SE Baltic Sea Research Articles

Invasive Ponto‐Caspian amphipods are less carnivorous outside their native range

AbstractA species' expansion beyond the native range is often assumed to be associated with an increased dietary niche breadth. However, empirical evidence remains limited due to a scarcity of studies comparing both the parental and invaded ranges. Here, we test the trophic niche expansion hypothesis by examining stable isotopes and functional morphology across native (NW Black Sea) and invaded (SE Baltic Sea) ranges of two amphipods, Dikerogammarus villosus and Pontogammarus robustoides, originating from the Ponto‐Caspian region—a major source of species invading Holarctic inland waters. Stable isotopes revealed that both species underwent a marked dietary niche contraction by becoming less carnivorous in the invaded range. This dietary shift was morphologically mirrored by an overall reduction of functional traits related to predation. The magnitude of dietary and morphological change was greater in D. villosus. Our findings indicate that previous experimental reports of aggressive predation in D. villosus reflect opportunistic foraging and align with local stable isotope studies which generally indicate a low trophic position. We conclude that Ponto‐Caspian species can undergo rapid dietary changes outside the native range, and that dietary niche expansion is not a prerequisite for successful non‐native establishment.

An assessment of nutrient removal by harvesting constructed floating wetlands in two coastal lagoons in the SE Baltic Sea

AbstractIn the last decades, so‐called internal or sea‐based mitigation measures have been suggested as nature‐based solutions to remove nutrients and improve water quality in semi‐enclosed coastal waters. However, these have rarely been tested in the field, especially in colder climates where winter ice cover is common. The aim of this experimental research was to investigate plant growth conditions in such an environment, as well to estimate nutrient removal capacity by harvesting constructed floating wetlands (CFWs). We tested small (24–28 m2) CFWs (Biomatrix®, Scotland, UK) at two demonstration sites: the Curonian lagoon (CL, Lithuania) and Szczecin lagoon (SL, Poland). In the CL, CFWs were planted predominantly with Carex acutiformes (Ehrh.), while the SL CFW was planted mainly with the reed Phragmites australis (Cav.) Trin. ex Steud. We aimed to test the amount of nutrient removal by plant harvesting over three subsequent years (2019–2021). We investigated carbon storage capacity and plant nutrient stoichiometry as indicators of potential nutrient limitation in the brackish coastal waters. Plant biomass increased annually, stabilising at 2.5–3.7 kg wet weight m−2. The total nutrient uptake per installed island area varied with the plant species composition. In the successive years, the harvested plants from the CL CFW dominated by Carex accumulated 10.4–13.1 g N m−2, 0.6–0.8 g P m−2 and 318–431 g C m−2 per year. The harvest from the SL CFW dominated by Phragmites contained a two‐times higher amount of nutrients, the respective figures being 21.2 g N m−2, 1.6 g P m−2 and 704 g C m−2. The nutrient stoichiometry in the vegetation did not suggest the presence of sub‐optimal growth conditions due to nitrogen limitation. However, the CL's dissolved nutrient supply was very low during the summer cyanobacteria bloom and indicated a severe nitrogen deficiency (as reflected in the dissolved inorganic nitrogen:dissolved inorganic phosphorus [DIN:DIP] molar ratio of 6). We suggest that to maximise nutrient removal capacity, tall plants with high biomass should be selected and/or plants with fine root systems to efficiently uptake the limiting nutrient from the water.

