Baltic Sea Research Articles

Скрининг и характеристика антиоксидантных свойств психрофильных микроводорослей и цианобактерий Балтийского моря

At present, the issue of obtaining a complex of biologically active substances with antioxidant activity from psychrophilic Psychrophilic microalgae and cyanobacteria are a prospective source of biologically active antioxidant substances. New antioxidant complexes could expand the scope of their industrial application. The research objective was to identify psychrophilic microalgae and cyanobacteria from the Baltic Sea in order to study their antioxidant properties. The research featured psychrophilic microalgae and cyanobacteria obtained from the Curonian Lagoon and the Baltic Bay in the Baltic Sea, Kaliningrad Region, Russia, in March – May 2022. The authors used the Pasteur method and the flow cytometry method to isolate pure cultures of psychrophilic microalgae and cyanobacteria. The method of spectrophotometry made it possible to study the antioxidant activity by analyzing radical scavenging, reducing ability, and chelating. The psychrophilic microalga Skeletonema pseudocostatum demonstrated the highest antioxidant activity in all three methods: 17.62 μmol/g trolox equivalents according to the ABTS method, 58.16 μmol/g trolox equivalents according to the DPPH method, and 3.91 μmol/g trolox equivalents according to the FRAP method. The psychrophilic microalga Thalassiosira pseudonana exhibited the following values of antioxidant activity: 12.08, 12.42, and 3.13 μmol/g trolox equivalents, respectively. The antioxidant activity of the psychrophilic microalgae Fragilariopsis kerguelensis was 13.53, 11.84, and 1.09 μmol/g trolox equivalents, respectively. The antioxidant activity of the psychrophilic cyanobacterium Aphanizomenon gracile was 15.73, 19.89, and 2.47 μmol/g trolox equivalents, respectively. The antioxidant activity of the psychrophilic cyanobacterium Anabaena cylindrica was 12.62, 13.16, and 2.16 μmol/g trolox equivalents, respectively. The samples of psychrophilic microalgae and cyanobacteria obtained from natural environment in the Russian Baltic Sea demonstrated good antioxidant properties, which makes them a potential raw material for new pharmaceutical substances.

Characteristics of Marine Heatwaves in the Southeastern Baltic Sea Based on Long-Term In Situ and Satellite Observations

Marine heatwaves (MHWs) are known to pose a threat to aquatic ecosystems and coastal communities and, as a result, they receive significant attention nowadays, thus motivating our scientific interest in better understanding the regional patterns of these events. In this study, we analyze MHWs in the SE part of the Baltic Sea, defining them as anomalously warm water events, where the water temperature exceeds the 90th percentile threshold of the corresponding calendar day for at least five or more consecutive days. Our study is based on a combination of long-term (1993–2023) in situ data, field measurements, and satellite-derived sea surface temperature data during the warm (May–August) period. Study results suggest that although short-lived (5–9 days) MHW events typically dominate throughout the analyzed period, the occurrences of longer (more than three weeks) and more intense MHWs have increased in our study region in the recent decade. The heatwaves are observed both in coastal and open waters, with SST anomalies up to around 5–6 °C above the 90th percentile threshold during extreme events, extending thermal influence as deep as 20 m during prolonged and more intense events. We believe that the results of this study contribute to a better understanding of MHW patterns in the study region, which is important from an ecological and socio-economic point of view, providing valuable insights for human health aspects as well.

First report of the presence of Pseudoterranova sp. in the body cavity of salmon (Salmo salar) from the Baltic Sea

Abstract Despite salmon (Salmo salar L.) being an important fish in the Baltic Sea ecosystem and its fisheries, knowledge about the parasite fauna of this top predator is scarce. The Anisakidae nematodes (Anisakis spp., Pseudoterranova spp., Contracaecum sp.) found in Baltic Sea fish species are zoonotic parasites that are hazardous to human health. Due to the marked increase in the numbers of grey seal (Halichoerus grypus), the definitive host of Contracaecum sp. and Pseudoterranova spp., increased dispersion of these parasites has been observed in recent years. The aim of our study was to investigate salmon caught in Polish marine waters for the presence of Anisakidae nematodes. Parasitological inspection of the body cavities of 89 individual salmon was conducted in 2012 and revealed the presence of a Pseudoterranova sp. L3 larva. The presence of the parasite is reported here for the first time in the muscle tissue of salmon from the Baltic Sea. The presence of Anisakidae nematodes in commercially important fish species may have implications for human health since these parasites pose a risk of anisakidosis.

