Gulf Of Finland Research Articles

Mapping microplastic pathways and accumulation zones in the Gulf of Finland, Baltic Sea – insights from modeling

Mapping microplastic pathways and accumulation zones in the Gulf of Finland, Baltic Sea – insights from modeling

Direct Evidence of Microbial Sunscreen Production by Scum-Forming Cyanobacteria in the Baltic Sea.

Mycosporine-like amino acids are water-soluble secondary metabolites that protect photosynthetic microorganisms from ultraviolet radiation. Here, we present direct evidence for the production of these compounds in surface scums of cyanobacteria along the Baltic Sea coast. We collected 59 environmental samples from the southern coast of Finland during the summers of 2021 and 2022 and analysed them using high-resolution liquid chromatography-mass spectrometry. Our results revealed the presence of microbial sunscreens in nearly all surface scum samples. Mycosporine-like amino acids are synthesised through the coordinated action of four biosynthetic enzymes encoded in a compact biosynthetic pathway. Bioinformatics analysis of the mysB biosynthetic gene from a surface scum indicated that the cyanobacteria responsible for production belonged to the Anabaena/Dolichospermum/Aphanizomenon species complex. We mapped the distribution of biosynthetic enzymes onto a phylogenomic tree, utilising 120 bacterial single-copy conserved genes from 101 draft or complete genomes within the species complex. This analysis showed that 48% of identified species possess the ability to produce these compounds, with biosynthetic pathways being most common in Dolichospermum and Aphanizomenon strains. We detected the production of porphyra-334 and shinorine, two widely reported family members, in Dolichospermum strains isolated from the Gulf of Finland's surface layer. The estimated content of porphyra-334 in Dolichospermum sp. UHCC 0684 was 7.4 mg per gram dry weight. Our results suggest that bloom-forming cyanobacteria could be a potential source of these compounds for cosmetic and biotechnological applications and may play a significant role in cyanobacterial bloom formation.

Microbially Enhanced Growth and Metal Capture by Ferromanganese Concretions in a Laboratory Experiment.

The growth and metal enrichment of ferromanganese minerals on the seafloor have intrigued many studies, yet the role of microbes in the process has remained elusive. Here, we assessed the microbial influence on the growth and trace metal accumulation and release of ferromanganese concretions from the Baltic Sea using 12-week microcosm incubation experiments. We studied three concretion morphotypes: Crust, discoidal, and spheroidal, with biotic and abiotic treatments. The concretion samples were collected into bottles containing artificial brackish seawater from the Gulf of Finland, incubated in in-situ simulating conditions, and sampled at the beginning and end of the experiment. Microscale X-ray-computed tomography confirmed the local growth of up to 10 μm thick patches on the concretion surface during the 12-week incubation period, corresponding to a growth rate of 0.04 mm/year. Scanning electron microscopy of glass slides in the microcosms revealed freshly precipitated cauliflower-like grains, typical of freshly formed Fe- and Mn-hydroxides. Decreased concentrations of dissolved trace metals (Mn, Fe Co, V, Ni, Zn, and Mo) in the incubation solutions indicated the accumulation of these elements into concretions in the biotic microcosms. In contrast, the dissolution of concretions was observed in abiotic microcosms, confirming that microbial activity enhanced the ferromanganese precipitation and the associated accumulation and release of P and trace metals into the ambient solution. The microbial contribution was confirmed by a strong decrease in headspace methane concentrations in biotic microcosms, further indicating the presence of active methanotrophs in the concretion communities.

