Tuesday, 20 August
15:30 – 17:00
Aula Magna right hall

 

Coastal water quality interactions, changes and solution pathways

Georgia Destouni, Stockholm University, georgia.destouni@natgeo.su.se

With an overarching “source-to-sea” perspective, this paper presents the EU project COASTAL, its Baltic-coast case study, and three complementary approaches to resolving the complexity of coastal land-sea interactions and pathways to future good coastal water status. Result highlights include interacting hydroclimate-management scenarios and researcher-stakeholder co-created causal loop diagrams.

Multiple change pressures from human activities on land, partly eutrophic conditions in the open sea, and climate change over both land and sea affect the Baltic coastal zones and ecosystems. With an overarching “source-to-sea” perspective, this paper presents the EU project COASTAL, its Baltic-coast case study, and three complementary approaches to modelling and resolving the complexity of coastal land-sea interactions and pathways to future good coastal water status. The approaches include: 1) Typology-based hydrodynamic-transport modelling of climate-change, land-load and coastal-flow effects on coast-sea physical and solute spreading conditions. 2) Management-focused modelling of coastal water quality under different hydro-climatic and management scenarios. 3) Participatory model-building, involving multiple stakeholders with land and coast-sea perspectives of the linked water quality pressures and impacts, and their interactions from source to sea. Result highlights for future coastal eutrophication conditions include the changing hydroclimate as key driver and researcher-stakeholder co-created causal loop diagrams of these conditions and their development pathways.

 

Fate of dissolved organic matter in four Baltic Sea estuaries

Maren Voss, Leibniz Institute for Baltic Sea Research, maren.voss@io-warnemuende.de

Eero Asmala, University of Helsinki; Ines Bartl, Leibniz Institute for Baltic Sea Research; Jacob Carstensen, Aarhus University; Daniel Conley, Lund University; Joachim Dippner, Leibniz Institute for Baltic Sea Research; Christoph Humborg, Stockholms Universitets Östersjöcentrum; Mindaugas Zilius, Klaipeda University; Kaarina Lukkari, Finnish Environment Institute; Heather Reader, Memorial University of Newfoundland; Colin Stedmon, Technical University of Denmark; Nicola Wannicke, Leibniz-Institute for Plasma Science and Technology; Colin Stedmon, Technical University of Denmark; Nicola Wannickem, Leibniz-Institute for Plasma Science and Technology

Few datasets exist worldwide encompassing dissolved organic nitrogen, carbon, and phosphorus across different coastal systems. We analysed a few hundred DOM values within the BONUS-COCOA project from four sites differing widely in salinity, nutrients, and fresh water inflow. POM displays typical C:N:P ratios, while DOM has much higher C:N and C:P and varies widely within but less across sites.

Few data sets exist worldwide that contain dissolved organic (DO) nitrogen (N), carbon (C) and phosphorus (P) across coastal systems. We have analysed a few hundred samples for dissolved organic matter (DOM) within the BONUS-COCOA project from Roskilde Fjord, Vistula and Öre estuaries and Curonian Lagoon differing widely in salinity, nutrient conc. and freshwater inflow. C:N:P ratios were calculated for 138 sampling points but the data set offers insight into understanding the dynamics and fate of DOM via conservative mixing or selective removal of specific fractions. While typical C:N:P POM ratios exists, DOM has an overwhelming quantity of DOC compared to DON and DOP - mean ratio of 960-2660:50-125:1. While C:N:P of POM are significantly related, this pattern can only be found for DOC and DON in the dissolved fraction. End member mixing plots suggest a predominance of conservative mixing. Notable exceptions are DOC concentrations that reveal production at mid salinities in Roskilde Fjord and a rapid decline of DON at low salinity in Vistula and Öre estuary suggesting DON uptake. DOM is highly variable within but not across the different learning sites caused by various processes.

 

Nitrogen fixed by cyanobacteria is incorporated in filamentous algae and associated fauna in seagrass beds

Agnes ML Karlson, Stockholm University, agnes.karlsson@su.se

Andrius Garbaras, Center for Physical Science and Technology; Martin Dahl, Stockholm University; Nellie Stjärnkvist, Stockholm University; Patrick Hernvall, Stockholm University; Thomas AB Staveley, Stockholm University; Sofia A Wikström, Stockholm University; Martin Gullström, Stockholm University

We use a multi-isotope approach (d13C, d15N and d34S in bulk material and d15N in amino-acids) to understand diet of four Baltic sea invertebrates in seagrass meadows with varying biomass of filamentous algae. The depleted d15N in the source amino-acid in all fauna and in the filamentous algae (but not in seagrass) strongly indicates that nitrogen fixation is the ultimate source of nitrogen.

Blooms of nitrogen-fixing cyanobacteria exacerbate eutrophication, however they also generate novel bioavailable nitrogen for the food web during summer, a critical time for fish growth. We use a multi-isotope approach (carbon, nitrogen and sulphur isotopes in bulk material and nitrogen isotopes in amino-acids) to understand diet of four Baltic sea invertebrates with different feeding modes; Mytilus edulis, Theodoxus fluviatilis, Idotea balthica and Gammarus spp. Grazers were collected from seagrass (Zostera marina) meadows with varying biomass of filamentous algae (six sites in the Askö region, northern Baltic proper). We found that filamentous algae was always the dominant food source for grazers and omnivores and that seagrass contribution to consumer diets was negligible. The highly depleted values of nitrogen in phenylalanine, a source amino-acid, in all fauna and in the filamentous algae (but not in seagrass) strongly indicates that cyanobacterial nitrogen fixation is the ultimate source of nitrogen. These grazers are important food components for coastal fish, and our results suggest a link between cyanobacterial blooms and fish via filamentous algae and invertebrate grazers.

 

Methane and carbon dioxide flux patterns during autumn overturn following a summer heat wave in the Baltic Sea

Christoph Humborg, Stockholm University, christoph.humborg@su.se

Marc Geibel, Stockholm University; Xiaole Sun, Stockholm University; Carl-Magnus Mörth, Stockholm University; Christian Stranne, Stockholm University; Martin Jakobsson, Stockholm University; Bo Gustafsson, Stockholm University; Alf Norkko, Stockholm University; Joanna Norkko, Stockholm University; Alexander Sokolov, Stockholm University

Following the high temperature of up to 22 oC in shallow Baltic coastal water in 2018, we found highly elevated CO₂ but depleted during the storm, as CO₂ was governed by respiration of organic carbon, whereas CH₄ remained high throughout the storm due to ebullition from sediments. The autumn overturn following heat waves is likely as significant for CH₄ and CO₂ sea-air fluxes as the ice breaks up.

The summer heat wave in 2018 led to 22 oC in shallow coastal waters in the Baltic Sea, the highest temperatures over the last 100 years. Such areas have been responsible for large outgassing especially CH₄, but are largely under sampled. We applied cavity ring-down spectrometer to continuously monitor CO₂ and CH₄ stripped from the water column along a west to east transect over the Baltic Sea. It allows us to i)follow an upwelling event near the Swedish coast, leading to elevated CO₂ outgassing, ii)derive CH₄ sediment flux along the Finish coast during a storm event. At the end of the heat wave we found CO₂ was elevated up to 1600 ppm, but got depleted during the storm, while CH₄ remained elevated throughout the storm. We applied a simple box model to estimate sediment CH₄ supply to sustain the elevated CH₄ concentrations and fluxes. We hypothesize that CO₂ water column inventories and sea-air fluxes are governed by respiration of autochthonous and allochthonous organic carbon, whereas CH₄ inventories are governed by sediment fluxes driven by ebullition. It indicates that the autumn overturn following heat waves is as significant for CH₄ and CO₂ sea-air fluxes as the ice breaks up.

 

The characteristics of the carbonate system in the estuary of the Vistula river (Poland)

Marcin Stokowski, Institute of Oceanology of the Polish Academy of Sciences, stokowski@iopan.gda.pl

Aleksandra Winogradow, Institute of Oceanology of the Polish Academy of Sciences; Monika Lengier, Institute of Oceanology of the Polish Academy of Sciences; Karol Kuliński, Institute of Oceanology of the Polish Academy of Sciences

Biological processes in the coastal mixing zones may change the riverine loads of the AT to the Baltic Sea via influencing CO₂ system. The A_T, pCO₂, pO2, salinity were investigated in the Vistula River mouth. Non-conservative AT-S behavior and pCO₂-pO2 negative correlation suggests the loss of A_T in the mixing zone caused by primary production what potentially alter the A_T loads to the Baltic Sea.

Rivers draining limestone-rich basins are potentially the main source of the total alkalinity (A_T) to the Baltic Sea. However, it is still unclear what happens to these riverine A_T loads in the coastal mixing zones, where biological processes are especially pronounced.

The research was conducted in the estuary of the Vistula River. Mean discharge of 1000 km³/s and A_T >3000 µmol kg^-1 make it likely the largest source of A_T to the Baltic Sea.

Four measurable parameters of the CO₂ system were measured (pCO₂, pH, A_T and C_T), salinity, temperature and oxygen. The pCO₂ showed seasonal dynamics and negative correlation with oxygen suggesting biological control in this region. The pH corresponded to the dynamics of pCO₂. The behavior of A_T-S and C_T-S was conservative in a non-productive season while non-conservative in the productive season suggesting loss of A_T in the mixing zone. The scale of this loss is, however, still unknown.

The transformations of the CO₂ system were identified in the Vistula River mouth what delivers information for better parametrization of the processes influencing riverine A_T loads thus possibly improves predictions of the pH changes in the Baltic Sea.

 

Distribution of ferromanganese concretion bottoms in the Norther Baltic Sea

Laura Kaikkonen, University of Helsinki, laura.m.kaikkonen@helsinki.fi

Elina Virtanen, Finnish Environment Institute (SYKE; Kirsi Kostamo, Finnish Environment Institute (SYKE; Aarno Kotilainen, Geological Survey of Finland (GTK)

We estimated the spatial variability and drivers of FeMn concretion bottoms in Finnish marine areas. Using an extensive data set from the Finnish Inventory Programme for the Underwater Marine Environment, we show that the distribution of concretion bottoms in the Northern Baltic is larger than previously thought. The results further enable examining the habitat role of concretion bottoms.

Ferromanganese concretions are mineral precipitates found in soft sediment floors both in the deep sea and coastal sea areas. While FeMn concretions are known to cover extensive areas of the Baltic Sea floor, specific information on their spatial distribution and significance for marine ecosystems is lacking. As concretion bottoms are included as a habitat type in the HELCOM underwater biotope and habitat classification system, further information on their spatial extent is needed to understand their role for Baltic Sea ecosystems.

In this work, we estimated the spatial variability and potential drivers of FeMn concretion bottoms in Finnish marine areas. Using an extensive data set (~150,000 observations) collected in the Finnish Inventory Programme for the Underwater Marine Environment (VELMU), we show that the spatial coverage of concretion bottoms in the Northern Baltic is more significant than previously estimated. The results provide new insights on seafloor complexity in coastal areas in the Baltic Sea and enable examining the role of concretion bottoms as a habitat.

 

Wednesday, 21 August
11:15 – 12:45
Aula Magna right hall

 

Biomass and carbon processing of benthic fauna in response to organic matter supply – a modelling study from the coastal Baltic Sea

Eva Ehrnsten, Stockholm University, Baltic Sea Centre and University of Helsinki, Tvärminne Zoological Station, eva.ehrnsten@su.se

Alf Norkko, University of Helsinki, Tvärminne Zoological Station and Stockholm University, Baltic Sea Centre; Karen Timmermann, Aarhus University, Department of Bioscience; Bo G. Gustafsson, Stockholm University, Baltic Sea Centre and University of Helsinki, Tvärminne Zoological Station

A new model of benthic macrofaunal biomass and metabolism coupled to a pelagic hydrodynamic-biogeochemical model showed that macrofauna can have a substantial role in organic matter degradation, as ca 80% of simulated organic carbon input to the sediments was ingested and ca 40% was mineralized by macrofaunal respiration in two coastal areas of the northern Baltic Sea.

Benthic macrofauna is an important component linking pelagic and benthic ecosystems, especially in productive coastal areas. We present a new model of carbon biomass and metabolism of benthic macrofauna in response to pelagic dynamics simulated by the hydrodynamic-biogeochemical BALTSEM model. Simulations in two coastal soft-sediment areas in the northern Baltic Sea indicate that the communities were food-limited in the 2000s, as ca 80% of organic carbon sedimentation was eaten by the deposit-feeding macrofauna. A major shift in community composition in the western Gulf of Finland site, due to an increase of the bivalve Macoma balthica, led to altered pathways of organic matter degradation: 39% of sedimentation was mineralized by macrofaunal respiration in 2005 compared to only 10% in 1995. The model is a first step to build predictive capacity of the effects of anthropogenic stressors, such as eutrophication and climate change, on benthic fauna as a functional component of coastal ecosystems.

 

Knowledge gaps in connectivity and ecological coherence of MPA networks in the Baltic Sea

Charlotte Berkström, SLU, charlotte.berkstrom@slu.se

Lovisa Wennerström, SLU; Ulf Bergström, SLU

Connectivity of organisms at multiple scales and ecological coherence of MPA networks within the Baltic Sea were reviewed. Studies focused on large, commercially important species and species of marine origin. Knowledge on small, littoral species is scarce. The MPA network was found to be non-coherent with respect to larval dispersal and placement of nursery grounds.

The dispersal capacity of different organisms varies greatly in the marine environment. In the past, most MPAs have been established on an individual ad hoc basis, ignoring spatial and functional connectivity among the species that they are meant to protect. The interest to include connectivity in marine spatial planning is, however, on the rise. Here, connectivity patterns for macrophytes, invertebrates, and fish on multiple scales (home ranges, dispersal of spores/larvae, genetics) and studies testing ecological coherence of MPA networks within the Baltic Sea were reviewed. Most studies focused on large, commercially important species. More information is found on species of marine origin than freshwater origin. Knowledge on small, littoral, and less commercially important species is scarce. Ten studies have tested the ecological coherence of Baltic Sea MPA networks, mainly focusing on modelling larval dispersal and to some extent nursery grounds. Most studies conclude that the MPA network is non-coherent. Gaps to be addressed are the dispersal abilities of small, littoral species that may be ecologically important, and the mapping of essential nursery and feeding grounds.

 

Can co-restoring seagrass and bivalves increase restoration success and revitalise coastal biodiversity and ecosystem services.

Karine Gagnon, Åbo Akademi University, karine.gagnon@abo.fi

Lukas Meysick, Åbo Akademi University; Christoffer Boström, Åbo Akademi University

We studied whether co-restoring seagrass and bivalves could increase restoration success and promote biodiversity and ecosystem services. Bivalves facilitated seagrass in aquaria, but could not counteract poor environmental conditions in the field. Successful habitat restoration in the Baltic Sea thus requires reducing anthropogenic stressors to improve environmental conditions prior to planting.