Provenance of clay-sized detrital sediments in the North Sea and the Skagerrak region based on radiogenic Nd-Sr-Hf isotopes and clay mineral compositions: assessing the impact of coastal and seabed erosion

The Skagerrak basin represents the main sink area for fine-grained sediment in the North Sea region and constitutes a natural deposition center for sediments that are supplied from the Atlantic, the Baltic Sea and the surrounding continental margins and coasts. However, the exact sources and their proportional contributions to the North Sea sediments and to the Skagerrak deposits are not well understood. To trace the predominant sources of the sediment and to gain a better understanding of the sedimentary processes in the North Sea and the Skagerrak basin, radiogenic Sr, Nd, and Hf isotope signatures and clay mineral compositions of the detrital clay fraction of surface sediment samples from the North Sea, the Scandinavian margins and the Baltic Sea were measured. The results indicate that the major source for Skagerrak clay-size sediments is the northern North Sea but Scandinavia as well as the southern North Sea including the southern England coast also contribute material. Seabed and coastal erosion in the northern North Sea are enhanced by the inflowing Atlantic Currents, which provide the Skagerrak with high amounts of clay size sediments. In contrast, the southern North Sea, the Baltic Sea and mid-European rivers such as Weser, Elbe and Ems are only minor contributors. As Skagerrak deposits are dominated by clay sized material (up to 60%), the reconstructed sediment processes in this study deviate from findings in previous sediment budget studies, which were based on both clay and silt fraction and indicated predominant influences from the southern North Sea. These results highlight that coastal and seabed erosion in the North Sea is a previously underestimated source of fine-grained sediments for depocenters in the entire North Sea. With regard to climate change, the global sea-level rise will likely enhance erosional processes and can therefore significantly influence the sediment budget of the entire North Sea.

A case study on microlitter and chemical contaminants: Assessing biological effects in the southern coast of the Gulf of Finland (Baltic sea) using the mussel Mytilus trossulus as a bioindicator

Chemical and microlitter (ML) pollution in three Estonian coastal areas (Baltic Sea) was investigated using mussels (Mytilus trossulus). Polycyclic aromatic hydrocarbons (PAH) in mussel tissues were observed in moderate levels with high bioaccumulation factors for the more hydrophilic and low molecular weight PAH (LMW PAH), namely anthracene and fluorene. Tissue concentrations of polybrominated diphenyl ethers (PBDE) and cadmium within mussel populations exceeded the Good Environmental Status thresholds by more than 200% and 60%, respectively. Multiple contamination at the Muuga Harbour site by tributyltin, high molecular weight PAH, including the highly toxic benzo[c]fluorene and PBDE, coincided with the inhibition of acetylcholinesterase activity and a lower condition index of the mussels. The metabolization and removal of bioaccumulated LMW PAH, reflected in the dominance of oxy-PAH such as anthracene-9,10-dione, is likely associated with the increased activity of glutathione S-transferase in caged mussels. Only a few microplastic particles were observed among the ML in mussel tissues, with coloured cellulose-based microfibers being the most prevalent. The average concentration of ML in mussels was significantly higher at the harbour area than at other sites. The integrated biomarker response index values allowed for the differentiation of pollution levels across studied locations representing high, intermediate, and low pollution levels within the studied area.