Assessing the effect of coastal upwelling on the air temperature at the south-eastern coast of the Baltic Sea

Coastal upwelling along the SE Baltic Sea coast is a common feature, especially during the warm season. It significantly lowers sea surface temperature (SST) in the coastal areas, and, therefore, may be responsible for modifying meteorological conditions in those coastal areas, where upwelling is most frequently observed. This study aims to assess the effect of coastal upwelling on the air temperature at the south-eastern coast of the Baltic Sea based on long-term period observations (2002–2021) from coastal hydrometeorological stations and satellite data. Overall, our study revealed that due to its high frequency and spatial extent, upwelling is responsible for lowering the mean summer season SST of the SE Baltic Sea coast by about 1°C. And even though upwelling is a short-term event, upwelling-induced SST drop results in cooling air temperatures in the coastal areas, i.e., the mean air temperatures during upwelling are typically 2−4°C lower than before. It was also observed that upwelling is favouring the development of advective fog. Thus, sudden changes in meteorological parameters during upwelling can have versatile effects on various socio-economic activities. The results of this study contribute to the understanding of upwelling feedback onto the lower atmosphere and, therefore, are important for advancing the accuracy of weather forecasts that are needed for coastal communities, including marine and coastal industries.

Temporal and spatial differences in nitrogen and phosphorus biogeochemistry and ecosystem functioning of a hypertrophic lagoon (Curonian Lagoon, SE Baltic Sea) revealed via Ecological Network Analysis

In coastal lagoons, eutrophication and hydrology are interacting factors that produce distortions in biogeochemical nitrogen (N) and phosphorus (P) cycles. Such distortions affect nutrient relative availability and produce cascade consequences on primary producer's community and ecosystem functioning.In this study, the seasonal functioning of a coastal lagoon was investigated with a multielement approach, via the construction and analysis of network models. Spring and summer networks, both for N and P flows, have been simultaneously compiled for the northern transitional and southern confined area of the hypertrophic Curonian Lagoon (SE Baltic Sea). Ecological Network Analysis was applied to address the combined effect of hydrology and seasonality on biogeochemical processes.Results suggest that the ecosystem is more active and presents higher N and P fluxes in summer compared to spring, regardless of the area. Furthermore, larger internal recycling characterizes the confined compared to the transitional area, regardless of the season. The two areas differed in the fate of available nutrients. The transitional area received large riverine inputs that were mainly transferred to the sea without the conversion into primary producers' biomass. The confined area had fewer inputs but proportionally larger conversion into phytoplankton biomass. In summer, particularly in the confined area, primary production was inefficiently consumed by herbivores. Most phytoplanktonic N and P, in the confined area more than in the transitional area, were conveyed to the detritus pathway where P, more than N, was recycled, contributing to the unbalance in N:P stoichiometry and favouring N-fixing cyanobacteria over other phytoplankton groups. The findings of this study provide a comprehensive understanding of N and P circulation patterns in lagoon areas characterized by different hydrology. They also support the importance of a stoichiometric approach to trace relative differences in N and P recycling and abundance, that promote blooms, drive algal communities and whole ecosystem functioning.

The Effect of Short-Term Upwelling Events on Fish Assemblages at the South-Eastern Coast of the Baltic Sea

Multiple stressors, such as overfishing, pollution, climate change, biological invasions etc., are affecting fish communities, and thus can have versatile effects on marine ecosystems and socio-economic activities as well. Understanding the changes in the fish community structure is ecologically and economically important, yet a very complex issue, requiring comprehensive analysis of multiple factors. The role of regional oceanographic variability, namely, coastal upwelling, is often neglected when it comes to the analysis of fish assemblages. In this perspective, we were aiming, for the first time in the Baltic Sea, to assess the upwelling influence on fish communities and fish community-based ecological indices used under Marine Strategy Framework Directive. The study covered a long-term period (2000–2019) for upwelling identified by satellite data analysis and fish gillnet surveys, performed in three distinct locations in the coastal waters of the SE Baltic Sea. Overall, our study revealed that temporal dynamics of fish abundance and community composition were associated with the presence of coastal upwelling. The study outcomes suggest that the fish community was more diverse and a higher number of some fish species was observed before upwelling. During upwelling, there was more evident dominance of 1–2 main marine fish species. Through the changes in fish abundance and species composition upwelling was also responsible for the changes in fish community structure-based indices for marine environment status, i.e., in the majority of the cases a decrease in Trophic, Piscivorous Fish, and Diversity indices were observed. Our study demonstrates that upwelling can affect both, the quantitative and qualitative characteristics of coastal fish communities, therefore, it is important to consider this when predicting shifts in the distribution of fish stocks or assessing environmental status indicators, especially under changing climate. We believe that our approach adds novel information to the study of coastal ecosystems of the Baltic Sea and is important for better management of socio-economic activities in the coastal zone.

