Eastern Gulf Of Finland Research Articles

Simulating sea level extremes from synthetic low-pressure systems

Abstract. In this article we present a method for numerical simulations of extreme sea levels using synthetic low-pressure systems as atmospheric forcing. Our simulations can be considered to be estimates of the high sea levels that may be reached when a low-pressure system of high intensity and optimal track passes the studied region. We test the method using sites located along the Baltic Sea coast and simulate synthetic cyclones with various tracks. To model the effects of the cyclone properties on sea level, we simulate internal Baltic Sea water level variations with a numerical two-dimensional hydrodynamic model, forced by an ensemble of time-dependent wind and air-pressure fields from synthetic cyclones. The storm surges caused by the synthetic cyclones come on top of the mean water level of the Baltic Sea, for which we used a fixed upper estimate of 100 cm. We find high extremes in the northern Bothnian Bay and in the eastern Gulf of Finland, where the sea level extreme due to the synthetic cyclone reaches up to 3.5 m. In the event that the mean water level of the Baltic Sea has a maximal value (1 m) during the cyclone, the highest sea levels of 4.5 m could thus be reached. We find our method to be suitable for use in further studies of sea level extremes.

Continuing long-term expansion of low-oxygen conditions in the Eastern Gulf of Finland

To develop an oxygen indicator for the eastern part of the Gulf of Finland (EGOF), a dataset covering 1900–2021 was compiled. The analysis revealed a long-term declining trend in dissolved oxygen concentrations in the EGOF deep layer of 0.022 mg L–1 a–1 and multi-decadal variations associated with the observed changes in hydrographic conditions. About 27% of the decline in oxygen concentrations for 1900–2021 and 40% for 1990–2021 can be explained by the decrease in solubility due to the temperature increase and changes in hydrographic conditions. The water volume and bottom area under low oxygen conditions in 2016–2021, characterized by dissolved oxygen concentrations <= 6 mg L–1, have increased, compared to the selected reference period with almost no human impact in the 1920s–1950s, from 9.8 km3 to 78.0 km3 (from 2.6% to 20.9% of the EGOF total volume) and from 1190 km2 to 4950 km2 (from 13.4% to 56.0% of the EGOF total area), respectively. The environmental status of the EGOF was assessed as not good based on the introduced oxygen indicator. We conclude that, in the long-term, low oxygen conditions have expanded mostly due to the excess load and accumulation of nutrients in the system and temperature-related changes in biogeochemical processes and fluxes. However, on a decadal scale, changes in hydrographic conditions, i.e. stratification and mixing, can significantly impact the sub-surface oxygen conditions in the EGOF and similar estuarine basins.

Impact of macroalgal blooms on biogeochemical processes in estuarine systems: a case study in the eastern Gulf of Finland, Baltic Sea

Impact of macroalgal blooms on biogeochemical processes in estuarine systems: a case study in the eastern Gulf of Finland, Baltic Sea

Probabilistic projections and past trends of sea level rise in Finland

Abstract. We explore past trends and future projections of mean sea level (MSL) at the Finnish coast, in the northeastern Baltic Sea, during the period 1901–2100. We decompose the relative MSL change into three components: regional sea level rise (SLR), postglacial land uplift, and the effect of changes in wind climate. Past trends of regional SLR can be calculated after subtracting the other two components from the MSL trends observed by tide gauges, as the land uplift rates obtained from the semi-empirical model NKG2016LU are independent of tide gauge observations. According to the results, local absolute SLR trends are close to global mean rates. To construct future projections, we combine an ensemble of global SLR projections in a probabilistic framework. In addition, we use climate model results to estimate future changes in wind climate and their effect on MSL in the semi-enclosed Baltic Sea. This yields probability distributions of MSL change for three scenarios representing different future emission pathways. Spatial variations in the MSL projections result primarily from different local land uplift rates: under the medium-emission scenario RCP4.5/SSP2-4.5, for example, the projected MSL change (5 % to 95 % range) over the 21st century varies from −28 (−54 to 24) cm in the Bothnian Bay to 31 (5 to 83) cm in the eastern Gulf of Finland.