Improving the Modeled Variability Estimates of Offshore Winds in Northern Europe by Nudging ASCAT-Derived Winds

Abstract The paper aims to demonstrate how to enhance the accuracy of offshore wind resource estimation, specifically by incorporating near-surface satellite-derived wind observations into mesoscale models. We utilized the Weather Research and Forecasting (WRF) Model and applied observational nudging by integrating ASCAT data over offshore areas to achieve this. We then evaluated the accuracy of the nudged WRF Model simulations by comparing them with data from ocean oil platforms, tall masts, and a wind lidar mounted on a commercial ferry crossing the southern Baltic Sea. Our findings indicate that including satellite-derived ASCAT wind speeds through nudging enhances the correlation and reduces the error of the mesoscale simulations across all validation platforms. Moreover, it consistently outperforms the control and previously published WRF-based wind atlases. Using satellite-derived winds directly in the model simulations also solves the issue of lifting near-surface winds to wind turbine heights, which has been challenging in estimating wind resources at such heights. The comparison of the 1-yr-long simulations with and without nudging reveals intriguing differences in the sign and magnitude between the Baltic and North Seas, which vary seasonally. The pattern highlights a distinct regional pattern attributed to regional dynamics, sea surface temperature, atmospheric stability, and the number of available ASCAT samples. Significance Statement We aim to showcase a method for improving the precision of hub-height estimation of wind resources offshore. This involves integrating wind observations obtained from near-surface satellites into the model simulations. To assess the accuracy of the simulations, we compare the simulated winds to data gathered from multiple offshore sources, including oil platforms, tall masts, and a wind lidar installed on a commercial ferry.

Domestic fish for more versatile and safer consumption EU‐fish IV

Abstract Fish is an important part of nutrition and well‐being. The challenge of Finnish wild fish is contaminants which accumulate in some species in higher concentrations, partially limit the usability of the fish in the food/feed market and weaken the assessment of the state of the marine environment. The aim of this study was to obtain data on the amounts of nutrients and contaminants in domestic fish species that are commercially important or should be increased in use according to national plans. The aim was also to produce information for updating the national fish use recommendations. The concentrations of contaminants in Finnish fish were mostly below the maximum levels set by the EU. The trend of dioxin and PCB compound concentrations in the Baltic Sea has been declining since the 1980s, and the concentrations in Baltic herring appear to have settled around or below the maximum levels in all sea areas and size classes. The PFAS concentrations in the studied fish samples were within the maximum limits, except for Baltic herring in the Archipelago Sea and the Bothnian Sea. Additionally, the PFAS concentrations in Baltic herring rose quite sharply between 2009 and 2023. During the current study, PFAS concentrations in Baltic herring from the same sea area and size classes increased significantly from autumn 2022 to spring 2023. The seasonal trend was suspected to be related to the fish's diet, but factors affecting PFAS concentrations in fish, such as the impact of seasons and fitness (function of weight and size of the fish), need further investigation, and PFAS concentrations in Baltic herring should be monitored. PBDE concentrations in Finnish fish were found to be very low, although they exceeded the environmental quality standard. Mercury concentrations in fish, except for two samples, were lower than the maximum levels set by Commission Regulation (EU) 2023/915. The proportion of methylmercury in total mercury was 56–94% in different fish species. Inorganic arsenic concentrations in all fish samples were below the detection limit of 0.01 mg/kg. The highest concentrations of omega‐3 fatty acids were measured in Baltic herring and vendace. Fish caught from marine areas had higher vitamin D concentrations than those from inland waters, and there was significant variation in concentrations within fish species. With current food consumption and concentration data, the health benefits of fish consumption outweigh the health risks associated with contaminants in fish for all age groups. The greatest health benefits are seen in those over 45 years old, where fish consumption reduces the burden of diseases such as cardiovascular diseases and breast cancer, as well as overall mortality. On a national scale, the current use of domestic and imported fish is estimated to reduce the disease burden annually by nearly 70,000 disability‐adjusted life years (DALYs). As a conclusion, the health benefits of fish consumption outweigh the harms of contaminants in all age groups. Increasing the consumption of fish in accordance with nutritional recommendations would benefit the health of the population. For children and expectant or breastfeeding mothers, a diverse fish consumption is useful. The safe use recommendations of the Finnish Food Authority help this risk group to direct their fish consumption to fishing areas and fish species with the lowest amounts of contaminants.