U–Pb-(SHRIMP-II)-age of zircon from granites of Bolshoy Tyuters Island (Gulf of Finland, Russia) and the problem of the Ediacaran thermal event in the region

New data on the U–Pb age (SHRIMP-II) and trace element composition (SIMS) of zircons from granites of Bolshoy Tyuters Island (Outer Islands of the Gulf of Finland) are presented. The upper intersection of the discordia (1825±11 Ma) is taken as the age of crystallization of granites cutting through secondary quartzites, and thereby determines their youngest age. Subconcordant zircons located in the upper part of the discordia has growth oscillatory zoning and geochemical characteristics of zircons of magmatic origin. The age of the lower intersection of discordia and concordia is about 570 Ma, supported by the independent generation of zircons, represented by black in the CL domains and rims in magmatic zircons, which are characterized by increased contents of non-formula elements (light REE, Ca, P, Ti, Nb, etc. ), up to anomalous values. The most probable interpretation of the age of the lower intersection of discordia and concordia can be considered the Timan (Ediacaran) or Finnmark (Early Caledonian) thermal activation of the Fennoscandian Shield, previously established based on zircons from gneisses of the Kola series.

Development of the scientific project “mendeleev classes” at the research base of the department of industrial ecology and life safety of the Irkutsk national research technical university

The article examines the results of implementing a new direction in education: the scientific project “Mendeleev Classes.” It outlines the project’s primary goal and objectives, along with participating regions, stakeholders, and executors. The project program has been implemented at Irkutsk National Research Technical University since 2021, utilizing the research facilities of the Department of Industrial Ecology and Life Safety. Students and staff from the department guide the project activities of the “Mendeleev” 8th-grade students from Lyceum No. 1 in Usolye-Sibirskoye. The article provides a detailed overview of the topics, objectives, and key findings of these projects. The article highlights how active engagement of lyceum students allows them to gain experience in scientific research, while university students broaden and acquire new theoretical knowledge, alongside practical skills in environmental safety. The article provides a description and brief report of four expeditions conducted across Russia in 2021 (“Baikal”), 2022 (“Finnish Gulf”), 2023 (“Southern Ural”), and 2024 (“Kamchatka”). The article notes the pressing ecological problems in Russia’s regions that students from various institutions, including Irkutsk National Research Technical University, encountered. It lists publications showcasing the research findings of participants and their supervisors. The article concludes that the implementation of the “Mendeleev Classes” project contributes to the improvement of the ecological education and upbringing system in Russia, fostering environmental culture and ecological literacy among young people.

Seasonal dynamics and regional distribution patterns of CO2 and CH4 in the north-eastern Baltic Sea

Abstract. Significant research has been carried out in the last decade to describe the CO2 system dynamics in the Baltic Sea. However, there is a lack of knowledge in this field in the NE Baltic Sea, which is the main focus of the present study. We analysed the physical forcing and hydrographic background in the study year (2018) and tried to elucidate the observed patterns of surface water CO2 partial pressure (pCO2) and methane concentrations (cCH4). Surface water pCO2 and cCH4 were continuously measured during six monitoring cruises onboard R/V Salme, covering the Northern Baltic Proper (NBP), the Gulf of Finland (GoF), and the Gulf of Riga (GoR) and all seasons in 2018. The general seasonal pCO2 pattern showed oversaturation in autumn–winter (average relative CO2 saturation 1.2) and undersaturation in spring–summer (average relative CO2 saturation 0.5), but it locally reached the saturation level during the cruises in April, May, and August in the GoR and in August in the GoF. The cCH4 was oversaturated during the entire study period, and the seasonal course was not well exposed on the background of high variability. Surface water pCO2 and cCH4 distributions showed larger spatial variability in the GoR and GoF than in the NBP for all six cruises. We linked the observed local maxima to river bulges, coastal upwelling events, fronts, and occasions when vertical mixing reached the seabed in shallow areas. Seasonal averaging over the CO2 flux suggests a weak sink for atmospheric CO2 for all basins, but high variability and the long periods between cruises (temporal gaps in observation) preclude a clear statement.