Mobility of metal-organic pollutants in the emerging coastal-marine sediment of the Baltic Sea: The case-example of organotin compounds in sediments of the Gulf of Finland

Results of organotin and heavy metals pollution study of bottom sediment within three key areas in the Eastern Gulf of Finland (Baltic Sea) in the vicinity of Gogland and Moschny Islands and Vyborg Bay sampled during two seasons of 2017 and 2018 are presented.The studied bottom sediments contain organotin compounds in amounts (∑OTs from 5.7 to 123 ng/g) exceeding the permissible international standards, which can have a toxic effect and lead to pathological changes of aquatic organisms. The tributyltin was the prevail component of organotin compounds in bottom sediments in 2017, which high content (average 6.3 and 30 ng/g for Moschny and Gogland islands respectively) and low degradation coefficient (BDI: 0.1–0.8) indicate a permanent source of pollution. But the 2018 samples show an increase in BDI up to 1.7–3.3 that reveals the degradation of tributyltin over the annual period. But further monitoring of environmental pollution in the study areas is obviously necessary in view of the potential impact of these components on the irreversible change in the environmental situation for the entire Baltic region.

Ecological State of Bottom Sediments in the Eastern Gulf of Finland

The work is carried out as part of the annual monitoring studies of the eastern part of the Gulf of Finland in 2020. Monitoring the state of water transport in this region. The objects of this study were bottom sediments in the northeastern part of the Gulf of Finland; they contain the content of petroleum hydrocarbons, phosphorus and ammonium. The results were compared with the results of experimental studies carried out in the same area in previous years, as well as with the results of studies of water samples. The features of the chemical composition and structure of sediments, which affect their ability to accumulate petroleum hydrocarbons and nitrogen and phosphorus compounds, are taken into account. Based on the results of a comparative analysis of the aggregate information, an assessment of the state of bottom sediments in the north-eastern part of the Gulf of Finland is given. Based on the studies carried out, we concluded that the quantitative values of the investigated parameters are within the permissible limits. At the same time, there is a need to control the state of bottom sediments in the potential impact of port services in the future.

The Key Environmental Factors Shaping Coastal Fish Community in the Eastern Gulf of Finland, Baltic Sea

A highly productive coastal zone plays an important role in various stages of fish life cycles, e.g., spawning migrations, fish reproduction, larval development, juveniles growing, etc. Therefore, coastal biotopes significantly contribute to commercial fish species recruitment. Although the eastern Gulf of Finland is rich in shallow coastal water, its coastal fish communities and the influencing environmental variables are still significantly understudied. We investigated the composition and distribution of coastal fish species and the impact of abiotic and biotic environmental factors in the eastern Gulf of Finland during field surveys in 2011–2017. In total, 34 fish species were recorded at shallows. The coastal fish community demonstrates a low degree of heterogeneity despite a highly heterogeneous environment. Five freshwater species are widely distributed and the most frequent in the area. Three key environmental variables influencing the coastal fish community of the eastern Gulf of Finland were: (i) salinity, (ii) filamentous algae presence, and (iii) macrophytes presence. Fish community structure was also influenced by the sampling season. Discriminating and typifying taxa were performed for each environmental variable. We suggest that obtained results might be useful for future environmental studies in the region and fish community modeling.

The state of the intestinal bacterial community in mollusks for assessing habitat pollution in the gulf of Finland (Baltic Sea)

In this study, we investigated the abundance and diversity of bacteria in the digestive tract of the bivalve mollusks Unio pictorum after 30-day exposure in experimental cages and field-collected gastropod mollusk Radix balthica in the eastern Gulf of Finland, Baltic Sea. Contamination of water and sediments with petroleum hydrocarbons had a significant impact on the intestinal bacterial community of mollusks stimulating the growth of hydrocarbon-oxidizing bacteria. The abundance of the intestinal hydrocarbon-oxidizing bacteria correlated with the concentration of the total hydrocarbons in the water of the coastal sites in the Gulf, where the mollusks were exposed. Metagenomic analysis revealed significant differences in the intestinal microbial community composition between polluted and unpolluted sites. The increased abundance of members of the phylum Gammaproteobacteria, including species of Aeromonas, Acinetobacter, Arenimonas, Pseudomonas, Rheinheimera, and Shewanella, and Bacteroidetes (Flavobacterium and Pedobacter) in the intestinal tracts of mollusks Unio pictorum were found at hydrocarbon-contaminated site: therefore, these bacteria are key players in the adaptation of intestinal community to this kind of pollution and hydrocarbon degradation. Our study suggests that hydrocarbon-oxidizing bacteria have the potential as a sensitive bioindicator for the further monitoring and ecological assessment of marine ecosystems.

