Baltic Sea Basin Research Articles

A New Shipping Canal Through the Vistula Spit as a Political and Transportation Project

In September 2022, a new shipping canal was opened connecting the Polish part of the Vistula Lagoon to the Baltic Sea. Largely political, the project links the lagoon and the port in Elbląg to the southern part of the Baltic, independent of the Russian Federation. In addition, its economic dimension enables the handling of small ships, as well as supporting tourism and yachting without the need to pass through the Russian-controlled Piława Strait. The scale of the new canal is relatively small—one and a half kilometre long and 25 metres wide. Nonetheless, it is sufficient for the navigation of small marine vessels of up to five-metre draft. The shipping canal through the Vistula Split is certainly not as important as the Corinth or North Sea Canals, still, it frees maritime and tourist traffic from Russian jurisdiction. The planned key port in the Vistula Lagoon is the port in Elbląg, a historic city that was once a member of the Hanseatic League, which brought together all the major cities of the Baltic Sea basin in the 14th and 15th centuries. The purpose of this article is to present the project’s historical context, its urban, technical, and shipping solutions, as well as the correlations between the new transport development and its anticipated impact on the environment (including the natural environment). The findings are complemented by a PESTEL analysis which shows the leading trends that are relevant to the implementation of the project in the region. The analysis identified areas that have a significant effect on the social, political, and economic settings of the new canal.

Mountains of plastic: Mismanaged plastic waste along the Carpathian watercourses

Plastic waste poses numerous risks to mountain river ecosystems due to their high biodiversity and specific physical characteristics. Here, we provide a baseline assessment for future evaluation of such risks in the Carpathians, one of the most biodiverse mountain ranges in East-Central Europe. We used high-resolution river network and mismanaged plastic waste (MPW) databases to map MPW along the 175,675 km of watercourses draining this ecoregion. We explored MPW levels as a function of altitude, stream order, river basin, country, and type of nature conservation in a given area. The Carpathian watercourses below 750 m a.s.l. (142,282 km, 81 % of the stream lengths) are identified as significantly affected by MPW. Most MPW hotspots (>409.7 t/yr/km2) occur along rivers in Romania (6568 km; 56.6 % of all hotspot lengths), Hungary (2679 km; 23.1 %), and Ukraine (1914 km; 16.5 %). The majority of the river sections flowing through the areas with negligible MPW (< 1 t/yr/km2) occur in Romania (31,855 km; 47.8 %), Slovakia (14,577 km; 21.9 %), and Ukraine (7492; 11.2 %). The Carpathian watercourses flowing through the areas protected at national level (3988 km; 2.3 % of all watercourses studied) have significantly higher MPW values (median = 7.7 t/yr/km2) than those protected at regional (51,800 km; 29.5 %) (median MPW = 1.25 t/yrkm2) and international levels (66 km; 0.04 %) (median MPW = 0 t/yr/km2). Rivers within the Black Sea basin (88.3 % of all studied watercourses) have significantly higher MPW (median = 5.1 t/yr/km2, 90th percentile = 381.1 t/yr/km2) than those within the Baltic Sea basin (median = 6.5 t/yr/km2, 90th percentile = 84.8 t/yr/km2) (11.1 % of all studied watercourses). Our study indicates the locations and extent of riverine MPW hotspots in the Carpathian Ecoregion, which can support future collaborations between scientists, engineers, governments, and citizens to better manage plastic pollution in this region.

High-resolution history of oxygen depletion in the SW Baltic Sea since the mid-19th century as revealed by bivalve shells

