Current research projects

Examples of larger research projects currently underway at TZS. 250-300 scientists work at TZS annually, conducting 5000-6000 working days, with ca 30 % international users. The research covers ecology, ecophysiology, ecotoxicology, taxonomy, and behavioural and evolutionary biology. To get the latest information on new publications and exciting developments in ongoing research projects, please also follow us on Facebook.

The breathing seascape: resolving ecosystem metabolism and habitat-function relationships across coastal habitats

Coastal ecosystems are exceptionally diverse and productive environments that maintain vital ecosystem functions and services. These ecosystems are, however, under threat from eutrophication, pollution, overfishing and construction. In order to manage the ecosystems wisely, we need to advance our understanding of the role of biodiversity for ecosystem functioning and metabolism. We use novel instruments (Aquatic Eddy Covariance), which for the first time allows us to measure oxygen production and consumption in different key habitats of the Baltic Sea, such as seagrass meadows, mussel beds, bladder wrack belts, bare sand and mud. The measurements can then be linked to the biodiversity and nutrient cycling in these different habitats. Using habitat maps from the national underwater mapping program VELMU, we will scale up our findings to the ecosystem level, i.e. to the scale of societal relevance and management.

People: Alf Norkko, Karl Attard, Iván Rodil and the rest of the benthic ecology team (TZS), Ronnie Glud (University of Southern Denmark)

Funding: Academy of Finland, Walter and Andrée de Nottbeck Foundation 

Team website

As climate change progresses and human activities intensify, many marine species decline in abundance or become regionally extinct, which affects functional stability of ecosystems. Research in this group focuses on the impact of climate change on biodiversity in pelagic food webs. Our approaches include field and laboratory experiments, data analyses and statistical models. We investigate species interactions within phytoplankton to understand how changes in diversity alter resource use efficiency and primary productivity in the sea. From the food web perspective, we examine how producer and consumer diversity affect elements cycling and energy transfer between trophic levels.

People: Aleksandra Lewandowska

Funding: Walter and Andrée de Nottbeck Foundation

Team website

Seagrasses and other aquatic plants are foundation species that maintain biodiversity and modify the abiotic and biotic environment including primary and secondary production. They form vast underwater meadows that can contain up to 8-9 co-occurring plant species. We aim to look at how this diversity of species and their traits, i.e. functional diversity, influence ecosystem processes for example primary production along gradients in salinity and wave exposure. We investigate the link between aquatic plant traits and ecosystem functioning in the brackish-water Baltic Sea and along the coast of Western Australia. The project outcome is to discern how diverse temperate meadows maintain ecosystem functioning locally in different habitats and in geographically contrasting regions.

People: Camilla Gustafsson, Charlotte Angove, Alf Norkko (TZS), Gary Kendrick and research team (University of Western Australia), Johan Eklöf and research team (Stockholm University) 

Funding: Walter and Andrée de Nottbeck Foundation, Academy of Finland, Svenska Kulturfonden, UWA Research Collaboration Award

The role of the coastal zone as a filter for nutrients from land to the sea is largely an unknown black box. The BONUS-project COCOA will analyse the pathways of nutrients in the coastal zones of the Baltic Sea by quantifying the role of bacteria, phytoplankton, benthic microalgae, seagrasses, macroalgae and fauna in transforming and accumulating nutrients in four different types of coastal ecosystems (learning sites: lagoons, river-dominated estuaries, embayments, and archipelagos). In the area around TZS, we concentrate on the links between biodiversity and nutrient cycling.

People: Alf Norkko, Anna Villnäs, Johanna Gammal, Mari Joensuu, Guillaume Bernard, Joanna Norkko (TZS), Marie Järnström, Erik Bonsdorff (Åbo Akademi), and partners in Finland, Denmark, Sweden, Germany, Lithuania, Poland, Russia, and the Netherlands.