Here to stay: evaluating establishment of eastern tubenose goby Proterorhinus semipellucidus (Kessler, 1877) in the Baltic Sea with otolith microchemistry and structure

In 2020, the presence of a novel non-indigenous species, eastern tubenose goby Proterorhinus semipellucidus (Kessler, 1877), was documented in the Gulf of Finland, Baltic Sea. As tubenose goby invasion may have a comprehensive ecological impact on the local ecosystem, it has to be confirmed whether the species has established an independently reproducing population or persists through continuous invasions in this area. We examined the otolith microstructure to determine the age of specimens sampled from the southern and northern coasts of the Gulf of Finland. Additionally, otolith microchemistry analysis was carried out on the southern coast specimens. Otolith microstructure revealed the population’s age structure, showing the presence of different age classes, including younger individuals. The microchemistry analyses suggested that the specimens had hatched in brackish water salinities similar to those found in the sampling areas. This indicates local reproduction instead of introduction from the virtually freshwater Neva Bay, which is most likely the donor area of the studied populations. These data confirm the establishment of a self-sustaining reproducing population of eastern tubenose goby in the Gulf of Finland, eastern part of the brackish Baltic Sea.

An adaptive trajectory compression and feature preservation method for maritime traffic analysis

Ship trajectory data extracted from Automatic Identification System (AIS) has been extensively used for maritime traffic analysis. Yet the enormous volume of AIS data has come with substantial challenges related to storing, processing, analyzing, transmitting, and transferring. Trajectory compression techniques have been widely investigated to remedy the challenge. However, conventional compression techniques such as Douglas-Peucker (DP) algorithm mainly depend on line simplification algorithms, falling short in accurately identifying and preserving crucial information within trajectories. Moreover, using kinematic information from AIS data has posed difficulties associated with compression threshold determination. Hence, an adaptive method capable of considering multiple information from AIS is required. In this paper, a Top-Down Kinematic Compression (TDKC) algorithm aimed at adaptive trajectory compression and feature preservation is proposed. By incorporating time, position, speed, and course attributes from AIS data, TDKC exploits a Compression Binary Tree (CBT) method to address the recursion termination problem and determine the threshold automatically. A case study was conducted to evaluate the performance of TDKC using AIS data from Gulf of Finland, where a comparison with conventional algorithms and their improved versions based on specific performance evaluation metrics was involved. The results demonstrate TDKC's superiority in facilitating maritime traffic analysis.

Interannual sea level variability in the North and Baltic seas and net flux through the Danish straits

The paper presents the reconstruction of sea levels in the North Sea and Baltic Sea using Kalman filter approach. Based on the statistical characteristics of one year of daily maps of sea level from the Geesthacht COAstal model SysTem (GCOAST) and daily data at tide gauges along the coastline of two basins, the method can reconstruct effectively and accurately the multidecadal sea level anomalies. The high accuracy reconstruction data were then used to investigate the interannual variability in both basins and to estimate the difference between outflows and inflows (net flux) through the Danish Straits. The highest mean, standard deviation, and extreme values of sea level anomalies appear in winter and are well reproduced in different regions, such as the German Bight, the Southern North Sea, the Bothnian Bay, the Gulfs of Finland and Riga. The sea level variability is highly correlated with the mean sea level pressure and the zonal wind, particularly in the German Bight and in the winter months. The contributions of river runoff and net precipitation on the net flux are significant in the spring. The local wind has a greater influence on the net flux than the remote drivers.

Commerce or Conflict? – A Reinterpretation of Two Late 16th-Century Shipwrecks from the Gulf of Finland

Commerce or Conflict? – A Reinterpretation of Two Late 16th-Century Shipwrecks from the Gulf of Finland

WRF-Chem Modeling of Tropospheric Ozone in the Coastal Cities of the Gulf of Finland

