of disturbed habitats were significantly less stable. Floristic changes that have occurred have been caused by the massive establishment of new species rather than the extinction of pre-existing taxa. Thus, most of these islands are still in the colonization (assortative) stage. While we found no relationship between island area and species number for stone-like islands, this relationship was seen on islet-like islands. [Copyright &y& Elsevier]

Abstract: The structure of the macrozoobenthic community in 2003–2004 in the southern part of the Onega Bay along a salinity gradient showed the poorest fauna (one species) was found in the estuarine area. In the open part of the bay the species richness up to 64 species. In the study area, as a whole, the zoobenthos abundance varied from 51 to 4590ind.m−2, biomass – from 0.51 to 651.4gm−2 and lower values occurred in the estuarine part of the Onega Bay. The Shannon diversity index [log2 basis] varied considerably – from 0.69 bits in the mouth of the Onega River up to 4.56 bits at the marine stations. Liner multiple regression analysis showed that species richness is related primarily to depth, distance, temperature and the amount of C org. in sediments; Shannon diversity is connected with salinity, temperature, depth, amount of C org. in sediments and chlorophyll concentration in the water. For abundance and biomass the main determining factors were distance and concentration of C org. in sediments. Fresh water input from the Onega River caused variations in the salinity regime in the top of the Bay which indirectly influenced zoobenthic populations via other parameters which changed as a result of river discharge. [Copyright &y& Elsevier]

Abstract: Identifying patterns and drivers of natural variability in populations is necessary to gauge potential effects of climatic change and the expected increases in commercial activities in the Arctic on communities and ecosystems. We analyzed growth rates and shell geochemistry of the circumpolar Greenland smooth cockle, Serripes groenlandicus, from the southern Barents Sea over almost 70 years between 1882 and 1968. The datasets were calibrated via annually-deposited growth lines, and growth, stable isotope (δ18O, δ13C), and trace elemental (Mg, Sr, Ba, Mn) patterns were linked to environmental variations on weekly to decadal scales. Standardized growth indices revealed an oscillatory growth pattern with a multi-year periodicity, which was inversely related to the North Atlantic Oscillation Index (NAO), and positively related to local river discharge. Up to 60% of the annual variability in Ba/Ca could be explained by variations in river discharge at the site closest to the rivers, but the relationship disappeared at a more distant location. Patterns of δ18O, δ13C, and Sr/Ca together provide evidence that bivalve growth ceases at elevated temperatures during the fall and recommences at the coldest temperatures in the early spring, with the implication that food, rather than temperature, is the primary driver of bivalve growth. The multi-proxy approach of combining the annually integrated information from the growth results and higher resolution geochemical results yielded a robust interpretation of biophysical coupling in the region over temporal and spatial scales. We thus demonstrate that sclerochronological proxies can be useful retrospective analytical tools for establishing a baseline of ecosystem variability in assessing potential combined impacts of climatic change and increasing commercial activities on Arctic communities. [Copyright &y& Elsevier]

Abstract: Catches of Atlantic salmon, Salmo salar, recorded in historical documents from the 17–18th Centuries have been analysed in four locations in the basins of the White and Barents Seas. Atlantic salmon was one of the most valuable products of the local economy in the 17–18th Centuries in the northern Russia. Therefore, catches were well recorded in the account books of state departments and monasteries. Salmon were fished mostly in the lower parts of rivers, using weirs which technologically were not changed over the centuries. This makes fishing effort commensurable and allows comparison of historical catch data of the 17–18th Centuries with statistical data available since the last quarter of the 19th Century. Notable fluctuations of catches, average weight and ratio of different seasonal forms of salmon were revealed. Decreasing catches tended to coincide with relatively colder periods. Comparison of historical and statistical data has shown that catches Atlantic salmon and therefore changes in size of their populations were most probably driven by natural factors before middle of the 20th Century. [Copyright &y& Elsevier]