Multi‐year monitoring shows higher species richness and diversity of fish assemblages in a Danish seagrass meadow as compared to neighbouring non‐vegetated areas

AbstractSeagrass meadows provide an important nursery and feeding habitat for fish, globally. However, limited data exist on how these vegetated coastal ecosystems affect local fish stocks over longer time periods. By means of beach seine hauling with a bio‐monitoring seine net, we collected fish data in Kronborg Bay (Denmark) over 4 years. The bay contains both vegetated and bare sediment areas in close proximity to Kronborg Castle in Elsinore and is part of the Øresund strait; a dynamic marine environment linking the Baltic Sea with the inner Danish waters (Kattegat). We investigated the biodiversity and fish abundance in a healthy seagrass meadow and compared it with a bare adjacent sediment area. We show that seagrass is important for fish species like the Atlantic cod, the two‐spotted goby, and the broadnosed pipefish. The seagrass meadow harboured more fish species and higher biodiversity, while the number of individuals was higher in the adjacent bare sediment area as a result of high abundances of lesser sand eel. Pilou's evenness and the Shannon‐Wiener index showed 2–4‐fold higher biodiversity in the seagrass meadow. The seagrass meadow harboured about 35% more fish species than the bare adjacent sediment. The Atlantic cod was almost entirely found in the seagrass meadow, while lesser sand eel that showed an overall increase in abundance in both habitats, represented the largest proportion of the total number of fish individuals (up to about 60%) and was mostly found on the bare adjacent sediment. Species abundance was analysed for changes over time, where, for example the European plaice showed an increase in abundance over the 4‐year period of investigation. Seagrass meadows can thus be very important for the Atlantic cod population in the Øresund strait and generally for local fish productivity, abundance and diversity.

Assessment of the potential area for the establishment of the Colorado potato beetle in Finland and Sweden

Summary The Colorado potato beetle (CPB, Leptinotarsa decemlineata) is a protected zone quarantine pest in the southern parts of Finland and Sweden. The units responsible for pest risk assessments in Finland and Sweden were requested to identify the geographical areas likely to be suitable for establishment of the CPB given a climate change scenario that covers the years 2023–2040. Based on previous studies, the northern limit of the potential range of the CPB appears to depend, above all, on where the summer temperatures enable the development of one complete generation. To identify such areas in Finland and Sweden, we first estimated the annual growing degree day (GDD) requirement (above 10 °C) of the CPB based on the two‐decade mean annual GDD in the northernmost locations where the CPB is present in Russia. The lowest mean annual GDD among these locations was 587 which was used as the GDD requirement of the CPB in this assessment. Next, we delineated the areas in Finland and Sweden where this GDD requirement was met in a recent time period (2003–2022) and in a future time period (2031–2050) assuming an intermediate greenhouse gas emission scenario, i.e., Representative Concentration Pathway (RCP) 4.5. The results show that the GDD requirement of 587 is met in large areas in southern Finland and Sweden, and by 2040, also in central Finland and the Baltic Sea coastline. We further assessed that there are enough hosts for the CPB to enable establishment in these areas. These areas were therefore assessed as likely to be suitable for the establishment of the CPB. Importantly, they include areas much further north than the current protected zones. This result was assessed to be rather robust since even a 20% higher GDD requirement (704) was met in a much larger area than the protected zones both in Sweden (in the recent and future climate) and in Finland (in the future climate). The greatest sources of uncertainty in the assessment are the uncertainty of the annual GDD that the CPB needs to complete its life cycle, the future climate projections, and the abundance of hosts necessary in a landscape to enable the CPB to establish.

