Wednesday, 21 August
15:30 – 16:30
De Geer lecture hall

 

State, structure and regulatory drivers in a Large Marine Ecosystem: the Central Baltic Sea case

Maciej Tomczak, Stockholm Univerisyt, maciej.tomczak@su.se

Bärbel Müller-Karulis, Stockholm University; Thorsten Blenckner, Stockholm University; Margit Eero, Technical University of Denmark; Brian MacKenzie, Technical University of Denmark; Alf Norkko, University of Helsinki; Karen Timmerman, Aarhus University; Bo Gustafsson, Stockholm University; Anna Luzenczyk, National Marine Fisheries Research Institute; Saskia Otto, Hamburg University; Christoph Humborg, Stockholm University

Climate and anthropogenic pressures have caused regime shifts in Baltic Sea ecosystem structure and function. Reconstructed long-term (1925-2005) time-series of fish, benthic, and plankton variables together with fisheries, climatic and nutrient drivers, showed a regime shift in the early 1970s, when a highly productive hypoxic ecosystem replaced a low productive oxic foodweb configuration.

Climate and anthropogenic pressures are known to have caused regime shifts in the Baltic Sea ecosystem structure and function in the recent past. Reconstructed long-term (1925-2005) time-series of fish, benthic, and plankton variables together with data of fisheries, climatic and nutrient drivers, now indicate an additional regime shift in ecosystem function in the early 1970s, when a low productive ecosystem was replaced by a highly productive, partly hypoxic ecosystem in the Central Baltic Sea. Strong sprat-cod interactions dominated the high productive system, whereas all trophic levels benefited from increased nutrient concentrations and primary production prior to the regime shift. Deep-water oxygen concentrations were an important driver for the foodweb configuration after the regime shift. Before the 1970s, temperature and salinity changes together with fishing pressure regulated flounder biomass, but had no measurable impact on cod and sprat. Also reconstructed zooplankton and phytoplankton time-series responded to increased temperatures, together with larger nutrient inputs.

 

Climate change challenges food web stability in the Baltic Sea

Susa Niiranen, Stockholm University, susa.niiranen@su.se

Steven Lade, Australian National University; Olle Hjerne, Svensk Kärnbränslehantering; H . E. Markus Meier, Leibniz-Institute for Baltic Sea Research; Saskia Otto, Hamburg University; Maciej Tomczak, Stockholm University; Johanna Yletyinen, Manaaki Whenua Landcare Research; Thorsten Blenckner, Stockholm University

We find that climate change decreases Baltic Sea food web stability in every nutrient and fisheries management scenario tested. We also show that due to the non-additive nature of multiple stressor interactions food web stability can vary unexpectedly between management scenarios affecting both the vulnerability of the ecosystem to external perturbation, as well as its potential for recovery.

Climate or other human-induced changes in species composition, relative species abundances and food web structure are increasingly recorded in marine ecosystems worldwide. However, it is often unclear how the system’s vulnerability, or system stability, develops together with changing conditions. We explore how future climate change in different combinations with fishing and nutrient load scenarios can affect Baltic Sea food web stability using the leading eigenvalues of Jacobian matrices, constructed based on food web model output, as a proxy of food web stability. We find that climate change decreases food web stability in every scenario, but the magnitude of this effect is dependent on the specific nutrient loads and fishing intensity. Particularly fisheries-induced changes at higher trophic levels impact food web stability, emphasizing the keystone role of top predator cod. Importantly for ecosystem management, we show that due to the non-additive nature of multiple stressor interactions food web stability can vary unexpectedly between management scenarios affecting both the vulnerability of the ecosystem to external perturbation, as well as its potential for recovery.

 

Death comes in many shapes - factors regulating populations of coastal predatory fish

Ulf Bergström, SLU Aqua, ulf.bergstrom@slu.se

Ronny Fredriksson, SLU Aqua; Karl Lundström, SLU Aqua; Maria Ovegård, SLU Aqua; Stefan Larsson, SLU Aqua; Lovisa Wennerström, SLU Aqua; Lena Bergström, SLU Aqua

Both fishing and predation from top predators may exert substantial pressures on coastal predatory fish, such as pike, perch and pikeperch. We present results from no-take areas comparing the impacts of fishing and predation. Their relative impacts vary among species and populations, showing the need for policies to address conflicting management objectives.

Several factors affecting coastal predatory fish in the Baltic Sea are rapidly changing, including fisheries and populations of predators, which are principal sources of mortality. Many populations of pike, pikeperch and perch show negative trends, despite that climate change is expected to improve conditions for their recruitment. To take adequate management measures there is a need to understand the relative role of different regulating factors. Here we present results from studies on factors affecting the mortality of predatory fish at the Swedish Baltic coast. We estimate effects of fishing by comparing no-take zones, where no fishing is allowed, with areas open to fishing, and evaluate the effects of predation from cormorants and seals using spatial analyses of abundance and diet data. The combined results show that recreational fishing, as well as predation from seals and cormorants, may all exert a substantial pressure on populations of predatory fish, and that the relative impacts differ among species and populations. Our results point at the need to resolve potentially conflicting management objectives in a spatially explicit ecosystem-based management setting.

 

Emergence of novelty in the Anthropocene: the Baltic Sea case

Yosr Ammar, Stockholm University, Stockholm Resilience Centre, yosr.ammar@su.se

Thorsten Blenckner, Stockholm University, Stockholm Resilience Centre; Susa Niiranen, Stockholm University, Stockholm Resilience Centre; Walter Finsinger, Palaeoecology, ISE-M (UMR 5554 CNRS/UM/EPHE)

Novelty is increasingly emerging in ecosystems due to natural and anthropogenic changes. Here we study novelty in the Baltic Sea context, during the past four decades. We discuss how novelty affects abiotic and biotic dimensions in the context of ecosystem dynamics and how these results will create new insights on measuring novelty in marine ecosystems.

Global changes have accelerated at unprecedented rates in the Anthropocene due to human activities. These changes have contributed to the increase of novelty in ecosystems. In fact, natural processes and anthropogenic drivers may affect ecosystem dynamics and species assemblages toward novel functions and associations. Here we study the emergence of novelty in biotic and abiotic dimensions, using long-term monitoring data covering over four decades from the Baltic Sea. We define novelty as the degree of dissimilarity of a system to its closest analog across time and space. Our results indicate that Baltic basins changing the most are not necessarily the most novel. We found that the degree of novelty in abiotic and biotic dimensions differs across the spatial and temporal scale and indicate different baseline trajectories. In addition, Baltic basins follow different baseline trajectories over time and trophic levels. We discuss how novelty affects abiotic and biotic dimensions in the context of ecosystem dynamics and how these results will create new insights on measuring novelty in marine ecosystems.

 

Thursday, 22 August
14:00 – 15:30
De Geer lecture hall

 

The origin and regeneration of free-living populations of Fucus vesiculosus in the Baltic Sea

Roxana Preston, University of Helsinki, roxana.preston@helsinki.fi

Using microsatellites we infer the genetic diversity and population connectivity between free-living and attached Fucus vesiculosus morphs within the Baltic Sea. Due to the significant molecular variance between attached and free-living individuals, we propose that free-living ecads form separate populations that have at least some capability to sustain themselves.

Fucus vesiculosus is a foundation species within the Baltic Sea, forming two distinct morph types: Free-living and attached. Intriguingly the origin of the free-living morph is still uncertain. Using microsatellites we will measure the levels of relatedness between populations and consequently infer the population connectivity. We hypothesise that free-living ecads are genetically distinct ecotypes, forming spatially confined populations maintained predominantly through asexual reproduction.

Similarly to attached F. vesiculosus, free-living morphs have demonstrated extirpation from areas they were once commonly recorded within. As a species ability to adapt to environmental change is related to the level of genetic diversity within the population; it is imperative that the gaps in knowledge relating to the levels of genetic diversity between these morph types are resolved.

Our preliminary analyses indicate significant molecular variance between attached and free-living individuals, suggesting some degree of isolation between the two subpopulations. Accordingly we propose that free-living ecads form separate populations that have at least some capability to sustain themselves.

 

Macrobenthic respiration rates and secondary production across shallow habitats of the Baltic coast

Iván Rodil, Tvärminne Zoological Station, ivan.rodil@helsinki.fi

Karl Attard, University of Southern Denmark; Joanna Norkko, Tvärminne Zoological Station; Ronnie Glud, University of Southern Denmark; Alf Norkko, Tvärminne Zoological Station

A central goal of benthic ecology is to describe the pathways and quantities of energy and material flow in seafloor communities over scales. We highlight the importance of using a combination of metrics of ecosystem functioning, such as respiration rates and secondary production, to fully assess the different services that macrofauna communities from contrasting coastal habitats can provide.

We estimated the respiration rates and secondary production of macrobenthic communities based on seasonal measurements of macrofauna biomass across key coastal habitats of the Baltic Sea. Estimates of respiration rates suggest ranking of macrofauna contribution to the overall seafloor respiration as blue mussel reef > seagrass canopy > mixed macrophyte canopy > bare sand > Fucus-canopy. The blue mussel reef had the highest secondary production, while canopy-forming macrophyte habitats ranked high because of dense macrofaunal communities. Thus, estimates of secondary production suggest ranking of relative habitat value as blue mussel reef > seagrass canopy > Fucus-canopy > mixed macrophyte canopy > bare sand. Our results show that approximately 12 % and 10 % of the overall soft sediment metabolism (i.e. primary production and respiration) translated into macrofauna community respiration and secondary production, respectively. On the other hand, the hard bottom habitats exemplified two end-points of the shallow coastal metabolism, with the Fucus-canopy as a high producer and active exporter of organic C, and the blue mussel reef as a high consumer and active recycler of organic C.

 

Warming modifies predator effects on traits further down in the benthic food web

Tiina Salo, Stockholm University, SaloTiinaE@gmail.com

Casey Yanos, University of Groningen; Britas Klemens Eriksson, University of Groningen; Andrea De Cervo, Stockholm University; Maïté Jacquot, Åbo Akademi University; Johan Eklöf, Stockholm University

We assessed whether warming modifies predator effects on traits in a benthic food web consisting of three-spined stickleback, meso-grazers and macroalgal foundation species. Warming modified meso-grazer responses to stickleback presence, while algal traits remained mainly unaffected. Our study illustrates how warming may modify the food web dynamics in the Baltic Sea.

Currently, there is an urgent need to research interaction effects between global warming and the removal of top-predators on trophic interactions in marine food webs. In the Baltic Sea, top-predatory fish have decrease dramatically since the 1980s, contributing to dramatic increases in smaller predatory fish, such as the three-spined stickleback. At the same time, the Baltic Sea is experiencing intense warming with a temperature increase almost three times the average rate of global oceans over the past decade. We assessed whether warming modifies predator effects on traits in a benthic food web. We conducted a mesocosm experiment with three trophic levels: meso-predators (three-spined sticklebacks), meso-grazers (gastropod, amphipod and isopod grazers) and macroalgal foundation species (Fucus vesiculosus and F. radicans) in ambient and warmed (+4°C) water and assessed how warming and stickleback presence altered traits at each trophic level. Sticklebacks modified meso-grazer trait responses to warming. These changes did not, however, cascade further down to modify the algal trait responses. The results illustrate how warming may modify food-web dynamics in the Baltic Sea.