Funding: BONUS (EU) and Academy of Finland

We are studying Baltic Sea eutrophication and the effects of increasing accumulations of drifting algal detritus on the functioning of shallow coastal habitats. Increasing eutrophication may lead to a shift in dominance from seagrass and perennial macroalgae to bloom-forming macroalgae and epiphytes in shallow coastal areas. An excess of ephemeral macroalgae and drifting detritus accumulations will influence almost all levels of ecology, from species interactions to productivity, food-web stability and population dynamics. The goal is to examine how detritus source dynamics and characteristics might affect benthic communities, oxygen dynamics and the composition of carbon in coastal areas influenced by large drifting accumulations. We will assess the relative importance of the organic carbon derived from primary producers and from detritus into the coastal food-web using stable isotopes (δ13C, δ15N and δ34S). The project is (a) expected to deliver significant advances with regards to an understanding of the ecological role of increasing algal detritus on the functioning of shallow habitats, and (b) provide new insights into the fate of organic carbon production in coastal ecosystems.

People: Iván F. Rodil, T. Kahma, Alf Norkko, Christoph Humborg (Baltic Sea Centre, Stockholm University)

Funding: Walter and Andrée de Nottbeck Foundation

Team website

In ABRU, we study how the essential elements of life are cycled in aquatic ecosystems. In particular, we focus on carbon, nitrogen, phosphorus and silicon cycling. These are the key nutrients whose availability determine the distribution of life in Earth’s aquatic environments. We are specialized in the study of sediments, where organic material is decomposed by microbes, releasing nutrients for further cycling in the environment. ABRU contains the research groups of three senior scientists: Assistant Professor Tom Jilbert, and Academy of Finland Research Fellows Susanna Hietanen (Nutrient Cycles in Aquatic Ecosystems group) and Karoliina Koho (Benthic Ecology and Sediment Biogeochemistry group). There are currently four Ph.D. students (read a blog from one of them), one Post-Doc and one University Researcher in the unit. In our current TZS-based projects we study methane and nitrous oxide production and consumption in the coastal zone, natural nitrogen removal (denitrification) in sandy and muddy sediments, point-source pollution in the benthic environment and the use of molecular biology for ecosystem assessment.

Phytoplankton is a key source of energy to the marine food web and drives the biological carbon pump. The various loss mechanisms of phytoplankton have far-reaching ecological consequences for the structure and functioning of marine food webs. Our group investigates the importance of sinking, cell death, and grazing in order to improve the understanding of how environmental change (salinity, increasing temperature, sea ice loss) affects the energy pathways and pelagic-benthic coupling. We are particularly interested in phytoplankton cell death, its role as a loss factor in dominant phytoplankton taxa, and the impact it has on the pelagic detritus pool and organic matter cycling. Our work is currently focused on the coastal and open Baltic Sea, where we combine historical data (environmental data, plankton phenology, production, export), with new data from the contemporary system.

People: Tobias Tamelander, Maria Degerlund, Samu Elovaara

Funding: Walter and Andrée de Nottbeck Foundation, Svenska Kulturfonden

This project focuses on plankton populations and communities and their responses to eutrophication and climate change. We are interested in how changes in nutrient availability, temperature, pH and salinity affect plankton physiology, evolution and ecology. We combine different approaches, such as monitoring data, field work, experiments, mesocosms and modelling. Our main research interest is multiple stress: different climate change-induced effects on ecology, such as respiration, feeding, survival and reproductive success of copepod crustaceans, cladocerans and diatoms. We also work with biochemical and molecular samples to study how changes in the marine environment affect oxidative stress and gene expression. Our work increases the understanding of climate change and eutrophication effects on our common sea.  

People: Jonna Engström-Öst, Matias Scheinin, Anna-Karin Almén, Olivier Glippa, Mirella Kanerva, Katja Koli, Louise Lindroos, Pankaj Pant

Funding: Academy of Finland, Onni Talaan säätiö, Victoriastiftelsen, Walter and Andrée de Nottbeck Foundation

Team website

Eiders in the Baltic Sea are currently in grave peril: predation pressure is rapidly increasing following the rapid recovery of a top predator, the white-tailed sea eagle. On top of this, the availability of the main prey, blue mussels, is threatened by the effects of climate change. Assessing the adaptive potential of eiders to cope with these challenges is therefore a key research priority. We address this question in a long-studied (25 yrs) population of eider ducks from the Tvärminne archipelago, SW Finland. We focus on antipredator adaptations associated with female-female cooperation during brood care, the role of individual variation in cognitive and personality traits and its life-history consequences, the causes and consequences of nest-site selection, and physiological stress adaptation mechanisms. The goal is to predict which individuals – and in which environments – will experience the strongest responses to the ongoing rapid environmental change facing the Baltic Sea. Our ultimate hope is to find new solutions for halting the current population decline.