Last ice sheet recession and landscape emergence above sea level in east-central Sweden, evaluated using in situ cosmogenic 14C from quartz

Abstract. In situ cosmogenic 14C (in situ 14C) in quartz provides a recently developed tool to date exposure of bedrock surfaces of up to ∼ 25 000 years. From outcrops located in east-central Sweden, we tested the accuracy of in situ 14C dating against (i) a relative sea level (RSL) curve constructed from radiocarbon dating of organic material in isolation basins and (ii) the timing of local deglaciation constructed from a clay varve chronology complemented with traditional radiocarbon dating. Five samples of granitoid bedrock were taken along an elevation transect extending southwestwards from the coast of the Baltic Sea near Forsmark. Because these samples derive from bedrock outcrops positioned below the highest postglacial shoreline, they target the timing of progressive landscape emergence above sea level. In contrast, in situ 14C concentrations in an additional five samples taken from granitoid outcrops above the highest postglacial shoreline, located 100 km west of Forsmark, should reflect local deglaciation ages. The 10 in situ 14C measurements provide robust age constraints that, within uncertainties, compare favourably with the RSL curve and the local deglaciation chronology. These data demonstrate the utility of in situ 14C to accurately date ice sheet deglaciation, and durations of postglacial exposure, in regions where cosmogenic 10Be and 26Al routinely return complex exposure results.

The first documented and characterized Norwegian acid sulfate soils

AbstractAcid sulfate soils (ASS) containing hypersulfidic material (pH >4) can, when drained, transform to ASS with a thionic horizon (pH <4), which can cause environmental effects due to the formation of sulfuric acid and the consequent mobilization and leaching of metals and acid into waterways, as well as cause geotechnical problems. Yet, the occurrence of ASS has till now not been a topic of research in Norway. The present pilot study was carried out on an area along the northern coast of Norway. Thirty‐nine localities were sampled and analysed near Alta. Of these, six were classified as ASS with either hypersulfidic or parahypersulfidic material. ASS is not as widespread as within the Baltic Sea area, but the analyses document the occurrence of ASS with hypersulfidic material with high acidifying potential in certain areas if oxidized. This pilot study shows that ASS occurs in specific areas. Three localities with documented ASS were studied in greater detail. Here, sections were excavated and analysed to help with the understanding of the geological context of these occurrences. In this way, the geological prerequisites considered of importance of soils with ASS with hypersulfidic material are outlined. The prerequisites for ASS occurrence that evolved during this study include young, marine, fine‐grained deposits and a low relief environment subjected to episodic sedimentation but otherwise calm water and little water exchange. The results are a starting point for further studies of ASS occurrences along the Norwegian coast.

Multi-Decadal Trends in Aerosol Optical Depth of the Main Aerosol Species Based on MERRA-2 Reanalysis: A Case Study in the Baltic Sea Basin

This study analyses the trends of total aerosol and the main aerosol species over nine capitals in the Baltic Sea basin from 1989 to 2019 based on the Modern-Era Retrospective Analysis for Research and Applications, Version 2 Reanalysis. Aerosol speciation includes mineral dust, sea salt, sulphate (SO4), organic carbon (OC), and black carbon (BC). The mean total aerosol optical depth (AOD) values were the highest (up to 0.216) over the continental capitals (i.e., Warsaw, Berlin, and Vilnius). For each capital, the mean SO4 AOD was the main aerosol species, with a trend specular to total AOD. Apart from Warsaw, the mean BC AOD was the aerosol species with the lowest level. The composition of aerosols changed with respect to the species of anthropogenic origins (i.e., SO4, OC, and BC), with the percentage contribution to the total AOD decreasing for the SO4 AOD and increasing for the BC AOD. Also, the OC AOD showed an increase in the percentage contribution to total AOD for Copenhagen, Oslo, Stockholm, and the continental capitals. Anthropogenic aerosols contributed up to 90.3% of the total AOD, with the highest values over the continental capitals. For each capital, the minimum in the percentage contribution of anthropogenic AOD was between 2007 and 2008, likely due to the global financial crisis. Anthropogenic AOD as a percentage of the total AOD decreased from 1989 to 2008. Both the total and the SO4 AODs decreased over each capital. By contrast, the BC AOD increased over Stockholm, and both the OC and BC AODs increased over Berlin, Copenhagen, and Oslo. The decoupling of carbonaceous aerosols and the SO4 AOD trends was likely due to concurrent factors such as biomass burning and low-sulphur fuel policies. From 2000 to 2019, the inverse relationships between gross domestic products and SO4 AODs suggest a relative decoupling of economic growth from fossil fuels for Oslo, Stockholm, Tallinn, and Vilnius.