 

Changes in sediment bacterial community composition and diversity patterns following a major inflow event into the Baltic Sea

Christian Sommer, Södertörn University, christian.sommer@sh.se

Yue O.O. Hu, Science for Life Laboratory,; Francisco Nascimento, Stockholm University; Jonas Gunnarsson, Stockholm University; Patrik Dinnétz, Södertörn University; Sara Sjöling, Södertörn University

The Baltic Sea is experiencing widespread hypoxia. In 2014, a major inflow occurred, bringing saline and oxygenated water into the Baltic Sea. Sediment bacterial community diversity patterns were studied in 2010 and 2015 by analysis of the 16S rRNA gene in 42 monitoring stations. After the inflow, alpha diversity increased, beta diversity decreased and a distance-decay relationship developed.

The Baltic Sea is heavily affected by eutrophication caused by nutrient overload, climate, and infrequent Major Baltic Inflow events, resulting in widespread oxygen minimum zones. In 2014, a major inflow occurred, bringing saline and oxygenated water into the Baltic Sea. Using a theoretical framework based on metapopulation and metacommunity theory we predicted a transition from a more heterogeneous community pattern driven by local colonisation-extinction dynamics, towards a more pronounced environmental gradient but with reduced beta diversities. Sediment community diversity patterns were investigated in 2010 and 2015 by analysis of the 16S rRNA gene in samples from 42 monitoring stations of the Baltic Sea. Results showed strong metapopulation dynamics with many satellite and a few core taxa. Ordination showed distinct geographical clustering both years. After the inflow, alpha diversity increased, beta diversity decreased and a distance-decay relationship developed. Changes in community composition were correlated with changes in oxygen and salinity. Furthermore, our results indicate strong metacommunity structuring of bacterial diversity and composition in the Baltic Sea.

 

Changes in macrofaunal trait groupings across estuarine gradients – implications for the coastal nutrient filter

Anna Villnäs, University of Helsinki, anna.villnas@helsinki.fi

Urszula Janas, University of Gdansk; Alf Josefson, Aarhus University; Halina Kendzierska, University of Gdansk; Henrik Nygård, Finnish Environment Institute; Joanna Norkko, University of Helsinki; Alf Norkko, University of Helsinki

By identifying trait groupings, we estimated the contribution of benthic macrofaunal communities to the coastal filter across the land-sea continuum in five coastal areas of the Baltic Sea. Our results emphasize that increasing eutrophication can cause shifts in benthic trait groupings, with major implications for the functioning of the coastal nutrient filter.

Benthic macrofaunal communities have a profound impact on the coastal filter, where nutrients and organic matter from land are transformed or retained before reaching the open sea. The contribution of faunal communities is, however, context-dependent and differs across highly heterogeneous coastal zones. By identifying groupings of biological traits important for directing carbon and nutrient turnover in the sediment, we seek for commonalities in faunal contribution to the coastal filter in five contrasting areas of the Baltic Sea. Estimates of benthic faunal bioturbation, longevity and size (i.e. stability) and energy- and nutrient contents gradually changed across the land-sea continuum in all coastal areas. Benthic trait groupings indicative of an enhanced nutrient turnover were often prevalent at inner sites (e.g. small, short-lived species with restrained bioturbation), while outer sites were often dominated by larger individuals, exhibiting traits that are likely to enhance nutrient uptake and retention. Our results emphasize that increasing eutrophication can cause shifts in benthic trait groupings, with major implications for the functioning of the coastal nutrient filter.

 

Distribution and size structure of cyanobacteria and other plankton in the Baltic Sea and the Kattegat-Skagerrak investigated using a multi-method approach

Bengt Karlson, SMHI, bengt.karlson@smhi.se

Felipe Artigas, Université du Littoral , UMR CNRS 8187 LOG; Johannes Johansson, SMHI; Malin Johansson, UiT The Arctic University of Norway; Sirpa Lehtinen, Finnish environment Institute, Marine Research Centre; Fabrice Lizon, University of Lille, UMR CNRS 8187 LOG; Arnaud Louchart, Université du Littoral, UMR CNRS 8187 LOG; Jukka Seppälä, Finnish environment Institute, Marine Research Centre; Lars Stemman, Observatoire Océanologique de Villefranche

Novel automated in situ methods and remote sensing were used together with traditional methods to investigate the phytoplankton community during a cruise in the Baltic proper and the Kattegat-Skagerrak in July 2017. A bloom of filamentous cyanobacteria was ongoing in the Baltic but autotrophic pico- and nanoplankton contributed significantly to phytoplankton abundance and biomass.

A combination of novel automated in situ methods and satellite remote sensing were used together with traditional methods to investigate the distribution, size structure and composition of plankton communities during a cruise in the Baltic proper and the Kattegat Skagerrak in July 2017. A bloom of filamentous cyanobacteria was ongoing in the Baltic Proper and near surface cyanobacteria was detected using satellite ocean colour and by radar sensors on satellites. Automated in situ imaging of cyanobacteria colonies and zooplankton was used to investigate their horizontal and depth distribution. Microscopy of filamentous cyanobacteria and in situ fluorometry were also used to investigate their horizontal and depth distribution. Automated flow cytometry revealed high numbers and biomass of pico- and nanoplankton. Fast Repetition Rate Fluorometry (FRRF) was used to investigate photosynthetic parameters through the euphotic layer of the water column. The study demonstrated that the novel methods give a different and complementary view of the phytoplankton community distribution and dynamics, compared to what is the result of traditional monitoring methods. JERICO contrib. www.jerico-ri.

Should information about the first author really be entered twice?

 

Thursday, 22 August
16:00 – 17:00
De Geer lecture hall

 

Modeling cyanobacteria life cycle dynamics and historical nitrogen fixation in the Baltic Sea.

Jenny Hieronymus, SMHI, jenny.hieronymus@smhi.se

Kari Eilola, SMHI; Inga Hense, Universität Hamburg; Malin Olofsson, SMHI; Johannes Johansson, SMHI; Markus Meier, IOW; Elin Almroth-Rosell, SMHI; Bengt Karlson, SMHI

A novel cyanobacteria life cycle was implemented in a 3d ocean biogeochemical model for the Baltic Sea. Phosphorus limitation was added as a new feature to the cyanobacteria life cycle model and is shown to be of great importance in the Baltic Sea. The new and improved model was used to show changes in cyanobacteria biomass and nitrogen fixation as well as their phenology over the 20th century.

Cyanobacteria blooms in the Baltic Sea have increased markedly over the later part of the 20th century. The chlorophyll maximum has shifted from the diatom dominated spring bloom to the bloom of filamentous cyanobacteria during summer. To consider the life-cycle of cyanobacteria is of great importance in order to model the seasonal timing of cyanobacteria blooms. Due to its large temperature dependence, capturing the seasonality makes it possible to obtain a better estimate of nitrogen fixation as compared to previous model attempts. We have implemented a novel cyanobacteria life cycle in a 3d ocean biogeochemical model for the Baltic Sea. In a model run spanning 1850-2009, we demonstrate the models ability to capture cyanobacteria seasonality and nitrogen fixation. Phosphorus limitation was added as a new feature to the cyanobacteria life cycle model and is shown to be of great importance in the Baltic Sea. The new and improved model was used to show changes in cyanobacteria biomass and nitrogen fixation as well as their phenology over the 20th century. Notably, the length of the summer bloom has increased, as indicated by an earlier onset as well as a later bloom termination.

 

Key trophic links of micro- and mesozooplankton evaluated with selective DNA metabarcoding

Andreas Novotny, Stockholm Univesity, andreas.novotny@su.se

Sara Zamora-Terol, Stockholm University; Monika Winder, Stockholm University

Selective metabarcoding gives invaluable insights in biotic interactions of meso- and microzooplankton. We have seen that different zooplankton species previously clustered together in similar niche groups in ecosystem models have distinct feeding strategies. This challenges old assumptions of food web structures and may form a base for more accurate modelling of energy flow in aquatic systems.

Zooplankton form an important link from primary producers to higher trophic levels. In marine systems microzooplankton are major consumers of the primary production. The sensitivity and efficiency of molecular tools has become so powerful that we now can amplify and sequence ultra-low levels of environmental DNA. A handful of zooplankton yields enough DNA for taxonomic identification of the selected organism and its associated microbiome and prey.

We have followed different consumer organisms, including rotifers, ciliates, cladocerans and copepods in the pelagic ecosystem of the Baltic Sea to characterize zooplankton grazing and other biotic interactions. We targeted rRNA genes with DNA metabarcoding of consumer organisms selected by microscopy directly sampled from their environment.

This has provided invaluable insights in biotic interactions of meso- and microzooplankton. We have seen that different zooplankton species previously clustered together in similar niche groups in ecosystem models have distinct feeding strategies. This challenges old assumptions of food web structures and may form a base for more accurate modelling of energy flow in aquatic systems.

 

Harmful planktonic invaders and their impact on the Baltic coastal ecosystems

Irena Telesh, Zoological Institute RAS, Irena.Telesh@zin.ru

The paper reports long-term dynamics of the invasive potentially toxic dinoflagellates Prorocentrum cordatum and the predatory cladocerans Cercopagis pengoi, and their impact on plankton in the Baltic coastal ecosystems. Harmful blooms and ecological niche of P. cordatum were studied; transformation of trophic webs and decrease of fish production under the impact of C. pengoi were revealed.

The paper reports long-term dynamics of the model invasive protistan and cladoceran species, and their impact on structure and functions of plankton communities in the Baltic coastal ecosystems. Harmful blooms and ecological niche of the highly adaptive, potentially toxic dinoflagellates Prorocentrum cordatum were investigated using large databases. Field studies allowed revealing that invasion of the planktonic invertebrate predators (the cladoceran crustaceans Cercopagis pengoi) caused restructuring of energy flows, transformation of trophic webs and decline of fish production in a coastal lagoon. It was discovered that on the long run the overall community structuredness boosted while abundance and production of the dominant species of Rotifera, Cladocera and Copepoda decreased after the impact of C. pengoi on plankton had scaled back. The algorithm for assessment of the invader’s predation pressure depending on the average daily production rate of herbivorous zooplankton was developed for prognostic purposes. Synergy of abiotic variability and biotic interactions in plankton as triggers and drivers of the aliens’ propagation and success is discussed. RFBR project 19-04-00217.

 

Different phosphorus fractions – how bioavailable are they?

Lisa Rönspieß, Leibniz-Institute for Baltic Sea Research Warnemünde, lisa.roenspiess@io-warnemuende.de

Günther Nausch, Leibniz-Institute for Baltic Sea Research Warnemünde; Detlef Schulz-Bull, Leibniz-Institute for Baltic Sea Research Warnemünde

The knowledge of the bioavailability of different phosphorus fractions could help to reduce the level of eutrophication. Experiments were performed in three approaches with different plankton communities. Especially in particle-rich waters the reactive phosphorus fractions were bioavailable and transformed into biomass. A hint for living biomass is also the particulate non-reactive phosphorus.

Phosphorus (P) is one of the driving forces for eutrophication. Within Germany’s Ministry of Education and Research funded project “Phosphorus from source to sea” the bioavailability of different P fractions is studied in the Warnow estuary discharging into the Baltic Sea. Beside the normally measured dissolved reactive P (DRP), particulate reactive P (PRP) and dissolved and particulate nonreactive P (DNP resp. PNP) were analysed. The bioavailability is important to propose efficient measures to mitigate the still high level of eutrophication. In lab experiments the bioavailability was examined seasonally in:

1.an unfiltered approach in which the P uptake via the natural community was studied,

2.a 10 µm-filtered approach in which the P uptake was observed in a mixed plankton community (mainly phytoplankton and bacteria)

3.and a 1.2 µm-filtered approach in which the P uptake was observed in the community (mainly bacteria).