Assessment of Four Major Fish Species Stocks in the Lithuanian and Russian Parts of Curonian Lagoon (SE Baltic Sea) Using CMSY Method

Fisheries in the Curonian Lagoon (1584 km2 coastal lagoon in South-East Baltic) can be classified as artisanal, small-scale, multi-species, and multi-gear. Such types of fisheries are characterised as data-poor and require appropriate investigation methods. We used CMSY (version CMSY_2019_9f. R) to assess maximum sustainable yield (MSY) and related indicators for freshwater bream, roach, pike-perch, and European perch. A decline in pike-perch and roach was identified, while the stocks of freshwater bream and European perch were sustained. As the CMSY model does not consider the impact of environmental factors, the decline in roach stock may be attributed to the increase in salinity rather than to overfishing. In the case of freshwater bream and pike-perch, the method cannot consider the increase of the percentage of small-sized fishes in catches due to the allowance of low-selectivity gears in the fishery. Additionally, in the case of the pike-perch, the model does not take into account the interannual fluctuations in the stock-recruitment system. The assessment of the European perch stock can be considered to be good. However, the accuracy of CMSY is limited, and it should be used for fisheries management only in combination with other methods.

Characterization and Diversity of Microcystins Produced by Cyanobacteria from the Curonian Lagoon (SE Baltic Sea)

Microcystins (MCs) are the most widely distributed and structurally diverse cyanotoxins that can have significant health impacts on living organisms, including humans. The identification of MC variants and their quantification is very important for toxicological assessment. Within this study, we explored the diversity of MCs and their potential producers from the Curonian Lagoon. MC profiles were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, while the potential producers were detected based on the presence of genus-specific mcyE gene sequences. Among the numerous MCs detected, one new potential MC variant with m/z 1057 was partially characterized. Moreover, two other MCs with m/z 1075 and m/z 1068 might belong to new variants with serine (Ser), rarely detected in position one of the peptides. They might also represent MC-Y(OMe)R and MC-WR, respectively. However, the application of a low-resolution MS/MS system made the unambiguous identification of the MCs impossible. Based on this example, the problems of peptide structure identification are discussed in the work. Genetic analysis revealed that potential MCs producers include Dolichospermum/Anabaena, Microcystis spp., and Planktothrix agardhii. The diversity and temporal variations in MC profiles may indicate the presence of several chemotypes of cyanobacteria in the Curonian Lagoon.

Expert-Based Assessment and Mapping of Ecosystem Services Potential in the Nemunas Delta and Curonian Lagoon Region, Lithuania

The Curonian Lagoon (SE Baltic Sea) and the coastal wetland system play a vital role in maintaining the overall cultural, economic and ecological health of the region. However, its value is still largely underestimated and there is a lack of integrated ecosystem management based on multiple ecosystem services assessment. In this study, 34 ecosystem services (ES) were identified, assessed and mapped following the Common International Classification of Ecosystem Services (CICES). Using expert opinion, 35 land cover classes were scored for their ES potential, these being 15 CORINE land cover classes (CLC) and 20 Natura 2000 areas of conservation (habitat types, i.e., Sites of Community Importance). The total ES potential was calculated by averaging the opinions of experts, using self-confidence scoring as weights, and the ES relative importance index was derived from a questionnaire. As a result, three maps corresponding to each ES potential category (provisioning, regulation and maintenance and cultural) were calculated and further used for hot- and coldspot analyses. Regulation and maintenance and cultural ES were highly interrelated and had the highest potential in the studied area. Forested areas had the highest total ES potential and contributed significantly to the land cover of the ES hotspots.