Seagrass meadows support diverse associated communities and provide many ecosystem services to humans, but are in steep decline around the world (e.g. Baltic seagrass is threatened by eutrophication, overfishing, and climate change), and restoration is necessary to revitalise these important habitats. However, seagrass restoration has thus far been low (37%), likely because seagrass meadows are structured by complex interactions and feedbacks between species and the physical environment.

Our goal was to determine whether incorporating interspecies interactions between seagrasses and bivalves could increase restoration success. Using aquarium and field experiments, we tested whether this was a viable solution to enhance both seagrass and bivalve populations in the northern Baltic Sea and their associated biodiversity. We found that bivalves could increase seagrass growth and stabilise sediment in aquaria, but in the field, they could not counteract poor environmental conditions (algal blooms, high turbidity). Successful habitat restoration in the Baltic Sea thus first requires reducing anthropogenic stressors and improving environmental conditions prior to replanting species.

 

Spatial variability in benthic macrofauna communities and associated ecosystem functions across coastal habitats

Johanna Gammal, University of Helsinki, johanna.gammal@helsinki.fi

Marie Järnström, Åbo Akademi University; Guillaume Bernard, Arcachon Marine Station, CNRS; Joanna Norkko, University of Helsinki; Alf Norkko, University of Helsinki

The variability in the role of benthic macrofauna for nutrient recycling processes across heterogeneous seascapes were examined through field studies in many different coastal habitats, along sedimentary gradients with varying organic matter and vegetation, and along costal gradients of hypoxia. The results contributed to an improved understanding of the natural variability in BEF-relationships.

It is well known that benthic macrofauna have an influence on several functions provided by sedimentary ecosystems, for example, through bioturbation and bioirrigation, macrofauna affects sediment biogeochemistry and the processes of nutrient retention and transformation at the sediment-water interface. Biodiversity-ecosystem function (BEF) relationships can however be very context dependent, which complicates our ability to generalize on the role of biodiversity and to predict the consequences of environmental change for ecosystem functions. To examine the variability in the role of benthic macrofauna for nutrient recycling processes across heterogeneous seascapes, field studies were conducted in many different coastal habitats, along sedimentary gradients and along coastal gradients of increasing hypoxia. These results contributed to an improved understanding of the natural variability in BEF-relationships.

 

Threatened habitat types in the Baltic Sea

Aarno Kotilainen, Geological Survey of Finland, aarno.kotilainen@gtk.fi

Suvi Kiviluoto, Centre for Economic Development, Transport and Environment; Lasse Kurvinen, Metsähallitus, Parks & Wildlife Finland; Matti Sahla, Metsähallitus, Parks & Wildlife Finland; Penina Blankett, Ministry of the Environment, Finland; Eva Ehrnsten, The Baltic Sea Centre of Stockholm University, Sweden; Ari Laine, Metsähallitus, Parks & Wildlife Finland; Hans-Göran Lax, Centre for Economic Development, Transport and Environment; Ari Ruuskanen, Monivesi Ltd., Finland; Tytti Kontula, Finnish Environment Institute

The second assessment of threatened habitat types in Finland was conducted 2016-2018. The Baltic Sea marine habitats were classified according to the HELCOM Underwater Biotopes classification. The assessment was based on IUCN Red List of Ecosystems Categories and Criteria. The assessment was carried out by a group of national experts from the universities, research institutes and authorities.

Benthic habitats are an essential part of functional and healthy Baltic Sea ecosystems. However, over the past decades anthropogenic activities have altered marine environments worldwide, and pose great challenges to sustainable marine management. Information on threatened habitat types is an important indicator when monitoring the status of marine ecosystem and biodiversity.

The second assessment of threatened habitat types in Finland was conducted between 2016 and 2018 (Kontula and Raunio, Eds., 2018). The Baltic Sea marine habitats were classified according to the HELCOM Underwater Biotopes classification (HELCOM, 2013) with some modifications. The assessment was based on IUCN Red List of Ecosystems Categories and Criteria (IUCN, 2015). The assessment was carried out by a group of national experts from the universities, research institutes and authorities.

The assessment listed a total of 42 Baltic Sea habitats, of which 10 were estimated to be threatened and 4 to be Near Threatened (Kotilainen et al., 2018). However, 14 habitat types were classified as Data Deficient, which shows that our knowledge of underwater marine habitats is still incomplete.

 

Monitoring and restoring fucoids in the Baltic Sea – a synthesis and knowledge gaps

Lena Kautsky, Stockholm University, lena.kautsky@su.se

Ellen Schagerström, Department of Ecology, Enviromment and Plant Science; Susanne Qvarfordt, Department of Ecology Evolution and Plant Science

Efforts to reduce nutrients to the Baltic Proper has resulted in natural recovery of Fucus. Results from field studies and competition for space in a changing climate in three Baltic Fucus-species will be presented, together with conceptual model. We specifically point out a need to monitor the fucoid communities at differ seasons and knowledge gaps related to seasonal changes and species traits.

Extensive declines of the brown macroalgae Fucus vesiculosus in the Baltic proper was reported during the 1970–1980´s, mainly attributed to eutrophication. Efforts have been made to reduce nutrient enrichment during the past 30-40 years in coastal areas. This has resulted in natural recovery of Fucus stands in some areas. Here, long-term field experiments on the seasonal dynamic of macroalgal establishment shows the importance of when space is available for settlement. Changes in the distribution from the mid 1940´ s until to today are also summarized. The recruitment success and ability to withstand competition in a changing climate in three common Baltic Fucus-species will be discussed. We further present our results in a conceptual model, specifically pointing out a need to monitor the fucoid communities at differ seasons and knowledge gaps related to seasonal changes and species traits.

 

Wednesday, 21 August
14:00 – 15:00
Aula Magna right hall

 

Biological values behind the Ecosystem services

Ingrida Purina, Latvian Institute of Aquatic Ecology, ingrida.purina@lhei.lv

Juris Aigars, Latvian Institute of Aquatic Ecology; Aurelija Armoskaite, Latvian Institute of Aquatic Ecology; Henning S. Hansen, Aalborg University

Theoretical concept of Ecosystem services (ES) has been developing over past 20 years. However, in the changing ecosystems theoretical approach to estimation of ES may be misleading, giving the false feeling of safety. Degradation of habitats may lead to overestimation of ecosystems capacity to deliver services by accounting for ecosystem components and functions, which may have already perished.

The concept of Ecosystem services (ES) has been developing over past 20 years, however, it is mainly theoretical. The mapping of ES often means estimating the potential of given ecosystem to perform the given service. In the meanwhile, as we are developing the concepts and approaches to help us understand and protect ecosystems, they are constantly changing. The aim of this study is to consider actual level of ecosystem services provided by coastal habitats and estimate implications caused by environmental changes. The analysis was performed on the model territory – coastal habitats (reefs) of Eastern Baltic. The results clearly demonstrate a discrepancy between the ES levels provided by coastal habitats based on purely conceptual estimates and localised, data driven assessment. Data analysed for the Latvian coastal waters suggests that the level of ES provision is far below its potential, largely due to the degraded state of habitats. Are we not in danger of overestimating our ecosystems capacity to deliver services by accounting for ecosystem components and functions, which may have already perished?

 

Assessing synergies and conflicts between marine human activities in close spatial-temporal proximity

Ida Maria Bonnevie, Aalborg University Copenhagen, idarei@plan.aau.dk

Henning Sten Hansen, Aalborg University Copenhagen; Lise Schrøder, Aalborg University Copenhagen

The pressures on marine space are increasing. It is thus important to examine conflicts and synergies of interactions between marine human uses in close spatial-temporal proximity. One solution to assess use-use interactions will be presented. It consists of a pairwise matrix-based approach for spatial decision support tools to assess use-use conflicts and synergies based on expert knowledge.

The pressures on marine ecosystems and on marine space are increasing with expanding marine human uses. Therefore, it is important to examine conflicts and synergies of interactions between marine human uses experiencing a close spatial-temporal proximity. A cross-sectoral theoretical framework to assess potential and actual spatial-temporal synergies and conflicts between marine uses is needed in maritime spatial planning.

One suggested solution to assess use-use interactions will be presented consisting of a pairwise matrix-based approach for spatial decision support tools to assess use-use conflicts and use-use synergies based on theoretical expert knowledge. The approach can be used at a larger regional basin-wide scale to produce raster-based maps that show potential conflicts and synergies between human-based marine uses. The theoretical knowledge can be explored with the purpose of minimising conflicts and increasing synergies in future scenarios by examining the matrix as well as producing different synergy maps and conflict maps. A focus on synergies can increase awareness of co-location options to optimise the use of space and decrease pressures on space elsewhere.

 

Fuzzy cognitive mapping of Baltic Archipelago Sea food webs reveal no cliqued views of the system structure between stakeholder groups

Laura Uusitalo, Finnish Environment Institute, laura.uusitalo@ymparisto.fi

Riikka Puntila, Finnish Environment Institute; Annaliina Koskinen, ; Patrik Korn,

Fuzzy cognitive mapping (FCM) allows quantitative evaluations of stakeholder views on ecosystem functioning. FCMs developed for Archipelago Sea food web reveal no school-of-thought differences between stakeholder groups. Fishing, salinity and oxygen were seen as the key drivers of the system. This approach enables two way discussion about the food webs and how management may impact them.

Incorporating stakeholder views is key to successful environmental management, particularly if the managed system delivers cultural and provisioning ecosystem services directly to the stakeholders, or there are conflicting views about the ecosystem functioning or its optimal management. One such system is the Finnish Archipelago Sea. Fuzzy cognitive mapping (FCM) offers a method to evaluate and quantitatively compare different actors’ views on ecosystem structure. The models can be compared quantitatively and simulated to illustrate how they respond to various driver scenarios. This may reveal differences in the views about the important interactions in the ecosystem, and how the system would respond to management measures, potentially explaining differing opinions about the best management strategy. In this work, 17 stakeholders created FCMs of the Archipelago Sea food web. The FCMs indicated somewhat varied, but shared view of the food web. The simulations indicated that the fishing was seen as a key driver affecting the food web together with increase of salinity and oxygen levels. This approach enables two way discussion about the food webs and how management may impact them.

 

Measurements of light transfer through sea ice in the northern Baltic Sea

Elina Kari, Stockholm University, elina.kari@iki.fi

Arttu Jutila, Alfred Wegener Institute; Anna Friedrichs, Carl von Ossietzky University of Oldenburg; Susanne Kratzer, Stockholm University; Matti Leppäranta, University of Helsinki

We present a unique dataset of in situ measurements of light transfer through sea ice in the northern Baltic Sea. The measurements include physical properties of ice cover and bio-optical properties within ice, which allows us to discuss their roles in the light transfer through ice cover. The study focuses on the light conditions both under drift ice in the open sea and coastal fast ice.

The seasonal sea ice cover lasts up to seven months in the northern Baltic Sea. As nutrients are often abundant in the coastal zone, light availability governs the annual cycle of primary production. Studies on light transfer through sea ice in the Baltic Sea are sparse and even fewer focusing on the bio-optical substances. The present study provides new information on sea ice optics in the Gulf of Bothnia. We performed field surveys on drift ice and on fast ice including in situ measurements of snow and ice structure, spectral and PAR irradiance, and concentrations of bio-optical substances: chlorophyll-a (Chl-a), coloured dissolved organic matter (CDOM), and suspended particulate matter (SPM). Snow cover was the dominant factor determining the light transfer. Depending on the properties of the snow cover, the light transmittance increased up to 22 times after removing the snow. Despite reducing the amount of light under ice, snow cover did not markedly change the spectral distribution of the light field. Additionally, our results confirm the differences in fast ice and drift ice due to differences both in their growth history and in the properties of their parent seawater.

 

Wednesday, 21 August
15:30 – 16:30
Aula Magna right hall

 

Evaluating transports and water renewal in the Archipelago Sea

Elina Miettunen, Finnish Environment Institute, elina.miettunen@ymparisto.fi

Laura Tuomi, Finnish Meteorological Institute; Kai Myrberg, Finnish Environment Institute; Klaipeda University

We studied water renewal in the Finnish Archipelago Sea with a high-resolution 3D hydrodynamic model. The model results showed that the water age in the inner archipelago can be up to half a year, thus making this complex archipelago vulnerable to e.g. eutrophication and various anthropogenic pressures.

We studied water renewal and transports in the Archipelago Sea, Baltic Sea. This complex coastal archipelago consists of over 40 000 small islands and islets, and is thus a very vulnerable area, heavily stressed with e.g. eutrophication. We simulated the currents and water age using a high resolution 3D hydrodynamic model COHERENS, and further evaluated the transports patterns and their seasonal variability by utilizing the Lagrangian particle model OpenDrift. The modelled water age varied from less than one month, in the outer archipelago and river mouths, up to seven months in the narrowest waterways of the inner archipelago. The effect of rivers to the water age was mainly seen up to 15 km away from the river mouth. The Lagrangian particle simulations showed that the transport of particles from the open sea areas across the Archipelago Sea mostly takes place through the outer archipelago. Only in few cases the particles entered the mid-archipelago. Finally, we studied the interaction between different weather and circulation conditions that induce particle transport to the mid-archipelago and evaluated the frequency of these events.

 

Non-stationary modeling reveals strong connection between extreme water level changes and NAO along the Baltic Sea coast

Nadezhda Kudryavtseva, Tallinn University of Technology, nadia@ioc.ee

Tarmo Soomere, Tallinn University of Technoolgy, Estonian Academy of Sciences

Understanding of extreme water levels is crucial for mitigation and adaptation for possible flooding, coastal erosion, and agricultural soil contamination. Analyzing 33 years of simulated sea level data, we found strong relation between the water level extremes and North Atlantic Climatic index in the Northern Baltic whereas the Southern Baltic Sea is influenced by different drivers.

Proper quantification of extreme water levels is crucial to establish appropriate mitigation and adaptation strategies for possible flooding, coastal erosion, agricultural soil contamination and changes in habitat for fish and plants. Using non-stationary extreme value modeling of Nemo-Nordic water level model results (1979-2012), linear trends in the location, scale, and shape parameters of the GEV distribution along the Baltic Sea coast are identified. We found significant linear trends in both location and scale parameters of GEV along the Baltic Sea coast showing non-homogeneous spatial distribution. The most notable linear trends in location parameter are detected along the Pomeranian Bay. The analysis showed strong correlation between the water level extremes and the North Atlantic Oscillation (NAO) in the Gulf of Bothnia, Gulf of Finland, Gulf of Riga, and along the Latvian coast, whereas the Southern Baltic Sea showed no significant relations to the NAO index. The same analysis applied to the in-situ water level variations confirmed the North-South pattern of NAO connection in the Baltic Sea. We discuss possible drivers for sea level extremes in the Southern Baltic Sea.