In general, DRP and PRP were bioavailable. Furthermore, there have been a positive correlation between PNP and the chlorophyll a. Additionally, there were differences between the seasons in the use and presence of the various P fractions.

 

Friday, 23 August
11:15 – 13:00
De Geer lecture hall

 

Effect of increased cyanobacteria blooms on benthic macrofauna in the Baltic Sea.

Per Hedberg, Stockholm University, per.hedberg@su.se

Séréna Albert, Stockholm University; Francisco Nascimento, Stockholm University; Monika Winder, Stockholm University

Phytoplankton species composition has a direct impact on food quality for benthic consumers. Climate warming predicts a transition towards more cyanobacteria and less diatoms in the Baltic Sea. In a mesocosm experiment we show that the clam Limecola balthica and the polychaete Marenzelleria sp. consume diatoms and cyanobacteria, but the amphipod Monoporeia affinis avoids the cyanobacteria.

Phytoplankton species composition has a direct impact on food quality for benthic consumers. Climate warming predicts a transition towards more cyanobacteria and less diatoms in the Baltic Sea. We hypothesize that phytoplankton species composition of settling organic matter affects benthic growth and secondary production of dominating macrofauna species. In a mesocosm experiment three common macrofaunal species, the amphipod Monoporeia affinis, the clam Limecola balthica and the polychaete Marenzelleria sp. were subjected to varying proportions of two sources of food; the diatom Skeletonema costatum and the potentially toxic cyanobacteria Nodularia spumigena that had been labeled with stable isotopes in order to detect consumption and incorporation. We show that all animals consumed diatoms and almost all clams and polychates consumed cyanobacteria, whereas amphipods did not consume any cyanobacteria. These findings suggest that Marenzelleria sp. and the less motile L. balthica have a less discriminatory feeding strategy than the highly motile M. affinis and could be better suited to handling a higher flux of organic matter of cyanobacterial origin without any adverse effects.

 

Effects of the seal-associated cods liver worm (Contracaecum osculatum) on the health status of Eastern Baltic cod

Marie Plambech Ryberg, National Institute of Aquatic Resources (DTU Aqua), mpla@aqua.dtu.dk

P.V. Skov, ; K. Buchmann, ; A. Nielsen, ; J.W Behrens, National Institute of Aquatic Resources (DTU Aqua)

Eastern Baltic cod (Gadus morhua) is in distress, revealed by historical poor nutritional status and few large fish. Known drivers of this are poor oxygen conditions and reduced food, but an additional driver may be the seal-associated cods liver worm (Contracaecum osculatum). We here describe effects of varying infections intensities of liver worm on cod health status, bioenergetics and mortality

The Eastern Baltic cod (Gadus morhua) is in distress. Today these fish are in a historical poor nutritional status (i.e. condition), growth has decreased, and large individuals are few. Known drivers of the stock into this distress are deteriorating oxygen conditions and reduced prey abundance. However, yet another potential driver of the health status of cod has emerged; the seal-associated cods liver worm (Contracaecum osculatum) to which grey seal is final host and cod one of several transport hosts. During recent years, infection load with this parasite in cod livers has increased markedly. The liver is a central organ for many vital processes related to e.g. growth and immune response, and it is an energy-rich ‘lunch box’ for the fish, and high parasite load may negatively affect the fish. We here present data describing effects of varying infections intensities of liver worm on the health status, bioenergetics and mortality of cod. Results are evaluated in relation to their applicability in bioenergetic modelling, contributing with new biological information to assessment models of Eastern Baltic cod.

 

Population- and size-specific distribution of Atlantic salmon in the Baltic Sea with implications for management

Philip Jacobson, SLU-Aqua, philip.jacobson@slu.se

Anna Gårdmark, SLU-Aqua; Magnus Huss, SLU-Aqua

Accounting for the distribution of organisms is key for understanding how they affect and are affected by their environment. Still, such knowledge is lacking for Baltic salmon. Using data from >125000 recaptures of tagged individuals, we show that the distribution at sea varies among Baltic salmon populations, suggesting that origin govern the experienced environment of Baltic salmon at sea.

Knowledge about population-specific distribution of fish is important to understand population-specific responses to environmental change. Still, despite a long history of mixed-stock sea fisheries on Baltic salmon and variation in dynamics among populations, information about distribution among populations in the Baltic Sea is generally lacking. Here, we test for differences in distribution at sea among and within ten Baltic salmon populations originating from 10 rivers along the Swedish Baltic Sea coast using individual data from >125000 tagged salmon, recaptured over six decades. We show strong population- and size-specific differences in distribution at sea, varying between year-classes and among individuals within year-classes. Based on our findings it is evident that there is great variation in environmental conditions and exploitation rates experienced by salmon at sea depending on origin. These results contribute to increase our understanding of why some populations are more synchronous in their dynamics than others and provide arguments for implementing population-specific management of salmon, also for management targeting the same life-stages at sea.

 

Linking structure and function in past and present Baltic Sea food webs: the Gulf of Riga case study

Susanne Kortsch, Åbo Akademi University, susanne.kortsch@abo.fi

Frelat R, Åbo Akademi University, Wageningen University & Research; Bonsdorff E, Åbo Akademi University; Pecuchet L, Åbo Akademi University, UiT - The Arctic University of Norway; Olivier P, Åbo Akademi University; Putnis I, Research Institute of Food Safety, Animal Health and Environment, Latvia; Nordström M, Åbo Akademi University

Despite long-standing interest, it is poorly understood how highly resolved marine food web structure is related to ecosystem functions (in terms of energy fluxes), and less so, how marine ecosystem functioning is linked to long-term variability in food web structure. In this study, we compared past and present food web structure over a 38-year period (1979-2016) in the Gulf of Riga. We found substantial structural alterations of the food web in the early 90s concomitant with documented reorganizations of multiple trophic groups in the Gulf of Riga. Based on food web topology, we could divide the 38-y study period into three distinct periods with similar food web characteristics: the 80s, 90s, and 2000s. Changes in food web structure in these periods were characterized by alterations in the composition and dominance of species, and by alterations in unweighted and weighted structural food web properties. Since the 90s, our fluxweb model showed an overall increase in the total amount of energy fluxes in the Gulf of Riga paralleled by increases in herring and other pelagic fish species. In conclusion, our topological food web analyses supports the previously documented structural and functional reorganizations in the Gulf of Riga food web. 

 

A population genomic analysis of blue mussels identifies genomic regions associated with sewage treatment plant effluents in the Baltic Sea.

Josefine Larsson, Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Huddinge, Stockholm, Sweden, josefine.larsson@sh.se

Mats Grahn, Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Huddinge, Stockholm, Sweden; Christopher Wheat, Department of Zoology, Stockholm University, Stockholm, Sweden

This study aimed to find genomic regions under selection of blue mussels from pairs of sewage treatment plant effluents affected sites and references sites across the Baltic proper. By using a whole genome pool-sequencing approach, we identify a number of genomic regions showing signs of within generation local selection at sewage treatment plant effluents affected sites.

To understand the long-term impact on populations from anthropogenic disturbances knowledge of the genetic background and novel evolutionary responses are crucial. The aim of this study is to discover and explore genomic regions of blue mussel populations exhibiting genetic differentiation between blue mussels from pairs of sewage treatment plant effluents affected (STP) site and references (REF) sites. Here, by using a whole genome pool-sequencing approach, we identify a number of genomic regions showing signs of within generation local selection. A low number of shared genetic regions between the replicated pairs of sewage effluent-affected and references sites were found. Five genomic scaffolds, shared among the replicated reference and sewage effluent-affected sites of Askö, Finland and Karlskrona were identified. Our results indicate that selection affects multiple loci, involving both parallel recruitment of the same genomic regions and the divergence of different genomic regions across the Baltic Proper. An initial functional characterization of these regions revealed functions related to immune and endocrine disruptive responses, oxidative stress and shell formation.

 

Soft-sediment biodiversity along environmental gradients of the Baltic Sea

Francisco Nascimento, Stockholm University, francisco.nascimento@su.se

Elias Broman, Stockholm University; Sven Iburg, Stockholm University; Stefano Bonaglia, Stockholm University

Predicting how benthic diversity and community composition respond to environmental change is a significant challenge in marine ecology. Here we report on a series of studies that investigated large-scale patterns of benthic diversity in the Baltic. Our results highlight the role of abiotic factors and cross-community ecological interactions in structuring this diversity.

Benthic communities are one the most productive and diverse assemblages on Earth and of global importance for ecosystem processes. Benthic ecosystems are under anthropogenic stress with potential severe consequences its diversity. Predicting how benthic diversity and community composition respond to environmental change is a significant challenge in marine ecology. Understanding the impact and consequences of this on-going and future pressures on biodiversity is particularly relevant for the Baltic Sea, a system under sharp environmental gradients and multiple anthropogenic stressors. Here we report on a series of studies that investigated large-scale patterns of benthic diversity of the three main communities of the benthos: macro-, meiofauna and prokaryotes in both shallow and deep Baltic soft sediments using new generation sequencing. Our results highlight the role of abiotic factors like salinity, oxygen, organic matter input and bay topography in structuring this diversity. We also discuss how cross-community ecological interactions between macro-and meiofauna and prokaryotes can shape benthic community composition with feedbacks that can mediate benthic ecosystem functions.

 

The diversity of benthic diatoms supports productivity across spatial gradients in the Baltic Sea

Leena Virta, University of Helsinki, leena.virta@helsinki.fi

Janne Soininen, University of Helsinki; Alf Norkko, University of Helsinki

We studied the relationship between benthic diatom diversity and ecosystem productivity at different spatial scales in the Baltic Sea. At all scales, diatom diversity was mostly controlled by the organic content, salinity and wave exposure, and had a strong relationship with ecosystem productivity. We found a linear and positive relationship at the smallest scale, and hump-shaped at larger scales.

Diatoms account for up to 40 percent of production in marine ecosystems, but the effects of benthic diatom diversity on ecosystem functioning are poorly known in the Baltic Sea. To narrow this knowledge gap, we performed a field sampling project to explore the relationship between diatom diversity and ecosystem productivity, and to quantify the environmental drivers for diversity across different spatial scales. We examined the patterns at a local scale in the Hanko archipelago, Finland, and expanded to a larger scale study that encompassed a freshwater-marine transition in southern Finland. Finally we expanded our study to a broad scale gradient of 2300 km along the entire Swedish coastline. At the smallest scale, diatom diversity and ecosystem productivity had a linear and positive relationship, but at larger scales it changed to hump-shaped. At all scales, the relationship was modified by organic content, salinity and wave exposure. Based on our findings, and considering the predicted decrease in salinity and increase in river runoff and wave action in the future, the Baltic Sea will most likely experience changes in the diatom diversity and, hence, in benthic productivity.

 

 

 

Posters, session 3B

Tuesday, 20 August
17:00 – 19:00
Aula Magna floor 5

Structural and functional response of microbenthic communities under different organic matter settling scenarios

Serena Albert, Stockholm University, serena.albert@su.se (presenter)

Per Hedberg, Stockholm University; Nisha Motwani, Södertörn University; Sara Sjöling, Södertörn University; Monika Winder, Stockholm University; Francisco Nascimento, Stockholm University

Indirect effects of climate change on the nature of organic matter settling to the seafloor will probably play an important role in shaping microbenthic communities and the processes that they mediate. In our experiment, microeukaryotes and bacteria taxonomic composition, as well as N-cycle gene expression, were significantly influenced by the type of phytoplankton input simulated to the sediment.