The Baltic Sea serves as a model region to study processes leading to oxygen depletion. Reconstructing past low-oxygen occurrences, specifically hypoxia, is crucial to understand current ecological disturbances and developing future mitigation strategies. The history of dissolved oxygen (DO) concentration in some Baltic Sea basins has been investigated in previous studies, but temporally well-constrained, inter-annual and better resolved DO reconstructions are still scarce. Here, we present precisely dated, high-resolution DO record since the mid-19th century reconstructed from Mn/Cashell values of Arctica islandica (Bivalvia) collected in the Mecklenburg Bight. According to the data, this area experienced similar low oxygenation during the second half of the 19th century and the late 20th century, but DO variability increased: A 12–15-yr oscillation prevailed in the 19th century, but a 4–6-year period dominated in the late 20th century. Shortly after the onset of the Industrial Revolution around 1850, Mn/Cashell values increased, indicating a DO decrease, probably caused by strong anthropogenic nutrient input. More recently, phosphate levels and inflows of oxygen-rich North Sea water have been identified as major factors controlling the bottom water oxygenation. For example, the increase in DO in the mid-1990s was linked to the decrease in phosphate content and several Major Baltic Inflows. The strong Ba/Cashell rise between the 1860s and the turn of the century most likely reflects changes in diatom community structure rather than a bloom of mass phytoplankton. This is supported by largely unchanged Mn/Cashell and shell growth. Decadal and multi-decadal cycles of shell growth rate correlated strongly with the Atlantic Multidecadal Variability, likely reflecting changes in atmospheric circulation patterns, precipitation rate and riverine nutrient supply. To further improve the management and protection of ecosystems in the Baltic Sea, a larger number of such high-resolution retrospective studies covering long periods of time and large regions are needed.

High-resolution characterization of the development and decay of seasonal hypoxia in the Gulf of Riga, Baltic Sea

The Gulf of Riga is a shallow basin in the eastern Baltic Sea connected to the Central Baltic Sea via shallow straits. Seasonal oxygen depletion occurs in the deep layer of the gulf. We conducted hourly measurements of dissolved oxygen, temperature, and salinity in the deep layer (50 m) of the gulf and observed the full cycle of development and relaxation of hypoxia in 2021. Hypoxia (&amp;lt;2.9 mg l-1) first occurred on 27 June and was observed for 71 days until its complete decay on 22 October. Average oxygen decline of 0.10 mg l-1 d-1 from saturation in mid-April until mid-July and 0.04 mg l-1 d-1 onwards until the end of August were observed. This seasonal pattern was superimposed by short-term variability in time scales from hours to days and was probably caused by inertial oscillations, (sub)mesoscale processes, deep layer currents, and pycnocline movements. Ventilation events with a relatively low impact and duration of up to ten days occurred in the deep layer due to the inflows of the saltier water from the Central Baltic. The inflowed water originated from the upper layer in winter and the thermocline in summer and was almost saturated in oxygen. Mostly mixing with existing oxygen-depleted water in the Gulf of Riga, but also local consumption declined the oxygen levels in the inflow water before it arrived at the observing station. Monthly standard deviations in oxygen varied from 0.3 to 2.8 mg l-1 and illustrated the added value of Eulerian measurements to complement the conventional monitoring.

A New Species of Golden Loach (genus Sabanejewia, Cobitidae) from the Sea of Azov Basin

A new species of golden loach is described from the Don River basin. This species is distinguished from all other Sabanejewia species by the following set of characters: a midlateral row of relatively large 9–16 (more often 13–14) dark blotches along flank usually well developed; no black line along flank; interspaces between midlateral blotches usually with dark pigmentation; some individuals with uniform dark lateral coloration; dorsal fin origin usually in front of pelvic fin origin; body relatively low: body depth noticeably less than the length of the caudal peduncle, usually does not reach 17% standard length—SL, it is contained more than 6 times in SL; dorsal adipose crest on caudal peduncle very weakly developed, ventral crest poorly visible; two black spots at caudal fin base usually merge with each other. Previously, this species was considered conspecific for S. baltica distributed in the Black and Baltic Sea basins, but recent phylogenetic studies have shown that they belong to separate mtDNA phylogenetic lineages.

A New Species of Golden Loach (genus Sabanejewia, Cobitidae) from the Sea of Azov Basin

A new species of golden loach is described from the Don River basin. This species is distinguished from all other Sabanejewia species by the following set of characters: a midlateral row of relatively large 9–16 (more often 13–14) dark blotches along flank usually well developed; no black line along flank; interspaces between midlateral blotches usually with dark pigmentation; some individuals with uniform dark lateral coloration; dorsal fin origin usually in front of pelvic fin origin; body relatively low: body depth noticeably less than the length of the caudal peduncle, usually does not reach 17% standard length—SL, it is contained more than 6 times in SL; dorsal adipose crest on caudal peduncle very weakly developed, ventral crest poorly visible; two black spots at caudal fin base usually merge with each other. Previously, this species was considered conspecific for S. baltica distributed in the Black and Baltic Sea basins, but recent phylogenetic studies have shown that they belong to separate mtDNA phylogenetic lineages

Contrasting distribution and speciation of sedimentary organic phosphorus among different basins of the Baltic Sea