Abstract: The paper describes the history of herring fisheries in the White Sea, analyses main trends in catches, and discusses factors, which effect herring catches from the end of the 17th Century up to 1930s. First records on the herring fisheries in the White Sea dated from the 16th Century, and by the 18th Century this fishery had become as economically important as the Atlantic salmon and cod fisheries. However, we found that significant spring herring fisheries in Kandalaksha Bay developed only in beginning of the 19th Century. Herring catches showed considerable short-term fluctuations. Assumed reasons for these were biological and physical factors. Among biological factors are fluctuations in size of herring populations, migration of herring schools which make herring available or unavailable for inshore fisheries. And among physical ones are meteorological influences such as wind forces and waves, ice conditions, air temperature, and social pressures, such as market demands and availability of salt and barrels. Accounting for these factors allows for better analysis of long-term trends. Currently our analyses of long-term trends revealed (i) positive relationship between catch size and human population in the area, likely reflecting an increase of fishing effort, and (ii) no relationship between catches and temperature in Western Europe. The latter can be explained by specific climate variation in the White Sea area and high short-term variability of catches. [Copyright &y& Elsevier]

Abstract: Dinophysis acuminata and D. norvegica were observed in plankton net samples during the summer of 2002 from the Kandalaksha Gulf in the White Sea (North European Russia). Prorocentrum lima was found as an epiphyte on subtidal macroalgae in August, but not observed in plankton net samples. Protein phosphatase 2A (PP2A) inhibition measured 127.8ng OA-equivalent/g of mussel (Mytilus edulis) hepatopancreas from samples collected a few days after when Dinophysis was recorded at a density of 1550cellsL−1. Liquid chromatography–mass spectrometry confirmed presence of several classes of lipophilic shellfish toxins associated with Dinophysis spp. in the mussels including okadaic acid, dinophysistoxin-1, pectenotoxins and yessotoxins. No azaspiracid was detected. This represents the first identification of phycotoxicity in the White Sea. [Copyright &y& Elsevier]

Abstract: Elevated concentrations of dissolved and particulate Cd, Cu, Pb and Zn have been determined in the waters of Kandalaksha Bay (White Sea, Russia), following the ice melt in the spring of 2000. Dissolved metal maxima in the surface waters were observed at some stations and concentrations generally decreased with depth. The suspended particulate matter (SPM) comprised a non-lithogenic fraction in the range 12–83%, and had elevated metal concentrations that showed no trend with depth or salinity and was compositionally distinct from the sediments. A log–linear relationship existed between the concentrations of metals in sediments and in SPM and their respective Al concentrations, indicating a source of metal-rich particles, with low Al content, to the Bay. The results suggest that Kandalaksha Bay has been impacted by industrial activity on the Kola Peninsula and that restricted water exchange will hinder its recovery from metal contamination. [Copyright &y& Elsevier]

A comparison of the Black and White Seas, which differ in their tectonic, glacial and climatic history but which share a strong dependence upon limited water exchange with the world ocean, represents an opportunity for the identification of major factors controlling sea level changes during the Lateglacial and Holocene and for the correlation of these changes. Existing data were critically analyzed and compared with the results of geological, geomorphological and palaeohydrological studies obtained by the present authors during the past two decades.We conclude that glacioeustatic processes played a major role in relative sea level changes on most coasts of both areas. However, along several coastlines, other factors overwhelm glacioeustasy during some time intervals. In the Black Sea, water level rose from its minimum position, -100–120 m, at 18–17 ka BP, to -20–30 m at nearly 9 ka BP. In the White Sea, the decreasing trend in relative sea level is well illustrated on the Kola Peninsula and in Karelia, subject to glacioisostatic emergence. A drastic sea level fall from +15 to -25 m occurred with the drainage of glacial lakes in the eastern White Sea (12.5–9.5 ka BP).The Black and White Sea histories changed drastically in the early Holocene or in the beginning of the middle Holocene (9.5–7.5 ka BP) due to the intrusion of water from the Mediterranean and the Barents seas, respectively. During this period, the White Sea developed under the strong influence of the formation of “ice shelves” and “dead ice” blocks, retreating glaciers, as well as of glacioisostatic and related processes. The Black Sea history, however, was determined by water exchange with the Mediterranean via the shallow Dardanelles and Bosporus straits (outflow from the Black Sea 10–9.5 ka BP and inflow from 9–7.5 ka BP according to various data), and, partially, by river discharge variations caused by climatic changes on the Russian Plain. The hypothesis of a catastrophic sea level rise from -120–150 to -15–20 m nearly 7550 calendar years BP is not supported by our data. Water intrusion from the Mediterranean was fast but not catastrophic.In the Black Sea, periods of high sea levels after the intrusion of Mediterranean waters are dated from four sedimentary complexes, Vityazevian, Kalamitian, Dzhemetian and Nymphaean, from nearly 7.5, 7–6, 5.5–4.5 and 2.2–1.7 ka BP, respectively. A fluctuating pattern of sea level change was established in the White Sea after the drainage of proglacial lakes and intrusion of ocean waters at the end of the early Holocene (nearly 8.5–8.2 ka BP). Major periods of sea level rise in the White Sea are dated from the late Boreal–early Atlantic (8.5–7.5 ka BP), late Atlantic (6.5–5.2 ka BP), middle Subboreal (4.5–4 ka BP) and middle Subatlantic (1.8–1.5 ka BP). Fluctuations of relative sea level during the middle and late Holocene were possibly on the order of several meters (from +2–3 to -2–3 m in the Black Sea and from +3–5 to -2–3 m in the White Sea). Lower estimates of regressive stages are principally derived from archaeological data on ancient settlements in tectonically submerging deltaic areas and cannot be regarded as reliable.Palaeohydrological analysis does not indicate that intensive (15–25 m or greater) sea level fluctuations were present in the Black Sea or in the White Sea during the middle and late Holocene. Instead, such analysis provides independent evidence to support the argument that significant differences in water level between the Black Sea and the Mediterranean could not be maintained for an extended period of time. [Copyright &y& Elsevier]