In aphotic sediments of the Baltic Sea, organic matter (OM) settling is a crucial process, as benthic organisms rely primarily on it as a food source. In this context, climate-driven changes in phytoplanktonic communities may have far-reaching consequences on microfauna biodiversity and ecosystem functioning, the extent of which remains poorly known.

In order to investigate this question, we conducted a mesocosm experiment using sediment cores from the Stockholm archipelago, where we simulated 5 scenarios of OM input, ranging from 100% diatoms to 100% cyanobacteria. After 4 weeks, metagenetic analyses revealed significant structural changes in the communities of microeukaryotes and bacteria. Such changes likely reflect differences in how they utilized the 2 types of microalgae as food, affecting their fitness and survival. We also observed functional changes, as denitrification gene expression positively correlated with increasing proportions of cyanobacteria input to the sediment.

Altogether, these results suggest that future changes in settling OM will have important implications on both the composition and function of microbenthic communities in the Baltic Sea.

 

An extensive catalogue of Baltic Sea bacterioplankton genomes

Anders Andersson, KTH/Science for Life Laboratory, anders.andersson@scilifelab.se (presenter)

Johannes Alneberg, KTH/Science for Life Laboratory; Christin Bennke, Leibniz Institute for Baltic Sea Research; Sara Beier, Leibniz Institute for Baltic Sea Research; Carina Bunse, Linnaeus University; Christopher Quince, University of Warwick; Karolina Ininbergs, Stockholm University; Lasse Riemann, University of Copenhagen; Martin Ekman, Stockholm University; Klaus Jürgens, Leibniz Institute for Baltic Sea Research; Matthias Labrenz, Leibniz Institute for Baltic Sea Research; Jarone Pinhassi, Linnaeus University

We have conducted large-scale genome reconstruction from 123 metagenome samples and assembled a catalogue of Baltic Sea prokaryotic genomes. In total, 1961 metagenome assembled genomes (MAGs) representing 352 prokaryotic species-level clusters (Baltic Sea clusters; BACL) were reconstructed. The catalogue of genomes will provide an important resource for future studies on the Baltic Sea ecosystem.

Each liter of seawater contains a billion microorganisms that play key roles in the marine ecosystem by driving the nutrient cycles and by forming the basis of the food web. Yet, our knowledge about aquatic microorganisms – e.g. how ecosystem functions are distributed across taxa, how their abundances and activities are regulated, how they evolve and adapt to changing conditions – is still limited.

Here we have conducted large-scale genome reconstruction from metagenome samples spanning the environmental gradients of the Baltic Sea and assembled a catalogue of Baltic Sea prokaryotic genomes. From the 123 samples we reconstructed 1961 metagenome assembled genomes (MAGs) that were further clustered into 352 prokaryotic species-level clusters (Baltic Sea clusters; BACL). The genomes were widely distributed over the prokaryotic tree of life, representing 20 different phyla. 320 out of the 352 BACLs could not be classified to the species-level. The corresponding numbers for genus- and family-level were 180 and 56. Thus, the dataset contains substantial genomic novelty. The genomes recruit on average 1/3 of the metagenome reads of the prokaryotic size fraction of the samples and thus represent a significant proportion of the planktonic prokaryotes in the Baltic Sea.

The catalogue of genomes will provide an important resource for future studies on brackish ecosystems and provides an unprecedented opportunity to investigate links between genome and ecosystem in general.

 

Bromoanisoles and Methoxylated Bromodiphenyl Ethers in Macroalgae from Nordic Coastal Regions

Terry Bidleman, Umeå University, terry.bidleman@umu.se (presenter)

Agneta Andersson, Umeå University; Sonia Brugel, Umeå University; Lars Ericson, Umeå University; Peter Haglund, Umeå University; Darya Kupryianchyk, Umeå University; Danny Lau, Umeå University; Per Liljelind, Umeå University; Lisa Lundin, Umeå University; Mats Tysklind, Umeå University

Sixteen species of red, green and brown macroalgae were collected in 2017-2018 from the northern Baltic Sea, Sweden Atlantic and Norway Atlantic, and analysed for bromoanisoles (BAs) and methoxylated bromodiphenyl ethers (MeO-BDEs), natural products based on bromophenols. Concentrations varied by orders of magnitude among species with higher concentrations of BAs in brown algae.

Marine macroalgae are used worldwide for human consumption, animal feed, cosmetics and agriculture. In addition to beneficial nutrients, macroalgae contain halogenated natural products, some of which have toxic properties similar to those of well-known anthropogenic contaminants.

Sixteen species of red, green and brown macroalgae were collected in 2017-2018 from coastal waters of the northern Baltic Sea, Sweden Atlantic (Skagerrak) and Norway Atlantic, and analysed for bromoanisoles (BAs) and methoxylated bromodiphenyl ethers (MeO-BDEs). Compounds quantified by gas chromatography─mass spectrometry were 2,4-DiBA, 2,4,6-TriBA, 2’-MeO-BDE68, 6-MeO-BDE47, and other tri- and tetrabromo-MeO-BDEs with unidentified substituent positions. Pentabromo-MeO-BDEs were also found in some macroalgae. Concentrations varied by orders of magnitude among species: ∑2 BAs 60─57700 and ∑5MeO-BDEs

 

Comparison of the assessment of the coastal waters of the Gulf of Riga by microbial food web and macrophyte communities

Elmira Boikova, University of Latvia, elmira@hydro.edu.lv (presenter)

Vita Licite, University of Latvia; Irina Kulikova, University of Latvia; Uldis Botva, University of Latvia

Microbial food web components have been investigated in different Baltic sea subregions since 80-is in relation to the eutrophication and anthropogenic stressors. In the case with ciliate communities, their biodiversity is close related to the seasonal succession and eutrophication level/trophic state index. Ciliates are represented by organisms with a different functional role in their communities (autotrophy, heterotrophy, mixotrophy). One of the key species of the ciliates – Mesodinium rubrum with autotrophic endosymbionts could perform remarkable diurnal migrations as well as a fast reaction on nutrient concentration by forming red tide phenomenon close to the river input area and coastal waters.

Long term investigations (1999 – 2018) of ciliates, pico, and nanoplankton in parallel with macrophyte ecology in the Gulf of Riga revealed close relations for both communities. Correlation and PCA analyses by PRIMER 6 software with environmental factors, macrophyte production, pico, and nanoplankton values illustrate closer relations of microbial food web elements with environmental factors and especially with Phaeophyta biomass and distribution.

 

Combining meta-omics and geochemical tools to study microbial diversity and function in Baltic Sea hypoxic sediments

Elias Broman, Stockholm University, elias.broman@su.se (presenter)

Stefano Bonaglia, Stockholm University; Ugo Marzocchi, Aarhus University; Per Hall, Gothenburg University; Francisco J.A. Nascimento, Stockholm University

The Baltic Sea is under severe stress due to eutrophication and expansion of hypoxia. Here we present novel meta-omics and geochemical data from four stations along an oxygen/depth gradient in the Eastern Gotland Basin. We expect that our findings will further increase the understanding of regulation mechanisms behind microbial diversity and role in these benthic ecosystems.

Baltic Sea benthic ecosystems are under severe stress due to eutrophication and expansion of hypoxic bottom zones. This leads to a number of consequences for biodiversity (loss of biodiversity, changes in community composition, etc.) and for ecosystem functions (decrease in aerobic metabolism, buildup of reduced compounds, etc.).

In 2018, we sampled sediment from four stations along an oxygen/depth gradient, from 60 to 210 m, in the Eastern Gotland Basin (EGB). We aimed to couple geochemical and modern molecular tools in order to elucidate the community structure, diversity, and functions of sediment microbial communities. Sediment pore-water microprofiles highlighted that the stations differed in degree of oxygen concentrations, ranging from normoxic to anoxic, with increasing hydrogen sulfide content. In addition, we extracted DNA and RNA and sequenced metagenomes and metatransriptomes, respectively.

These results are part of an ongoing project that will be presented for the first time at the BSSC 19. We expect that our findings will further increase the understanding of regulation mechanisms behind microbial diversity and role in these benthic ecosystems.

 

Littering of marine coasts after severe storms

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

Irina Chubarenko, Shirshov Institute of Oceanology, Russian Academy of Sciences; Aleksandra Volodina, Shirshov Institute of Oceanology, Russian Academy of Sciences; Tatiana Bukanova, Shirshov Institute of Oceanology, Russian Academy of Sciences (presenter)

Situations of massive beaching of marine debris to the sea shores (South-Eastern Baltic, Kaliningrad region) after stormy episodes are monitored and examined in order to attend the composition of the debris patches and to evaluate the fraction and the amount of anthropogenic litter in them.

Situations of massive beaching of marine debris to the sea shores after stormy episodes are monitored and examined in order to attend the composition of the debris patches and to evaluate the fraction and the amount of anthropogenic litter in them.

In frames of ERA.Net RUS Plus S&T project 429 ""Litter rim of the Baltic Sea coast"", litter beaching was monitored during fall-winter season of 2018/2019 along the northen and western shores of the Sambian peninsula (South-Eastern Baltic, Kaliningrad region). It is confirmed that after storms the marine debris appeares on the beach in patches (ca. 40-100 m long), with the distance between them of about 300-400 m. The patch contains strongly inter-mixed matter of both natural and anthropogenic origin, e.g., algae, wooden pieces, roots of land plants, etc., - and plastics, fishing nets, metallic cans, glass, etc.

It is concluded that macrophytes (e.g., Furcellaria lumbricalis in the Baltic), cut by stormy currents off their base, and lost fishing nets serve as centers of aggregation of all the kinds of debris suspended by turbulent currents in the sea surf zone. The results aim at developing of most effective cleaning measures.

 

Phytoplankton production alongside the Sambia Peninsula and the Curonian Spit (the Baltic Sea) during the end summer vegetation period 2018

Elena Kudryavtseva, Shirshov Institute of Oceanology, Russian Academy of Sciences, kudryavtzeva@rambler.ru

Sergey Aleksandrov, Atlantic Research Institute of Marine Fisheries and Oceanography; Sergey Mosharov, Shirshov Institute of Oceanology, Russian Academy of Sciences; Tatiana Bukanova, Shirshov Institute of Oceanology, Russian Academy of Sciences (presenter); Olga Dmitrieva, Atlantic Research Institute of Marine Fisheries and Oceanography; Aleksander Krek, Shirshov Institute of Oceanology, Russian Academy of Sciences; Elena Ezhova, Shirshov Institute of Oceanology, Russian Academy of Sciences

This study examines the feature of primary production processes that occur in the southern and eastern Baltic Sea during the end summer vegetation period 2018. The primary production, chlorophyll a, phytoplankton, nutrients, and PAR were measured. Information on the marine state was examined from satellite imagery.

This study examines the feature of primary production processes that occur in the southern and eastern Baltic Sea during the end summer vegetation period 2018. The primary production, chlorophyll a, phytoplankton, nutrients, and PAR were measured. Information on the marine state was examined from satellite imagery. The differences in the primary productivity level were observed along the northern and the western shores of the Sambia Peninsula and the Curonian Spit, indicating the different environmental conditions. The production rates were considerably lower to the north-east of Cape Taran, owing to the regenerated nutrients only and limited nitrogen fixation.

