Search Results (65)

In this study, we investigate the diversity and spatiotemporal distribution of gelatinous zooplankton (GZ) in the central Baltic Sea (coastal waters of Gotland and adjacent Eastern and Western Gotland Basins), a region characterised by low salinity and ecological sensitivity. Despite the Baltic Sea being the largest brackish water body globally, knowledge about its GZ, specifically, medusae and ctenophores, is limited. Our research synthesises the existing literature, open-access data, and local reports. Three to five GZ species occur within the studied area, with the common jellyfish Aurelia aurita dominating. Peak sightings of A. aurita happen between July and October, whereas the ctenophore Mertensia ovum and scyphozoan Cyanea capillata display sporadic occurrences. We identify notable gaps in understanding GZ phenology and food web impacts due to historical neglect and insufficient monitoring, particularly under low-salinity conditions (between 5 and 8), which restricts species richness. Jellyfish and ctenophores fall under the Essential Ocean Variable (EOV) “Zooplankton Biomass and Diversity” governed by the Global Ocean Observing System, UNESCO-IOC. EOVs are an approach for globally usable data and adhere to Findable, Accessible, Interoperable, and Reusable (FAIR) data principles. Including EOVs in routine collection and reporting would significantly enhance regional and global understanding, contributing to a holistic ecosystem view. Thus, we advocate for global ocean observation frameworks to comprehensively monitor GZ populations and their ecological, biogeochemical, and socioeconomic roles. Our findings serve as a crucial step towards understanding the implications of climate change for GZ assemblages in the Baltic Sea, promoting a holistic approach to marine ecosystem management. Full article

This study demonstrates changes in the hydrodynamic regime associated with climate change in the southern Baltic over more than 70 years. The analysis of long-term data about sea level, the occurrence of ice cover, waves, and storm surges in the southern Baltic enabled the identification of spatiotemporal variability, including the detection of changes in intensity, frequency, and repeatability of these phenomena. The sea level in the southern Baltic rose by approximately 1 cm/decade from 1886 to 1955. Then, from 1956 to 2019, intensification was observed, and the sea level rose by 1.6 cm/decade and 1.9 cm in the western and eastern parts, respectively. The most intense decadal sea level change in 1955–2019 occurred in March (3.1 cm) and January (2.5 cm), while from July to December, it was at 0.8–1.3 cm. Statistical direct correlation analyses using Spearman’s rank method showed a weak but statistically significant relationship between the mean daily sea level with water temperature and air temperature measured at the same stations. An increase in the frequency of storms in individual decades and a decrease in the number of days with ice was demonstrated. There was no clear trend in the wave conditions regime during the period covered by the analysis in 1980–2021. Full article

Compound wind and precipitation extremes (CPWEs) pose significant threats to infrastructure, economies, the environment, and human lives. In this study, the recurrence, spatial distribution, intensity, and synoptic conditions leading to the formation of CPWEs were assessed in the eastern part of the Baltic Sea region. Using ERA5 reanalysis data, CPWEs were identified when both daily precipitation and maximum wind speed exceeded the 98th percentile thresholds on the same day at the same grid cell. Due to the proximity of the Baltic Sea and the influence of terrain, CPWEs were most frequent on the windward slopes of highlands in the western part of the investigation area. The most severe CPWEs occurred in the second half of summer and early September. Based on data from the Hess–Brezowsky synoptic classification catalogue and various synoptic datasets, the formation of CPWEs during the cold season (October–March) is associated with intense zonal (westerly) flow, while during the warm season (April–September), it is linked to the activity of southern-type cyclones. The number of CPWEs increased across all seasons, with the largest changes observed during the summer. However, the majority of changes are insignificant according to the Mann–Kendall test. Full article

We present the reconstruction of palaeoenvironmental conditions in the Gdansk, Bornholm, and Arkona Basins of the Baltic Sea over the last millennium. A multiproxy study (including geochemical, XRF, grain size, AMS, and micropalaeontological analyses) of five short sediment cores was performed. The relative age of the sediments was determined based on the Pb distribution along the sediment sequences, as radiocarbon dating has resulted in an excessively old age. The retrieved cores cover two comparable warm periods, the Medieval Climate Anomaly and the Modern Warm Period, for which the increase in surface water productivity was reconstructed. Notably, the production of diatoms was higher during the colder periods (the Dark Ages and Little Ice Age), but this was also the case within the Modern Warm Period. In the Gdansk Basin, the initial salinity increase during the Littorina transgression started after 7.7 cal. a BP. The increased inflow activity was reconstructed during the Medieval Climate Anomaly, even in the Gdansk Basin, despite, in general, very low foraminiferal amounts and diversity. The strongly positive North Atlantic Oscillation Index during this period led to the prevalence of westerly winds over the Baltic region and stronger saltwater intrusions. In the recent sediments, the reconstructed inflow frequency demonstrates a variability against the reduction trend, and a general decline compared to the Medieval Climate Anomaly is seen. Full article