Rare noisy observations of the dissolved and suspended Cs137, and the dissolved Sr90 collected for years 1985 and 1994, respectively, are utilized through an inverse method to estimate the radionuclide pollution and the mixing time scale, namely the age, of the White and Kara Seas. We demonstrate how uncertainties, such as measurement noise, inhomogeneous station disposition and others depress the identification utility of the radioactive observations in the Arctic Seas to validate regional radioecological models. The special approach estimates the current and mean radionuclide pollution from the rare observations. We found the mean integral amount of cesium (strontium) pollution of the White Sea (in 1985) and Kara Sea (in 1992) did not exceed ∼70 (41) TBq and ∼16 (9) TBq, respectively, and radioactive background of these seas is low in comparing to the Black and Barents Seas. Estimations of the age confirm the fact of the rapid ventilation of the Kara Sea, but not the White Sea. The age ranges from 1–2 years for the Kara Sea till 5–6 years for the White Sea. That factually says about the possibility of the long-term accumulation of radionuclides in the White Sea. [Copyright &y& Elsevier]

Persistent organochlorines (OC) contaminants, including polychlorinated biphenyl (PCB) congeners, Dichlorophenyltrichloroethane (DDT)- and chlordane (CHL) related compounds, hexachlorocyclohexanes (HCH) isomers and chlorobenzenes (CBz) were determined in blubber of harp seals (Phoca groenlandica), ringed seals (Phoca hispida) and bearded seals (Eringnathus barbatus) as well as in fishes and invertebrates from the White Sea, in northwest Russia. Highest ∑PCB and ∑DDT concentrations were found in samples from two male bearded seals (means of 4150 ng/g lw and 3950 ng/g lw, respectively). Female harp seals had mean ∑PCB and ∑DDT concentrations of 1070±504 ng/g lw and 619±328 ng/g lw, respectively. Male and female adult ringed seals had similar mean ∑PCB concentrations as harp seals (955±385 ng/g lw and 999±304 ng/g lw, respectively). ∑CHL concentrations ranged from 63±29 ng/g lw in blubber of female adult ringed seals, to 322±156 ng/g lw in adult harp seals and averaged 465 ng/g lw in bearded seals. HCH isomers, mirex and chlorobenzenes were detected in all seal samples but were present at lower levels than ∑CHL, ∑DDT and ∑PCB. Concentrations of ∑CHL, ∑DDT and ∑PCB in ringed seals from the White Sea were within the range reported for the Barents Sea but lower than in ringed seals from the Kara Sea. Temporal trends were investigated by comparing concentrations of OCs in blubber of harp seal pups collected in 1992 with pups of the same age collected in 1998. The declines over the 6 year period ranged from approximately 33% for ∑DDT to 60% for ∑PCB. These declines are consistent with reports of declining concentrations ∑DDT in seawater from the White Sea and inflowing rivers in the 1980''s and early 1990s. The major OC contaminants in fishes from the White Sea were DDT-related compounds and PCBs. Navaga (Eleginus navaga) had the highest concentrations of the 5 fish species studied with mean ∑PCB of 41±6 ng/g wet wt. while lowest mean concentrations were present in cod muscle (16±8 ng/g ww). Concentrations of hexachlorobenzene (HCB), DDT, CHL—related compounds and PCB congeners were strongly correlated with trophic level of the organisms assigned using δ15N values, while β-HCH, γ-HCH and cis-chlordane showed no relationship with trophic level. Food web magnification factors (FWMFs) for p,p′-DDE, α-HCH, oxychlordane and trans-nonachlor the White Sea were similar to those from marine food webs in the Barents Sea and the Canadian arctic, while FWMFs for HCB and PCBs were generally lower. Overall the results suggest that the White Sea marine food differs in terms of the availability of contaminants in comparison to studies of open ocean arctic food webs due to proximity to urban/industrial areas and greater importance of benthic food sources. [Copyright &y& Elsevier]