In the marine plankton cryptomonad flagellates reached high population densities. The influence of the Vistula Lagoon outflow on pelagic zone was resulted in the increase of nutrients and primary production and associated with the bloom of toxic nitrogen-fixing cyanobacteria Nodularia spumigena. Additionally changes in phytoplankton community were observed in the areas where coastal sub-mesoscale eddies and objects of human activity occurred.

The study was done with a support of the state assignment № 0149-2019-0013.

 

Distribution and feeding of abundant coastal fish species in the eastern Gulf of Finland

Anna Demchuk, Zoological Institute of the Russian Academy of Sciences, anndemch@gmail.com (presenter)

Anton Uspenskiy, State Research Institute on Lake and River Fisheries n.a. L.S. Berg (GosNIORKh); Sergey Golubkov, Zoological Institute of the Russian Academy of Sciences

Our study of fish distribution and diet along the coastline of the eastern Gulf of Finland showed that the fish community consisted of 30 species from 11 families including 5 invasion species. Species from family Cyprinidae were prevail. The main food components of fish were organisms from groups of crustaceans, molluscs, and insects. Chironomids were the most important food resource in this area.

The research material on the abundance and distribution of coastal fish species was obtained in the period from May to October 2014. We investigated the diet of the most abundant species, fish species (Rutilus rutilus, Alburnus alburnus, Gasterosteus aculeatus, Gobio gobio, Perca fluviatilis). It was established that the main food components of all fish species were organisms from 8 major taxonomic groups: crustaceans (Copepoda, Cladocera, Ostracoda and Amphipoda), molluscs (Bivalvia and Gastropoda), and insects (Chironomidae and other Diptera).

For a formalized estimate of diet heterogeneity of different species, we used the Principal component analysis (PCA) for the relative proportion of all prey items in non-empty stomachs. Two clouds of points, which were formed by the samples of perch juveniles and adult stickleback, were located separately. The main feature of the diet of perch juveniles was abundant planktonic preys. The diets of adult sticklebacks distinguish by the presence of unique and great variety of relatively uncommon prey items compare with diet of other fish species. Clouds of other species overlapped and benthic organisms dominated in the diet on all study area.

 

What distinguishes Baltic Sea coastal sediment microbial ecosystem functions and community structure – global comparative metagenomics of cold polluted sediments from high latitude

Hebe Dionisi, CESIMAR, CONICET, Centro Nacional Patagónico, Puerto Madryn, Argentina, (presenter)

Fernando Espínola; Mariana Lozada CESIMAR, CONICET, Centro Nacional Patagónico; Walter Mac Cormack, Instituto Antártico Argentino; Janet Jansson, Lawrence Berkeley National Laboratory; JoLynn Carroll, The Arctic University of Norway, ,; Sara Sjöling, Södertörn University,

Growing awareness of the importance of microbial diversity for ecosystem functioning contrast with the limited understanding of sediment microbial functional capacity at cold highlatitude regions. Comparative metagenomics reveal distinctive guilds present in the Baltic Sea and deepen understanding of how high-latitude sediment microbial functions relate to environmental conditions and pollutants.

Growing awareness of the importance of microbial diversity for ecosystem functioning and the impact of environmental stressors, contrast with the limited understanding of sediment microbial functional capacity at cold high-latitude regions. These communities are also particularly exposed to climate and pollution. How are high-latitude sediment communities structured by this exposure? How do patterns of key functional capacities compare among communities of both Hemispheres and how are these structured by environmental conditions?

Results from comparative metagenomics analysis in two large scale community sequencing projects reveal communities with distinct phylogenetic structures with high diversity. Interesting differences metabolic capacity emerge. For example, in some steps in C-turnover such as anaerobic hydrocarbon degradation and macroalgal degradation distinctive guilds are present in the Baltic Sea sediment, and salinity suggest an important role in the structuring of these guilds. These studies have deepened our understanding of how high-latitude sediment microbial functions relate to environmental conditions and a number of organic pollutants.

 

Multidecadal dynamics of the Arctic copepod Limnocalanus macrurus in relation to the environmental variability in the Baltic Sea

Heli Einberg, University of Tartu, heli.einberg@ut.ee (presenter)

Riina Klais, EcoStat Ltd; Gunta Rubene, Institute of Food Safety; Georgs Kornilovs, Institute of Food Safety; Ivars Putnis, Institute of Food Safety; Henn Ojaveer, University of Tartu

Limnocalanus macrurus is a prominent representative of large copepods which preforms several essential functions in freshwater and marine pelagic ecosystems. We looked at the long-term changes of L. macrurus abundance in the Baltic sea. The most imporant environmental paramaters explaining the interannual variability were herring spawning stock biomass, winter sevirity and bot. water temperature.

Limnocalanus macrurus is a prominent representative of large copepods which performs several essential functions in both freshwater and marine pelagic ecosystems. Being a cold stenotherm species, its distribution is primarily confined to deeper water layers.

Based on the long-term observations originating from one of the largest spatially confined natural populations of this glacial relict species in the epicontinental Baltic Sea (Gulf of Riga), we detected profound long-term variability of L. macrurus during 1958-2016: very high abundances before the 1980s, then nearly disappearance in the 1990s and recovery in the 2000s. The main environmental parameters explaining the interannual variability of L. macrurus in spring were herring spawning stock biomass in preceding year, winter severity and bottom water temperature in preceding summer. The effect of winter severity and water temperature was also non-linear. The sliding window correlation analysis further pointed to a non-stationary relationship between the abundance of L. macrurus and all three key variables.

 

Aquatic alien species in the Russian waters of the Eastern and South-Eastern Baltic Sea

Elena Ezhova, Shirshov Institute of Oceanology Russian Academy of sciences, igelinez@gmail.com

An analysis of regional alien diversity of two Russian EEZ, the South-Eastern Baltic (SEB) and the Gulf of Finland (GoF), is given.

Biological invasions shape now the regional biodiversity in a same degree as a climate change. To date, 132 aliens are known in the Baltic Sea. An analysis of regional alien diversity of two Russian EEZ, the South-Eastern Baltic (SEB) and the Gulf of Finland (GoF), is given.

In GoF and SEB 38 and 48 introduction events were ever recorded. In GoF–22, in SEB–33 species were established, the status of 3 is unclear in both areas. The main donor regions are the Ponto-Caspian basin and the Atlantic coast of North America. The most successful group is crustaceans (14 species) and polychaetes (5) in contrast of fish, the most ecosystem-impacting –clams and polychaetes. The main vector is shipping - 63% in GoF, 44% in SEB. A quite large share of introductions is connected with the natural factors (GoF –26, SEB-15). The role of the artificial canal system is much higher in SEB (13%) than in GoF(1.5%).

Considering intensive shipping, the composition and dominant role of alien biota and a low diversity of aboriginal fauna, impacted both by anthropogenic and climatic factors, a lasting increase of introductions, and an increase of warm-water species ecosystem impact should be expected.

 

Mercury content in European perch (Perca fluviatilis) as a function of the food source

Anete Fedorovska, Latvian Institute of Aquatic Ecology, anete.melanija@gmail.com (presenter)

Juris Aigars, Latvian Institute of Aquatic Ecology; Rita Poikane, Latvian Institute of Aquatic Ecology; Juris Tunens, Latvian Institute of Aquatic Ecology; Mintauts Jansons, Latvian Institute of Aquatic Ecology

The aim of the study was to determine Hg content in Perch muscle samples caught at the coast of the Gulf of Riga during May-September 2018 and to determine Hg dependence on fish size, season and diet preferences. Hg content varied from 33-165 µg kgˉˡ WW by different size groups (10-27 cm). Stomach content analysis showed that main composition of perch diet included Mysids, Copepods and Round goby.

The aim of the research was to determine Hg content in the European perch (Perca fluviatilis) muscle samples caught at the coast of the Gulf of Riga during May-September 2018 and to determine Hg dependence on fish size, season and diet preferences.

Hg concentrations in fish muscle were analysed according to US EPA 7473 method. Stable carbon and nitrogen isotope ratios (δ 15 N and δ 13 C values) were used for description of perch food source preferences by fish size. In addition, stomach content analyses were performed. Hg content displayed a wide range of disparity in studied tissues defined by the season and diet preferences and varied from 33 µg kgˉˡ WW to 165 µg kgˉˡ WW by different size groups (10-27 cm).

The observed concentration could be related to the specific diet. Stomach content analysis showed that main composition of perch diet included Mysids, Copepods and Neogobius melanostomus. The relative composition of food items varied with fish size (outgrowing 14 cm fishes reach next trophic level) and season (most likely due to changes in food item availability). Hg concentrations exceeded EQS level in muscle tissue in all samples according to EU Directive 2013/39/EU.

 

Effect of organic sediment content on gut microbiome of gravid Monoporeia affinis: an experimental approach

Julie Garrison, Stockholm University, julie.garrison@su.se (presenter)

Agnes Karlsson, Stockholm University; Francisco Nascimento, Stockholm University

M. affinis is one of the most abundant macrofauna species in soft sediments of the northern Baltic Proper and an important bioindicator of environmental stress. Bacteria present in guts of animals are important in digestion and health. We ran an experiment to look at the role of sediment organic matter content on gut microbiomes of gravid M. affinis and offspring development and gut microbiomes.

Monoporeia affinis is one of the most abundant macrofauna species in soft sediments of the northern Baltic Proper and is an important bioindicator of environmental stress. Bacteria present in animal digestive tracts have been shown to be important in digestion and organism health. Gut microbes are affected by an organism’s environment, influence development, and can indicate stress. There is support that a more diverse gut microbiome is indicative of better digestive function, enhances growth and impacts population dynamics, but invertebrate research is lacking in this field. We have conducted an experiment to investigate the role of sediment organic matter (OM) content on gut microbiomes of gravid M. affinis and the effect on offspring development and gut microbiomes. As far as we are aware, this is the first experiment investigating the role of gut microbiomes on invertebrate fecundity in the Baltic Sea related to anthropogenic stress.

M. affinis was collected from 2 stations in the Baltic Proper, one high OM and one low OM. A fully-crossed experiment was set up for several weeks. DNA metabarcoding and sequencing of associated microbes was performed with an Illumina MiSeq.

 

Can the “green tides” affect the metal distribution in the coastal sediments? A case study in the eastern Gulf of Finland, Baltic Sea

Yulia Gubelit, Zoological Institute of the Russian Academy of Sciences, Yulia.Gubelit@zin.ru (presenter)

Yulia Polyak, Scientific Research Center for Ecological Safety Russian Academy of Sciences; Tatyana Shigaeva, Scientific Research Center for Ecological Safety Russian Academy of Sciences; Anna Demchuk, Zoological Institute of the Russian Academy of Sciences; Ludmila Bakina, Scientific Research Center for Ecological Safety Russian Academy of Sciences; Valentina Kudryavtseva, Scientific Research Center for Ecological Safety Russian Academy of Sciences

Our study along the coastline of the eastern Gulf of Finland showed that accumulation of the green algae biomass caused by green tide, significantly influenced the metal distribution in the surface sediments. Taking into account a global climate change, we may conclude that in the future extended green tides may provoke intense sediment contamination by organic matter and associated metals.

Our study has been conducted along the coastline of the eastern Gulf of Finland for three years. Our study showed significant changes in concentrations of Zn, Cd and Pb, which reflected influence of the sources of anthropogenic contamination such as the port Vysotsk and a new one - Bronka. Some results of the principal component and classification analysis have shown that main factors, which affected the metal distribution in the coastal zone of EGoF were related to riverine water discharge and terrestrial input from the new anthropogenic sources.