Ozone in the troposphere is a pollutant and greenhouse gas. Atmospheric models can add valuable information to observations for studying the spatial and temporal variations in tropospheric ozone content. The present study is intended to evaluate the variability in tropospheric ozone and its precursors near the Gulf of Finland with a focus on St. Petersburg (Russia) and Helsinki (Finland) in 2016–2019, using the WRF-Chem 3-D numerical model with a spatial resolution of 10 km, together with observations. The diurnal cycle of the near-surface ozone concentrations (NSOCs) in both cities is caused by the variability in NO2 emissions, planetary boundary layer height, and local meteorological conditions. The seasonal variations in NSOCs and tropospheric ozone content (TrOC) are caused by the variability in total ozone content and in ozone formation in the troposphere. The model reveals a VOC-limited regime in the ~0–1 km layer around St. Petersburg, Helsinki, and the Gulf of Finland and a pronounced NOx-limited regime in the 0–2 km layer in the forests of southern Finland, Karelia, some Russian regions, and the Baltic countries in July. The WRF-Chem model overestimates the measured NSOCs by 10.7–43.5% and the TrOC by 7–10.4%. The observed differences are mainly caused by the errors in chemical boundary conditions and emissions of ozone precursors and by the coarse spatial resolution of the modeling.

Comparison and Evaluation of Learning Capabilities of Deep Learning Methods for Predicting Ship Motions

The development of intelligent ship control systems in real-world conditions relies heavily on the accurate identification and prediction of ship seakeeping and maneuvering trajectories. In this study, we comprehensively evaluate a selection of deep learning methods to assess their learning capabilities in terms of idealizing ship motion behavior in realistic operational environments. To recover real conditions, we utilize historical Automatic Identification System (AIS) data and a time domain 6 Degree of Freedom (6- DoF) grounding dynamics model to generate ship motion sequences for a Ro-Ro passenger ship operating in the Gulf of Finland. Via a rigorous evaluation process, we validate the performance of these methods using extensive data streams. The analysis includes the identification and estimation of uncertainties between two ports. The paper demonstrates the proficiency of the selected deep learning methods in capturing ship maneuvering features, their potential use in the design of ship control and intelligent decision support systems.

Sensitivity of microbial bioindicators in assessing metal immobilization success in smelter-impacted soils

While plant toxicity reduction remains the primary metric for judging the success of metal immobilization in soil, the suitability of microorganisms as universal indicators of its effectiveness in various contaminated soils remains a point of contention. This study assessed the sensitivity of microbial bioindicators in monitoring metal immobilization success in smelter-impacted soils. It compared plants and microorganisms as indicators of the efficiency of natural Fe–Mn nodules from the Gulf of Finland in immobilizing metals in soils contaminated by a Ni/Cu smelter, on the Kola Peninsula, Murmansk region, Russia. Perennial ryegrass (Lolium perenne) was grown on nodule-amended and control soils. Plant responses in the smelter-impacted soils proved to be sensitive and robust indicators of successful metal immobilization. However, microbial responses exhibited a more complex story. Despite the observed reductions in soluble metal concentrations, shoot metal contents in ryegrass, and significant improvements in plant growth, certain microbial bioindicators were unresponsive to metal immobilization success brought about by the addition of Fe–Mn nodules. Among microbial bioindicators studied, community-level physiological profiling, microbial biomass carbon, and basal respiration were sensitive indicators of metal immobilization success, whereas the number of saprotrophic, oligotrophic, and Fe-oxidizing bacteria and fungi, the biomass of bacteria and fungi, and enzymatic activity were less robust indicators. Interestingly, the correlations between different microbial responses measured were weak or even negative. Some microbial responses also exhibited negative correlations with plant biomass. These findings underscore the need for further research on comparative evaluations of plants and microorganisms as reliable indicators of metal immobilization efficacy in polluted environments.

U–Pb (SHRIMP-II) Age of Zircon from Granites of Bolshoi Tyuters Island (Gulf of Finland, Russia) and the Problem of the Ediacaran Thermal Event in the Region

U–Pb (SHRIMP-II) Age of Zircon from Granites of Bolshoi Tyuters Island (Gulf of Finland, Russia) and the Problem of the Ediacaran Thermal Event in the Region

Validation of the coupled physical–biogeochemical ocean model NEMO–SCOBI for the North Sea–Baltic Sea system