We studied age and size dependence of pumping and respiration rates, mortality during prolonged air exposure and the changes in behavioural response to cyclic salinity fluctuations combined with elevated temperatures in the White Sea blue mussels Mytilus edulis L. Five age groups (2–9 years) and three size groups: small (S, mean wet tissue mass 0.12 g), medium (M, mean wet tissue mass 0.39 g) and large (L, mean wet tissue mass 0.78 g) were analysed. Respiration rate was measured in closed respirometers. Pumping rate was determined by a laser beam to monitor the changes in water level when the inhalant and exhalant siphons were in separate compartments of the aquarium. To study their response to environmental stress, the mussels were subjected to cyclic salinity fluctuations at normal (10 °C) and elevated (20 °C) temperatures. Two parameters were noted: (1) the salinity at which shell valves either opened or closed at both temperatures, and (2) intra-individual variation of the behavioural response to salinity changes at both temperatures. Size and age affect physiological processes in the blue mussel. The responses of M. edulis to environmental stress including low salinity, elevated temperature and air exposure as well as respiration rate are generally size-dependent. Effects of age on sensitivity to low salinity and survival in air are minor. Pumping rates of mussels are significantly affected by both size and age of the animals. The disproportional decrease of pumping rate is observed at the age of about 7–8 years old. [Copyright &y& Elsevier]

A fundamental question underlying skeletal mineral secretion in marine invertebrates is the extent to which the physico-chemical parameters of seawater (e.g., salinity, temperature) and animal physiology influence their skeletal mineralogy and chemistry. Groups with more complex mineralogies, such as bryozoans, have the ability to actively control their own skeletal composition in response to environmental conditions and could be considered indicators of global environmental change. Thus, this study aims to reveal how the unique environmental conditions of low salinity (circa 24–26), prominent seasonality and semi-isolation of the White Sea (WS) subarctic region caused by the last glaciation (12,000 ya) affect the carbonate skeletal geochemical composition of bryozoans. X-ray diffraction analysis of 27 bryozoan taxa (92 specimens) revealed a completely monomineral calcite composition of skeletons with a mean value of 6.9 ± 1.8 mol% MgCO 3 and moderate variability at the species and family levels. Most specimens (43.5%) precipitated skeletal magnesium within the range of 7–8 mol% MgCO 3. Regional analysis of the mineralogical profile of the White Sea bryozoans shows that they differ statistically from bryozoan species living in the neighbouring Arctic and temperate Scotland regions in terms of magnesium content in calcite (approximately 7 mol% MgCO 3 in the White Sea versus 5 mol% MgCO 3 in other regions). We suggest that the effect of low salinity on magnesium content was compensated by relatively high summer temperature causing rapid growth and calcification and possibly resulted in the increased Mg contents in the White Sea (WS) bryozoans. However, on a local scale (between sampling locations), the influence of temperature and salinity could be excluded as a source of observed intraspecific variability. The concentration of MgCO 3 in skeletons of the studied bryozoans is controlled by other environmental variables or is species-specific and depends on the physiological processes of the organisms. • Chemical composition of the White Sea bryozoans deviates from nearby regions. • Rapid summer calcification and growth stimulates high skeletal magnesium content. • Taxonomic/phylogenetic patterns controls skeletal magnesium content locally. [ABSTRACT FROM AUTHOR]