The current research paper presents the results of the first regional assessment of sediment contamination by dioxins (polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs)) in the south-eastern part of the Baltic Sea (Lithuanian and Polish marine areas) during the periods of 2014 and 2019–2020. In total, 143 surface and core sediment samples were taken of existing offshore dredged-soil-disposal sites in the area of the former shipyard in the Port of Gdynia (Poland), as well as in a profile from the nearshore to the deeps of the Gdansk basin, following the natural pattern of sediment migration in the region. The obtained results indicated wide variation in both the total content of the investigated compounds as well as the profiles of congeners, indicating the likely sources of their origin. Based on the obtained concentration characteristic profiles of the congeners, we determined the amount of dioxins and the likely sources of their origin in the Gdansk Basin. The profiles showed elevated contents of octa- and hepta-chlorodibenzodioxins (OCDD and HpCDD) in the sediments, while the fractions of most other toxic congeners were considerably lower. The domination of OCDF in the spectrum of the studied PCDFs suggests the possible contribution of industrial processes. The obtained results have filled the gaps in our knowledge while providing a perfect background for more detailed discussions concerning the accumulation of dioxins in surface sediments from the south-eastern part of the Baltic Sea. Full article

Coastal areas provide ecosystem services (ES), including a wide range of cultural ecosystem services (CES). This study aims to operationalize the ES approach for integrated assessment and mapping of coastal CES through the case of the eastern Baltic Sea coast in Latvia. It explores an interdisciplinary approach to enhance coastal planning, leveraging the strengths of plural disciplines to ensure a more holistic representation of coastal CES. A set of methods and techniques from landscape ecology (e.g., landscape characterization, quality assessment, biophysical mapping) and social sciences (participatory GIS, stakeholder engagement events, nationwide survey) are developed and tested, particularly demonstrating links and correlations between landscape character and CES values and well-being dimensions. The results illuminate the main perceived well-being benefits that people gain from the coastal areas, highlighting the different perspectives of stakeholders. Finally, the integrated assessment results helped to construct proposals for sustainable tourism development in the area. The outcomes of the study are intended to assist planners and decision-makers in evaluating the potential for development and trade-offs in coastal regions. This research contributes to the advancement of coastal spatial planning methodologies, emphasizing the importance of stakeholder engagement and ES assessment for informed decision-making. Full article

The aim of the present study was to evaluate the morphological and physiological responses of P. maritima plants from five geographically isolated sites growing in habitats with different conditions to different substrate moisture levels in controlled conditions. Plants were produced from seed and cultivated in a greenhouse at four relatively constant soil moisture regimes: at 25, 50, and 75% soil water content and in soil flooded 3 cm above the surface (80% F). The two morphological traits that varied most strikingly among P. maritima accessions were the number of flower stalks and the number of leaves. Only plants from two accessions uniformly produced generative structures, and allocation to flowering was suppressed by both low moisture and flooding. Optimum shoot biomass accumulation for all accessions was at 50 and 75% soil moisture. The Performance Index Total was the most sensitive among the measured photosynthesis-related parameters, and it tended to decrease with an increase in soil water content for all P. maritima accessions. The initial hypothesis—that plants from relatively dry habitats will have a higher tolerance against low soil water levels, but plants from relatively wet habitats will have a higher tolerance against waterlogged or flooded soil—was not proven. The existence of three ecotypes of P. maritima within the five accessions from geographically isolated subpopulations on the eastern coast of the Baltic Sea at the level of morphological responses to soil water content can be proposed. P. maritima plants can be characterized as extremely tolerant to soil waterlogging and highly tolerant to soil flooding and low soil water content. Full article

One of the main effects of climate change is rising sea levels, which presents challenges due to its geographically heterogenous nature. Often, contradictory results arise from examining different sources of measurement and time spans. This study addresses these issues by analysing both long-term (1995–2022) and decadal (2000–2009 and 2010–2019) sea-level trends in the Baltic Sea. Two independent sources of data, which consist of 13 tide gauge (TG) stations and multi-mission along-track satellite altimetry (SA), are utilized to calculate sea-level trends using the ordinary least-squares method. Given that the Baltic Sea is influenced by geographically varying vertical land motion (VLM), both relative sea level (RSL) and absolute sea level (ASL) trends were examined for the long-term assessment. The results for the long-term ASL show estimates for TG and SA to be 3.3 mm/yr and 3.9 mm/yr, respectively, indicating agreement between sources. Additionally, the comparison of long-term RSL ranges from −2 to 4.5 mm/yr, while ASL varies between 2 and 5.4 mm/yr, as expected due to the VLM. Spatial variation in long-term ASL trends is observed, with higher rates in the northern and eastern regions. Decadal sea-level trends show higher rates, particularly the decade 2000–2009. Comparison with other available sea-level datasets (gridded models) yields comparable results. Therefore, this study evaluates the ability of SA as a reliable source for determining reginal sea-level trends in comparison with TG data. Full article