Symbiotic species diversity can explain invasion success and host–parasite system stability: The case of gammarid hosts

AbstractA major current challenge related to invasions is the absence of a comprehensive theoretical basis for preventing the introduction of alien species and controlling their populations. By using a macroecological framework, we aim to examine patterns of symbiotic species diversity across native and invasive hosts to understand the mechanisms underlying the host–parasite system stability. The symbiotic communities of seven gammarid species, two native and five invasive, were analyzed at 16 fresh and brackish water sites along the Baltic coast of Poland. We investigated the influence of four factors—locality, habitat, host species, and host origin—on diversity patterns and assessed their relative contribution to diversity variation. Our results indicate that all factors are crucial in determining the composition and abundance of symbiotic communities in gammarids. Among these factors, locality and host species apparently have a greater influence on symbiotic communities than habitat conditions and host origin. Comparative analysis of diversity indexes of symbiotic organisms from native and invasive hosts showed that the richer communities of native gammarids were paradoxically less diverse. We assume that these rich and uneven symbiotic communities keep the host–parasite system of native gammarids in equilibrium. Highly dominant symbiotic species with a high load per host individual may stabilize the growth of the host population. Symbiotic communities of the invasive host exhibited lower species richness but displayed a relatively even distribution of species with moderate loads per individual, resulting in a scarcity of heavily infected gammarids within the population. Thus, the survival rate of invasive gammarids is expected to be relatively high, facilitating their population growth and further spread. We conclude that complex communities of native gammarids constructed from many symbiotic species may prevent host populations from undergoing explosive growth, while such mechanisms may be completely or partially reduced in invasive hosts.

Methodological Aspects of using the frequency of occurrence Indicator for an analysis of Ichthyocenoses, the Ichthyofauna of the Baltic Sea Coastal zone Taken as an Example

The specificity of utilizing the frequency of occurrence indicator in relation to the study of the species structure of a fish community is considered. The coastal ichthyocenosis of the Baltic Sea within the Kaliningrad Region was used as a study object. Fishing was carried out at up to 20 m depths using a set of collection of gillnets with a mesh size of 12 to 80 mm in the period 2006–2022. In total, data on 894 catches were summarized, in which 11.8 thousand fish were caught. It is shown that the frequency of occurrence of a species can be presented in several ways: (1) as the average for the catches of the entire set of mesh, (2) as the maximum for the mesh size optimal for a given species, (3) as a structural characteristic that determines the nature of an ichthyocenosis’ species organization. In general, in the catches of a collection of gill nets the coastal ichthyocenosis was found to be represented by 29 species of fish, among which the river flounder, Baltic herring, round goby and smelt dominate in terms of occurrence. In the interannual aspect, the occurrence rate is demonstrated to show certain stability and is characterized by a confidence interval ranging within ±10–20%. Taking into account that the indicator of occurrence is quite simply determined just through the capture record of a species, it is recommended to use it in addition to the traditional indicators of the relative abundance and biomass of the species. Using multi-cell fishing gear for the assessment of the structure of a fish community is prerequisite.