Spatial and Temporal Diversity of Cyanometabolites in the Eutrophic Curonian Lagoon (SE Baltic Sea)

This work aims to determine the profiles of cyanopeptides and anatoxin synthetized by cyanobacteria in the Lithuanian part of the Curonian Lagoon (SE Baltic Sea) and to characterize their spatial and temporal patterns in this ecosystem. Cyanometabolites were analysed by a LC-MS/MS system and were coupled to a hybrid triple quadrupole/linear ion trap mass spectrometer. During the investigation period (2013–2017), 10 microcystins, nodularin, anatoxin-a, 16 anabaenopeptins, including 1 oscillamide, 12 aeruginosins, 1 aeruginosamide, 3 cyanopeptolins and 4 microginins were detected. The most frequently detected metabolites were found at all investigated sites. Demethylated microcystin variants and anabaenopeptins had the strongest relationship with Planktothrix agardhii, while non-demethylated microcystin variants and anatoxin had the strongest relationship with Microcystis spp. Low concentrations of some microcystins: [Asp3]MC-RR, MC-RR, MC-LR, as well as a few other cyanopeptides: AP-A and AEG-A were found during the cold period (December–March). Over the study period, Aphanizomenon, Planktothrix and Microcystis were the main dominant cyanobacteria species, while Planktothrix, Microcystis, and Dolichospermum were potentially producers of cyanopeptides and anatoxin detected in samples from the Curonian Lagoon.

Morphology and origin of the palaeo cliff area in the Sambia Peninsula nearshore (SE Baltic Sea)

The article scrutinizes stratigraphy, morphology, and origin of the terraced underwater slope of the Sambia Peninsula next to the Taran Cape, the SE Baltic Sea, using a combination of multi-beam and single-beam bathymetry, side-scan sonar survey, CHIRP, single-channel seismoacoustic data, and sediment grain-size results. The underwater slope and its minor landforms were formed by changes of a relative sea-level during the Late Pleistocene and Holocene. Landforms, such as terraces and palaeo cliffs, sinks, remnants, stacks, karst sinkholes, ravines, cuestas, and drowned valleys, are associated with positions of older shorelines, sea-level changes and outcropped Pre-Quaternary formations. Six main stages of the underwater slope development have been recognized. The most important topographic feature is a high palaeo cliff (10 m high) with its toe at a water depth of 26–34 m. The cliff was cut in Cretaceous deposits and has different age and origin in different locations. Its northern sector with a toe at a depth of 34–35 m is polygenetic, formed by tectonic faulting and subsequent abrasion at the Baltic Ice Lake stage. The southern sector, with a toe at a depth of 26–27 m, was cut by wave erosion at the Ancylus Lake stage. Terraces on the underwater slope at depths of 29 m, 34 m, 40 m, 43 m, 48 m and 52 m b.s.l. were formed probably by the Baltic Ice Lake and Yoldia Sea transgressions and survived owing to relatively rapid and short changes of the sea-level. At a depth of 0–26 m, at a sea-level slowstand, selective erosion formed a transgressive wave ravinement surface with karst and cuesta-like landforms on monoclinal Paleogene beds. The depths and the locations of described terraces and palaeo cliffs in the SE Baltic Sea allow us to rectify the relative sea-level curve for the Late Pleistocene-Holocene.