During our study the biomass of macroalgae at the study sites exceeded the means reported during the previous long-term monitoring. We found the significantly higher metal contamination of sediments under algal mats, that can be evidence that algal mats may promote the sediment contamination because of the hypoxia and release of the accumulated metals from the biomass. Taking into account a global climate change and the results of our study, we may conclude that in the future extended macroalgal blooms may provoke intense sediment contamination by organic matter and associated metals.

 

Effects of PAH contamination on Benthic microbial and meiofauna communities in the Baltic Sea

Sven Iburg, Stockholm University, sven.iburg@su.se (presenter)

Francisco Nascimento, Stockholm University

Benthic communities play a fundamental role in regulating important ecosystem functions of the Baltic Sea. Currently, how benthic interactions and biodiversity are affected by chemical contaminant exposure is not well understood. Here, we focused on changes in active communities by DNA and RNA-based inference of species composition in response to a mixture of organic contaminants.

Efforts to study the effects of chemical contaminants on the structure and function of microbial and meiofauna communities have traditionally focused on single contaminants and single species. This has left the complex interactions between mixtures of contaminants and their effects on the functions and structure of sediment microbial communities mostly overlooked.

In our effort to improve our insights on these effects, we set up an experiment with the aim to study the interactions between a mixture of reported organic contaminants and microbenthic organisms. We spiked pristine Baltic Sea sediments with an ecologically relevant mixture of organic contaminants and used metabarcoding to monitor changes in microbial and meiofauna diversity and structure. In addition, following previous data on the exposure of contaminants on benthic microbial activity, we investigated key-genes in the microbial nitrification and PAH degradation pathways.

We found notable differences between treatments in microbial and meiofauna community composition as well as PAH gene expression levels.

 

Reproductive rate of grey seals as an indicator of Baltic Sea environment

Kaarina Kauhala, Natural Resources Institute Finland, Luke, kaarina.kauhala@luke.fi (presenter)

Samuli Korpinen, Finnish Environment Institute; Maiju Lehtiniemi, Finnish Environment Institute; Jari Raitaniemi, Natural Resources Institute, Luke

We studied the effects of environmental factors on the birth rate of Baltic grey seals. Birth rate was significantly related to herring and sprat quality, which in turn were influenced by sprat and cod abundance and zooplankton. Birth rate was also affected by winter weather in the birth year of females. It can thus be used as an indicator of the status of the Baltic Sea environment.

Reproductive rate of Baltic grey seal (Halichoerus grypus) females has fluctuated during the 2000s, although reproductive disturbances, which occurred a few decades earlier, are rare at present.

We studied variation in the birth rate and the possible effects of environmental factors (food resources and winter weather) on the birth rate using seal data from the Finnish sea area. Our results showed that the birth rate of grey seals was significantly related to herring (Clupea harengus) and sprat (Sprattus sprattus) quality (weight) which, in turn were influenced by sprat and cod (Gadus morhua) abundance, as well as zooplankton biomass and plankter size. This suggests strong trophic coupling over three trophic levels. We also found that winter weather conditions in the birth year of female seals influenced their birth rate as adults: birth rate of females born in cold winters was higher than birth rate of females born in warm winters.

We thus conclude that the birth rate of grey seals can be used as an indicator of the status of the Baltic Sea environment. We also suggest a threshold value for good food web status for a stable, non-growing seal population.

 

Functional diversity of macrozoobenthos under adverse oxygen conditions

Halina Kendzierska, University of Gdańsk, halina.kendzierska@ug.edu.pl (presenter)

Urszula Janas, University of Gdańsk; Natalia Miernik, University of Gdańsk

We studied how different oxygen conditions affect the functional diversity of macrozoobenthos. In hypoxia, loss of the functionality of macrobenthos is significant but existing taxa still provide important functions. The role of benthic communities above halocline is crucial, not only due to its impact on habitats but also as a potential source of organisms for recolonization of the deeper areas.

In the Baltic Sea, the number of observations of the oxygen depletion above halocline is increasing, while in the deeper regions hypoxia is recorded regularly. These studies were conducted to determine how the different oxygen conditions affect the structure and functioning of macrozoobenthos.

The samples were collected along a gradient of bottom waters oxygen concentration in the Gdańsk Basin. Standard characteristics of macrozoobenthic communities were specified. Biological Traits Analysis was performed on the basis of the taxa composition, biomass and traits matrix. The dataset was developed to calculate the several aspects of functional diversity.

In hypoxia, loss of the functionality of macrozoobenthos was significant but remained taxa still provided a significant number of functions. In almost all cases these functions were rare or very rare. The role of benthic communities above halocline is crucial, not only due to its impact on habitats but also as a potential source of organisms for recolonization of the deeper areas.

 

Multi-year dynamic of the algae blooms in the Batic Sea during the MODIS era

Marta Konik, The Institute of Oceanology of the Polish Academy of Sciences, mk@iopan.pl (presenter)

Mirosław Darecki, The Institute of Oceanology of the Polish Academy of Sciences

The main aim of the research was to identify if there is a trend in the occurrence of the algae blooms in the Baltic Sea. The time series covered data from the 2002 until the 2018. Analyses of the area and duration of the algae blooms in the last years that were the warmest in modern history may shed light on future response of cyanobacteria to the rise of water temperatures in the Baltic Sea.

The past five years were the warmest years observed in the history of modern temperature records. The climate change progresses faster than we expected a few years ago. Due to the fact that temperature is one of the key factors affecting phytoplankton growth, it is relevant to track potential changes in phenology of the cyanobacteria blooms that occur in the Baltic Sea.

The main aim of the research was to identify whether there is a trend in the occurrence of the algae bloom in the Baltic Sea, taking into account the most recent satellite data. Analysis of the spatial and temporal variability of the algae blooms in the Baltic Sea measured by an ocean colour sensor - MODIS AQUA will be shown. The presented time series covered data from the beginning of the MODIS operation in 2002 until the 2018. The algae blooms were identified based on the cyanobacterial index, a version dedicated for the MODIS bands distribution. Special attention was paid to the situation in the recent years in relation to the previous summer seasons.

Analyses of the area and duration of the blooms may shed light on future response of cyanobacteria in the Baltic Sea to the gradual rise of water temperatures.

 

Functional diversity of zooplankton in the SE Baltic Sea

Evelina Griniene, Klaipeda University, MRI, evelina.griniene@apc.ku.lt

Jurate Lesutiene, Klaipeda University, MRI; Zita R. Gasiunaite, Klaipeda University, MRI (presenter)

Our objective is to find linkages between the environmental variables and zooplankton traits related to the respective ecosystem service i.e. phytoplankton regulation and energy transfer in the food chain. We found, that distribution of traits such as body size, trophic group and feeding type, are linked to depth, nutrient and organic matter concentrations in the water column.

We investigated mesozooplankton community in the Eastern Gotland Basin. We performed sampling at 18 sites located in three parallel transects covering depths 1) from 14 to 89m, 2) 49 - 150m and 3) 67 - 237m on August 23-25, 2016. The oxiclyne was present at 60-80m depth (salinity ~9). The temperature in the surface layer was homogeneous – 16.2-18.2⁰C; total chl a concentration varied from 3.5 to 8.5 µg l^-1. Visually we observed no cyanobacteria bloom areas, and flourimetric analysis of algal groups revealed dominance of diatoms and cryptophytes.

Our objective is to find linkages between the environmental variables and zooplankton traits related to the respective ecosystem service i.e. phytoplankton regulation and energy transfer in the food chain. Selected traits (body size, trophic group and feeding type) were analyzed using R package ade 4 and functional diversity calculated using program PRIMER as proposed by Petchey&Gaston (2002). Species with omnivorous-algivorous feeding type (Acartia spp., Centropagis hamatus) were positively linked to the abundance of bacteria and cryptophytes; small size (Bosmina, Rotifera) was positively linked to higher temperature and total nitrogen.

 

Spatial variation in elemental stoichiometry of benthic consumers

Saara Mäkelin, University of Helsinki, saara.makelin@helsinki.fi (presenter)

Anna Villnäs, University of Helsinki

We explore how benthic consumers affect sediment carbon and nutrient pools in coastal habitats by adapting methods of ecological stoichiometry. The C:N ratios of individual species vary spatially, and changes in food sources and abiotic conditions affect the C:N:P content ratios of benthic communities. This alters the role of benthic fauna as a temporal nutrient pool within the coastal ecosystem.

Benthic communities play a pivotal role in modulating coastal biogeochemical cycles. By adapting the framework of ecological stoichiometry, we evaluate the effects of benthic consumers on sediment carbon and nutrient pools in coastal habitats.

This study provides a baseline for stoichiometric and allometric characteristics of benthic species over a spatial gradient. We also explore, if imbalances in the elemental content ratios between the consumers and their food sources can direct community composition. Initial results show, that the C:N content ratios of individual species vary spatially. Furthermore, changes in food sources and environmental conditions affect the stoichiometry of the community composition. This inter- and intraspecific variation in elemental stoichiometry is likely to impact species ability to recycle carbon and nutrients, which alters the role of benthic key species as temporal nutrient sources and sinks within coastal habitats. This information is initially used to quantify the size and turnover rates of benthic faunal carbon and nutrient pools over spatial scales, by utilizing large-scale monitoring data from the Baltic Sea.

 

Intraspecific traits variability and plasticity of Alexandrium ostenfeldii and Skeletonema marinoi at different salinity levels

Iris Orizar, University of Helsinki, iris.orizar@helsinki.fi (presenter)

Aleksandra M. Lewandowska, University of Helsinki

Climate change causes changes in salinity with low latitude seas becoming saltier and high latitude seas, such as the Baltic Sea, becoming fresher. We tested intraspecific response of two phytoplankton species (a diatom and a dinoflagellate) to changing salinity. All diatom straits had a narrow salinity optimum, whereas some dinoflagellate strains were more resistant to salinity change.

Phytoplankton traits greatly vary within species, and exhibit plasticity at different environmental conditions. Here, intraspecific trait variability and plasticity were investigated in Alexandrium ostenfeldii and Skeletonema marinoi at different salinity levels (0, 5, 15, 20, 30, and 35 psu). None of the S. marinoi and A. ostenfeldii strains were able to significantly grow at 0 and 35 psu, while all strains were able to grow at 5 psu with varying cellular chlorophyll a concentrations. Growth rate and maximum carrying capacity varied among the strains. S. marinoi had overall narrow salinity optimum, whereas some strains of A. ostenfeldii were more resistant to salinity change. Furthermore, cysts forming was observed in A. ostenfeldii cultures at high salinity.

Results of these experiments elucidate the importance of intraspecific plasticity of phytoplankton in coping with environmental change and highlight different survival strategies of diatoms and dinoflagellates that might lead to reorganization of phytoplankton communities in the future Baltic Sea.

 

Daily and seasonal variation of spatial distribution of biological objects in the Puck Bay (southern Baltic Sea)

Patryk Pezacki, University of Gdańsk, patryk.pezacki@phdstud.ug.edu.pl (presenter)

Natalia Gorska, University of Gdańsk; Jakub Idczak, University of Gdańsk; Aleksandra Brodecka-Goluch, University of Gdańsk

Much of the potential of the existing multifrequency hydroacoustic techniques has not yet been fully used in the past studies of Baltic sea. The presented research attempts to address it. The hydroacoustic profiling at different acoustic frequencies was done in different seasons for the period of one year. Three broadband split-beam echosounders with frequencies 38, 120 and 333 kHz were used.