People: Markus Öst (Åbo Akademi), Kim Jaatinen (Nature and Game Management Trust Finland), Mikael Kilpi and partners from Finland, France, Canada and Norway.

We strive to understand the function of food webs as well as how they are affected by environmental change. The Baltic Sea is a great environment in which to study these effects. We focus on a community module consisting of blue mussels, eider ducks and white tailed sea eagles. This module is a central part of the Baltic ecosystem and contains a keystone species, a mesopredator and a top predator and it links the marine and the terrestrial environments. We investigate the direct and trophically mediated impacts of environmental change within this group of closely interacting species representing three different trophic levels. Special emphasis is put on the trophic interactions surrounding the eider duck and how these affect its population development. The eider populations are in precipitous decline and the species was recently classified as endangered within the EU. We hope to understand what processes are driving the eider populations and to mitigate potential threats.

People: Kim Jaatinen (Nature and Game Management Trust Finland), Alf Norkko (TZS), Mats Westerbom (TZS), Markus Öst (Åbo Akademi), Mika Kilpi and partners from Finland, Sweden, Denmark and USA.

Research on social evolution, genetics and ecology of ants has been carried out at TZS for decades, resulting in textbook examples and unique long-term data on how social evolution works. Current research is very diverse, and combines field studies with experiments and modern genetic and genomic methods.

The populations of Formica exsecta on the islands outside the station have been closely monitored since the early 90s. This extensive data set answers questions about the effects of inbreeding and population subdivision on colony and population success. Understanding how species cope in fragmented habitats is increasingly important in a world where humans constantly modify the landscape.

We also study social organization and speciation in Formica wood ants and red Myrmica ants. Why do some nests have many queens and some only one? Why do some queens disperse from their nests, and some stay home? Which genes underlie social polymorphism and speciation? These studies help us to understand how evolution works to produce individuals with different social strategies and eventually new species.

Finally, we study how ants deal with pathogens. In addition to responding with immune defenses, we have shown that ants medicate themselves when challenged with pathogens! To put all this into its ecological context, we use genomics to study the fungal, bacterial and viral associates of ants, both in the nest environment and intracellularly. Discoveries on the pathogen defenses of ants also have relevance to health of pollinators such as honeybees.

Evolution, Sociality & Behaviour research group

Costly female ornaments and male mate choice under different light environments (University of Oulu, Department of Ecology)

We focus on basic questions in behavioural ecology related to sexual selection and the effect of light pollution on species distribution. In the common glow-worm (Lampyris noctiluca, Lampyridae), wingless females glow to attract males which fly in search of females.  It is exceptional that females (but not males) have sexual ornaments. In the glow-worm adult females do not eat thus their behaviour is limited by energy constraints so female ornamentation is unexpected.

The purpose of potentially costly sexual ornamentation in a species where even small costs may be catastrophic is one of the major themes of the project. As part of this theme we also study whether alternative reproductive strategies have developed to compensate for any costs. We are also interested in the interplay between female luminous signals and any other lights in the environment. Additionally, artificial lights seem to be very attractive for males and may leave females without a partner, possibly causing local extinctions. As a part of the project, we study the effect of light pollution on the decline of this species.

Currently, the research group consists of Prof. Arja Kaitala, Dos Ulrika Candolin, Dos Phillip Watts and PhD students Juhani Hopkins, Gautier Baudry and Anna-Maria Borshagovski. The project is financed by the Academy of Finland (2016-2020).


The MONICOAST coastal observatory sends data to an online portal, where you can follow how temperature, salinity, oxygen, pH and turbidity changes in the sea outside Tvärminne Zoological Station on the Hanko peninsula.

MONICOAST (MONItoring of COASTal habitats) is about understanding and visualising the impacts of long-term environmental change on biodiversity and ecosystem functioning in key habitats. Automatic data loggers are deployed in coastal habitats such as seagrass meadows, bladder wrack belts and mussel beds. These habitats are highly diverse and provide crucial habitats for a wide range of organisms. Nevertheless, information on the natural variability (on a daily, seasonal and interannual scale) as well as the impact of long-term changes in, for example, temperature, salinity, oxygen, pH and turbidity for the functioning of these habitats is lacking.