 

Hidden secrets of transverse coastal upwelling jets revealed using a synergy of data in the Gulf of Finland, Baltic Sea

Nicole Delpeche-Ellmann, Tallinn University of Technology, nicole.delpeche@taltech.ee

Tarmo Soomere, Tallinn University of Technology; Nadezhda Kudryavtseva, Tallinn University of Technology

This study presents a methodology that connects nearshore bottom slope on the generation of transverse upwelling jets in the Gulf of Finland, Baltic Sea. Utilizing a synergy of various data, it was found that transverse jets prefer steeper slopes and that the upwelled waters originates from an intermediate depth. Identifying this source depth allows deeper understanding of algae bloom formation.

This study presents a methodology that connects nearshore bottom slope to the generation of transverse upwelling jets in the Gulf of Finland, Baltic Sea. Recent studies have shown that signatures of coastal upwellings often takes the shape of transverse coastal jet that extend dozens of kilometers at distinct locations. Thus understanding the trigger of these jets with respect to their location and formation plays a vital role in the transport and mixing properties of substances.

To accomplish this a synergy of data was used: satellite derived sea surface temperature, high resolution bathymetry, surface current drifters, hydrological and meteorological stations. Using statistics and mathematics a method is derived to quantify the role of the bottom slope and the possible source depth of cooler upwelled waters. Results indicate that transverse jets originate from the steepest sections and the cooler water most likely originates from an intermediate depth. Identification of the source depth of the upwelled waters plays a vital role in understanding the transport of dominant nutrients (e.g. nitrates vs phosphates etc.) and their formation of cyanobacteria blooms in the Baltic Sea.

 

Sea level extremes simulated from atmospheric reanalyses in the Baltic Sea

Jani Särkkä, Finnish Meteorological Institute, Jani.Sarkka@fmi.fi

Milla Johansson, Finnish Meteorological Institute

We present simulations of the sea level in the Baltic Sea in 1900-2010. The internal variations of the Baltic Sea are calculated with a two-dimensional hydrodynamic model, and the water volume variations of the Baltic Sea are evaluated using a statistical model based on wind speeds near the Danish Straits. The simulation results have good agreement with the Finnish and Swedish tide gauge records.

Sea level extremes have a major impact on coastal dynamics, as for the erosion of beaches and transport of sediments. We present simulations of the sea level in the Baltic Sea in 1900-2010. The internal variations of the Baltic Sea are calculated with a numerical two-dimensional hydrodynamic model, and the water volume variations of the Baltic Sea due to the water exchange between the North Sea and the Baltic Sea are evaluated using a statistical model based on wind speeds near the Danish Straits. The atmospheric forcing (wind and air pressure data) for the sea level model is obtained from reanalyses, e.g., ERA-20C reanalysis by ECMWF. The simulation results have good agreement with the Finnish and Swedish tide gauge records, although the highest sea level extremes are underestimated due to the low spatial and temporal resolution of the ERA-20C data. We analyze the trends in frequencies and heights of sea level extremes for different coastal locations. The effects of the long-term changes in atmospheric factors on the sea level extremes are also studied.

 

Thursday, 22 August
11:15 – 12:45
Aula Magna right hall

 

Locating and investigating submarine groundwater discharge in the Horsens Fjord estuary, Denmark

Klaus Hinsby, GEUS, khi@geus.dk

Jørgen O. Leth, GEUS; Lærke T. Andersen, GEUS; Jacob Kidmose, GEUS; Lærke Thorling, GEUS; Jan F. Schröder, CAU; Jan Scholten, CAU; Jakob Lanstorp, GEUS; Martin Hansen, GEUS

Integrated groundwater – surface water modelling of the catchment to the Horsens Fjord estuary, Denmark indicate potential submarine groundwater discharge (SGD) at the bottom of the estuary. We present the main results of off- and onshore investigations conducted to locate SGDs in the estuary and develop an improved integrated geological and hydrological model of the land-sea continuum.

The major part of Danish coastal waters do not comply with good status objectives of the Water Framework Directive due to excessive nutrient loadings. While nutrient loadings to coastal waters via streams are relatively well monitored and modelled the potential contribution by submarine groundwater discharge (SGD) is unknown and difficult to identify. Several studies e.g. in Germany and Poland indicate that SGDs may discharge significant amounts of nutrients and other pollutants to coastal waters and that a better quantification of these are required to better evaluate their impacts on the chemical and ecological status of these. We present the main results of off- and onshore investigations conducted to locate SGDs in the estuary and develop an improved integrated geological and hydrological model of the land-sea continuum that identify and include the potential SGD component. In addition, we develop web services for illustrating integrated on- and offshore 3D geological models for improved assessment of land-sea interactions and near real-time measurements from SGD monitoring stations. These web services will be made available within the European Geological Data Infrastructure.

 

A submarine groundwater discharge at the Hanko Peninsula, south Finland

Joonas Virtasalo, Marine Geology, Geological Survey of Finland (GTK), joonas.virtasalo@gtk.fi

Jan Schröder, Institut für Geowissenschaften, Christian-Albrechts-Universität Kiel; Samrit Luoma, Groundwater, Geological Survey of Finland (GTK); Nina Hendriksson, Groundwater, Geological Survey of Finland (GTK); Jan Scholten, Institut für Geowissenschaften, Christian-Albrechts-Universität Kiel

A submarine groundwater discharge (SGD) site was discovered at the Hanko Peninsula in south Finland. SGD takes place through pockmarks on the seafloor at ~11 m water depth. Elevated radon concentrations in above the pockmarks indicate SGD of roughly 1 cm/d. Isotope data show that the fraction of groundwater in pockmark porewaters is about 83%, whereas it is about 9% in the overlying water column.

In the frame of the BONUS SEAMOUNT project, a submarine groundwater discharge (SGD) site was recently discovered at the Hanko Peninsula in south Finland. The local stratigraphy and aquifer geometry were studied using marine seismic profiles, multibeam images of seafloor, and onshore ground-penetrating radar profiles. SGD takes place through pockmarks on the seafloor, as confirmed by radon measurements of groundwater and seawater, and by multielement and stable isotope analyses of pockmark porewaters, groundwater and seawater.

Elevated radon concentrations in near-bottom water above the pockmarks in 11m water depth indicate SGD of roughly 1 cm/d. Strong vertical gradients of Cl in porewater profiles from sediments underlying the pockmarks reflect mixing of groundwater and seawater. End-member modeling using δ2H and δ18O shows that the fraction of groundwater in pockmark porewaters is about 83%, whereas it is about 9% in the whole overlying water column.

BONUS SEAMOUNT project is supported by BONUS (Art 185), funded jointly by the EU, the Academy of Finland (Grant 311983), and the Federal Ministry of Education and Research, Germany (Grant 03F0771B).

 

Coastal forest ecosystems: a cross-regional approach

Zrinka Mendas, Island Dynamics Research Network, z.mendas@gmail.com

Coastal forests in Baltic Sea cover 60% of the land, contributing to the economies, biodiversity and protecting from the erosion and flooding. Increasing demand for forest products, societal and political changes are a threat to achieving a Good Environmental Status. A cross-regional approach, applied to the Baltic, North and the Adriatic Sea, gives the insight into the issues and forest policy.

Coastal forests in Baltic Sea region cover up to 60% of the coastline and islands, including the Baltic Sea, Gulf of Bothnia and the Continental and Atlantic forest regions. These multifunctional ecosystems not only contribute to the local and regional economies but also preserve the biodiversity and minimise the impact from the coastal erosion and flooding. Yet, the increasing demand for forest products and societal and political changes remain the main challenges and a direct threat to the balance between the national and local needs and wants. To deal with this, the EU Forest Strategy advocates a shift toward the smarter sustainable management of the forest ecosystems more broadly. We examine this in the context of the coastal forest ecosystems with the cross-regional approach using the case studies from three EU regions; Baltic Sea (states), North Sea (UK) and Adriatic Sea (Croatia). It is hoped that this approach could provide a useful and practical insight into the broader set of issues and considerations facing the coastal forest regions, the process of achieving a good Environmental Status of the Baltic region and the policy-making concerning the EU Forestry Strategy.

 

Geohazard assessment of the coastal zone – examples from the southern Baltic Sea

Grzegorz Uścinowicz, Polish Geological Institute - National Research Institute, grzegorz.uscinowicz@pgi.gov.pl

Tomasz Szarafin, Polish Geological Institute - National Research Institute; Urszula Pączek, Polish Geological Institute - National Research Institute; Mirosław Lidzbarski, Polish Geological Institute - National Research Institute; Ewa Tarnawska, Polish Geological Institute - National Research Institute

The research was focused on the identification and assessment of geohazards occurring on the Polish coast (southern Baltic). Main hazards are exogenic processes: coastal erosion, landslides, dune breakage and flooding, hydrogeohazards, seabed erosion. Endogenic factors are of lesser importance.

Coastal regions around the world are characteristic places subjected to pressure on both the people-oriented management and impact of natural forces. The important aspect of these interrelations is a balanced assessment of the conditions supported by specialized research as well as identification of risks in a particular part of the coast. The southern Baltic coast is not unique in this matter and requires a proper methodological approach. In the course of research tasks in the coastal zone of the southern Baltic, geological, hydrogeological and landslide mapping, remote sensing and land surface analysis, as well as bathymetric and geophysical surveys of the marine area were performed. This enabled identification of potential and actual hazards occurring in the discussed area and these are: exogenic factors — coastal erosion, landslides, dune breakage and flooding, hydrogeohazards, seabed erosion and endogenic factor — earthquakes. Research aimed at identifying land-sea interactions and the information they carry, are the starting point for any work related to the determination of susceptibility to possible occurrence of geohazards and assessment of their potential effects.

 

Assessment of spatial fluctuations in rhythmic shoreline patterns related to sediment magnetic characteristics

Donatas Pupienis, Vilnius University / Nature Research Centre, donatas.pupienis@gf.vu.lt

Ilya Buynevich, Temple University; Darius Jarmalavičius, Nature Research Centre; Gintautas Žilinskas, Nature Research Centre; Dovilė Karlonienė, Vilnius University; Aira Dubikaltienė, Vilnius University; Kristina Viršilaitė, Vilnius University

The coastal morphodynamic response to rapidly changing hydro-meteorological conditions is difficult to predict and model. We use the spatial fluctuations in rhythmic patterns related to sediment magnetic characteristics as proxies for the interpretation of coastal erosional-depositional trends. This study is based on surface sediment magnetic susceptibility measurements and wind data analysis.

Coastal areas are sensitive to rapid climatic shifts. The coastal morphodynamic response to rapidly changing hydro-meteorological conditions is difficult to predict and model. We use the spatial fluctuations in rhythmic patterns (RP) related to sediment magnetic characteristics as proxies for the interpretation of coastal erosional-depositional trends. This study is based on surface sediment magnetic susceptibility (MS) measurements and wind data analysis. To assess the patterns in spatial fluctuations of mineralogical anomalies on sandy beaches of the Curonian Spit (Lithuania), MS was measured at 0.5 km intervals in the middle of the beach. The statistical analysis allowed identification of RP varying in range from 1.3 to 7.1 km. The averaged wind speed and sedimentological data show a strong positive relationship between the magnitude of westerly wind speed and lithological patterns. The weaker wind causes smaller RP (1.3-1.9 km), whereas a stronger forcing produces larger phases (4.2-7.1 km). This suggests that hydro-meteorological regime controls spatial distribution of sedimentological RP, with resultant wind field acting as one of the dominant factors.

 

Beach-foredune sediment budget response to sea level fluctuation. Lithuanian Curonian Spit coast.

Viktoras Karaliūnas, Nature research centre, viktoras.karaliunas@gamtc.lt

Darius Jarmalavičius, Nature research centre; Gintautas Žilinskas, Nature research centre; Donatas Pupienis, Nature research centre; Rasa Janušaitė, Nature research centre

Sea level fluctuations can affect the beach-foredune sediment budget, while at the same time transform the coastal landscape. On the basis of the annual measurements of cross-shore profiles on Curonian Spit during the 2002-2019 period were identified changes in the sediment budget on beach and foredune depending on the sea level change.

Beach-dune sediment exchange maintains the coastal system stability. Sea level fluctuations – one of the most important factors modifying the beach and foredune sediment budget, leading to the transformation of the coastal landscape.

This study aims to assess the beach and foredune sand budget changes depending on sea level fluctuations. On the basis of the annual measurements of 29 cross-shore profiles on Curonian Spit were calculated the sediment volumes on the beach and foredune and their changes between 2002 and 2019.

Obtained data revealed that in the case of sand surplus the relative low sea level rise does not have a significant impact on the development of foredune on decadal time-scale.

Short-term sea level fluctuations are reflected in the year-to-year variability in beach sediment budget. However, the significant relationship between the year-to-year variability in sea level fluctuation and foredune sediment budget haven’t been identified. Nor is there a reliable year-to-year variability relationship between the foredune and beach sediment budget. The foredune sediment budget remained positive both by an increase and by a reduction in the sediment volume on the beach.

 

Thursday, 22 August
14:00 – 15:30
Aula Magna right hall

 

Surface turbulent transport processes and eddy diffusivity in the central Baltic Sea inferred from modeled Lagrangian trajectories

Inga Koszalka, MISU, Stockholm University, Sweden, ikoszalka@geomar.de

Joost Hemmen, Kiel University, Germany; Ulf Graewe, Leibniz Institute for Baltic Sea Research Warnemünde, Germany

We use an ocean circulation model and Lagrangian particle simulations to study turbulent flows and surface transport processes in the central Baltic Sea. These reveal e.g. large coherent eddies in the Landsort Deep that are also evident in the satellite chlorophyll images. We also map lateral eddy diffusivities and discuss parameterizations of turbulent transport in coarse resolution models.

Although the Baltic Sea is one of the best-surveyed seas on Earth, the turbulent flows that populate its waters: coastal upwelling fronts, jets and eddies, are still poorly quantified in spite of their impact on transport processes and marine ecosystem.

We use a state-of-the-art ocean model (General Estuarine Transport Model, GETM) in a high resolution configuration (dx=600m, 200 adaptive vertical levels) and a suite of Lagrangian analysis techniques to study turbulent flows and associated surface transport processes in the central Baltic Sea. We quantify turbulence with traditional techniques (vorticity, Okubo-Weiss parameter) while kinematics and transport properties are addressed with 100,000 Lagrangian particle trajectories simulated using velocity output from the model. Lagrangian trajectories reveal rich turbulent field including large eddies in the Landsort Deep that are also evident in the chlorophyll satellite imagery testifying to their impact on plankton variability. We map lateral eddy diffusivities and discuss paramaterizations of turbulent transport in ocean models with coarser resolution,

 

Towards coupled circulation-wave modelling of the Baltic Sea

Tuomas Kärnä, Finnish Meteorological Institute, tuomas.karna@fmi.fi

Hedi Kanarik, Finnish Meteorological Institute; Laura Tuomi, Finnish Meteorological Institute

The effect of wave-current interactions was investigated with NEMO v4.0 model in the Baltic Sea. The model was forced with wind wave fields from WAM spectral wave model. The results indicate that sea-state dependent drag coefficient, surface stress, and the Stokes-Coriolis forcing can have a significant impact on water elevation and mixed layer dynamics.