The Baltic states—Estonia, Latvia, and Lithuania—are situated on the eastern coast of the Baltic Sea between Russia and the Scandinavian countries. This region is characterized by diverse landscapes and numerous bodies of water, including lakes, peat bogs, and marshes, which serve as natural habitats for aquatic invertebrates, including leeches. Despite the rare and uncertain taxonomic status of leech species in the area, research in the Baltic region has been inadequate. Therefore, this study aims to examine the composition of leech species in the Baltic countries, drawing on both past and current research. The study also seeks to assess the status of Hirudo medicinalis in the Baltic region and discuss the rare, questionable, and potentially present leech species in the Baltic states. A scoping review method was employed, surveying published references, books, and databases. In total, the study found records of 21 leech species in Estonia, 15 in Latvia, and 26 in Lithuania, belonging to the families Glossiphoniidae, Erpobdellidae, Hirudinidae, Haemopidae, and Piscicolidae. Hirudo medicinalis L. is distributed throughout all Baltic countries, but the most recent records on their location are only available for Estonia. The data on a few Piscicolidae species is questionable and requires verification, but further research on Piscicolid leeches can potentially lead to the discovery of rare species. Full article

Adaptation to environmental variation caused by global climate change is a significant aspect of fisheries management and ecology. A reduction in ocean salinity is visible in near-shore areas, especially in the Baltic Sea, where it is affecting the Atlantic cod population. Cod is one of the most significant teleost species, with high ecological and economical value worldwide. The population of cod in the Baltic Sea has been traditionally divided into two subpopulations (western and eastern) existing in higher- and lower-salinity waters, respectively. In recent decades, both Baltic cod subpopulations have declined massively. One of the reasons for the poor condition of cod in the Baltic Sea is environmental factors, including salinity. Thus, in this study, an oligonucleotide microarray was applied to explore differences between Baltic cod subpopulations in response to salinity fluctuations. For this purpose, an exposure experiment was conducted consisting of salinity elevation and reduction, and gene expression was measured in gill tissue. We found 400 differentially expressed genes (DEGs) involved in the immune response, metabolism, programmed cell death, cytoskeleton, and extracellular matrix that showed a subpopulation-dependent pattern. These findings indicate that osmoregulation in Baltic cod is a complex process, and that western and eastern Baltic cod subpopulations respond differently to salinity changes. Full article

Worldwide, fisheries have experienced change over time. An excess of exploitation for providing food has led to overfishing and the depletion of fish stocks. However, fishing communities are also part of the cultural heritage and contribute to the attractiveness of coastal areas to tourists. Our aim is to identify if ecosystem service assessments (ESA) can reflect the condition of fisheries and their economic and social aspects. We developed a tailored, expert-based ESA and applied it to two case studies in the eastern German Baltic Sea under different fishery management scenarios. The results show that reducing fishing pressure, actively restoring habitats, and improving their ecological status increase the provision of most ecosystem services. We discuss and conclude that ESAs allow for a holistic view on fisheries that goes beyond the economic importance of fisheries and shows both the interdependence between fisheries and healthy marine ecosystems, and their relevance for coastal communities. Such a holistic view is necessary for a sustainable approach to fisheries management. Our approach is easily transferable to other regions, and can be used to structure discussion on fisheries management scenarios, as well as to track and visualize societal changes. Full article