Abstract. The North Sea and the Baltic Sea still experience eutrophication and deoxygenation despite large international efforts to mitigate such environmental problems. Due to the highly different oceanographic frameworks of the two seas, existing modelling efforts have mainly focused on only one of the respective seas, making it difficult to study interbasin exchange of mass and energy. Here, we present NEMO–SCOBI, an ocean model (NEMO-Nordic) coupled to the Swedish Coastal and Ocean Biogeochemical model (SCOBI), that covers the North Sea, the Skagerrak–Kattegat transition zone and the Baltic Sea. We address its validity to further investigate biogeochemical changes in the North Sea–Baltic Sea system. The model reproduces the long-term temporal trends, the temporal variability, the yearly averages and the general spatial distribution of all of the assessed biogeochemical parameters. It is particularly suitable for use in future multi-stressor studies, such as the evaluation of combined climate and nutrient forcing scenarios. In particular, the model performance is best for oxygen and phosphate concentrations. However, there are important differences between model results and observations with respect to chlorophyll a and nitrate in coastal areas of the southeastern North Sea, the Skagerrak–Kattegat transition zone, the Gulf of Riga, the Gulf of Finland and the Gulf of Bothnia. These are partially linked to different local processes and biogeochemical forcing that lead to a general overestimation of nitrate. Our model results are validated for individual areas that are in agreement with policy management assessment areas, thereby providing added value with respect to better contributing to international programmes aiming to reduce eutrophication in the North Sea–Baltic Sea system.

Warming drives phenological changes in coastal zooplankton

Climate warming has led to phenological changes over time, typically displayed as earlier emergence of various organisms in spring or summer in temperate terrestrial and marine systems alike. Similarly, warm conditions can extend seasonal occurrence. Using a time series of zooplankton data from a coastal area in the Gulf of Finland, we calculated the start, end and the length of the season for the occurrence in rotifers and for adult and juvenile stages of three calanoid copepods. We investigated whether the start and end of the season of these taxa have shifted earlier and later, respectively, and whether the season length has increased. We further investigated if potential changes are driven by climate warming. We show that both copepods and rotifers do indeed emerge earlier, but that the pattern in recent years was not conclusive, and that both temperature and ice conditions influenced the seasonal abundance patterns of some taxa. Warmer years led to earlier occurrence of Temora longicornis copepodites. Earlier ice break-up coincided with longer seasons for Acartia and earlier emergence of Eurytemora affinis. The phenological changes in zooplankton demonstrated here may have cascading effects on other trophic levels in the food web. We also demonstrate how decreased sample number influences the ability to capture intra-annual abundance patterns and discuss the implications for monitoring.

Different approaches to estimate benthic metazoan diversity associated with free-living macroalgae (Fucus vesiculosus) on shallow soft sediments

Habitat complexity can boost biodiversity by providing a wide range of niches allowing species co-existence. Baltic Sea benthic communities are characterised by low species diversity. Thus the occurrence of the habitat forming macroalga Fucus vesiculosus may influence benthic communities and promote diversity. Here biodiversity estimates were obtained through conventional and eDNA approaches for the benthic assemblages associated with free-living Fucus and the adjacent bare-sediment habitats at six sites from the Northern Baltic Proper and the Gulf of Finland. Free-living F. vesiculosus habitats are heterogeneous with biodiversity estimates varying considerably among sites. The additional habitat complexity provided by F. vesiculosus tended to improve taxa richness as a result of additional epifauna assemblages, although macroinfaunal taxa richness and abundance was often reduced. Consequently the complex habitats provided by free-living F. vesiculosus often improve biodiversity, yet alters the composition of assemblages in soft sediment habitats and consequential ecosystem functioning. The study emphasised the disparity in biodiversity estimates achieved when employing different biodiversity approaches. Biodiversity estimates were more similar within approaches compared to between habitat types, with each approach detecting exclusive taxa. Consequently, biodiversity estimates can benefit from a multi-approach design where both conventional and eDNA approaches are employed in complement.