Surface waves play an important role in the upper ocean mixing. In order to account for these effects coupled wave-ocean models are needed. To enhance our numerical modeling capabilities in the Baltic Sea, we have implemented NEMO v4.0 circulation model. The model's configuration was derived from 1 nm Nemo-Nordic setup, based on NEMO v3.6 (Hordoir et al. 2019). A two-year hindcast simulation (from June 2016 to June 2018) shows that the model captures seasonal sea surface elevation and temperature variability very well. Thermo- and halocline structure tends to be somewhat smoother than in the observations, but in general the model captures the main features of the flow. In subsequent runs, NEMO was forced with wind wave fields from WAM spectral wave model simulations. We investigated the influence of sea-state dependent surface drag coefficient, surface stress, and the Stokes-Coriolis forcing on the circulation and surface layer dynamics. The results indicate that wind wave effects can have a significant impact on sea surface elevation, mixed layer dynamics, and coastal upwelling. The present work lays a foundation for a coupled circulation-wave forecast system for the Baltic Sea.

 

GCOAST Model System: coupling of ocean and atmosphere through a dynamic wave interface

Joanna Staneva, Helmholz Zentrum Geesthacht, joanna.staneva@hzg.de

Corinna Scrum, Helmholtz-Zentrum Geesthacht; Arno Behrens, Helmholtz-Zentrum Geesthacht; Sebastian Grayek, Helmholtz-Zentrum Geesthacht; Marcel Ricker, Helmholtz-Zentrum Geesthacht

The coupling of models is a commonly used approach when addressing the complex interactions between different components of earth system. Here we present the development of a new, high -resolution, coupled ocean, wave and atmosphere (COSMO-CLM), model system for the North Sea and the Baltic Sea, which is part of the Geestacht COAstal model SysTem GCOAST. We focus on the nonlinear feedback between strong tidal currents and wind -waves, which can no longer be ignored, in particular in the coastal zone where its role seems to be dominant.

In NEMO stand-alone model, the momentum flux from the atmosphere, which is related to the wind speed, is passed directly to the ocean and this is controlled by the drag coefficient. However, in the real ocean, the waves also play the role of a reservoir for momentum and energy because different amounts of the momentum flux from the atmosphere is taken up by the waves. In the coupled model system the momentum transferred into the ocean model is estimated as the fraction of the total flux that goes directly to the currents plus the momentum lost from wave dissipation. Sensitivity experiments are designed to investigate the influence on the simulation of storms, thermodynamics, and the upwelling in the Baltic Sea. Introducing the of wave effects in the circulation model improves the model performance compared with the stand-alone simulations in terms of sea level height, temperature and circulation. The sea state-dependent momentum and turbulent kinetic energy fluxes prove to be of higher importance than the Stokes drift related effects investigated in this study. Additionally, we demonstrate that the wave-induced Stokes Coriolis force leads to a deflection of the current. During extreme events the Stokes velocity is comparable in magnitude to the current velocity. The resulting wave -induced drift is crucial for the transport of particles in the upper ocean. The performance of the coupled modelling system is also illustrated for the cases of several extreme events. The use of a coupled model system reveals that the newly introduced wave effects are important for the upwelling performance. Since the nutrient supply to the nutrient-depleted summer mixed layer can trigger phytoplankton blooms, proper simulations of those processes are important for further coupling to the biogeochemical modelling. It also reflects the increased demand on improving the ocean state estimates and providing consistent meteo-ocean forecasts for in the near-coastal areas that is very often requested by the end-users

 

Importance of Stokes drift in modelling the drift of substances and objects in the Gulf of Finland

Olga Vähä-Piikkiö, Finnish Meteorological Institute, olga.vaha-piikkio@fmi.fi

Pekka Alenius, Finnish Meteorological Institute; Antti Westerlund, Finnish Meteorological Institute; Laura Tuomi, Finnish Meteorological Institute

The drift of surface objects is affected by wind, currents and waves. To study the importance and the proportion of each component in different conditions, we did a modelling study using the OpenDrift model with inputs from 3D NEMO-LIM, WaveWatchIII and HIRLAM. The drift forecast system is evaluated by comparing the simulated results to drift experiments done in the Gulf of Finland in 2010 – 2012.

The Gulf of Finland is an area of high volumes of oil transport. The risk of a major oil accident is ever-present. Other chemicals are transported via the Gulf of Finland as well. Drift modelling is essential for accurately forecasting the trajectory of an oil or chemical spill and consequently clearing it up before it reaches the shore. Drift modelling can also be used to predict the movement of organic matter, such as algae blooms and fish eggs, and larger objects and people in case of a rescue mission. The drift of surface objects is affected by wind, currents and waves. In order to study the importance and the proportion of each component in different conditions, we did a modelling study using the OpenDrift model with inputs from 3D NEMO-LIM, WaveWatchIII and HIRLAM. The wave and circulation fields were produced with high horizontal resolution (0.25 NM). The drift forecast system is evaluated by comparing the simulated results to drift experiments conducted in the Gulf of Finland in 2010 – 2012.

 

Wave-induced bottom shear stress in the Gulf of Bothnia

Laura Tuomi, Finnish Meteorological Institute, laura.tuomi@fmi.fi

Aarno Kotilainen, Geological Survay of Finland; Hedi Kanarik, Finnish Meteorological Institute; Joonas Virtasalo, Geological Survay of Finland; Olga Vähä-Piikkiö, Finnish Meteorological Institute; Heidi Pettersson, Finnish Meteorological Institute

We study the effect surface wave-induced bottom shear stress on sediment resuspension in the Gulf of Bothnia. We utilise wave model simulations and seabed sediment data to evaluate the e extent of areas that experience considerable wave-induced stress. Based on 30-years model data we estimate how often and for how long periods wave-induced resuspension in these areas occurs.

Waves, bottom currents and ice are the main drivers of seafloor erosion. In the Gulf of Bothnia, the measured maximum value of significant wave height is 8.1 m, with the highest individual wave of 15 m. In the future climate, the ice season is estimated to get shorter and the ice extent smaller, thus the effect of waves on the sediment erosion is expected to increase. We used wave model WaveWatchIII to simulate wave conditions in the Gulf of Bothnia. The 30-year simulation provides estimates of wave-induced bottom shear stress based on the wave spectrum including different wave heights and wave lengths. We evaluate the extent of areas that presently experience significant wave-induced stress. Furthermore, we'll estimate how often and for how long periods the wave-induced stress exceeds the critical values for sediment resuspension to take place. When estimating the critical values for resuspension we utilise the seabed sediment data available for the Gulf of Bothnia. The adequacy of the results is evaluated by comparing the known erosional seafloor areas to the model estimates. This study is part of the SmartSea project of the Academy of Finland (grant no. 292 985).

 

Baltic Sea wave climate variability and its connection with climatic indices deduced from Empirical Orthogonal Functions

Fatemeh Najafzdeh, Tallinn University of Technology, Department of Cybernetics, fatemeh@ioc.ee

Nadezhda Kudryavtseva, Tallinn University of Technology, Department of Cybernetics; Tarmo Soomere, Tallinn University of Technology, Department of Cybernetics, Estonian Academy of Sciences

We are aimed to investigate patterns of wave height variability in the Baltic Sea. Empirical Orthogonal Functions are calculated from satellite altimetry wave height data. The analysis showed a few different modes of wave climate variability with one of the modes suggesting a strong meridional pattern. Correlations between the observed patterns and various climatic indices are discussed.

Understanding the wave climate and its variability is crucial in coastal planning for minimizing future coastal hazards and economic loss. In fetch-limited and semi-enclosed basins like the Baltic Sea, small changes in the wind direction can lead to complex behavior of the wave climate. Prominent advances in satellite altimetry make it feasible to collect a large number of wave height measurements with good spatial and temporal coverage which help to scrutinize the wave climate variability in great detail. In order to understand patterns of wave height variability, an Empirical Orthogonal Function (EOF) analysis is performed on the satellite altimetry data. The monthly averaged satellite altimetry Significant Wave Height data from 1990-2015 with ~700000 measurements (thoroughly validated, corrected for ice cover, distance from the land, and biases between different missions) were used in the study. The analysis showed a few different modes of wave climate variability with one of the modes suggesting a strong meridional pattern. We discuss correlations between the observed patterns and various climatic indices, such as North Atlantic Oscillation, Arctic Oscillation, and WIBIX.

 

Thursday, 22 August
16:00 – 17:00
Aula Magna right hall

 

Advantage of hyperspectral airborne imagery for spatial and temporal heterogeneity of water quality in the Curonian Lagoon (the Baltic Sea)

Diana Vaičiūtė, Marine Research Institute, Klaipeda University, diana.vaiciute@jmtc.ku.lt

Claudia Giardino, Optical Remote Sensing Group, CNR-IREA; Mariano Bresciani, Optical Remote Sensing Group, CNR-IREA; Stefan Simis, Plymouth Marine Laboratory; Martynas Bučas, Marine Research Institute, Klaipeda University; Edgaras Lukšys, Marine Research Institute, Klaipeda University; Ilaria Cazzaniga, Università degli Studi Milano-Bicocca; Ils Reusen, Flemish Institute for Technological Research (VITO)

The study presents an application of airborne hyperspectral data for assessing the spatial and temporal heterogeneity of water quality in the Curonian Lagoon (Baltic Sea). From the Chl-a and phycocyanin maps we discovered pronounced variability and intraday dynamics of cyanobacteria, the hydrodynamic effects of the Nemunas River and the Baltic Sea, towards the spatial distribution of CDOM and TSM.

This study presents an application of airborne hyperspectral data acquired with Airborne Prism EXperiment (APEX) for assessing the spatial and temporal heterogeneity of water quality (WQ) in the largest Baltic Sea lagoon. The APEX campaign was performed in September 2016 over the Curonian Lagoon (Lithuania). Multiple approaches were adopted to retrieve WQ from APEX reflectance: a semi-empirical band-ratio for Chl-a; a hyperspectral inversion of a bio-optical model (BOMBER) for CDOM and TSM; and a hyperspectral analytical bio-optical inversion for phycocyanin (PC). The APEX-derived concentration showed a good correspondence with in situ data. From the APEX-derived Chl-a map we discovered pronounced variability of phytoplankton distribution, driven primarily by meteorological conditions. APEX imagery repeated within a 3 hour window uniquely showed how Chl-a and PC concentrations described the fine-scale intraday dynamics of cyanobacteria, which is still beyond the capability of current satellite sensors. The fine-scale mapping showed the hydrodynamic effects of the main tributary (the Nemunas River) and the Baltic Sea, towards the spatial distribution and variability of CDOM and TSM.

 

On hydrodynamic modelling of coastal areas with complex coastline

Alexander Sokolov, Stockholm University, alexander.sokolov@su.se

This work is focussed on modelling the hydrodynamic processes in small coastal areas using a 3-D model on unstructured mesh with fine spatial resolution. A finite element based three-dimensional baroclinic model TELEMAC-3D was applied to the Öre estuary (Bothnian Bay) and to the Tvärminne Storfjärden (Gulf of Finland).

This work is focussed on modelling the hydrodynamic processes in small coastal areas using a 3-D model on unstructured mesh with fine spatial resolution. A finite element based three-dimensional baroclinic model TELEMAC-3D was applied to the Öre estuary (Bothnian Bay) and to the Tvärminne Storfjärden (Gulf of Finland). The TELEMAC modelling suite is developed by the National Laboratory of Hydraulics and Environment (LNHE) of Electricité de France (EDF).

Öre estuary is a small fjord-like bay about 8 by 8 km with maximum depth of 35 metres. Modelling domain was approximated by an unstructured mesh with element size varies from 50 to 500 m. This setup was used to study river plume dynamic during snowmelt in April 2015 when river discharge increased from 8 m³/s to 160 m³/s in 18 days.

Tvärminne Storfjärden is located at the entrance to the Gulf of Finland and is linked with the estuary of the river Mustionjoki. The size of the study area is 35 by 15 km. Maximum depth is 44 m. Area was approximated by a mesh with element size varying from 10 – 50 m along the coast to 200 m offshore. Modelling of upwelling event in September 2018 is discussed.

 

Seasonal variability of the CO₂ system in the mouth of the Vistula River and in the Gulf of Gdansk

Karol Kulinski, IO PAN, kroll@iopan.gda.pl

Aleksandra Winogradow, IO PAN; Beata Szymczycha, IO PAN; Marcin Stokowski, IO PAN

The potential source of total alkalinity increase in the Baltic Sea can be the changes in the riverine AT loads. In our study we have investigated the AT, CT and pH variability biweekly in the Vistula River mouth and weekly at the Sopot Pier in the Gulf of Gdansk over the period 2016-2018. The obtained data provide new parametrisation for the riverine AT and CT loads to the southern Baltic.

The Baltic Sea due to its low salinity and thus also low total alkalinity (AT) is the basin potentially endangered to the ocean acidification (OA). The recent studies showed, however, that OA in the Baltic Sea is to large extent mitigated by the observed here AT increase. The potential source of that increase can be the changes in the riverine AT loads. In our study we have investigated the AT, CT and pH variability biweekly in the Vistula River mouth and weekly at the Sopot Pier in the Gulf of Gdansk over the period 2016-2018. The obtained data provide new parametrization for the riverine AT and CT loads to the southern Baltic as well as give new insights on the CO₂ system functioning in this region. The huge variability was found in the Vistula mouth (AT: 2400 – 3700 µmol kg^-1, CT: 2000 – 4000 µmol kg^-1, pH: 7.5 – 8.5) compared to the moderate one observed in the seawater (AT: 1700 – 2000 µmol kg^-1, CT: 1500 – 2000 µmol kg^-1, pH: 7.6 – 8.5). For river water, the maxima for both AT and CT concentrations have been found in winter while the lowest in summer. For the seawater, the seasonality was less pronounced and depended more on the salinity distribution.

 

Seasonal variation in sediment erodibility and resuspension in shallow coastal environments of the Baltic sea

Mari Joensuu, University of Helsinki, mari.joensuu@helsinki.fi

Conrad C. A. Pilditch, University of Waikato; Alf Norkko, Tvärminne Zoological Station, University of Helsinki

In coastal areas, episodic resuspension events may play a prominent role for the benthic-pelagic coupling of nutrients, matter and energy. Our findings demonstrate how seasonal changes in environmental conditions are reflected to the sediment erodibility, and hence resuspension, in different coastal environments.

In coastal areas, sediment resuspension events may dominate the sediment-water exchange of nutrients, matter and energy. Sediment resuspension is often linked to episodic wind-wave events and storms that create shear stress on the sediment surface, initiating sediment erosion and resuspension, if the erosion threshold (τc) is exceeded. Biogeochemical sediment properties define sediment erodibility and thus the tendency of sediments to resuspend. There’s only limited knowledge of the temporal variability in sediment properties regulating sediment erodibility and resuspension. We measured resuspension potential metrics from three sites in Hanko archipelago every second month from April to December 2015 with a core-based erosion device (EROMES). Macrofauna and sediment properties were quantified and analyzed after erosion measurements. Our findings show a gradual swift from a sheltered muddy sediment with a clear seasonal pattern in resuspension potential metrics to a more exposed sandy sediments with some or negligible seasonal variation. The dry bulk density was found to be the best predictor for sediment erodibility at all sites despite its small temporal variation.