AbstractRecycling of phosphorus (P) from deoxygenated sediments perpetuates eutrophic conditions in parts of the Baltic Sea. Sedimentary organic P is a major source of dissolved P to the water column, but also a sink for permanent P burial. The mechanisms behind these two pathways are, however, largely unknown. Using new methods, we determined P in DNA and phospholipids, which are both found in all organisms. We also identified inositol phosphates that are particularly important in eukaryotes. Sediment cores were collected from contrasting basins in the Baltic Sea to study their relative contribution to the total P pool. We found high DNA‐P/phospholipid‐P ratios in surface sediments from the Bothnian Bay and Bothnian Sea. However, these ratios were low throughout profiles in euxinic Baltic Proper sediments. The elevated ratios present in sediments overlain by oxic bottom waters might indicate the presence of a microbial community stimulated by bioturbation, whereas the low DNA‐P/phospholipid‐P ratios in Baltic Proper sediments likely indicate an energy‐limited microbial community, typical to the “deep biosphere” environment. Inositol‐P was almost absent in euxinic Baltic Proper sediments that had a low total P amount compared to those in the other basins. We suggest that variability in the composition of sedimentary microbial communities among the Baltic Sea basins might cause differences in organic P forms that in turn affects its turnover.

CHEMICAL COMPOSITION OF WATER AND ION FLOW OF RIVERS WESTERN BUG, NAREV AND VISTULA (BALTIC SEA BASIN)

CHEMICAL COMPOSITION OF WATER AND ION FLOW OF RIVERS WESTERN BUG, NAREV AND VISTULA (BALTIC SEA BASIN)

Transformation of Eurasian railway logistics in the context of growing supplies towards East Asian markets

Objective: to analyze trends in the cargo turnover of the ports of the Baltic basin with an emphasis on restoring the volume of port cargo transshipment, starting from the end of 2022. Methods: supply chain modeling, geo-economic analysis and parameterization of the main technical and operational indicators in transport and logistics systems. As a result of the conducted research: the analysis of changes in cargo transshipment at the ports of the Baltic Sea basin of Russia in comparison with the shipment of cargo through the ports of the Azov-Black Sea, the Far-East basin and other directions, the changes of participants from among the world and national sea container operators in the directions through the Russian ports of the Baltic basin, new container lines are given the dynamics of cargo turnover at Russian ports in the context of various types of cargo is also shown.

DICHOTOMY IN THE DISTRIBUTION OF MARITIME ACTIVITY BETWEEN MARINE SUB-REGIONS OF EUROPE

Coastal settlements tend to have higher population density and economic clustering compared to inland territories. The tendency of an increasing socio-economic disbalance in favor of coastal spaces – the coastalization, has attracted the attention of the global academic community. Numerous assumptions are made on the cause of the coastalization phenomenon with the maritime activity and tourism being the primary ones. The aim of this study is to evaluate the role of the coast and tourist seaport infrastructure in the distribution of the population and tourist accommodations in cities across different sea basins of Europe. The research design implies verification of the two hypotheses: the area around the tourist seaport will have H1. The highest population density and H2. The highest density of collective accommodation facilities (CAFs) in the coastal zone of the municipality, decreasing with distance. The methodology has a two-stage structure. Firstly, the quantitative evaluation is done to allocate the tourist seaports of 28 European countries using MarineTraffic database and measure the density of population and CAFs by territorial zones using statistics. Secondly, the qualitative assessment is done presenting highlights of case studies by four sea basins (Baltic Sea, Black and Azov Sea, Northeast Atlantic Ocean, Celtic Sea, and Mediterranean Sea) and six sub-basins. 43 seaports of Europe specialize on tourism (over 90% of inbound ships). Most tourist seaports belong to the Mediterranean basin (58.1%), followed by the basin of the Northeast Atlantic Ocean (25.6%), the Azov-Black (11.6%) and Baltic (4.7%) sea basins. Cities with the tourist seaports are represented by a variety population sizes: from under 50 thousand people to over a million. Despite the differences across sea basins, the general pattern suggests a decline of population density and CAFs with the distance from the tourist seaport. Tourist seaports act as the nuclei of coastalization in Europe. The spatial proximity to the seaport has a positive influence on the density of population – the highest in the territorial zone of 2-5 km distance from the seaport, and an even higher effect on the concentration of CAFs – the highest numbers up to 1 km of the tourist seaport. We should note that population structure and tourism activity of some smaller cities are skewed towards larger adjacent cities, with the agglomeration effect outbreaking the role of the seaport.