Variability of Primary Productivity as an Initial Link in Carbon Flux Under the Influence of Hydrological Conditions in the Baltic Sea

Investigating variability in phytoplankton primary productivity as a key component of the “biological pump” is critical to quantifying flux in the marine environment. We hypothesized that under certain hydrological conditions, changes in phytoplankton productivity are greater with changes in photosynthetic efficiency (the ratio of primary production (P P ) to the rate of electron transport in the phytoplankton photosystem, P P /ETR) than with changes in chlorophyll content. This study showed that increase of P P during sharp changes in hydrological parameters in the temporary frontal South-East Baltic (SEB) is achieved by increasing the efficiency of photosynthesis, i.e., the degree of use of light energy captured by chlorophyll a (Chl a). In the Gulf of Finland (GF), an increase in P P followed an increase in salinity from the Neva mouth to the sea and controls chlorophyll contents with low variability in photosynthetic efficiency. For SEB and GF, measurements of parameters of phytoplankton productivity and chlorophyll a content in late autumn (November) are carried out. The first stage of carbon flow (in biological pump), expressed in terms of primary production, was higher in the SEB than in the GF

Linking contaminant exposure to embryo aberrations in sediment-dwelling amphipods: a multi-basin field study in the Baltic Sea

Embryo development of sediment-dwelling amphipod Monoporeia affinis is sensitive to contaminant exposure. Therefore, embryo aberrations in gravid females are used to detect the biological effects of contaminant exposure in the Baltic Sea benthic habitats. The indicator based on the aberration frequencies in wild populations (ReproIND) is currently used for environmental status assessment within the Marine Strategy Framework Directive, Descriptor 8.2. However, so far, it has mainly been applied in the Bothnian Sea (BoS) and the Western Gotland Basin (WGB), where it was found to respond to contaminant pressure and non-chemical environmental factors, such as temperature.To expand the applicability of the indicator to other Baltic Sea basins, we used field data from the gulfs of Finland and Riga, BoS, and WGB to investigate the relationships between reproductive disorders and contaminants and environmental factors, thus evaluating the indicator suitability in these areas. Despite the natural variability of the environments and contaminant distribution across and within the basins, we found that high concentrations of contaminants, e.g. metals, PAHs, and PCBs, contribute significantly to the embryo aberrations in M. affinis. These findings support ReproIND applicability in the Baltic Sea and, perhaps, in other marine areas.

Fatty acid profiles reveal dietary variability of a large calanoid copepod Limnocalanus macrurus in the northern Baltic Sea

Eutrophication, climate-induced warming, and salinity fluctuations are altering the fatty acid profiles and the availability of essential polyunsaturated fatty acids (PUFAs) in marine zooplankton communities. Limnocalanus macrurus Sars G.O., 1863 is a large calanoid copepod inhabiting the low-salinity areas in the Baltic Sea, where it is a major source of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) to commercially important fish. L. macrurus is sensitive to warming, eutrophication and hypoxia. As an opportunistic feeder, it is capable of dietary shifts, which affects its fatty acid profiles. Although much studied in boreal lakes, there are only a few studies on the fatty acid profiles of the Baltic Sea populations. This study aimed to compare the fatty acid profiles of L. macrurus in three basins of the Baltic Sea, in relation to the community fatty acids and environmental variables. We collected samples of L. macrurus and filtered plankton community for gas chromatographic fatty acid analyses in August 2021 on R/V Aranda. The nutritional quality of L. macrurus to consumers was lower in the Gulf of Finland (GoF) compared to the Gulf of Bothnia, indicated by the low levels of DHA and EPA, as well as the low n-3/n-6 ratio of PUFAs. The lower ratio of 18:1n-7 to 18:1n-9 implied higher degree of omnivory in GoF. In contrast, a diatom marker 16:1n-7 had high proportion in the Bothnian Bay. High temperatures in GoF may have restricted feeding in the upper water column, possibly forcing a shift towards cyanobacteria or seston-based diet, as interpreted from a high proportion of 18:2n-6 and 18:3n-3. We conclude that the ability of L. macrurus to utilize multiple food sources increases its resilience to environmental change, while the consequences on the nutritional quality may have further cascading effects on the food webs.