Temporal dynamics and extreme events in solar, wind, and wave energy complementarity: Insights from the Polish Exclusive Economic Zone

The Polish Exclusive Economic Zone (EEZ) in the Baltic Sea is an area of increasing strategic importance for Poland's pursuit of renewable energy, especially offshore wind. This research investigates the complementarity among solar, wind, and wave energy resources within the Polish EEZ to examine these energy sources' temporal dynamics, correlations, and extremes. The primary data source corresponds to a 31-year hourly time series dataset from the ERA5 reanalysis, whose reliability was evaluated through performance metrics. The results from complementarity metrics indicate varying levels of association among the three variable renewable energy resources (VRES) in the EEZ, spanning from weak similarity to weak complementarity. The findings of this research indicate that blackouts are most probable at offshore locations during winter and autumn for renewable power systems integrating wind and solar energy, with over 70 % of occurrences within these seasons. The investigation of extreme events highlights critical elements when evaluating VRES and their complementarity. This understanding aids in effectively planning and managing renewable energy systems, ensuring resilience and reliability under challenging weather conditions. Furthermore, while the complementarity may be consistent throughout the entire Polish EEZ, the feasibility and cost of implementing hybrid power systems can significantly vary between locations.

Baltic herring hydrolysates: Identification of peptides, in silico DPP-4 prediction, and their effects on an in vivo mice model of obesity

Baltic herring is the main catch in the Baltic Sea; however, its usage could be improved due to the low processing rate. Previously we have shown that whole Baltic herring hydrolysates (BHH) and herring byproducts hydrolysates (BHBH) by commercial enzymes consisted of bioactive peptides and had moderate bioactivity in in vitro dipeptidyl peptidase (DPP)-4 assay. In this study, we identified the hydrolysate peptides by LC-MS/MS and predicted the potential bioactive DPP-4 inhibitory peptides using in silico tools. Based on abundance, peptide length and stability, 86 peptides from BHBH and 80 peptides from BHH were proposed to be novel DPP-4 inhibitory peptides. BHH was fed to a mice intervention of a high-fat, high-fructose diet to validate the bioactivity. The results of the glucose tolerance and insulin tolerance improved. Plasma DPP-4 activities, C-peptide levels, and HOMA-IR scores significantly decreased, while plasma glucagon-like peptide-1 content increased. In conclusion, BHH is an inexpensive and sustainable source of functional antidiabetic ingredients.

Observed beach nourishment development in a semi-enclosed coastal embayment

Beaches are important coastal features that provide vital ecosystem services; however, these systems are threatened by coastal erosion, sea-level rise, and coastal squeeze. Beach nourishments are a commonly applied coastal protection measure to mitigate erosion and flood risks while maintaining or enhancing recreational values. Nourishments vary in scale from mega-nourishments to small-scale nourishments, where the latter has typically been less studied due to the limited resources for monitoring. Meanwhile, with rising sea levels, the implementation of small-scale nourishments is expected to increase, and there is a need for more knowledge about the morphological evolution and technical lifetime of these interventions. In this study, the morphological responses of small-scale beach nourishment (total volume 20,000 m3 which amounts to 30 m3 added per m alongshore) are observed and quantified over various timescales, considering the initial adjustment, long-term development, and event-driven response. The investigated nourishment is implemented in a partly sheltered coastal embayment in the semi-enclosed Baltic Sea, which has a complex interaction between waves and water levels. Furthermore, the beach is surrounded by hard structures, a rock revetment at the back, and a harbor mole and a groin, influencing the longshore and cross-shore sediment transport. The results show that substantial reduction in subaerial volume can be attributed to specific events. In addition, we observed considerable spatial variation in the sediment re-distribution induced by hard structures and variability in the nearshore bathymetry. The lifetime of the beach nourishment is just over two years. The nourished material remains in the system at the end of the lifetime but is not available for beach recovery. Still, the added subaerial volume has eroded at the midsection, and the protective beach width has been reduced, leaving the rock revetment exposed with reduced protection for the hinterland. The energy conditions at the site are highly episodic, which impacts morphological evolution, and observations indicate that the development is event-driven.