 

 

 

Posters, session 2

Thursday, 22 August
17:00 – 19:00
Aula Magna floor 5

How to link ecosystem benefits and values to ecosystem components and functions providing them? A communication support tool.

Aurelija Armoškaitė, Latvian Institute of Aquatic Ecology, aurelija.armoskaite@lhei.lv (presenter)

Ingrīda Puriņa, Latvian Institute of Aquatic Ecology; Juris Aigars, Latvian Institute of Aquatic Ecology; Solvita Strāķe, Latvian Institute of Aquatic Ecology

We introduce our approach to Ecosystem Services (ES) assessment for the Latvian coastal water benthic habitats featured in the BONUS BASMATI project. It employs the revised BONUS BASMATI ES framework. We present a diagram based on an expert opinion matrix evaluating ecosystem contribution in benefit provisions. It depicts value of links between units, aids communication and stakeholder engagement.

The ecosystem approach has been widely used to bring together social, cultural, economic and environmental aspects and has laid the foundations for standardised goods and services assessments providing evidence for marine spatial planning.

Here we introduce our approach to ES provisions assessment for the Latvian coastal water benthic habitats featured in the BONUS BASMATI project. We applied the revised CICES typology developed during the project and the cascade model. Our thinking is presented in the shape of an alluvial diagram based on an expert opinion matrix evaluating ecosystem component, function and services contributions in provisions of benefits in the Latvian context. The matrix and tree-like diagram were developed as assessment support tools during cooperation between experts. Based on the cascade the method provides order, a common ground for interdisciplinary communication and reduces the risk of double counting. However, it also delivers a means of depicting values of links between elements, whilst illuminating the need for support tools. Given the interactive nature the diagram could be used to for stakeholder engagement or to promote ocean literacy.

 

The role of aquatic vegetation for ecosystem multifunctionality

Åsa Austin, Stockholm University, asa.austin@su.se (presenter)

Joakim Hansen, Stockholm University; Ulf Bergström, Swedish University of Agricultural Sciences; Serena Donadi, Swedish University of Agricultural Sciences; Britas Klemens Eriksson, University of Groningen; Göran Sundblad, Swedish University of Agricultural Sciences; Johan Eklöf, Stockholm University

Diversity is important, but why and how do you deal with it? We sampled 32 bays along the Swedish Baltic Sea coast to find out if different measures of diversity of the underwater vegetation affect ecosystem multifunctionality – in this case the provision of clear water, juvenile fish and high diversity of invertebrates.

Aquatic vegetation sustains many ecosystem functions in shallow waters such as good water quality, high diversity and abundance of invertebrates and juvenile fish. Studies have shown that high biodiversity is needed to uphold many ecosystem functions simultaneously so-called ecosystem multifunctionality (EMF). Most studies measure diversity using species richness. However, in theory, the complementarity and facilitation among species should benefit from a large species pool (γ-diversity) and a high spatial turnover of species (β-diversity). A high average species richness (α-diversity) could be an even spread of species, and is not necessarily the best measure of diversity. We therefore examined whether α-, β- and γ-diversity, or simply total cover of all species affected EMF in 32 shallow bays in the Baltic Sea. We also examined, using structural equation modelling (SEM), how strong this effect was compared to important abiotic factors. Preliminary results suggest that the average EMF increases with α- and γ-diversity but that the positive effect of total cover on average EMF is stronger. This study highlights the importance of aquatic vegetation abundance and diversity for EMF.

 

Hydrodynamic properties of the shallow Bay of Gdansk and implications for the coastal filter function

Ines Bartl, Leibniz-Institute for Baltic Sea Research Warnemünde, ines.bartl@io-warnemuende.de (presenter)

Kirstin Schulz, NIOZ Netherlands Institute for Sea Research; Peter Holtermann, Leibniz-Institute for Baltic Sea Research Warnemünde; Maren Voss, Leibniz-Institute for Baltic Sea Research Warnemünde

In open coastal zones lateral transport and vertical mixing may have a strong impact on water residence time and thus the coastal filter efficiency. In the Vistula Estuary (Bay of Gdansk) the current regime, vertical mixing and water residence times are investigated and combined with nutrient distributions and microbial process rates to evaluate the coastal filter potential of this ecosystem.

Water residence time is an important factor determining the coastal filter efficiency in lagoons and semi-enclosed coastal zones, while in open bays lateral transport and vertical mixing have a strong impact. These physical processes may result in seasonally and spatially (surface vs. bottom) differing residence times which influence biological nutrient retention processes and their connection to permanent nutrient removal in the sediment. We examined the current regime, vertical mixing and water residence times in the shallow Bay of Gdansk, near the Vistula River outflow, using a highly resolved circulation model (GETM). Mean current velocities show a two-layer exchange flow east of the river mouth, while to the west surface and bottom currents are highly variable. Water residence times were higher in summer (40 days) than in winter (16 days) and are moreover influenced by wind. The model results are discussed along with nutrient concentrations and process rates observed during cruises to evaluate the potential of this coastal system to biologically retain or remove nutrients imported by the Vistula River.

 

Validating WAM, SWAN and WAVEWATCH III in the Helsinki archipelago

Jan-Victor Björkqvist, Finnish Meteorological Institute, jan-victor.bjorkqvist@fmi.fi (presenter)

Olga Vähä-Piikkiö, Finnish Meteorological Institute; Victor Alari, Tallinn University of Technology; Alexandra Kuznetsova, Russian Academy of Sciences; Laura Tuomi, Finnish Meteorological Institute

We implemented the wave models WAM, SWAN and WAVEWATCH III, and compared the results with three years of wave buoy observations. The significant wave height was modelled accurately inside the archipelago, but the models disagreed on the peak period and the friction velocity. A tuning of the physics specifically for archipelago conditions might further improve the simulations.

Accurate simulations and predictions of nearshore waves are important for marine traffic and coastal planning, but the complex Finnish coastal archipelago still pose a challenge for models. We implemented three state-of-the-art wave models (WAM, SWAN and WAVEWATCH III) to the Helsinki archipelago and compared the simulations with extensive coastal wave buoy observations from the years 2012–2016. The accuracy of the forcing winds were established using measurements from four weather stations. All three models modelled the significant wave height accurately inside the archipelago. Nevertheless, a comparison between the simulated wave spectra showed small differences in the model behaviours that strongly affected the modelled peak period. Also, under certain conditions the models disagreed on the short-wave energy, which we surmise to be caused by different parameterizations of the wind input, thus leading to varying estimates of the friction velocity. All three models performed well, but the tuning of the physics specifically for archipelago conditions might further improve the simulations. Implementing the models with unstructured grids should also be explored.

 

Impressions from the use of unmanned aerial vehicle for mapping of macrophytes in the Curonian Lagoon

Martynas Bucas, Klaipeda University, martynas.bucas@jmtc.ku.lt (presenter)

Edvinas Tiskus, Klaipeda University; Vaiva Stragauskaite, Klaipeda University

The aim of this study was to test the use of a drone for mapping of macrophytes in the estuarine part of the Curonian Lagoon (Lithuanian part). In parallel of traditional in situ macrophyte mapping, commercial DJI Phantom 4 advanced drone was applied. In the results, the dominant macrophyte species and their coverage could be accurately (94 %) assessed from the images obtained at 10-70 m altitude.

The biggest advantage of using unmanned aerial vehicles (UAVs or drones) is very high resolution of images and ability to get them during cloudy conditions and on a demand. There are attempts to use drones for mapping coastal macrophytes, whereas classical in situ techniques usually are limited in space and time. In marine waters, the results are in general promising but for brackish estuarine waters, usually affected by turbid riverine waters, the application of drones is a challenge. Therefore, the aim of this study was to test the use of a drone for mapping of macrophytes in the estuarine part of the Curonian Lagoon (Lithuanian part). In parallel of traditional in situ macrophyte mapping in the lagoon during vegetation period in 2018, commercial DJI Phantom 4 advanced drone was applied. From the mosaics of orthophotos, the macrophyte species were recorded and their coverage were estimated. In the results, the dominant macrophyte species could be distinguished from the images obtained at 10-70 m altitude. Comparing orthophotos to in situ measurements, the accuracy was 94 % showing potential of application of drones for monitoring of macrophytes in the transitional water-bodies.

 

Alongshore variations of shore cliff height and beach width in relations to morphodynamic type of the shores of South-Eastern Baltic

Aleksander Babakov, Shirshov Institute of Oceanology, Russian Academy of Sciences, babakov_temp@mail.ru

Boris Chubarenko, Shirshov Institute of Oceanology, Russian Academy of Sciences (presenter)

The relations between terrace height (fore dune or cliff), beach width and morphodynamic type of the shore segments in the South-Eastern Baltic were discussed on the basis of field survey made during May-July 2018 with a step of 1 km along 147 km sea shore at the Kaliningrad Oblast (Russia).

Estimates of the input of eroded material to the Baltic Sea differ by more than 2 times (8.4–19.0 million m³/year) due to the lack of reliable data on the length and height of an eroded shore. The field survey (in the frame of RFBR Project 18-05-01145) was made during May-July 2018 with a step of 1 km along 147 km sea shore at the Kaliningrad Oblast (Russia), the South-East Baltic. The beach width, the height of cliff, geomorphological characteristics were collected.

The heights of fore dune on the Vistula and Curonian spits are within 5–8 m and 6–12 m, respectively, the heights of the fore dune at the eroded segments are somewhat less — between 5–6 m and 6–9 m, respectively.

The cliff at the western shore of the Sambian Peninsula is partly protected by fore dune (3-5 m height) along with 30 km, the eroded part (35-40 m height) has the length of 6 km. The cliff at the northern shore of the Samian Peninsula (varies from 45-50 m to 5-6 m) is eroded along its entire length (18 km). Further towards the Curonian Spit, the foredune (6-8 m) is formed. The inverse relations between shore bench (terrace) and beach width was revealed. The higher is fore dune or cliff the less is beach width.

The relations between terrace height (fore dune or cliff), beach width and morphodynamic type of the shore segments in the South-Eastern Baltic were discussed on the basis of field survey made during May-July 2018 with a step of 1 km along 147 km sea shore at the Kaliningrad Oblast (Russia).

 

Geothyntetic debris on the beaches of Kaliningrad Oblast – result of systematic assessment of 2018

Elena Esiukova, Shirshov Institute of Oceanology, Russian Academy of Sciences, elena_esiukova@mail.ru

Aleksandr Kileso, Immanuel Kant Baltic Federal University; Boris Chubarenko, Shirshov Institute of Oceanology (presenter), Russian Academy of Sciences; Vasilii Pinchuk, Immanuel Kant Baltic Federal University

The continuous inspection of the entire coastal strip of the Kaliningrad Oblast (135 km) by groups of tree observers revealed contamination of beaches by debris of geosynthetic materials which probably were initiated during partial damage of coastal protection constructions.

In 2018, within the framework of the RFBR Project 18-55-76002, the entire coastal strip of the Kaliningrad Oblast was surveyed using the continuous visual scanning. This technique involves a continuous passage by tree observers along the entire shoreline (135 km) covering total width of the beach (30 m in average) from the water edge to the fore dune.

The initial analysis showed visible contamination of beaches of the northern shore of the Sambian Peninsula and the Curonian Spit by debris of geosynthetic material and other large litter. The integral amount of debris of geotextile objects was more than 190 m2, the integral length of the geotextile braids from gabions was about 100 m. Similar pollutants on the western shore of the Sambian Peninsula and the Vistula Spit were practically not found.

This fact well correlates with the location of the main engineering structures that have geosynthetic material in their content. The bulk of the debris of geosynthetic materials such as «Dornit»-type geotextiles, geocells and geogrids, were found within a radius of 2-5 km from the expected sources, but mostly to the east of them.

 

Rate of recession of shoreline in the South-Eastern Baltic in different time scales

Valentina Bobykina, Shirshov Institute of Oceanology, Russian Academy of Sciences, bobyval@mail.ru

Mikhail Drobiz, Baltic Aerogeodetic Enterprise; Boris Chubarenko, Shirshov Institute of Oceanology, Russian Academy of Sciences (presenter)

The aim of the study was to compare the rate of recession of shoreline in the South-Eastern Baltic over a 100-year period (retrospective analysis, topographic maps of 1:25 000 scale of 1830-1835, 1834-1860 and 1908-1939, 2005 and 2015) with the current dynamics (2002-2017, land-based coastal monitoring).

The aim of the study was to compare the rate of recession of shoreline in the South-Eastern Baltic over a 100-year period (retrospective analysis) with the current dynamics (2002-2017, land-based coastal monitoring) using data available for Kaliningrad Oblast. A retrospective analysis was performed using topographic maps of 1:25 000 scale of 1830-1835, 1834-1860 and 1908-1939 editions, combined with a 2015 digital topographic map of a similar scale (RFBR # 18-05-01145). Coastal monitoring data were obtained within theme No. 0149-2019-0013 (State Assignment of AIORAS) as a result of annual leveling of coastal profiles at fixed locations.

For the entire Sambian Peninsula a weakening of the abrasion was revealed. On the northern shore, the secular retreat is of 0.2 -0.8 m per year, and the retreat during last 15 years was of 0.1 - 0.4 m per year. In contrast, the retreat of shoreline on sandy spits increased during recent time: locally from 1.4 to 2.0 m per year for the Visula Spit shore, and from 0.7 to 1.5 m for the Curonian Spit shore. Few cases of change of the tendency (from retreat to advance) were found.

 

Record breaking sea levels in Baltic Sea projections

Christian Dieterich, SMHI, christian.dieterich@smhi.se (presenter)

Hagen Radtke, IOW

An ensemble of regional sea level projections for the Baltic Sea shows that the probability for record breaking sea levels rises significantly in the southern part of the Baltic Sea. The higher expectation of a record breaking event can be attributed to land uplift and mean sea level rise. Record breaking sea levels are expected less frequently in the RCP2.6 scenarios than in the RCP8.5 scenarios.

We analyze an ensemble of regional sea level projections for the Baltic Sea to answer whether projected climate change leads to a higher probability of record breaking sea levels. Will record breaking sea levels occur less frequently if climate change follows a more ambitious socio-economic scenario with lower CO₂ emissions? We show that the model ensemble is capable of reproducing the observed statistics for record breaking sea levels in the past. In spite of post-glacial land uplift, projected sea level rise will lead to rising mean sea level relative to land along most of the Baltic Sea coast, except for the Bothnian Sea and the Bothnian Bay where relative sea level keeps falling. We show that the probability for record breaking sea levels rises significantly in the Kattegat, Belt Sea, Sound and the southern part of the Baltic Sea, including the Gulf of Riga. We demonstrate that the higher year-to-year expectation of a record breaking event can be attributed to this long-term trend in the combined land uplift and mean sea level rise signal. Our analysis shows that record breaking sea levels are to be expected less frequently in the RCP2.6 scenarios than in the RCP8.5 scenarios.