Cadmium in the Eastern Gulf of Finland: Concentrations and Effects on the Mollusk Limecola balthica

Cadmium in the Eastern Gulf of Finland: Concentrations and Effects on the Mollusk Limecola balthica

Evolution of Sedimentation Environment of Postglacial Basins in the Eastern Gulf of Finland during the Holocene under the Changing Climate

Evolution of Sedimentation Environment of Postglacial Basins in the Eastern Gulf of Finland during the Holocene under the Changing Climate

Coregonine fisheries in the eastern Gulf of Finland, Baltic Sea: history and current status

Coregonine fisheries in the eastern Gulf of Finland, Baltic Sea: history and current status

Keeping the Frontier: Steps “Towards Neolithization” in the Eastern Gulf of Finland

Abstract This article is an attempt to understand the driving forces behind the process of Neolithization in the Eastern Europe Forest zone, where the consumption economy existed till the Bronze or even till the Early Iron Age. Main peculiarities of the sociocultural development in the eastern part of the Gulf of Finland region (EGF) on the transition from Mesolithic to farming societies (sixth – first ka. BC) are discussed in relation to the changes in material culture, subsistence strategy, communication system and settlement pattern. The process of neolithization lasted there for several thousand years. Overview of the dynamics of the social and cultural development in the region revealed several phases of substantial changes in archeological materials (presumably reflecting considerable sociocultural changes). These changes happened later than in the neighboring territories and were preceded by dramatic environmental transformations that affected prehistoric communities in the coastal zone. For the population of the region, innovations could be considered as not “steps toward,” but “retreat in the face of” neolithization. Resistance of the population of EGF to the innovations could be based on environmental conditions that were extremely favorable for hunter–gatherers’ subsistence, but made farming (especially early farming) rather risky.

Population characteristics of the non-indigenous round goby, Neogobius melanostomus (Actinopterygii: Perciformes: Gobiidae), in the eastern Gulf of Finland

The round goby, Neogobius melanostomus (Pallas, 1814), is a fish of Ponto-Caspian origin that has been invading the Baltic Sea since the 1990s. Currently, it is abundant and commercially important in some areas of the sea. This species was first reported in the eastern Gulf of Finland (GoF) in 2012. Its occurrence increased thereafter, however it has remained largely unstudied in this region. The aim of this study was to investigate the population characteristics of the round goby in the eastern GoF to better understand its expansion trend and whether it will become abundant enough to be exploited by the local fishery. Fish were caught using multi-mesh gillnets (12–60 mm mesh) and a beach seine (0.5–10 mm mesh). Occurrence, density, catch per unit effort, biomass per unit effort, relative number and biomass in catches, as well as age, size and sex ratio were studied. The species regularly occurred in samplings along the southern coastline of the GoF, as well as some central areas and along the northern coast. Within 2012–2019, its occurrence in catches increased, with the highest frequency in 2015–2019 in shallow waters (&amp;lt;1.5 m) of Koporye Bay (70%) and in the deeper waters of Narva Bay (74%). Similarly, the highest density in the shallow waters was also observed in Koporye Bay (10.0 ind. ∙ 100 m−2), and offshore in Narva Bay. Relative abundance and biomass usually did not exceed 23%, although it reached 93% in Narva Bay. The oldest specimen was five years old. Young-of-the-year (YOY) juveniles predominated in the shallow waters (85%), while three-year-olds prevailed in deeper waters (75%). Among the fish older than two years, females were more predominant (mean ratio 3 to 1), and males were larger than females. Specimens in all life stages were found in the eastern GoF, and their abundance increased annually, suggesting that the round goby has successfully colonized this region of the Baltic Sea. However, compared to other areas of the Baltic Sea inhabited by longer-established populations, its population size is still relatively low.