No strict host specificity: Brain metacercariae Diplostomum petromyzifluviatilis Müller (Diesing, 1850) are conspecific with Diplostomum sp. Lineage 4 of Blasco-Costa et al. (2014).

Metacercariae of Diplostomum petromyzifluviatilis (Digenea, Diplostomidae) from the brain of European river lamprey Lampetra fluviatilis from the Baltic Sea basin and Arctic lamprey Lethenteron camtschaticum from the White Sea basin were studied with the use of genetic and morphological methods. Phylogenetic analysis based on cox1 marker showed that the parasites of both lamprey species were conspecific with Diplostomum sp. Lineage 4 of Blasco-Costa et al. (2014). The name Diplostomum petromyzifluviatilis Müller (Diesing, 1850) has historical precedence as a species described from the brain of lampreys and should be used in genus nomenclature. There were no morphological qualitative differences between the metacercariae from the two lamprey species but those from L. fluviatilis were larger than those from L. camtschaticum. We expanded the data on the second intermediate hosts and the localization of D. petromyzifluviatilis, showing that its metacercariae occur not only in the brain of lampreys but also in the brain and the retina of three-spined stickleback Gasterosteus aculeatus and the vitreous humour of the perch Perca fluviatilis across the European part of the Palearctic.

Shifting Shores and Stone Age Settlement: The Former Ventspils Lagoon Area, Latvia

ABSTRACT This article considers a newly developed model of Holocene shoreline displacement in the southern part of the former Ventspils Lagoon of the Baltic Sea basin (present-day western Latvia) in relation to data from previous and new archaeological research in the area, assessing the changing pattern of Stone Age settlement and resource utilisation during the Mesolithic and Neolithic. An extensive lagoon was formed at the time of the maximum level of the Ancylus Lake and once again during the Littorina Sea maximum. In the south of the lagoon, the former shores from the two separate phases of the lagoon’s existence lie at similar elevations, providing the conditions for site re-occupation. There were river mouth sites on the continental shore of the lagoon and island sites on the seaward side, whereas in the periods with a low water level, human settlement focused on the relict waterbodies and watercourses within the exposed low-lying terrain of the former lagoon bed. The water-level fluctuations and resulting landscape changes were much more rapid during the Ancylus stage, the loci of settlement and resource exploitation necessarily shifting at fairly short intervals. The two lagoon phases also represent rather different aquatic environments.

Possibility of breeding of Atlantic sturgeon at the Konakovsky fish factory

The results of the analysis and economic calculations for ensuring the entire cycle of growing Atlantic sturgeon from caviar to producers in the Konakovskiy fish factory, and the planned total costs are shown. Information on the financial assessment of the breeding of the Atlantic sturgeon will allow fish farms to assess their ability to keep the Atlantic sturgeon in order to restore the population of this species in the Baltic Sea basin.

A new species of the genus Cottus (Scorpaeniformes, Cottidae) from the Baltic Sea Basin and its phylogenetic placement

The genus Cottus contains more than 60 species that are common in freshwater bodies of northern Eurasia and North America. Despite the abundance of species, this genus has been insufficiently studied in Eastern European rivers and lakes. The new taxon Cottus cyclophthalmus sp. nov. was found in the Neman/Nemunas and Venta river systems (Baltic Sea Basin). Cottus cyclophthalmus is sister and most morphologically similar to Cottus gobio. The new species has the following diagnostic characters: round, protruding (tubular) eyes near front of head; dermal papillae on top and sides of head, naked body, absence of bony prickles, full trunk canal with 32–36 pores. The description of Cottus cyclophthalmus and a new finding of Cottus microstomus improved understanding of the Eastern European biodiversity.