 

Aquatic Ecosystems at Risk for Occurrence of Pathogenic Bacteria

Karolina Eriksson, Umeå University, karolina.eriksson@umu.se (presenter)

Agneta Andersson, Umeå University; Johanna Thelaus, The Swedish Defence Research Agency, FOI; Jon Ahlinder, The Swedish Defence Research Agency, FOI

Pathogenic bacteria are commonly resistant to predation by protozoa. A hypothesis is that there is an evolutionary connection between the ecosystem in which the bacteria is operating and the development of their pathogenicity. General ecosystem drivers for the development of pathogenic bacteria will therefore be investigated through water samples collected in the Baltic Sea.

Infectious diseases are getting more and more attention, both due to antibiotic resistance and climate change. Bacteria defend against predators like protozoa, both by using intracellular and extracellular mechanisms. By utilizing these defense systems bacteria have the potential to become dangerous to humans, partly because the human immune cells handle bacteria comparable to phagotrophic protists. Pathogenic bacteria are commonly resistant to predation by protozoa. A hypothesis is that there is an evolutionary connection between the ecosystem in which the bacteria is operating and the development of their pathogenicity. Due to anthropogenic changes, predictive models could be useful for preventing sudden outbreaks. General ecosystem drivers for the development of pathogenic bacteria will therefore be investigated by identifying the organism composition from water samples collected in the Baltic Sea and by correlating the composition of organisms to the environmental information of each sampling site. The development of predation resistance will be investigated genetically and functionally.

 

Cape Taran area – coastal seascapes of unique complexity in the Southeastern Baltic: approaches to conservation

Elena Ezhova, Shirshov Institute of oceanology Russian Academy of Sciences, igelinez@gmail.com (presenter)

Olga Kocheshkova, Shirshov Institute of oceanology Russian Academy of Sciences; Alexandra Volodina, Shirshov Institute of oceanology Russian Academy of Sciences; Julia Manukyan, Shirshov Institute of oceanology Russian Academy of Sciences

One of the valuable coastal seascape in Kaliningrad region is the Cape Taran area. The area has a set of unique geological and biological features and is a site of Maritime Cultural Heritage objects location. R#64BalticRim Project proposes to integrate such cultural-natural landscapes in the MSP process for both economic benefit and conservation purposes.

One of the valuable coastal seascape in Kaliningrad region is the Cape Taran area. This area has a set of unique geological features: a layer of amber-bearing Blue Clay is crop out to a zero sea depth; it is the rare in South Baltic coast type, dominated by bedrock and boulders; well-preserved fragments of paleo-shorelines are present up to 25 m depth. The abiotic features are shaping an outstanding biological characteristic of the seascape. It is the richest area in the region in terms of biodiversity, abundance and biomass of algae and zoobenthos; fish spawning grounds, location of a valuable Baltic biotopes as Baltic photic rock and boulders dominated by 1. Mytilidae and 2. perennial red algae. Additionally, it is a place of on-land and underwater location of Maritime Cultural Heritage objects (one of the oldest East Baltic light-house and a site of stone ship ballast discharge). A new approach is now under development in flagship BSR Project R#64BalticRim, propose to reach the economic benefit by the integration of maritime cultural landscapes, if possible, in a synergy with a natural ones, in the MSP process. The Cape Taran seascape complex is a promising area in a such view.

 

Pollution transport in coastal Baltic sea - Liepaja port – Liepaja lake system

Vilnis Frishfelds, University of Latvia, frishfelds@latnet.lv (presenter)

Juris Sennikovs, University of Latvia; Uldis Bethers, University of Latvia

Pollution transport in coastal Baltic sea – Liepaja port – Liepaja lake system is considered. The main sources are “winter port”, Karosta docks and southern part of Liepaja lake. Currents are modeled by HBM ocean circulation model adapted for coastal waters. Transport of pollutants is estimated either by passive tracers or drift model. Seasonal effects in pollution transport are examined.

Pollution transport in coastal Baltic sea – Liepaja port – Liepaja lake system is considered. There are polluted sites in this system which are chategorised by LEGMC. One of main pollution sites is at “winter port” area due to handling of transit freight. The second significant source is at Karosta docks due to old Soviet military remains. There is also pollution source at the southern part of Liepaja lake, where ground water is slightly contaminated from pesticide depositories. Currents in gates of Liepaja port are influenced by sea level changes and currents in the Baltic sea. Therefore, coupled system Baltic sea – Liepaja port – Liepaja lake is considered. The highest resolution needs to be at Liepaja port and entrance to Liepaja lake. The atmospheric forcing is provided by DMI Harmonie model which provides high resolution winds in coastal zone. The modeling is performed by HBM 3D software adapted for coastal areas. Estimates of river discharge are provided by observation data. Drift modeling of pollutants is performed either by studying passive tracers or using separate drift model which accounts possible transformation of pollutants like oil products.

 

The Influence of Multiple Sandbar System Behavior on Coastal Erosion and Accretion, Curonian Spit, Lithuania

Rasa Janušaitė, Nature Research Centre, rasa.janusaite@gamtc.lt (presenter)

Darius Jarmalavičius, Nature Research Centre; Viktoras Karaliūnas, Nature Research Centre; Laurynas Jukna, Vilnius University, Institute of Geosciences; Gintautas Žilinskas, Nature Research Centre; Donatas Pupienis, Nature Research Centre; Vilnius University, Institute of Geosciences

The impact of multiple sandbar system behavior on coastal erosion and accretion along the middle part of the Curonian Spit is analyzed, using aerial and satellite images, data of bathymetric and topographic surveys of 1998-2018. Study results imply that coastal erosion was determined by outer bar switching and decay whereas accretion was associated with overall growth of the bar zone.

Coastal erosion and accretion strongly affect socioeconomic conditions of the coastal environment. Dynamics of nearshore sandbars is one of the factors controlling these processes, although their relation is not yet well understood. In this study the impact of multiple sandbar system behavior on the coastal erosion and accretion processes along the central part of the Curonian Spit is investigated, using a data set of aerial and satellite images, bathymetric and topographic surveys from 1998 to 2018. Study results suggest that behavior of nearshore sandbars has direct impact on the state of coastal environment. In the study area coastal erosion was determined by longshore obliquity of the outer bar development followed by bar switching and decay. During bar switching episode sandbar system shifted from triple to double north of the conjunction of the third and second bars where coastal erosional processes became dominant. After triple sandbar system recovered and continuity in the bar zone was retrieved, accumulation in the beach and foredune set in.

 

Correlation of wind waves and sea level variations on the coast of the seasonally ice-covered Gulf of Finland

Milla Johansson, Finnish Meteorological Institute, Milla.Johansson@fmi.fi

Jan-Victor Björkqvist, Finnish Meteorological Institute; Jani Särkkä, Finnish Meteorological Institute (presenter); Ulpu Leijala, Finnish Meteorological Institute; Kimmo Kahma, Finnish Meteorological Institute

Sea level variations and wind-generated waves both contribute to flooding risks. We analysed correlation of sea level and waves at Helsinki based on sea level data, coastal wave buoy measurements, and wave simulations. We used a copula method to determine the bivariate probability distribution, from which the distribution of the sum of sea level and wave run-up was determined.

Sea level variations and wind-generated waves both contribute to flooding risks, making the assessment of their joint effect crucial for coastal safety. The mutual correlation of these two phenomena complicates the estimates of their joint effect on the exceedance levels for the continuous water mass. We analysed this correlation based on 27 years of sea level data and three years of coastal wave buoy measurements from outside the city of Helsinki. We complemented the wave observations with a 27 year long wave simulation using a parametric wave model, which was forced with wind observations from a nearby weather station. Our results show that the sea level and the wave height at Helsinki are positively correlated for southwesterly winds, while the correlation is negative for northeasterly winds. In order to estimate events with probabilities lower than those captured by direct observations, we first extrapolated the marginal distributions of the sea level and the wave run-up separately. Using these distributions, we then adopted a copula approach to determine the bivariate probability distribution, from which the distribution of the sum of the two variables was determined.

 

A triple-isotope study of the diet of Macoma balthica, Marenzelleria spp. and Mytilus edulis

T.I. Kahma, University of Helsinki, ti.kahma@elisanet.fi (presenter)

A. Norkko, University of Helsinki; C. Humborg, University of Stockholm; A. Karlsson, University of Stockholm; C-M. Mörth, University of Stockholm; I.F. Rodil, University of Helsinki

The diets of Macoma balthica, Marenzelleria spp. and Mytilus edulis were studied with a triple-isotope (CNS) approach. For M. balthica and Marenzelleria spp., macrophyte-derived carbon seemed to be an important food source at shallower areas, while at deeper pelagic areas the importance of seston particulate organic matter increases.

The diets of two benthic infauna species (Macoma balthica and Marenzelleria spp.) and a filter feeder (Mytilus edulis) were examined with a triple-isotope approach (i.e. 13C, 15N and 34S) to study the importance of organic carbon derived from different primary sources and from imported organic matter to their diets at Storfjärden bay, southwestern Finland. The relative contribution of these components to the diets were studied at the landscape scale following a depth-gradient profile (from 3 m to 40 m), and a freshwater-marine gradient. Bayesian mixing models (MixSIAR) were constructed to estimate the proportions of different food sources.

M. balthica and Marenzelleria spp. showed 13C depletion with increasing depth. With both species, the proportion of macrophyte-derived carbon in their diet decreased following a depth gradient, while the proportion of particulate organic matter (seston) increased. Mytilus edulis showed slight 13C enrichment at the sample points closest to the sea influence.

 

Effect of surface currents on modelled wave fields in the Baltic Sea

Hedi Kanarik, Finnish Meteorological Institute, hedi.kanarik@fmi.fi (presenter)

Laura Tuomi, Finnish Meteorological Institute; Tuomas Kärnä, Finnish Meteorological Institute; Antti Westerlund, Finnish Meteorological Institute; Jan-Victor Björkqvist, Finnish Meteorological Institute

The effect of sea surface currents on modelled WAM wave fields is studied using surface current and ice fields from the NEMO model. This is done to identify areas and conditions in the Baltic Sea where this addition to the WAM model gives us new information of the prevailing wave fields.

Sea surface currents can noticeably refract surface waves in certain conditions. We study this phenomenon in the Baltic Sea using the WAM model forced with surface current and ice fields from the NEMO model. Changes in the significant wave height, spectral peak period and direction are examined to identify the areas and conditions, in which currents have a notable effect on the wave field. The quality of the model runs is verified against available wave buoy and altimeter measurements. Preliminary results show that there are areas, such as the western coast of Saaremaa and Hiiumaa islands, where strong currents tend to steer the higher waves away from the coast. The difference in the modelled significant wave height between the runs with and without current refraction were up to 20 cm. Such differences were induced by currents of over 40 cm/s. In some areas, such as the Gulf of Finland, even weaker currents, of c. 20 cm/s had distinctive effects on the wave field.

 

Features of the natural-technogenic system in the area of industrial extraction of amber on the Baltic Sea coast (Kaliningrad region of the Russian Federation)

Alexej Korkin, Immanuel Kant Baltic Federal University, a.korkin@ambercombine.ru (presenter)

Vadim Sivkov, Shirshov Institute of Oceanology, RAS; Marina Ulyanova, Shirshov Institute of Oceanology, RAS

For more than a century industrial mining of amber has been carried out on the Baltic Sea coast of Kaliningrad. The study attempts to characterize the natural-technogenic system in the area of amber mining. The positive effect of the delivery of overburden from amber quarries to the beach is considered from the point of view of the stability of the coastline of the sea.

The coastal zone of the Kaliningrad region (Russia) is a place of mining, port construction, intensive fishing, recreation, etc. In the context of environmental management objectives arising from the principle of sustainable development, there is a need for a holistic perception of man-made objects and the environment. In the most capacious and concentrated form, such interaction reflects the natural-technogenic systems (NTS). For more than a century industrial mining of amber has been carried out on the Baltic Sea coast of Kaliningrad, which is accompanied by the delivery of large amounts of rock to the sea. The study attempts to characterize the NTS in the area of industrial amber mining. Its spatial and temporal boundaries, structure, properties and state are determined. Analyzed the concentration of technogenic suspended matter, its chemical composition compared with the parent rocks. The PTS spatial contour is conducted along the outer boundary of the zone of environmental impact of mining. The positive effect of the delivery of overburden from amber quarries to the beach is considered from the point of view of the stability of the coastline of the sea. 

 

The differentiation of the sub-basins of Baltic Sea due to the occurrence of extreme sea levels

Tomasz Wolski, University of Szczecin, Faculty of Geosciences, tomasz.wolski@usz.edu.pl

Halina Kowalewska-Kalkowska, University of Szczecin, Faculty of Geosciences (presenter); Bernard Wiśniewski, Maritime University of Szczecin, Faculty of Navigation

Extreme sea levels, usually of a stormy nature, often lead to catastrophic situations, such as flooding of coastal areas, disappearance of beaches, as well as the destruction of coastal infrastructure. In the study long-term series of sea level data were used to recognize the geographical differentiation in the occurrence of extreme water levels in the particular sub-basins of the Baltic Sea.

Extreme sea levels, usually of a stormy nature, often lead to catastrophic situations, such as flooding of coastal areas, disappearance of beaches, as well as the destruction of coastal infrastructure. In the study long-term series of sea level data were used to recognize the geographical differentiation in the occurrence of extreme water levels in the particular sub-basins of the Baltic Sea. The analysis was carried out based on hourly sea level records collected at 49 tide gauges located at the coasts of the whole Baltic Sea. Among them hourly information on water levels in 1960-2010 was available from 37 gauges. The study revealed that the differentiation of extreme sea levels resulted mainly from the various exposures (directions) of the Baltic coasts (coastline configuration) to the trajectories of low-pressure systems passing over the Baltic Sea, the location of the water level stations in relation to the open areas of the Baltic Sea as well as the bathymetric and morphological characteristics of the examined coasts. Clear regularities found in the occurrence of extreme sea levels within the particular regions of the Baltic Sea enabled to determine their geographical pattern."

 

The extent of storm surges in the Odra River mouth area (the southern Baltic Sea)

Halina Kowalewska-Kalkowska, University of Szczecin, Faculty of Geosciences, halina.kowalewska@usz.edu.pl (presenter)

Multivariate methods of data analysis were applied to assess the extent of sea impact on the water level in the Szczecin Lagoon and the lower Odra River during storm surges that occurred at the Pomeranian Bay coast (the southern Baltic Sea) in the seasons from 1993/94 to 2018/19. Due to them it was possible to identify hydrological factors affecting the extent of storm surges in the studied area.