The oeuvre of beloved Polish painter Ferdynand Ruszczyc (1870–1936) reflected the patriotic Neo-Romantic landscape trend of the fin-de-siècle prevalent in Germany and the Nordic countries (Denmark, Finland, Norway, Sweden). It should be considered in the context of Nordic visual culture for two reasons: (1) until the affiliation of Central and Eastern European nations with the Soviet Union in the wake of World War Two, nations bordering the Baltic formed a single, fluid territory of cultural exchange, and (2) Ruszczyc’s oeuvre displays significant commonalities with dominant patriotic and Neo-Romantic trends of progressive artists around the Baltic Sea, where landscape became a vehicle for expressing dreams and emotions, as well as love of homeland. This article situates Ruszczyc’s national and artistic identity at the crossroads of cultures and artistic impulses, regional as well as international. Ruszczyc was born in Bohdanów near Vilnius (now Belarus) to a Polish father and a Danish mother. Like many Polish artists from the Russian partition, he was educated at the Imperial Academy of Fine Arts in St. Petersburg, where he studied with Ivan Shishkin (1832–1898) and Arkhip Kuindzhi (1878–1910). He also travelled to Sweden. Ruszczyc was influenced by the Russian art circle Mir Iskusstva (World of Art, est. 1898) and is often compared with Nordic (e.g., Akseli Gallen-Kallela; Finnish, 1865–1931) and German (e.g., Otto Modersohn; 1865–1943) artists. His visions of nature are sometimes raw monumental images of the northern landscape or fairy-tale fantasies containing symbolic allusiveness and a mythical, poetic element that evoke intimate memories of the land of his childhood. In his paintings, Ruszczyc presented the changeability of seasons, orchards, soil and streams, clouds formations, and tree trunks with palpable emotion. By exposing the material substance of nature, his paintings also reveal its mystical aspect, its ability to transform in accordance with the cyclical, cosmic rhythm of growth, maturation, death, and rebirth. Full article

The intraspecific genetic diversity of freshwater fish inhabiting hydro-systems of the macrogeographic area spreading from the Black to Baltic Seas requires comprehensive investigation from fundamental and practical perspectives. The current study focused on the involvement of the mtDNA ATP6 region in the adaptability and microevolution of Perca fluviatilis within phylogeographic and anthropogenic contexts. We sequenced a 627 bp fragment encompassing the ATP6 region and used it for genetic analysis of 193 perch caught in Latvia, Lithuania, Belarus, and Ukraine, representing natural and anthropogenically impacted populations. We evaluated patterns of intraspecific genetic diversity in the ATP6 region and phylogeographic trends within the studied area compared with previously established D-loop trends. Evaluation of ATP6 coding sequence variability revealed that among 13 newly detected haplotypes, only two were caused by non-synonymous substitutions of amino acids of the protein. PCoA revealed three genetic groups (I–III) based on the ATP6 region that encompassed four previously described genetic groups established based on the mtDNA D-loop. The two mtDNA regions (D-loop and ATP6) have microevolved at least partially independently. Prolonged anthropogenic impacts may generate new point mutations at the ATP6 locus, but this phenomenon could be mainly concealed by natural selection and reparation processes. Full article

Summer blooms of potentially harmful cyanobacteria are common in the Baltic Sea. Under clear sky conditions, the cyanobacterial blooms are easily detectable from space. We propose a new regional algorithm for cyanobacteria biomass estimation from satellite data in the eastern part of the Gulf of Finland, developed on the basis of field measurements in July–August 2012–2014. The multi-regression equation defines the cyanobacteria biomass as a function of the particle backscattering coefficient and chlorophyll concentration. The use of this equation provides the best performance in comparison to the linear one, which is reflected in both R² and RMSE values (0.61 and 272 mg m⁻³ respectively). Unlike other algorithms, which determine only the cyanobacteria bloom area in the Baltic Sea, our algorithm allows the determination of both a bloom area and its intensity. Considering the algorithm errors, the bloom detection threshold has been shifted from the 200 mg m⁻³ determined by biologists to 300 mg m⁻³. Based on data from the MODIS-Aqua satellite ocean color scanner, the spatial and temporal variability of cyanobacterial blooms in this region from 2003 to 2022 was analyzed. Significant interannual variability of cyanobacteria biomass was revealed in the central part of the studied region, with minimum values in 2014 and maximum in 2004. The record bloom during the studied period occurred in July 2004 (the average cyanobacteria biomass was 780 mg m⁻³). The weakest blooms were observed in 2009, 2010, and 2014, when both in July and August, the bloom areas did not exceed 30% of the study region. Full article

Regional studies of precipitation changes over Europe show that its eastern part is characterized by small changes in annual precipitation and insignificant aridity trends compared to central and southern Europe. However, a frequency analysis over the past 30 years showed statistically significant increasing dryness trends in eastern Europe and an increase in the occurrence of extremely high rainfall as well as prolonged no-rain intervals during the warm season. The largest increase in aridity was observed in the western and central parts of Belarus. During 1990–2020, the frequency of dry periods doubled in all river basins along the Black, Caspian, and Baltic Sea water divide areas of eastern Europe. From 1970 to 1990, there were high streamflow rates during the winter low-flow season. Consequently, over the past 50 years, in spring, we observed here a continued decrease in maximal discharges across all river basins. In summer, we detected a statistically significant increase in the number of days with anticyclonic weather over eastern Europe, a decrease in rainfall duration by 15–20%, an increase in daily precipitation maxima by 20–30%, and an increase in the number of days with a low relative humidity by 1–4 days per decade. Full article