Unique ecosystem of the Puck Bay is particularly sensitive to the human impact. This requires, among others, searching for new effective methodological approaches to ecosystem studies. Much of the potential of the existing multifrequency hydroacoustic techniques has not yet been fully used in the past studies of Baltic ecosystems. The presented research attempts to address it.

The main purpose of the interdisciplinary study was to improve the understanding of the backscattering by biological aggregations in the Puck Bay. In order to implement the objective, the hydroacoustic profiling at different acoustic frequencies was done in different seasons for the period of one year. Three broadband split-beam echosounders with the central frequencies 38, 120 and 333 kHz (Simrad EK 80, Kongsberg company echosounders) were used. To interpret and verify the hydroacoustic data, the environmental parameters were measured and ROV inspection was conducted.

Based on the collected data and sampled materials, characteristic features of backscattering for different organisms from the Puck Bay were determined. The study enhances the development of the hydroacoustic classification techniques.

 

Diversity strikes back: Does functional diversity enhance resilience in vegetated benthic habitats?

Tiina Salo, Stockholm University, tiinaesalo@su.segmail.com (presenter)

Laura Kauppi, University of Helsinki; Camilla Gustafsson, University of Helsinki

While coastal ecosystems face multiple environmental challenges, we still lack the knowledge on how community trait assemblages relate to community stability. In a long-term field experiment in the northern Baltic Sea, we use aquatic plant communities to illustrate how certain plant traits facilitate faster recovery of benthic communities.

The knowledge on which species traits are critical for community stability in benthic communities during and after disturbance is still lacking. We use aquatic plant communities in the northern Baltic Sea to study how plant trait diversity relates to plant and animal community resilience. In a long-term field experiment (5 yrs), we simulated drift algal coverage and exposed pre-selected plant communities with a varying degree of trait diversity to decreased light and O2 levels for four weeks, resulting in extensive plant mortality in our study plots (2 m2). In this study, we 1) assess if trait diversity affects community resilience, 2) explore how plant trait assemblages change during and after disturbance, as well as 3) identify the key traits in the recovering communities.

Results from the first two years show that plant morphology during the recovery is directly dependent on the traits present in the pre-disturbance communities (e.g. specific leaf area, leaf complexity and biomass). The results suggest that some traits may facilitate faster recovery of plant communities, supporting the notion that functional diversity is essential for community stability.

 

Metabarcoding successfully tracks temporal changes in eukaryotic communities in coastal sediments

I. S. Salonen, University of Helsinki, Helsinki Institute of Sustainability Science (HELSUS), iines.salonen@helsinki.fi (presenter)

P.-M. Chronopoulou, University of Helsinki, Helsinki Institute of Sustainability Science (HELSUS); E. Leskinen, University of Helsinki; K. A. Koho, University of Helsinki, Helsinki Institute of Sustainability Science (HELSUS)

Metabarcoding is a method that combines high-throughput DNA sequencing and DNA based identification. Previously, this method has been successfully used to target spatial variation of eukaryote communities in marine sediments, however, the temporal changes in these communities remain understudied. Here, we follow the temporal changes of the eukaryote communities in Baltic Sea surface sediments collected from two coastal localities during three seasons of two consecutive years.

Our study reveals that the structure of the sediment eukaryotic ecosystem was primarily driven by annual and seasonal changes in prevailing environmental conditions, whereas spatial variation was a less significant factor in explaining the variance in eukaryotic communities over time. Therefore, our data suggests that shifts in regional climate regime or large-scale changes in the environment are the overdriving factors in shaping the coastal eukaryotic sediment ecosystems rather than small-scale changes in local environmental conditions or heterogeneity in ecosystem structure.

Furthermore, this work contributes to the recent efforts in developing metabarcoding applications for environmental biomonitoring, proving a comprehensive option for traditional monitoring approaches.

 

Associated fauna and flora of the red-listed free-living Fucus vesiculosus habitat in the Baltic Sea

Ellen Schagerström, Stockholm University, ellen.schagerstrom@su.se (presenter)

Susanne Qvarfordt, Stockholm University

There are fewvecological studies of the free-living forms of Fucus vesiculosus in the Baltic Sea. The habitat as such was recently put on the HELCOM red list of endangered habitats.

We compare the associated flora and fauna of free-living Fucus to the attached Fucus vesiculosus habitat, and compare the fanua duting early spring and summer, discussing the functional role of this neglected habitat.

There are few ecological studies of the free-living forms of Fucus vesiculosus in the Baltic Sea, although they have been noted along the Swedish and Finnish coast of the Baltic proper and on the southern Baltic Sea coast of Germany.

On the Swedish coast, free-living F. vesiculosus mostly occur in sheltered bays on soft or sandy substrate. The habitat as such was recently put on the HELCOM red list of endangered habitats. We hypothesize that such perennial habitats, formed by a wide range of free-living Fucus morphotypes, have important ecological functions for the associated flora and fauna on shallow sheltered bottoms.

Comparisons of six sites with free-living Fucus habitats to mixed rooted soft-bottom vegetation showed differences in both species richness and abundance of the associated fauna and flora. Comparing the free-living Fucus to the attached F. vesiculosus habitat on hard substrate, showed a higher abundance of associated fauna in the free-living Fucus.

Comparing free-living Fucus in early spring to summer, revealed it as habitat for several species during the winter season. The ecological significance of this habitat and how to protect it is discussed.

 

Effects of oxytetracycline and sulfamethoxazole on growth and chlorophyll a fluorescence in green algae (Chlorella vulgaris), diatom (Phaeodactylum tricornutum) and cyanobacteria (Microcystis aeruginosa and Nodularia spumigena)

Grzegorz Siedlewicz, Department of Marine Chemistry and Biochemistry, Institute of Oceanology, Polish Academy of Sciences

Adam Żak, University of Gdańsk; Lilianna Sharma, Polish Academy of Sciences, lsharma@iopan.pl (presenter); Alicja Kosakowska, Polish Academy of Sciences; Ksenia Pazdro, Polish Academy of Sciences

The aim of the study was to evaluate the influence of a wide range of oxytetracycline and sulfamethoxazole concentrations by conducting prolonged toxicity tests (lasting 10 days). In conclusion, it appears that the use of standard chronic toxicity tests (72h) does not allow to accurately assess the chronic impact of bioactive compounds including drugs and their metabolites on water organisms.

The aim of the study was to evaluate the influence of a wide range of oxytetracycline and sulfamethoxazole concentrations with particular attention to the low levels of the antibiotics on cyanobacteria Microcystis aeruginosa and Nodularia spumigena, diatom Phaeodactylum tricornutum and the model green algae Chlorella vulgaris by conducting prolonged toxicity tests (lasting 10 days).

The obtained results go beyond previous reports showing that oxytetracycline present at concentration levels lower than those applied in ecotoxicity tests and described in the literature adversely affects tested microorganisms. It was found to decrease photosystem II efficiency and disrupt the photosynthesis process. A careful analysis of OJIP measurements results allowed a better understanding of the mode of action of both oxytetracycline and sulfamethoxazole in relation to non-target photoautotrophic organisms.

In conclusion, it would appear that the use of standard chronic toxicity tests (72h) does not allow to accurately assess the chronic impact of bioactive compounds including drugs and their metabolites on water organisms. On this basis, we recommend application of extended duration tests.

 

Translational Aquatic Ecology approach discloses effects of potentially toxic dinoflagellates in the Baltic coastal ecosystems

Sergei Skarlato, Institute of Cytology RAS, sergei.skarlato@mail.ru

Translational Aquatic Ecology which implies close linkage of cell biology and molecular ecology with classical ecological practices is a promising perspective for studies of harmful algal blooms (HABs) caused by invasive dinoflagellates in the Baltic Sea coastal waters. This approach provides reliable tools for predicting HABs and suggests preventive environmental policymaking measures.

Harmful algal blooms (HABs) caused by potentially toxic dinoflagellates Prorocentrum minimum seriously deteriorate coastal ecosystems impairing their recreational and socio-economic services. The ongoing expansion of P. minimum witnesses for its powerful invasion potential and high competitive advantages that allow this mixotrophic species conquering new coastal environments.

In this paper, current knowledge on biology of P. minimum, its response to abrupt external stresses, metabolism and population heterogeneity, cellular and molecular adaptation strategies that empower distribution of this harmful species in the Baltic coastal waters is revised. Usage of advanced methodologies in combination with classical research techniques and close linkage of cell biology and molecular ecology with the ecological theories and practices ensures promising perspectives for the future studies and combatting of HABs. This approach is in the mainstream of Translational Aquatic Ecology – the recently emerged discipline that capitalizes on the newest findings and promotes their actual use in fisheries, aquaculture, environmental management and nature protection.

Funded by RSF project 19-14-00109.

 

On coexistence of native Eurytemora affinis and invasive Eurytemora carolleeae in the Baltic Sea

Natalia Sukhikh, ZIN RAS, Susikh1@mail.ru (presenter)

Victor Alekseev, ZIN RAS

Eurytemora affinis (Poppe) is a widely distributed group of species.The group includs now: E. affinis, E. carolleeae Asian E. caspica.In 2007 American copepod E. carolleeae was found in the eastern part of the Gulf of Finland.Nowadays E. affinis and E. carolleeae coexist in the same places of the Baltic Sea.These species here differed in morphology, genetics and fecundity.

Eurytemora affinis (Poppe) is a widely distributed group of species inhabiting fresh- and brackish waters of Holarctic. The group is highly variable and so far taxonomically challenging. Considered as a complex of cryptic species, it includs at least three valid species: E. affinis with Palearctic distribution; North American E. carolleeae Alekseev et Souissi; and Asian E. caspica Sukhikh et Alekseev.

In 2007 American copepod E. carolleeae was found in the eastern part of the Gulf of Finland. Later, this species was also detected in the Gulf of Riga and in the Amsterdam channels, and possibly in additional locations of the Baltic and North Seas. Nowadays E. affinis and E. carolleeae coexist in the same places. The detection of these species in Baltic is likely the result of recent invasion via the ballast water of ships from the Atlantic coast of the United States.

Our study of two these species was conducted in nearshore stations in Luga Bay (the Gulf of Finland).These species here differed in morphology, genetics and fecundity. Usually E. affinis dominated, but sometimes (2010 and 2015) E. carolleeae replaced it.

Supported by RFBR grants: 17-04-00027А и 19-04-00217.

 

Morphological and genetic differences in two sister species of Eurytemora affinis group in the Baltic Sea

Natalia Sukhikh, Zoological Institute of RAS, Saint Petersburg, Russia, Susikh1@mail.ru (presenter)

Victor Alekseev, Zoological Institute of RAS, Saint Petersburg, Russia

We studied morphologically and genetically two species Eurytemora from the Baltic Sea: E.affinis and invasive E.carolleeae. Geographically distant populations of E. affinis from Europe were analised. A phylogenetic tree of the species showed 15% of nucleotide differences in CO1 part of gene. A convenient illustrated morphological key for these two Eurytemora species is provided.