Hot moments and hotspots of cyanobacteria hyperblooms in the Curonian Lagoon (SE Baltic Sea) revealed via remote sensing-based retrospective analysis

A temporally and spatially detailed historical (1985–2018) analysis of cyanobacteria blooms was performed in the Curonian Lagoon (Lithuania, Russia), the largest coastal lagoon in the Baltic Sea. Satellite data allowed the mapping of cyanobacteria surface accumulations, so-called “scums”, and of chlorophyll-a concentration. The 34-year time series shows a tendency towards later occurrence (October–November) of the cyanobacteria scum presence, whereas the period of its onset (June–July) remains relatively constant. The periods when scums are present, “hot moments”, have been consistently increasing in duration since 2008. The differences in the starting, ending and annual duration of cyanobacteria blooms have been significantly altered by hydro-meteorological conditions (river discharge, water temperature, and wind conditions) and their year-round patterns. The most important environmental factors that determined the temporal changes of the scum presence and area were the standing stock of cyanobacteria and the ambient wind conditions. The “hotspots”, the areas where the blooms most likely occur, were distributed in the south-southwestern and central parts of the lagoon. The least affected areas were the northern part, which is connected to the coastal waters of the Baltic Sea, and the Nemunas River delta region. The longstanding, well-established spatial patterns of cyanobacteria blooms were linked to hydrodynamic features, namely water renewal time and current patterns, and to potential nutrient sources that included muddy sediments and the locations of colonies of piscivorous birds. Our findings confirmed that the annual and seasonal variations of cyanobacteria blooms and their regulation are a complex issue due to interactions between multiple factors over spatially and temporally broad scales. Despite great progress in the prevention and control of eutrophication and cyanobacteria blooms, the lagoon is still considered to be in a poor ecological status. This work provides a new and missing understanding on the spatial and temporal extent of cyanobacteria blooms and the factors that govern them. Such an understanding can help in planning management strategies, forecasting the magnitude and severity of blooms under changing nutrient loads and potential climate scenarios.

Application of the Spatial Statistic Methods to Coastal Zone Management: SE Baltic Sea Coast Case

Borisenko, I.; Kondrat, V.; Valaitis, E.; Kelpšaitė-Rimkienė, L., Olšauskaitė Urbonienė, R., 2020. Application of the spatial statistic methods to coastal zone management: SE Baltic sea coast case. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 753–758. Coconut Creek (Florida), ISSN 0749-0208.The coastal zone is one of the most dynamic environments in the world. Climate change is having an undeniable influence on coastal areas. The main climatic factors driving change in the Baltic Sea coastal zone are wind, waves, storm surges and flooding. Shoreline change is affected by a multitude of complex processes operating at various time- and length-scales.The presented work aims at clarification of the effects of different hydro meteorological factor to the short-term shoreline evolution at the Palanga beach. The analysis of the hydrometeorological factors, in order to assess the dependence of the beach response on the wind, sea level and wave characteristics with the focus on short term effects of the coastal protection structures in the rapid transition stage immediately after beach nourishment activities.

Effect of round goby (Neogobius melanostomus) invasion on blue mussel (Mytilus edulis trossulus) population and winter diet of the long-tailed duck (Clangula hyemalis)

The invasive round goby has established a viable population within 9 years of its first introduction to Lithuanian coastal waters (SE Baltic Sea). During its expansion phase, abundances increased 23-fold, which led to the near complete eradication of its main prey, the blue mussel, at < 20 m depth. The round goby population showed a stabilizing trend after blue mussel biomass was depleted; however, their abundance has not declined. The round goby feeds efficiently on newly settled mollusks, causing a severe constraint for blue mussel recovery. Changes in blue mussel availability and size structure induced a dietary shift in wintering long-tailed duck towards fish prey. An energetically dense food source sustains a good body condition in long-tailed ducks, however the change in trophic position (from 3.1 to 4.3 trophic level) suggests the potential for a reduction in their carrying capacity. Results from this study also show that coastal habitats with low and unpredictable population dynamics of blue mussel become less attractive wintering sites for long-tailed duck in the Baltic Sea. We also document a cascading effect of invasive species in the food web.