Impact of Biomass Burning, Wildfires, and Wind Events on Aerosol Optical Depth: Implications for Climate Change

In this article, we describe multiannual variations of the atmospheric aerosol optical depth values in the widely understood area of the Baltic Sea. We present the trends in the changes and depict unusual aerosol situations. As a result of analyses, we focus on 2019, since unusually high values of aerosol optical depth were recorded in several stations around the Baltic. We match the high aerosol levels with an unusually high number of wildfires across Europe in spring and summer, which emitted large quantities of aerosols into the atmosphere that were distributed over vast European areas in part by the wind. We then connect this case with the climate change consequences. Since aerosols influence the radiative budget of the planet by directly affecting the atmospheric radiation budget, it is obvious that human well-being is in danger due to wildfires, as well as from the atmospheric perspective. Climate change will lead to more frequent fires; thus, humans need to develop solutions to decrease the risk of fire outbreaks.

Limited Parallelism in Genetic Adaptation to Brackish Water Bodies in European Sprat and Atlantic Herring.

The European sprat is a small plankton-feeding clupeid present in the northeastern Atlantic Ocean, in the Mediterranean Sea, and in the brackish Baltic Sea and Black Sea. This species is the target of a major fishery and, therefore, an accurate characterization of its genetic population structure is crucial to delineate proper stock assessments that aid ensuring the fishery's sustainability. Here, we present (i) a draft genome assembly, (ii) pooled whole genome sequencing of 19 population samples covering most of the species' distribution range, and (iii) the design and test of a single nucleotide polymorphism (SNP)-chip resource and use this to validate the population structure inferred from pooled sequencing. These approaches revealed, using the populations sampled here, three major groups of European sprat: Oceanic, Coastal, and Brackish with limited differentiation within groups even over wide geographical stretches. Genetic structure is largely driven by six large putative inversions that differentiate Oceanic and Brackish sprats, while Coastal populations display intermediate frequencies of haplotypes at each locus. Interestingly, populations from the Baltic and the Black Seas share similar frequencies of haplotypes at these putative inversions despite their distant geographic location. The closely related clupeids European sprat and Atlantic herring both show genetic adaptation to the brackish Baltic Sea, providing an opportunity to explore the extent of genetic parallelism. This analysis revealed limited parallelism because out of 125 independent loci detected in the Atlantic herring, three showed sharp signals of selection that overlapped between the two species and contained single genes such as PRLRA, which encodes the receptor for prolactin, a freshwater-adapting hormone in euryhaline species, and THRB, a receptor for thyroid hormones, important both for metabolic regulation and the development of red cone photoreceptors.

Migratory pathways and winter destinations of Northern Gannets breeding at Helgoland (North Sea): known patterns and increasing importance of the Baltic Sea

We analysed the migratory behaviour of adult Northern Gannets (Morus bassanus) breeding at Helgoland in the North Sea, based on data obtained from geolocation devices in the non-breeding season 2016–2017. Birds moved east and south-west to a broad range of wintering sites, ranging from the western Baltic Sea to North-West Africa. Three out of 12 birds spent the winter in Africa, while 9 birds wintered in Europe, with the primary wintering sites in the North Sea. All but one tagged bird spent some time in the Baltic Sea or in the transitional waters between the North Sea and Baltic Sea. We also analysed data from online databases (dofbasen.dk, ornitho.de) and the German Seabirds at Sea database to explore the extent to which Northern Gannets used the western Baltic Sea, as well as the Kattegat and Skagerrak, during the winter months. Records of Northern Gannets in Danish waters have increased substantially over the last 18 winters, with particular increases in the Baltic Sea. There was also a notable increase in sightings of Northern Gannets in German Baltic Sea waters, but this occurred later than in the more northerly Danish waters. Both analyses demonstrated that Northern Gannets explored the western part of the Baltic Sea, as well as the Kattegat and Skagerrak, increasingly intensively. This recent increase in sightings is in accord with the establishment and exponential increase in the nearest breeding colony of Northern Gannets at Helgoland.