We studied morphologically and genetically two species Eurytemora from the Baltic Sea: Eurytemora affinis (Poppe) and invasive Eurytemora carolleeae Alekseev et Souissi. Geographically distant populations of Eurytemora affinis from the White Sea, Elbe, Seine, Scheldt, Tamar, Loire, Gironde, the Gulfs of Finland and of Riga, the Vistula Lagoon, the Swedish coast of the Baltic Sea were analised. A phylogenetic tree of the species showed 15% of nucleotide differences in CO1 part of gene.

Classical and new established morphological signes were studied to elucidate differences in both males and females among: E. affinis and E. carolleeae species. A convenient illustrated key for these two Eurytemora species is provided.

Supported by RFBR grants: 17-04-00027А и 19-04-00217.

 

Interactions between prokaryotes and eukaryotes in a coastal late summer Baltic Sea community.

Eva Sörenson, Linnaeus University, eva.sorenson@lnu.se (presenter)

Hanna Farnelid, Linnaeus University; Elin Lindehoff, Linnaeus University; Catherine Legrand, Linnaeus University

To reveal interactions, community responses to ambient nutrient conditions and community composition shifts, a characterization, using 16S and 18S rRNA amplicon sequencing and metatranscriptomics, of a phytoplankton and bacterial community in a coastal Baltic Sea (Åland archipelago) habitat was performed. In order to understand the community impact on ecosystem production and transfer of energy.

Shallow eutrophied bays are common in the Baltic Sea, but little is known about the interactions between the phytoplankton and bacteria inhabiting them, and the impact they together have in shaping the production and transfer of energy. This study presents a detailed characterization of both the phytoplankton and the bacterial community, during the progression of a small late summer dinophycea bloom (two timepoints). Samples were taken from the shallow bay, in the Åland archipelago, and were used for both amplicon (16S & 18S) sequencing and metatranscriptomics.

We show that the two trophic levels react similarily to nitrogen, phosphorpus and carbon availability, especially with regards to uptake and assimilation of inorganic and organic nutrient forms, but at different scales. While there is a clear a division between nutrient uptake between phototrophic and heterotrophic phytoplankton, the total bacterial community show a homogenous response to ambient nutrient conditions. But taxa belonging to Bacteriodetes, Alpha-, Beta- and Gammaproteobacteria, Firmicutes and Tenericutes display differences in their nutrient strategies.

 

Does the non-indigenous talitrid Platorchestia platensis have the same ecological role as indigenous Talitrus saltator?

Marta Tykarska, University of Gdańsk, marta.tykarska@phdstud.ug.edu.pl (presenter)

Urszula Janas, University of Gdańsk

The non-indigenous Platorchestia platensis has extended its range of occurrence since the first record in 2005 and has successfully colonized the Gulf of Gdańsk. Moreover, it was found to coexist with both indigenous and non-indigenous Talitridae species. Its ecological role was examined by testing its feeding rate with emphasis on the coexisting with indigenous species.

In the southern Baltic Sea four species of talitrids (Crustacea: Amphipoda: Talitridae) have been recorded, including two indigenous species and two presumably non-indigenous ones. The non-indigenous Platorchestia platensis has extended its range of occurrence since the first record in 2005 and has successfully colonized the Gulf of Gdańsk. It has been observed in a variety of habitats, like wrack beds, sandy shores, boulders and driftwood, unlike other species of Talitridae. Moreover, P. platensis was found to coexist with both indigenous and non-indigenous Talitridae species.

Talitrids feed on stranded macrophytes, thus they serve as a link between marine and terrestrial ecosystems. They play an important role in the processing of organic matter and beach cleaning. Before the introduction of P. platensis, indigenous T. saltator was likely to be the most important of the macrofaunal consumers of the stranded macrophyte detritus. To verify the ecological role of each talitrid species currently occurring in the southern Baltic, their feeding rate was tested with the emphasis on the coexisting of indigenous and non-indigenous species.

 

A gut full of gobies? Predation on an introduced fish by native predators in the Baltic Sea

Isa Wallin, SLU, isa.wallin@slu.se (presenter)

Heidi Herlevi, Åbo Akademi University; Karl Lundström, SLU; Ann-Britt Florin, SLU; Katri Arnio, Åbo Akademi University; Johanna Mattila, SLU

To assess the role of the invasive round goby in the Baltic Sea food web, we study the diet of potential predators (native fish, birds and mammals). Preliminary results show that round goby is a common prey for fish in the southern Baltic Sea, but less so in the northern Baltic Sea. In the future, knowledge about food web interactions will help reach goals of an ecosystem-based management.

Round goby, Neogobius melanostomus, originates from the Ponto-Caspian area and is currently widely established in the Baltic Sea since the first observations in 1990. To assess the ecological role of the invasive round goby in the food web, we study the diet of a range of potential predators (native fish, birds and mammals) on a geographical, seasonal and inter-annual scale. Sampling of predators is carried out during two consecutive years in the Karlskrona area in the southern Baltic Sea and on Åland in the Bothnian Sea. Predator diets are investigated via traditional stomach content analysis, DNA-analysis (meta-barcoding) and stable isotope analysis.

Preliminary results from traditional stomach content analysis show that round goby is a very common prey for cod and pike from the Karlskrona area. However, cod from the Åland area does not yet seem to utilize the round goby as prey. In the future, knowledge about the effects of round goby on predator populations will help reach goals of an ecosystem-based management of both predator and invasive prey populations. This is a cornerstone in achieving sustainable commercial and recreational fisheries in the Baltic Sea.

 

Biodiversity inventories in support of conservation and sustainable use of marine areas – highlights of the Finnish VELMU Programme

Markku Viitasalo, Finnish Environment Institute SYKE, markku.viitasalo@ymparisto.fi (presenter)

Penina Blankett, Ministry of the Environment; Jyrki Hämäläinen, Geological Survey GTK; Meri Kallasvuo, Natural Resources Institute LUKE; Lasse Kurvinen, Parks & Wildlife Finland; Juho Lappalainen, Finnish Environment Institute SYKE; Jouko Nuorteva, Naval Academy; Anu Riihimäki, Parks & Wildlife Finland; Matti Sahla, Parks & Wildlife Finland; Sonja Salovius-Laurén, Åbo Akademi University; Elina Virtanen, Finnish Environment Institute SYKE, VELMU Programme Participants

We show how VELMU, the Finnish Inventory Programme for Underwater Marine Environment, has in less than 10 years made ca. 140.000 observations throughout the Finnish sea area, and present some research highlights, such as updating the Red Lists of habitats and species, assessment of the ecological efficiency of the Finnish MPA network, and sustainable siting of aquaculture and wind power.

Baltic Sea is one of the most studied sea areas in the World. However, spatially explicit information on underwater species and habitats is in many areas still inadequate for assessing how human activities affect biodiversity patterns, or for implementing ecosystem-based Marine Spatial Planning.

We show how VELMU, the Finnish Inventory Programme for Underwater Marine Environment, has in ca. 10 years made 140.000 observations throughout the complex Finnish sea area, forming a massive database of species, habitats, environmental factors and human activities on sea.

We present our cost-effective sampling plan and inventory and modelling methods, and show some of the research highlights. We discuss the strengths, weaknesses and future of the Programme, and show how the data has been used for updating the Finnish Red Lists of habitats and species, reporting for the EU Habitats Directive, description of CBD EBSAs (Ecologically or Biologically Significant Marine Areas), assessment of the ecological efficiency of the Finnish network of marine protected areas, and for solving spatial planning problems, such as ecologically sustainable siting of aquaculture and wind power.

 

The annual cycle of zooplankton in the Baltic Sea

Monika Quinones Winder, Stockholm University, Monika.Winder@su.se (presenter)

Øystein Varpe, Stockholm University

Zooplankton have a key role by concentrating and channeling carbon and essential nutrients from primary producers to upper trophic levels. Yet, their seasonal dynamics and interannual patters are not well described across the Baltic Sea.

Here, we identify succession and year-to-year variability in phenology linked to zooplankton annual routines from the Baltic Sea. The zooplankton community shows distinct peak periods for different taxonomic groups. Phytoplankton spring blooms appear early in the year at low temperature at which zooplankton development rates are low. Protozoans and rotifers reach high abundances prior to the peaks of slower growing copepods and cladocerans. These mesozooplankton peak during the summer months, when waters are warmer, and are temporally decoupled form the spring phytoplankton bloom. Interannual variability of peak timing and duration varies among zooplankton taxa with some species having a narrow time window while peak duration and timing is more variable for others.

Given that zooplankton perform an important ecosystem service as the main prey of fish, understanding the temporal dynamics of zooplankton is important for improved ecosystem management.

 

Feeding relationships of piscivorous fish and birds in the Pomeranian Bay

Helmut Winkler, Rostock University, helmut.winkler@uni-rostock.de (presenter)

Cristoph Stark, Rostock University; Michael Gabel, Rostock University; Anja Förster, Rostock University; Dennis Myts, Rostock University

The food compositions of six piscivorous fish species have been studied in the German part of the Pomeranian Bay over several years. Additionally, the food composition of cormorants preying in the same region has been studied. The increasing number of round gobies in the cormorant’s diet is likely to decrease their feeding pressure on native fish species.

The food compositions of perch, pikeperch, and four lesser abundant piscivorous species have been studied in the German part of the Pomeranian Bay over several years. During this time each September fish samples were taken based on bottom trawl surveys thereby recording species, abundances and biomasses of all fish. Additionally, between 2010 and 2015 the food composition of cormorants preying in the same region has been studied.

While the most important food items for almost all fish species studied are small native gobies and shrimps (Crangon) (rather small sized and 0+ group fish were of minor importance as food for them), the food spectrum of cormorants is dominated by other species of bigger sizes. Cormorants are commonly preying mainly on perch, roach and pikeperch, being species important for commercial fisheries. However, the increased occurrence of alien round gobies has obviously influenced the food composition of cormorants. Given this, the increasing number of round gobies in the cormorant’s diet is likely to decrease their feeding pressure on native fish.

 

Communities of macrophytobenthos in the Cape Taran area, South-Eastern Baltic Sea

Elena Ezhova, Shirshov Institute of Oceanology RAS, igelinez@gmail.com

Alexandra Volodina, Shirshov Institute of Oceanology RAS (presenter)

In frame of R#64BalticRim Project the analysis of 2008-2016 data on macroalgae beds near the Cape Taran, Russian South-Eastern Baltic Sea (SEB), was done. The algae communities of the Cape Taran are characterized by the high level of diversity, biomass and coverage of perennial species in the Russian SEB. This biotope is vulnerable and threatened and needs in creation of MPA.

A published data on macrophytes are scarce for the Russian South-Eastern Baltic Sea (SEB). In frame of R#64BalticRim Project the analysis of 2008-2016 data on macroalgae beds near the Cape Taran, SEB, where stony substrates are stretching from the coastline, was done. An irregular macrophyte belts structure was found. Deeper, at 3.5-6 m, rarely up to 7-9 m, macroalgae assemblages with the dominance of F. lumbricalis occur. The deepest belt, at 8-12 m, is presented by red perennial algae Coccotylus truncatus exceptionally. Any benthic macrophytes were not found deeper.

The algae communities of the Cape Taran are characterized by the highest level of diversity, biomass and coverage of perennial species in the Russian SEB. This biotope is vulnerable because on uniqueness or rarity of species or habitats, functional significance of the habitat, fragility, and ecosystems that are structurally complex or have life-history traits that hinder the chance of recovery (e.g., slow growth rates) (FAO, 2009). The biotope is also threatened because on a sharp slope, wave exposure and low water transparency, redoubled by coastal sewages. This small area (12 km²) needs in creation of MPA.