Occurrence of pharmaceuticals in the Eastern Gulf of Finland (Russia).

The presence of substances of emerging concern-pharmaceuticals-in marine environments has been studied to a lesser extent compared to fresh and wastewaters. This is the first study of pharmaceutical distribution in the Russian part of the Baltic Sea. Among 18 pharmaceuticals previously detected in influent waters of Saint-Petersburg WWTPs, 7 compounds (caffeine [81% of samples], carbamazepine [81%], ketoprofen [60%], diclofenac [23 %], ciprofloxacin, trimethoprim, and clarithromycin) were recorded in seawater samples in a range of measured concentrations from 0.1 to 4452 ng L-1. Antibiotics were presented in trace concentrations. In sediment samples, 6 pharmaceuticals (0.1-66.2 ng g-1) were detected. The most common was carbamazepine (80%). The remaining compounds were located in decreasing frequency as follows: ketoprofen, trimethoprim, drotaverine, tetracycline, and ciprofloxacin. Some specific features of the Gulf of Finland affecting the distribution of pharmaceutical concentrations were highlighted-among the most important, the megapolis of St. Petersburg with its population over 5 million and freshwater input by the Neva River (high urbanization of the territory with a potent dilution factor). We discussed the suitable set of anthropogenic markers for the Russian part of the Gulf of Finland.

Food-web modification in the eastern Gulf of Finland after invasion of Marenzelleria arctia (Spionidae, Polychaeta)

The paucity of data on non-indigenous marine species is a particular challenge for understanding the ecology of invasions and prioritising conservation and research efforts in marine ecosystems. Marenzelleria spp. are amongst the most successful non-native benthic species in the Baltic Sea during recent decades. We used stable isotope analysis (SIA) to test the hypothesis that the dominance of polychaete worm Marenzelleria arctia in the zoobenthos of the Neva Estuary after its invasion in the late 2000s is related to the position of this species in the benthic food webs. The trend towards a gradual decrease in the biomass of Marenzelleria worms was observed during 2014–2020, probably due to significant negative relationships between the biomass of oligochaetes and polychaetes, both of which, according to SIA, primarily use allochthonous organic carbon for their production. The biomass of benthic crustaceans practically did not change and remained very low. The SIA showed that, in contrast to the native crustacean Monoporeia affinis, polychates are practically not consumed either by the main invertebrate predator Saduria entomon, which preys on M. affinis, oligochaetes and larvae of chironomids or by benthivorous fish that prefer native benthic crustaceans. A hypothetical model for the position and functional role of M. arctia in the bottom food web is presented and discussed. According the model, the invasion of M. arctia has created an offshoot food chain in the Estuary food webs. The former dominant food webs, associated with native crustaceans, are now poorly developed. The lack of top-down control obviously contributes to the significant development of the Marenzelleria food chain, which, unlike native food chains, does not provide energy transfer from autochthonous and allochthonous organic matter to the upper trophic levels. The study showed that an alien species, without displacing native species, can significantly change the structure of food webs, creating blind offshoots of the food chain.

Hazardous substances in the sediments and their pathways from potential sources in the eastern Gulf of Finland

Contamination by hazardous substances is one of the main environmental problems in the eastern Gulf of Finland, Baltic Sea. A trilateral effort to sample and analyse heavy metals (HMs), polycyclic aromatic hydrocarbons (PAHs), and organotins from bottom sediments in 2019–2020 were conducted along with harvesting historical data in Russian, Estonian and Finnish waters. We suggest that the input of organotins still occurs along the ship traffic routes. The tributyltin content exceeded the established quality criteria up to more than 300 times. High contamination by PAHs found near the ports, most likely originate from incomplete fuel incineration processes. The Neva River Estuary and Luga Bay might potentially suffer from severe cadmium contamination. The high ecological risk attributed to the HMs was detected at deep offshore areas. The simulated accumulation pattern qualitatively agrees with field observations of HMs in sediments, demonstrating the potential of numerical tools to tackle the hazardous substances problems.