Current and projected hydroclimatic changes in the Baltic and Arctic sea basins in the territories of Belarus and Russia

The article presents an assessment of current changes in air temperature, precipitation, snow and river runoff in the Baltic and Arctic Seas basins in the territories of Belarus and Russia. It is shown that the observed positive air temperature trends during the winter season are associated with the sea level pressure distribution in the North Atlantic and NAO indices. In summer, the temperature growth is correlated strongly with the Atlantic multi-decadal oscillation. Changes in the precipitation regime are synchronized with an increase in the sea level pressure in the baroclinic active zones of the Atlantic Ocean, which led to the precipitation increase in Europe since the second half of the 20th century. Interdecadal precipitation fluctuations in the study region are associated with the dynamics of the circumpolar vortex and Arctic oscillation (AO) indices. In winter, a precipitation increase is observed in the negative AO phase and is caused by an increase in the frequency of southern cyclones. In summer, when the AO phase is negative, the cyclonic activity decreases, and the precipitation growth is associated with convective processes in the atmosphere. Snow precipitation and snow water equivalent are decreasing during recent decades due the air temperature significant growth. That led to the spring floods height decreasing in the region. In the next 30 years, a decrease in the winter air temperature in the Baltic Sea basin and its increase in the Arctic Sea are expected. In summer, the air temperature increase will slow down on the descending AMO branch in the coming decades. In the precipitation regime, the growth of seasonal and daily total precipitation is expected.

Postglacial Expansion Routes and Mitochondrial Genetic Diversification of the Freshwater Pearl Mussel in Europe and North America

The freshwater pearl mussel Margaritifera margaritifera is a unionid species distributed across Northwestern Russia, Fennoscandia, Western and Southwestern Europe, and the Atlantic Coast of North America. In this study, we reconstructed the post-glacial expansion routes of this species based on FST genetic distances and the fact that M. margaritifera distribution is directly connected with salmonid expansion. The freshwater-pearl-mussel populations from North America and Northeastern Europe were the closest groups, judging by FST distances, supporting the concept of the North Atlantic Salmo salar colonization of the Barents and White Sea basins. We also documented that unique haplotypes in the populations of the Baltic and White Sea basins may have originated in isolated glacial refugia in Eastern and Northeastern Europe. The Iberian clade was the most distant group of populations, which is consistent with the previously observed role of the Iberian Peninsula as a glacial refugium. The high genetic diversity in the populations of Northern and Eastern Karelia was facilitated by migrants utilizing complex periglacial hydrological networks and by admixture in the contact zone where the migration flows met. We confirm that this region should be considered as a major center of genetic diversity within the European part of the species’ range.

Quantifying the Physical Impact of Bottom Trawling Based on High-Resolution Bathymetric Data

Bottom trawling is one of the most significant anthropogenic pressures on physical seafloor integrity. The objective classification of physical impact is important to monitor ongoing fishing activities and to assess the regeneration of seafloor integrity in Marine Protected Areas. We use high-resolution bathymetric data recorded by multibeam echo sounders to parameterize the morphology of trawl mark incisions and associated mounds in the Fehmarn Belt, SW Baltic Sea. Trawl marks are recognized by continuous incisions or isolated depressions with depths up to about 25 cm. Elevated mounds fringe a subset of the trawl marks incisions. A net resuspension of sediment takes place based on the volumetric difference between trawl mark incisions and mounds. While not universally applicable, the volume of the trawl mark incisions is suggested as an indicator for the future monitoring of the physical impact of bottom trawling in the Baltic Sea basins.

Triploid forms’ karyotypes of spined loaches from the genus Cobitis (Actinopterygii: Cypriniformes: Cobitidae) of the upper Dnieper and Western Dvina rivers: Analysis of the triploids’ origin