Assessing nature and dynamics of POM in transitional environment (the Curonian Lagoon, SE Baltic Sea) using a stable isotope approach

The nature of the particulate organic matter (POM) as well as its temporal and spatial distribution and dynamics in the Curonian Lagoon (south-eastern part of the Baltic Sea) were investigated. The organic matter was characterized by the organic carbon and nitrogen content, δ13C and δ15N signatures as well as POC/Chl-a and C/N ratios. Additionally, data on hydrological, chemical and biological parameters were used for better understanding the POM distribution and dynamics. The sampling was performed at 13 stations in the Curonian Lagoon and its outflow in the Baltic Sea during the 2012–2013 period. Samples were also collected at the Nemunas River mouth in order to test the riverine impact. Obtained results showed that isotopic values of carbon and nitrogen ranged from −36.1‰ to −25.2‰ and from −0.9‰ to 15.5‰, respectively. The isotopic composition, together with the low C/N molar (∼7) and POC/Chl-a ratios (<100) of the POM, suggested the dominance of living phytoplankton in POM throughout the year with the higher input of detrital material (C/N >10, POC/Chl-a ratios >100) in late autumn − winter.The results of multivariate analysis evidenced a spatial distinction of POM distribution in the northern-transitional and central confined areas and allowed us to distinguish the main driving factors. The seasonal variation of the δ13C and δ15N values in POM (towards higher δ13C and lower δ15N values in the summer − early autumn period and lower δ13C and higher δ15N values in the late autumn − spring period) was determined by combination of factors such as availability of inorganic carbon and nitrogen, the riverine discharge, seasonal phytoplankton succession and by the short-term saline water intrusion to the northern-transitional part of the lagoon.

Size-selective microzooplankton grazing on the phytoplankton in the Curonian Lagoon (SE Baltic Sea)

Summary Dilution experiments were performed to estimate phytoplankton growth and microzooplankton grazing rates at two sites: freshwater (Nida) and brackish water (Smiltyne) in the Curonian Lagoon (SE Baltic Sea). Using the size-fractionation approach and dilution experiments, we found that the microzooplankton community was able to remove up to 78% of nanophytoplankton (2–20 μm) standing stock and 130% of the total daily primary production in the brackish waters of the lagoon, and up to 83% of standing stock and 76% of the primary production of picophytoplankton (0.2–2 μm) in the freshwater part. The observed differences were attributed to the changes in ciliate community size and trophic structure, with larger nano-filterers (30–60 μm) dominating the brackish water assemblages and pico-nano filterers (

Feeding activity and diet composition of round goby (Neogobius melanostomus) in the coastal waters of SE Baltic Sea

Feeding activity and diet composition of round goby (Neogobius melanostomus) in the coastal waters of SE Baltic Sea

Basic intrusives and hydrocarbonic potential of the South-East Baltic

The Paleozoic rocks of Kaliningrad oblast and the adjacent areas of the SE Baltic Sea have recently became exploration targets. The small size and number of prospective structures, as well as the small size of the oil reserves in the onshore areas, have resulted in a decline in production and a decrease in exploration activity. At the same time, previous studies conducted by the Institute of Oceanology of the Russian Academy of Sciences and other institutions show that the SE Baltic Sea contains numerous yet-to-be-explored structures, which could be attractive exploration targets. Recent studies indicate that the region was intensely intruded by numerous diabase sills, which cut across Paleozoic reservoir rocks. This fact may have both positive and negative implications for the petroleum potential of the basin and should be taken into account in outlining the possible future directions for resource exploration. This study presents data on the distribution, sizes, ages, composition, and volumes of the mafic intrusions and discusses their thermal effects on the petroleum potential of the SE Baltic Basin.