Multivariate methods of data analysis were applied to assess the extent of sea impact on the water level in the Szczecin Lagoon and the downstream reach of the Odra River during storm surges that occurred at the Pomeranian Bay coast (the southern Baltic Sea) in the seasons from 1993/94 to 2018/19. Due to them it was possible to identify various hydrological factors affecting the extent of storm surges, which during the most severe events, such as those observed in October 2009 and January 2017, reached as high up the Odra River as to Bielinek (more than 130 km from the coast). The multivariate analyses demonstrated that the extent of sea impact on the water level in the downstream Odra reach during storm surges depended first of all on the dynamics of sea level changes and the distance from the sea. However other factors, like the level of filling of the Baltic Sea as well as the magnitude of the Odra discharge, the degree of accumulation of water within the whole Odra mouth area or the appearance of ice phenomena and ice cover in the lower Odra channels modified the extent of storm surges as well. 

 

Modelling of coastal upwelling in the southern Baltic Sea using the high-resolution PM3D model

Halina Kowalewska-Kalkowska, University of Szczecin, Faculty of Geosciences, halina.kowalewska@usz.edu.pl (presenter)

Marek Kowalewski, University of Gdańsk, Institute of Oceanography

A new version of the high-resolution hydrodynamic model of the Baltic Sea (PM3D) was used to simulate coastal upwelling in the southern Baltic. Parallel calculations applied to the PM3D enabled to increase the resolution to 0.5 NM, which enhanced the statistics describing the predictive quality of the model and resulted in a more realistic reflection of thermal variability during examined events.

A new version of the high-resolution hydrodynamic model of the Baltic Sea (PM3D), developed at the Institute of Oceanography, University of Gdańsk in Poland, was used to simulate upwelling events in the southern Baltic Sea in 2010–2017. The model, based on the POM, assimilates the sea surface temperature data retrieved from the AVHRR and MODIS radiometers. Validation of the model, undertaken using in situ observations and satellite derived sea surface temperature data, revealed that an increase in the model resolution to 0.5 NM enhanced the statistics describing the predictive quality of the model and resulted in a more realistic reflection of thermal structures during examined upwelling events. In cases of high variability of thermal conditions, such as those observed in August 2013, July 2014 and August 2015, the model properly reproduced observed hydrodynamic variability. Parallel calculations used in the PM3D enabled to reduce significantly the computation time of simulations and apply the high-resolution grid to the operational version of the model available within the SatBałtyk System (http://satbaltyk.iopan.gda.pl). 

 

Impact of IW-induced currents on submersed construction elements for hydrological conditions of the Baltic Sea shelf

Andrey Kurkin, Nizhny Novgorod State Technical University n.a. R.E. Alekseev, aakurkin@gmail.com

Oxana Kurkina, Nizhny Novgorod State Technical University n.a. R.E. Alekseev; Ekaterina Rouvinskaya, Nizhny Novgorod State Technical University n.a. R.E. Alekseev

Presenter: Ayrat Giniyatullin

This study is devoted to investigation of the impact of internal waves on pillars (with the use of MOJS equation) and pipelines (the critical Shields parameter level for the suspension of the local dominant sediment) in the conditions of stratified Baltic Sea shelf.

We study the impact of intensive internal gravity waves on the hypothetic pillars of marine structures and pipelines for hydrological conditions of certain regions in the Baltic sea. We use temperature and salinity vertical profiles from GDEM climatology. The structure of the bottom velocities, the critical Shields parameter level for the suspension of the local dominant sediment are calculated in the context of potential impact on pipelines. Variations of the horizontal and vertical velocities throughout the depth of the fluid for selected points in the assumed location of the hydrotechnic constructions are studied. Morison's (or MOJS) formula is used to calculate the pressure force on the lateral surface of the elongated cylinder (pile). In the framework of this approach flow pressure contains the inertial (linear, depending on the acceleration of fluid particles in the wave) and the drag (non-linear resistance force, quadratic in velocity) components. It is shown that the inertial force is mainly smaller in absolute value than the drag force during this process. A distribution of the loads and torques upon unit length of the pillar in time is considered. 

 

Application of floating wetlands for nutrient removal, enhancement of biodiversity and cultural services in coastal lagoons

Jūratė Lesutienė, Klaipeda University, MRI, jurate.lesutiene@apc.ku.lt (presenter)

Małgorzata Bielecka, Institute of Hydro-Engineering of the Polish Academy of Sciences; Žilvinas Grigaitis, Curonian Spit National Park; Raimonda Ilginė, Klaipeda University, MRI; Maria Posern, EUCC- The Coastal Union Germany e.V.; Artūras Razinkovas-Baziukas, Klaipeda University, MRI

The LiveLagoons project (funded by Interreg South Baltic Programme 2014-2020) aims at improving the water quality in eutrophic lagoons in the South Baltic by the use of floating wetlands for nutrient removal. We test technology along with socio-economic benefits in different environments at three pilot installation sites: Curonian Lagoon, Szczecin Lagoon and Darss-Zingst Bodden Chain.

The LiveLagoons project (funded by Interreg South Baltic Programme 2014-2020) aims at improving the water quality in eutrophic lagoons in the South Baltic by the use of floating wetlands for nutrient removal. We test nutrient removal technology along with socio-economic benefits in different environments at three pilot installation sites: Curonian Lagoon (Lithuania), Szczecin Lagoon (Poland) and Darss-Zingst Bodden Chain (Germany). We present variable experience of macrophyte growth on floating installations, both custom made and constructed by commercial producer.

We aim to investigate the possible positive side effects of installations such as offering habitat for invertebrates, fish and birds as well as other organisms attached to the roots of macrophytes. We did find the willow stems at ~40cm below water surface nearly fully covered by zebra mussels, which further brought us to the idea of combining mussel with plants to enhance the nutrient removal capacity of artificial islands. Additional island was installed in the coastal resort area to examine attitudes of coastal community and National park visitors towards island as an aesthetically attractive object.

 

Linking the development of stratification with the variability of velocity profiles in the Gulf of Finland

Urmas Lips, Tallinn University of Technology, urmas.lips@taltech.ee

Taavi Liblik, Tallinn University of Technology; Irina Suhhova, Tallinn University of Technology (presenter); Madis-Jaak Lilover, Tallinn University of Technology; Jaan Laanemets, Tallinn University of Technology

We study advection and mixing roles in the development of stratification in coastal seas. The simultaneous time-series of vertical profiles of temperature, salinity and current velocity acquired by autonomous vertical profilers and bottom mounted ADCP in the Gulf of Finland are analysed. An attempt was made to link velocity shear and density stratification at shorter time scales.

The experimental knowledge about the roles of advection and mixing in the development of stratification in coastal seas is insufficient. We analyze the simultaneous time-series of vertical profiles of temperature, salinity and current velocity acquired by autonomous vertical profilers and bottom mounted ADCP in the Gulf of Finland. The measurement periods covered different types of atmospheric forcing patterns and consequent longer-scale development of vertical stratification. Westerly-south-westerly winds caused an inflow in the surface layer and strong outflow in the near-bottom layer. During the period of weak winds, an outflow in the surface and inflow in the near-bottom layer occurred. Concurrently, either a deepening of the seasonal thermocline or forming of a shallow and warm near-surface layer were observed. Depending on the forcing, the energetic peaks in velocity spectra with periods from inertial to the typical transition time scale of atmospheric cyclones were revealed. An attempt was made to link velocity shear and density stratification at shorter time scales analyzing the time series of the current shear, buoyancy frequency and gradient Richardson number. 

 

Is sediment resuspension important in benthic-pelagic coupling in the largest Baltic lagoon?

Jovita Mėžinė, Marine Research Institute, Klaipeda University, Lithuania, jovita.mezine@apc.ku.lt (presenter)

Christian Ferrarin, CNR-ISMAR, Venice, Italy; Jolita Petkuvienė, Marine Research Institute, Klaipeda University, Lithuania; Irma Vybernaitė-Lubienė, Marine Research Institute, Klaipeda University, Lithuania; Georg Umgiesser, Marine Research Institute, Klaipeda University, Lithuania; CNR-ISMAR, Venice, Italy; Petras Zemlys, Marine Research Institute, Klaipeda University, Lithuania; Mindaugas Žilius, Marine Research Institute, Klaipeda University, Lithuania; University of Ferrara, Italy

In shallow lagoons sediment resuspension could be considered a relevant processes in benthic-pelagic coupling. In comparison to advection process, resuspension can increase more phosphate concentration than ammonia or silica. Nevertheless, that sediment resuspension is limited in time but it could be important mechanism maintaining phytoplankton when nutrients are limited.

The benthic-pelagic coupling is important in aquatic systems, especially in the shallow lagoons. In the summer season during basic riverine flow, the bottom sediments become a relevant source of nutrient to overlaying water column. There nutrients can be transported through diffusion, advection or resuspension processes. The later process remains poorly studied in shallow Baltic lagoons which are frequently subjected to strong winds. In this study, we aimed to estimate frequency of sediment resuspension, and quantify how much of nutrient is delivered through this process in comparison to advection. The SEDTRANS05 module from SHYFEM modeling system was used to simulate the resuspension events in the Curonian Lagoon. The first results show that during stronger winds events when the wave height is >0.5 m it can be resuspended more than 1 mm of muddy sediments, which contains a high amount of dissolved inorganic nutrients. In comparison to advection process, resuspension increase more phosphate concentration than ammonia or silica. Nevertheless fact, that sediment resuspension is limited in time but it could be important mechanism maintaining phytoplankton when nutrients are limited.

 

Offshore large scale bedforms and related shoreline chnages on southern Baltic

Urszula Pączek, Polish Geological Institute – National Research Institute, urszula.paczek@pgi.gov.pl (presenter)

Szymon Uścinowicz, Polish Geological Institute – National Research Institute; Tomasz Szarafin, Polish Geological Institute – National Research Institute; Piotr Szmytkiewicz, Institute of Hydro-Engineering of Polish Academy of Sciences; Grzegorz Uścinowicz, Polish Geological Institute – National Research Institute

The research refers to bedforms and their influence on shoreline changes on the southern Baltic. On the foreland of the quasi-sine coastline, outside the sandbar zone, a series of sandy ridges oriented obliquely to the shore was found. Landward edges distance of the ridges’ depressions (measured parallel to the shore) comes to approx. 3-4 km and matches up to the nodal points of the coastline.

The results refer to 25 km of the Polish barrier coast. The coastline has a shape of a gentle (amplitude about 250-300 m) quasi-sine with a spacing of nodal points about 3-4 km.

Bathymetric, sonar and geophysical survey in the 2 km wide zone from the shore into the sea enabled identification of the megascale form of the sea bottom - a series of sandy ridges oriented obliquely to the shore, on the NW-SE axis. These forms are found in the seabed on the foreland of the barrier coastline outside the sandbar zone on the depth of 10 to 16 m. The ridges are slightly asymmetrical with steeper slopes facing NE. Wavelength of the forms (crest spacing) ranges from approx. 0.7 to 1.0 km, and their relative height is approx. 3-5 m. They are made of fine and medium sand. The thickness of sand in depressions between ridges usually does not exceed 0.5 m. Distance between landward edges of the depressions (measured parallel to the shoreline) comes to approx. 3 - 4 km.

The research presents a hypothesis on the impact of large scale bedforms (sandy ridges) on the distribution of waving energy and associated zones of erosion and accumulation of the coast.

 

Multiple drivers of cyanobacterial blooms in a large estuary: the role of phosphorous

Jolita Petkuviene, KU Marine Research Institute, jolita.petkuviene@apc.ku.lt (presenter)

Diana Vaiciute, KU Marine Research Institute; Irma Vybernaite-Lubiene, KU Marine Research Institute; Rasa Morkune, KU Marine Research Institute; Julius Morkunas, KU Marine Research Institute; Mindaugas Dagys, Nature Research Center; Cristina Bondavalli, Department of Chemistry, Life Science and Environmental Sustainability, University of Parma; Marco Bartoli, Department of Chemistry, Life Science and Environmental Sustainability, University of Parma

The project PatCHY aims to understand the mechanisms that promote cyanobacteria hyperblooms in the Curonian lagoon. It analyses blooms (satellites), external and internal P sources, the role of aquatic birds and validate hypotheses via experiments and modelling. Results suggest the relevance of within lagoon processes as P sources, impairing nutrient stoichiometry and favouring blooms.

This study aims to understand the mechanisms that promote cyanobacteria hyperblooms in the Curonian lagoon, focusing on the role of phosphorus. The Curonian lagoon is the largest in Europe, lays between the Nemunas River watershed and the Baltic Sea and it is threated by N-fixing cyanobacteria hyperblooms (CHY). Large summer P excess, is considered a driver of such events. We identified, via satellite remote sensing, interannual and spatial variability in the intensity of blooms with the proliferation of cyanobacteria in summer. Our results suggest that the external N and Si inputs to the lagoon drop during the summer leading to N:P and Si:P ratios <16 and <15, respectively. The analysis of benthic fluxes suggests that sediment may recycle nearly 3 times the external P input, and more under hypoxia. Large bird colonies fasten local P cycling and faeces addition experiments demonstrated to increase algal growth. ENA will provide an integrative framework for investigating key compartments and interactions in P dynamics. This work is based on the national project “PatCHY”.

 

 

 

Community composition of the rocky bottoms across the Finnish marine area using HELCOM HUB -classification

Henna Rinne, Åbo Akademi University, henna.rinne@abo.fi (presenter)

Minna Boström, Åbo Akademi University; Charlotta Björklund, Åbo Akademi University

The algal and invertebrate communities of rocky bottoms are important components of the Baltic Sea ecosystem. To describe variation in these communities across the environmental gradients of the Finnish coast, we used mapping data (~160 000 sites) classified to HELCOM HUB-biotopes. The results provide a holistic view of spatial variation in hard bottom communities across the Finnish marine area.

The rocky bottoms across the Baltic Sea host algal and invertebrate communities that are of key importance to the Baltic Sea ecosystem. Due to gradients in e.g. depth, salinity and exposure, their community composition varies highly.

We used extensive mapping data collected during the Finnish inventory program for the marine environment (VELMU) and in a mapping project in the Åland Islands to describe the composition of communities occupying hard bottoms across environmental gradients in the Finnish marine area. Survey data, consisting of ~160 000 study sites, were classified into biotope classes defined in the HELCOM underwater biotope and habitat classification system (HUB). Figures showing the proportional occurrence of each biotope class at different depths were created to allow comparison of community composition across the different sea areas from the Bothnian Bay to the Gulf of Finland and in inner vs. outer archipelagos.

The results provide a holistic view of spatial variation occurring in hard bottom communities along the Finnish coast, and give a great example of mapping outcomes. The results can be used e.g. as baseline information in status assessments.