The study presents the results of the field expedition in the Russian Arctic held by a group of NGO members, scientists and volunteers in summer-autumn 2020 in the Arkhangelsk Region (Russia). The survey showed microplastics presence in 7 out of 13 remote and sparsely inhabited locations in lakes, rivers and coastal areas of the White Sea basin, with microplastic particle average concentration 1.14 part/m3, that is in agreement with other recent regional studies. Mostly PE, PET and PVC were found. A simple, cheap and easy-to-use microplastics monitoring protocol was developed and tested to be used by volunteers in remote Arctic communities. Video-lectures and tutorials are available online in an open-aсcess mode. 200 volunteers from polar communities are trained in microplastic sampling and litter separation, learning about microplastic pollution, including local residents, schoolchildren and students. • MP was found in 7 out of 13 samples from the White Sea basin. • Remote and sparsely populated areas of the Russian Arctic are polluted with plastic litter. • Robust and easy-to-use MP sampling protocol was developed for use in citizen-science. • 200 volunteers from polar communities are trained in MP sampling, including local residents, schoolchildren and students. • Educational materials, eco-lessons and field trip diary are available online in an open-aсcess mode. [ABSTRACT FROM AUTHOR]

To date, it has been increasingly clear, that microbiota plays essential role in the host microorganism. Due to high phylogenetic diversity and wide distribution understanding of gut microbiota of fish is ambiguous. We elucidate previously undescribed diversity of bacteria in the White Sea fish posterior intestine based on 16S rRNA metabarcoding: shorthorn sculpin (Myoxocephalus scorpius), lumpfish (Cyclopterus lumpus) arctic flounder (Liopsetta glacialis), cod (Gadus morhua), and herring (Clupea pallasii). Proteobacteria were most abundant in all the samples. All datasets contained high number of reads corresponded to Psychrobacter , Halomonas , Pseudoalteromonas and Vibrio abundant in the White Sea water.Vast majority of bacterial reads corresponded to the Vibrionaceae (Aliivibrio , Vibrio , and Photobacterium). It is in accordance with our previous study focused on bioluminescent bacteria, where we isolated strains of these genera from the same fish intestine samples. The datasets of G. morhua and Cl. pallasii were enriched by reads of Shewanella (also isolated previously microbiologically due to luminescence of some its strains); the datasets of G. morhua and M. scorpius contained high number of Mycoplasma , which is in line with previous reports on the microbiome of marine fish gut from other geographical regions. Collectively, on the one hand, the study is a confirmation of known data on marine fish gut microbiome, on the other hand, it reveals some specific patterns of White Sea fish gut microbiota, e.g. presence of bacteria common for water from this region. • The diversity of the White Sea fish gut bacteria was described. • All datasets contained high number of Psychrobacter , Halomonas , Pseudoalteromonas and Vibrio abundant in the White Sea water. • Vast majority of bacteria corresponded to the Vibrionaceae. • The data is in accordance with previous microbiological result on bacteria isolation. [ABSTRACT FROM AUTHOR]

The spring blooms of phytoplankton play a key role in the functioning of marine ecosystems in the polar regions. A spring bloom in the Subarctic White Sea was observed in order to determine the effect of ice cover on the distribution, composition, and temporal changes of phytoplankton communities. The obtained results clearly show that in the White Sea, as in other freezing Arctic seas, ice melting and ice removal both play an essential role in the onset and development of spring phytoplankton blooms. This facilitates the release of ice algae and ice-pelagic algae into the water, as well as the rapid development of true planktonic taxa within the euphotic zone. One major peak of algal biomass is associated with ice removal while the other is recorded in the early summer. Comparison of our results with earlier data from 1960s to 1990s indicated strong year-to-year variation in terms of ice removal, the onset of the spring bloom, and the abundance and composition of the dominant phytoplankton taxa. • In the White Sea ice removal determines the onset and development of spring bloom. • 130 taxa of phytoplankton were determined during spring bloom in the White Sea. • Three major groups of algal communities were revealed during spring bloom. • High year-to-year variation in ice removal and spring bloom features was recorded. [ABSTRACT FROM AUTHOR]