Trophic position and basal energy sources of the invasive prawn Palaemon elegans in the exposed littoral of the SE Baltic Sea

We investigated the abundance, trophic position, and linkages to basal energy sources of the non-indigenous prawn Palaemon elegans in shallow (0.5–1.6 m) stony habitats of the exposed coast of the SE Baltic Sea. Prawn abundance at the site with artificial stone was higher than that in the natural stony habitats. Stable isotope analysis (SIA) suggested similarity in feeding between different size classes of P. elegans. However, SIA of stomach contents showed greater variability of ingested food among large individuals (body length > 25 mm). Trophic position was estimated at 3.0 ± 0.8 suggesting the prevalence of animal prey in the assimilated diet of P. elegans. However, filamentous green algae was also consumed by large-sized individuals, as indicated by their isotopic signature and the elemental (C:N) ratio of their stomach contents. Modeling of the contribution of Cladophora and particulate organic matter, as basal food sources, to the diet of P. elegans (two end-member mixing model) revealed that only 40% of the assimilated biomass was derived from macroalgae, either directly or through intermediate consumers. This finding suggests that pelagic production was the main carbon source supporting prawn’s nutrition. In an experimental study, P. elegans readily consumed mysids, suggesting that this prey may be the prawn’s link to the pelagic food chain.

Tracing the isotopic signal of a cyanobacteria bloom through the food web of a Baltic Sea coastal lagoon

This study shows that cyanobacteria blooms support secondary production in a diverse group of benthic and pelagic consumers and illustrate the utility of stable isotopes for tracking the cyanobacteria signal in aquatic food webs. We characterized seasonal patterns in δ13C and δ15N signatures of particulate organic matter (POM) and consumers in a eutrophic coastal lagoon (Curonian Lagoon, SE Baltic Sea) before, during and after a cyanobacteria bloom. We found that during the pre- and post-bloom periods (spring and autumn), POM from the lagoon was isotopically indistinguishable from riverine POM. During the bloom, the increase in phytoplankton biomass and dominance by N2-fixing cyanobacteria resulted in higher δ13C and lower δ15N of POM. These changes in POM were reflected in isotopic signatures of primary consumers with greatest response among fast-growing planktonic and nectobenthic crustaceans and chironomids. Results from end-member mixing analyses suggest that cyanobacteria accounted for 50–80% of production by these consumers during the bloom period. Weaker responses were observed among slow-growing species, particularly long-lived bivalves such as Dreissena. Cyanobacteria-induced shifts in δ13C and δ15N could be tracked to secondary consumers, particularly fast-growing forms such as predatory zooplankton (Leptodora) and juvenile fishes (European perch). We suggest that reconstruction of the food web at the upper trophic levels should incorporate isotopic baselines of both fast- and slow-growing primary consumers to reflect the contribution of blooms events.

Upwelling dynamics in the Baltic Sea studied by a combined SAR/infrared satellite data and circulation model analysis

Data from the space-borne synthetic aperture radar (SAR) aboard the Envisat satellite and MODIS spectroradiometers on board the Terra/Aqua satellites, and the high resolution Sea Ice-Ocean Model of the Baltic Sea (BSIOM) have been used to investigate two upwelling events in the SE Baltic Sea. The combined analysis was applied to the upwelling events in July 2006 along the coasts of the Baltic States, and in June 2008 along the Polish coast and Hel Peninsula. Comparisons indicated good agreement between the sea surface temperatures and roughness signatures detected in satellite imagery and model results. It is shown that BSIOM can simulate upwelling events realistically. The utilization of modelled hydrodynamics and wind stress data together with SAR and SST information provides an extended analysis and deeper understanding of the upwelling processes in the Baltic Sea.During the active phase of upwelling when the wind is strong, the resulting coastal jet is controlled by vorticity dynamics related to depth variations in the direction of the flow. Typical upwelling patterns are related to the meandering coastal jet and thus associated with topographic features. The longshore transport of the coastal jet is of the order of 104ms−1, and the offshore transport at the surface is of the order of 103ms−1, which respectively correspond to the total and largest river runoff to the Baltic Sea.