 

On an impact of rotation and dissipation in modeling of internal gravity waves in the Baltic Sea

Ekaterina Rouvinskaya, Nizhny Novgorod State Technical University n.a. R.E. Alekseev, e.rouvinskaya@gmail.com

Oxana Kurkina, Nizhny Novgorod State Technical University n.a. R.E. Alekseev; Andrey Kurkin, Nizhny Novgorod State Technical University n.a. R.E. Alekseev; Ayrat Giniyatullin, Nizhny Novgorod State Technical University n.a. R.E. Alekseev (presenter); Pavel Lobovikov, Nizhny Novgorod State Technical University n.a. R.E. Alekseev

This study is devoted to investigation of the impact of dissipation (different models are used) and rotation on the spectral, dynamic and kinematic characteristics of the internal waves’ field during the transformation of internal solitary wave in the conditions of stratified Baltic Sea shelf in the framework of weakly nonlinear models.

Though the Baltic Sea is micro-tidal and meteorological conditions are unstable and impede remote sensing of the surface of the Baltic sea, surface manifestations of internal waves are regularly observed in this region. In this study we consider transformations of internal solitary waves along certain pathways in the Baltic Sea. We use weakly nonlinear models (Gardner equation and its generalizations) to simulate wave dynamics. Whereas the Baltic Sea is situated in middle and rather high latitudes, we take into account effects of the Earth’s rotation (Gardner-Ostrovsky equation) and analyze its impact on the spectral, dynamic and kinematic characteristics of the internal waves’ field for such relatively short initial impulses. Usually dissipation is weak enough, especially for long waves, so they can propagate over long distances. However, dissipation in the turbulent bottom layer should be taken into account for practical calculations, when the internal wave reaches shallow near-shore. Different models of dissipation in the conditions of the Baltic sea shelf are applied.

 

Atmospheric nitrogen fixation in the largest Baltic lagoon: evidences from metagenomic analysis

Aurelija Samuilovinė, Klaipeda University, aurelija.samuiloviene@jmtc.ku.lt (presenter)

Rūta Stanislauskinė, Vilnius University; Anastasija Zaiko, Klaipeda University/Cawthron Institute/University of Auckland; Stefano Bonaglia, Klaipeda University/Stockholm University/University of Southern Denmark; Mindaugas Zilius, Klaipeda University/Ferrara University

In the Baltic Sea lagoons, diazotrophic microorganisms are responsible for critical external input of nitrogen. By combining three HTS technology based approaches we analysed the diversity and activity of diazotrophic community in the Curonian lagoon. We indicated temporal variation in composition and activity of diazotrophic community and confirmed that this system is a hotspot for N2 fixation.

In the Baltic Sea lagoons, regularly reoccurring summer blooms is mostly contributed by heterocystous cyanobacteria. However, there is growing evidence that community of diazotrophs is much diverse and includes heterotrophs. Although dinitrogen input might affect lagoon functioning, but diazotrophic microorganisms and their genetic capacity remains poorly characterized. Here, we combined three HTS technology based approaches to study the diversity, activity and temporal dynamics of pelagic diazotrophs in the Curonian Lagoon. The results based on barcode marker gene (16S rRNA) show that 28 bacterial phyla were observed in this eutrophic lagoon. Cyanobacteria was dominant phyla followed by Proteobacteria, Actinobacteria, Bacteriodetes and Verrucomicrobia. However, Euryarchaeota was only archaeal phyla found. By combining shotgun metagenomics and functional gene (nifH) HTS analysis we estimated genetic potential and activity of these communities. Preliminary results show that composition of diazotrophs community and their activity varied among seasons suggesting strong environmental control. Overall, metagenomic analysis confirms that the Curonian Lagoon is a hotspot for N2-fixation.

 

Submarine Groundwater Discharge along the shorelines of the Eckernförde Bay, Baltic Sea

Jan Scholten, Kiel University, Coastal Geology and Sedimentology, jan.scholten@gmail.com (presenter)

Matthias Kreuzburg, Leibniz Institute for Baltic Sea Researchng; Feng-Hsin Hsu, National Taiwan University; Michael Schlüter, Alfred-Wegener-Institute; Ingrid Stimac, Alfred-Wegener-Institute; John Rapaglia, Department of Biology, Sacred Heart University, US; Michael Schubert, Helmholtz Centre for Environmental Research - UFZ Leipzig

Submarine Groundwater Discharge (SGD) is known to be an important process for dissolved material fluxes to the coastal environment, but this process is not considered in most Baltic Sea nutrient balances and in any EU marine policies. Here we report from studies in the Eckernförde Bay, Germany, showing the widespread occurrence of SGD with relatively high nutrient loads.

Little information is available on the nutrient supply to the Baltic Sea associated with submarine groundwater discharge (SGD). We investigated the occurrence and magnitude of SGD along the coastline of the Eckernförde Bay, Germany, using a variety of different methodological approaches. Widespread occurrences of SGD as indicated by surface sediment pore water salinities lower than ambient seawater were detected at 15 out of the 18 locations investigated. Monitoring of sediment pore water salinities for several weeks at various locations in the Eckernförde Bay suggests a very dynamic system with rapid salinity changes largely depending on wind-driven sea-level variations. The mean SGD flux as determined by seepage meters is 21 cm/d. SGD consists on average of 16.8% of freshwater with recirculated seawater forming the remainder. SGD-borne dissolved inorganic nitrogen (DIN = NO3 + NH4 + NO2) concentrations are on average 96 µmol/l) with higher concentrations (mean 265 +/- 99 µmol/l) in low saline waters (salinity < 0.2) suggesting their terrestrial source.

 

 

 

Deep Submarine Groundwater Discharge in the Eckernförde Bay, Western Baltic Sea

Jan F. Schröder, Institute of Geosciences, University of Kiel, Germany, jan.schroeder@ifg.uni-kiel.de (presenter)

Jan Scholten, Institute of Geosciences, University of Kiel, Germany; Volker Liebetrau, GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany; Ingrid Stimac, Alfred-Wegener-Institute Helmholtz Centre for Polar and Marine Research Bremerhaven, Germany; Michael Schlüter, Alfred-Wegener-Institute Helmholtz Centre for Polar and Marine Research Bremerhaven, Germany

In frame of the BONUS SEAMOUNT project, we investigated deep (>20 m) submarine groundwater discharge sites in the Eckernförde Bay, western Baltic Sea. We measured the water column radium (²²⁴Ra, ²²³Ra, ²²⁸Ra) and radon (²²²Rn) distribution. In addition, pore waters extracted from short sediment cores (Rumohrlot) were analyzed for ²²²Rn, nutrients and for selected major and minor elements.

The poor ecological status of the Baltic Sea is believed to be related to an excessive nutrient supply by rivers and the atmosphere. Whereas these nutrients sources to the Baltic Sea are relatively well quantified, little is known about the amount of nutrients associated with submarine groundwater discharge (SGD). Investigations of SGD are often restricted to water depths ~ 20 m) SGD sites and was selected for testing these vehicles. For “ground-truthing” of the instrumental setup, we investigated the water column radium (²²³Ra, ²²⁴Ra, ²²⁸Ra) and radon (²²²Rn) distribution. In addition, pore waters extracted from short sediment cores (Rumohrlot) were analyzed for ²²²Rn, nutrients and for selected major and minor elements. First results indicate elevated ²²⁴Ra and ²²²Rn activities in the water column close to known deep SGD hotspots in the Eckernförde Bay. However, high ²²⁴Ra and ²²²2Rn activities in deep waters were also detected in other parts of the Eckernförde Bay. Preliminary results indicate a strong temporal variability of ²²⁴Ra close to the sea floor, whose cause needs to be further explored. 

 

Parametrization of coastal sources of geosynthetic pollution in the SHYFEM model based on the random walk algorithm

Andrei Sokolov, Shirshov Institute of Oceanology, Russian Academy of Sciences, tengritag@gmail.com (presenter)

Irina Chubarenko, Shirshov Institute of Oceanology, Russian Academy of Sciences; Boris Chubarenko, Shirshov Institute of Oceanology, Russian Academy of Sciences; Georg Umgiesser, ISMAR-CNR

Coastal protection structures are sources of debris of geosynthetics released from them by storms. They are distributed along the shore and serve as secondary sources. The mean square deviation from the source is =2*D*t. Diffusivity coefficient D was estimated during field campaigns 2018-2019 and used in numerical simulations by the SHYFEM model for the Sambian Peninsula.

Coastal protection structures become sources of new type of pollution: debris of geosynthetics is released from them after damage by storms. These pieces are distributed along the shore as marine litter and serve as secondary sources of synthetic macro and micro particles during the next storms. Since (i) spatial distribution of such secondary and following sources can be assumed as random due to the variability of wind and currents in coastal zone during rather long period, and (ii) the next state of its distribution depends on the current state only and not on the past history, the approach of random walk (proposed for marine litter in RFBR Project 18-55-76001) could describe the alongshore effective diffusion of particles without absorption. The mean square deviation from the mother source is =2*D*t, where t is the time. Diffusivity coefficient (D) was estimated during field campaigns 2018-2019 of RFBR Project 18-55-76002, and used to reproduce numerically the geotextile debris distribution along the northern shore of the Sambian Peninsula (South-Eastern Baltic). The numerical simulations were conducted by the Simple Sediment Transport module of the SHYFEM model.

 

Spatial distribution of arsenic in Baltic Sea bottom sediments

Marta Szubska, Institute of Oceanology of the Polish Academy of Sciences, szubi@iopan.gda.pl (presenter)

Jacek Bełdowski, Institute of Oceanology of the Polish Academy of Sciences

Arsenic is an element occurring naturally in the environment. Some parts of the Baltic Sea are characterized with highly elevated arsenic concentrations resulting from the anthropogenic activity on land. There is also an inner source of arsenic in the Baltic – arsenic containing Chemical Warfare Agents (CWA) from chemical munitions dumped after the World War II and remaining on the sea bottom.

Arsenic is an element occurring naturally in the environment. It is assumed to be toxic to plants, animals and human and is considered as a potential carcinogen. It disrupts enzymatic processes in cells, causes cell walls breakdown, inhibits mitochondria functions, affects proteins formation by its high affinity to sulfhydryl groups, inhibits phosphate insertion to DNA, affecting transmission of genetic information. Chronic exposure to elevated arsenic concentrations can cause disturbance in nervous system and heart diseases. It is also believed that bladder and lung cancer may be caused by chronic arsenic poisoning. As fish and seafood is the main source of arsenic in human diet it is very important to investigate the marine environment for arsenic concentrations.

Some parts of the Baltic Sea are characterized with highly elevated arsenic concentrations resulting from the anthropogenic activity on land. There is also an inner source of arsenic in the Baltic – arsenic containing Chemical Warfare Agents (CWA) from chemical munitions dumped after the World War II and remaining on the sea bottom.

 

SGD as a source of pharmaceuticals to the Bay of Puck, southern Baltic Sea

Beata Szymczycha, IOPAN, beat.sz@iopan.gda.pl (presenter)

Marta Borecka, University of Gdansk; Anna Białk-Bielińska, University of Gdansk

The study describes the pharmaceutical occurrence in river, seawater, groundwater and submarine groundwater discharge. The obtained results revealed that residues of pharmaceuticals were present in area in the Bay of Puck, southern Baltic Sea at a concentration level from ng/L up to µg/L.

Pharmaceuticals comprise one of the few groups of chemicals specifically designed to act on living cells. Therefore their occurrence in the environment presents a special risk and is intensively discussed in environmental sciences. Groundwater has been enriched in pharmaceuticals worldwide while submarine groundwater discharge (SGD) has been recognized as an important exchange pathway between land and sea. SGD to the Bay of Puck, southern Baltic Sea is a significant source of dissolved organic and inorganic substances however there have been no studies related to contamination by the pharmaceuticals residues. The obtained results revealed that pharmaceuticals were present in area in the Bay of Puck, southern Baltic Sea at a concentration level from ng/L up to µg/l . SAKNAS DET NÅGOT HÄR???

Utilising airborne laser scanning and geoid model for examining marine processes

Sander Varbla, Tallinn University of Technology, Department of Civil Engineering and Architecture, sander.varbla@taltech.ee

Artu Ellmann, Tallinn University of Technology, Department of Civil Engineering and Architecture; Nicole Delpeche-Ellmann, Tallinn University of Technology, Department of Cybernetics (presenter)

Usability of Airborne Laser Scanning is explored for examining marine processes. By emitting laser pulses and registering the reflections, a sea surface height point cloud (SSH) is obtained. For sea level dynamics, tide gauge records in conjunction with hydrodynamic models are used. Inter-comparisons of a high-resolution marine geoid model and SSH are conducted for detecting abnormalities.

On a global scale, dynamics of marine processes and sea surface heights (SSH) can be utilized by employing satellite altimetry. For evaluating (sub)mesoscale dynamics, the achieved data resolution can be relatively low whereas in the near coastal areas the satellite altimetry data are known for having a poor accuracy. Instead, this study explores the usability of Airborne Laser Scanning (ALS) for examining marine processes. ALS device (mounted on an aircraft) emits laser pulses and registers the reflections from liquid surface, resulting in a SSH point cloud. The marine ALS profiles have thus the potential to provide constraints in modelling of marine processes. The developed method is tested by measuring several ALS profiles over Gulf of Finland. Tide gauge records in conjunction with hydrodynamic models are used for accounting sea level dynamics. The sea surface topography is determined with respect to a high-resolution marine geoid model. Inter-comparisons of the geoid model and SSH are conducted for detecting abnormalities. Identifying reasons for the detected discrepancies enables to determine whether these are due to poor hydrodynamic representation or/and geoid model errors. 

 

Variable loads of N, Si and P affect algal blooms and functioning of a large estuary

Irma Vybernaite-Lubiene, Klaipeda University, (presenter)

Mindaugas Zilius, Klaipeda University; Jolita Petkuviene, Klaipeda University; Petras Zemlys, Klaipeda University; Gianmarco Giordani, University of Parma; Marco Bartoli, University of Parma/Klaipeda University

An understanding of the dynamics and the processes regulating nutrient fluxes at the landscape is critical to management efforts aimed at reducing anthropogenic impacts on coastal waters. Within the frame of the COCOA project we analysed transport and fate of the nutrients along their pathway to the Baltic Sea. We show that nutrient loads and stoichiometry can effect lagoon filter functions.

An understanding of the dynamics and the processes regulating nitrogen (N), phosphorus (P) and silica (Si) export from watersheds is critical to management efforts aimed at reducing anthropogenic impacts on transitional and coastal waters. Within the frame of the COCOA project we analysed transport and fate of the three nutrients to the Baltic Sea through the Curonian Lagoon. The analysis of 5-year (2012-2016) nutrient inputs suggests a significant drop in total P loads to the lagoon as compared to historical data, while N loads remain high. Despite P reduction, a regular, strong limitation of N and Si occurs in the summer, favouring the diatoms-cyanobacteria shift. Mass balance calculations shows that large cyanobacteria blooms impact the nutrient retention capacity of the Curonian Lagoon. This is due to large export of particulate matter and regeneration of nutrients from sediments. Under a scenario of climatic and socio-economic changes, the regular monitoring of nutrient loads and stoichiometry along the River-Lagoon-Sea continuum must be conducted further and it is important to pay attention on lagoon functioning as it can be a filter for nutrients entering the sea.