Spatiotemporal structure of Baltic free sea level oscillations in barotropic and baroclinic conditions from hydrodynamic modelling

Abstract. Free sea level oscillations in barotropic and baroclinic conditions were examined using numerical experiments based on a 3-D hydrodynamic model of the Baltic Sea. In a barotropic environment, the highest amplitudes of free sea level oscillations are observed in the northern Gulf of Bothnia, eastern Gulf of Finland, and south-western Baltic Sea. In these areas, the maximum variance appears within the frequency range corresponding to periods of 13–44 h. In a stratified environment, after the cessation of meteorological forcing, water masses relax to the equilibrium state in the form of mesoscale oscillations at the same frequencies as well as in the form of rapidly decaying low-frequency (seasonal) oscillations. The total amplitudes of free baroclinic perturbations are significantly larger than those of barotropic perturbations, reaching 15–17 cm. Contrary to barotropic, oscillations in baroclinic conditions are strongly pronounced in the deep-water areas of the Baltic Sea proper. Specific spatial patterns of amplitudes and phases of free barotropic and baroclinic sea level oscillations identified them as progressive–standing waves representing barotropic or baroclinic modes of gravity waves and topographic Rossby waves.

New data on deglaciation in the Eastern Gulf of Finland: results of high-resolution geological mapping

New data on deglaciation in the Eastern Gulf of Finland: results of high-resolution geological mapping

Distribution and population characteristics of the invasive tubenose goby Proterorhinus marmoratus (Pallas, 1814) in the eastern Gulf of Finland

The article examines the characteristics of the invasive tubenose goby population that has become established in the eastern Gulf of Finland in the last 15 years. The species inhabits the most part of the studied area, and mainly occurs in waters with salinity equal to or lower than 3 ‰. Abundance of the tubenose goby is positively correlated with the density of filamentous algae, but not with other estimated parameters (substrates, macrophytes, water characteristics). The tubenose goby in the Gulf of Finland reached 62 mm Sl and age 1+. Age composition changed from mature female predominance to the male predominance during the season. Numerous juveniles and spawning adults were observed. The tubenose goby demonstrates successful naturalization in the new conditions and was numerically dominant in the coastal fish assemblage in summer.

Impact of climate change on sedimentation processes in the eastern Gulf of Finland during the Middle to Late Holocene

This paper presents the results of high‐resolution sedimentological analyses of sediment cores from the eastern Gulf of Finland (Baltic Sea). Sampling sites in the periphery of sedimentary basins were selected on the basis of acoustic profiling analyses. The research allowed tracing of the transition from the freshwater Ancylus Lake to the Littorina Sea. A specific transitional layer of ‘blue clays’, indicating the first stage of brackish water inflow into the Gulf of Finland, was dated to 9.1 ka BP. The date of first appearance of Littorina silty clay sedimentation was as follows: from 8.0 ka BP near Gogland Island, from 7.0 ka BP near Moshchny Island and from 5.9 ka BP near the Berezovye Islands. Holocene cycles of hypoxia, associated with periods of warming, were identified and cycles of ‘warming – transgression – anoxic conditions’ and ‘cooling – regression – oxygen‐rich conditions’ were revealed. During the first stage of Littorina transgression (8.0–7.0 ka BP), the near‐bottom environment in the deepest sedimentary basin of the eastern Gulf of Finland was characterized by oxygen deficiency. In contrast, 7.0–6.0 ka BP was dominated by oxygen‐rich conditions and active processes of bioturbation. Anoxic conditions occurred again from 6.0–4.8 ka BP (Holocene Climatic Optimum), resulting in the accumulation of undisturbed silty clays with subhorizontal lamination. The interval from 4.8–2.0 ka was then characterized by oxygen‐rich near‐bottom conditions favourable for benthic organisms. The grain‐size distributions throughout the sediment cores from the easternmost sedimentary basins suggest a relative lowering of the sea level from 3.5–1.8 ka and a rise after 1.8 ka BP.