Unisexual forms of lower vertebrates (fish, amphibians, and reptiles) reproduced by parthenogenesis, gynogenesis, or hybridogenesis are represented by diploids, triploids, or tetraploids, whose origin is associated with interspecific hybridization. Among fish species, the highest variability of unisexual polyploids was found in the genus Cobitis. The structure of their genomes and putative parental species holds great interest for the investigation in association with questions about possible evolutionary success. In particular, it serves to elucidate the possible high colonization properties of a few polyploid forms, in contrast to the local history of rather numerous hybrid forms with a limited distribution. Therefore, the aim of this study was to describe the karyotype structure of two newly discovered triploid forms of the genus Cobitis, to analyze their origin and putative parental species. The karyotype structure of 182 spined loach individuals from the Western Dvina River and 91 individuals from the upper Dnieper River of the Smolensk District of Russia was studied. A total of 121 studied individuals from the Western Dvina comprised triploid females with a chromosome number 74 and karyotype consisting of 13 meta-, 39 submeta-, and 22 subtelo-acrocentric chromosomes. Among loaches collected in the upper Dnieper River, 42 triploid females were found with 74 chromosome number including 23 meta-, 26 submeta-, and 25 subtelo-acrocentric chromosomes. Other individuals from both localities were karyologically identified as Cobitis taenia Linnaeus, 1758 with 2n = 48. The triploid form of spined loaches of the Western Dvina River most likely arose as a result of the hybridization of Cobitis tanaitica Bǎcescu et Mayer, 1969 and C. taenia. The range of C. tanaitica, whose karyotype is characterized by an evolutionarily fixed Y-autosomal translocation, is limited to the rivers of the northern coast of the Black Sea. Therefore, hybridization probably happened in late Pleistocene in the Dnieper River system, where both parental species occur. The triploid form that arose here is unique for the Baltic Sea basin. Probably, it colonized the Western Dvina through the artificial Berezinskaya water system (Berezina Canal = Daugava–Dnieper Canal), but at the same time it was forced out of its area of origin by other triploid forms which are now widespread there. According to the karyotype structure, the triploid form, common for both the upper and lower reaches of the Dnieper, has a trihybrid origin, with probable hybridization of Cobitis elongatoides Bǎcescu et Mayer, 1969, C. tanaitica, and yet unidentified species Cobitis sp. Both studied triploid forms are parts of unisexual-bisexual complexes, in which their putative diploid maternal species (C. tanaitica and C. elongatoides) are absent, and the role of the host species involved in reproduction belongs to C. taenia.

Wind effect on zooplankton distribution in the estuary of the Pregolya River (the Baltic Sea basin) after technogenic transformation of its riverbed

In 2014–2018, large-scale hydrotechnical works were carried out in the estuary of the Pregolya River. The structural changes in the summer zooplankton in the river mouth in 2019 were revealed in comparison with the data obtained prior the riverbed transformation. In June 2019, zooplankton total abundance and biomass were of (136 ± 111) thousand ind.·m−3 and (860 ± 840) mg·m−3, respectively. It is comparable with mean annual data of 1996–2006: (71 ± 66) thousand ind.·m−3 and (664 ± 337) mg·m−3, respectively. In the summer of 2019, for the first time, the euryhaline species Eurytemora affinis inhabiting the Vistula Lagoon was recorded in the Novaya Pregolya branch. The presence of this species in the river branches, as well as the values of water salinity, may result from an increase in the frequency or intensity of water surges into the river from the Vistula Lagoon. In this regard, the wind conditions in 1998–2006 and 2011–2019 were analyzed. In 2011–2019, there was no increase in the frequency of winds acting along the effective surge direction (southwest and west ones) compared with those in 1996–2006. However, a rise in the frequency of storms was noted, inter alia in summer. Westerly storm winds cause upstream water inflow from the Vistula Lagoon and channel. Probably, the destruction of river macrophyte communities, concreting of embankments, and a change in the channel bottom configuration affected the intensity of water inflow from the lagoon into the river branches during surges and became the main factor affecting the distribution of euryhaline species from the lagoon in the river branches.

Wind-Controlled Transport of Saltwater in the Southeastern Baltic Sea: A Model Study

We hypothesized that the saltwater transport in a system of the southeastern Baltic basins including the Gdańsk and Gotland deeps connected by the Hoburg Channel, is greatly controlled by wind forcing, which has a clear physical explanation. Namely, the westerly winds develop the Ekman transport in the upper layer to the south from the Gotland Deep to the Gdańsk Deep which causes a compensatory saltwater countercurrent in the deep layer to the north from the Gdańsk Deep toward the Gotland Deep, and, vice versa, the easterly winds develop the Ekman transport to the north from the Gdańsk Deep toward the Gotland Deep causing a compensatory saltwater countercurrent in the deep layer to the south from the Gotland Deep to the Gdańsk Deep. To confirm the hypothesis, results of numerical modeling of the Baltic Sea circulation for a 10-year period (2010–2019) are applied. The daily saltwater transport to the northeast through a cross-section of the Hoburg Channel is found to be highly correlated with the wind stress component toward southeast (the correlation coefficient is 0.812) which can be considered as a straightforward confirmation of the hypothesis indicating the strong wind-driven circulation also in the deep layers of the Baltic Sea. Estimates of the daily saltwater transport through the above-mentioned and several other cross-sections of the southeastern Baltic Sea basins confirm a rule stating that the maximum correlation takes place between the saltwater transport and a wind stress component directed perpendicularly to the right relative to the direction of saltwater transport.