This study is focused on the analysis of microplastic concentrations in the surface waters of the White, Barents and Kara Seas. Sampling took place during the "Arctic Floating University 2018" expedition using a manta trawl. Particularly high concentrations of the microplastics were found off the west coast of Novaya Zemlya archipelago with a maximum in a highly productive region – Gusinaya bank. The microplastic distribution pattern in the Barents Sea correlates both with the oceanic circulation and the fishing activities. The results show the first recorded estimation of microplastic concentrations in the White Sea with the higher concentrations located in the area affected by the Severnaya Dvina River discharge. Relatively low concentrations of microplastics were found in the Kara Sea. • Concentrations of microplastics in regions of the Barents Sea reach subtropical area values. • Severnaya Dvina River possibly plays the main role in the transfer of microplastics to the White Sea. • Kara Sea remains relatively clean, being separated from the Atlantic water inflow. [ABSTRACT FROM AUTHOR]

Bioluminescence is a spectacular feature of some prokaryotes. In the present work, we address the distribution of bioluminescence among bacteria isolated from the White Sea finfishes. Luminous bacteria are widely distributed throughout the World Ocean. Many strains have been isolated and described for tropical latitudes, while Nordic seas still remain quite a white spot in studying bioluminescence of bacteria. We describe the strains related to the two main genera of luminous bacteria, Photobacterium and Aliivibrio , as well as Shewanella and Vibrio. They are related to families Vibrionaceae and Shewanellaceae of the Gammaproteobacteria class. Here, we at the first time, report the bioluminescence of the Enterobacteriaceae Kosakonia cowanii. Moreover, we applied the polyphasic approach to identify and describe the isolated microorganisms. The data on sequencing, diversity of cell fine structure, and light emission spectra at room temperature on the solid medium are discussed. The bacteria are characterized by features in their light emission spectra. It may reflect possible molecular mechanisms of bioluminescence as well as features of bacterial composition. The obtained data expands the existing body of knowledge about the bioluminescence spread among the bacteria of Nordic latitudes and provides complex information that is crucial for their precise identification. • The data about distribution of bioluminescence among bactreia have has been exanded. • For the first time bioluminescence of the Kosakonia bacterium has been described. • Strains of five genera of luminous bacteria were discovered in the White Sea fish organisms. [ABSTRACT FROM AUTHOR]

The extent of environmental contamination and sources of polycyclic aromatic hydrocarbon (PAH) compounds to sediments of the White Sea are evaluated and compared with previously published results for adjacent Arctic Sea areas. Concentrations of two- to six-ring PAHs of molecular mass 128/278 including perylene and sediment characteristics areconsidered in this investigation. Mean Sigma PAH concentration was 61+/-34 ng/g dw (n=11) for all samples and 87+/-43 ng/g dw (n=6) for pelite-rich samples (>83% pelite). These concentrations are 2/3 times lower than were previously reported for the SE Barents Sea. Concentrations of Sigma PAH and Sigma CPAH in the central White Sea have increased by a factor of 2-5 over pre-industrial background levels based on 210Pb age-dating of one sediment core. Using principal component analysis (PCA), two common factors explained 87.5% of the total variance for the White Sea data. Factor 1 is associated with high-temperature combustion processes and is related to emissions from a local aluminium smelter. Factor 2 is associated mainly with the introduction of petrogenic PAH compounds and perylene into Dvina Bay via the Severnaya Dvina River. A comparison of the White Sea and SE Barents Sea data indicates that similarities exist in the composition of parent PAH compounds. However, based on a comparative analysis of parent PAH ratios and relative contents of alkyl-substituted homologues, acommon atmospheric source of anthropogenic pollutants can be ruled out. Further investigations are needed to determine whether sedimentary PAH signatures in areas of the Barents Sea that are in closer proximity to the White Sea are related to emissions from the aluminium smelter. [ABSTRACT FROM AUTHOR]