MONICOAST will also convey the importance of these habitats to the general public through underwater photos, videos and 360 Virtual Reality videos that will be filmed next year.   

This project runs on external funding and was initiated as a collaboration between DROPP and TZS. If you are interested in sponsoring a new data logger (or part of a logger), please contact Joanna Norkko.


We are a research group studying marine microlitter in the Baltic Sea. We started our work in 2012 with the testing and development of microlitter monitoring in offshore areas. We have widened our scope and at present collect microlitter samples from the water surface, water column, sediment and biota (e.g. mussels and fish). In addition to monitoring work we also do experimental laboratory work with a focus on the potential harm of microplastics in Baltic Sea food webs. We have shown that common invertebrate taxa; rotifers, larger crustaceans, polychaetes and bivalves, as well as unicellular microzoopankton (ciliates) ingest microplastics, and that these plastics are transferred within food webs to higher trophic levels. We are also studying the role of sewage treatment plants and snow collected from urban areas as transport routes for microplastics to the sea. Our research group consists of two senior researches (Maiju Lehtiniemi and Outi Setälä), PhD students (Julia Talvitie and Pinja Näkki), MSc students (Saana Railo, Kaisa Pikkarainen, Erika Zidbeck) and an assistant researcher (Stjepan Budimir). Our main funding sources are the Academy of Finland, Ministry of Environment, Nessling and Nottbeck Foundations.

The rock pools on the Skerry islands of the Baltic Sea harbor freshwater communities often dominated by planktonic crustaceans of the genus Daphnia. We study the ecology and evolution of these Daphnia and their parasites. This project addresses aspects of local adaptation, metapopulation and metacommunity dynamics, inbreeding, parasitism, and genetic population structure. Methods include field surveys, experimental evolution and next generation sequencing.

The dynamics of Daphnia in Baltic rock pools have been studied intensively, and much is known about local extinction and colonization. This long-term research project was started by V. Ilmari Pajunen and his wife Irmeli in 1982. The backbone of the research are the assessment of presence/absence of the three Daphnia species in more than 500 rock pools twice a year and records of the Daphnia parasites. Besides these we have metadata for every pool in the study region. Experiments in the field and the laboratory complement this work.

The Daphnia populations in the rock pools are very dynamic across the years. For example, on average 17% of the rock pools are occupied by D. magna; 16% of the occupied pools go extinct per year, but re-colonization approximately balances this loss in the long run. Colonization is usually connected to founder events (genetic bottlenecks), which has a strong impact on the evolution of the system. Further factors that influence the metapopulation dynamics, include interspecific competition, the presence of parasites and predators, isolation in space, salinity, pH, organic matter and pool size.

Participants of the project:

  • Basel University: Dieter Ebert, Jürgen Hottinger, Peter Fields, Andera Cabalzar
  • Helsinki University: Ilmari and Irmeli Pajunen
  • Tel Aviv University: Frida Ben-Ami
  • CNRS, Montpellier: Christoph Haag

Elemental stoichiometry of benthic invertebrates as predictor of biogeochemical cycles

What is the role of benthic faunal carbon and nutrient pools in the coastal ecosystem? This project will provide new information regarding carbon (C) : nitrogen (N): phosphorous (P) content ratios and allometric traits of important benthic species. By performing field sampling over temporal and spatial scales, the project will provide novel insight into the intra- and interspecific variability in nutrient stoichiometry of macrobenthic species in relation to available food sources (as revealed by stable isotope analysis) and environmental conditions. The information will be used to quantify the contribution of benthic communities to sediment nutrient storage and recycling rates over temporal and spatial scales, by utilizing existing, large-scale monitoring data from the Baltic Sea.

People & Collaborators: Anna Villnäs (PI), Saara Mäkelin, Aleksandra Lewandowska, Iván Franco Rodil (TZS), Agnes Karlsson, Christoph Humborg (Stockholm University), Michael Vanni (Miami University).

Funding: Academy of FinlandUniversity of Helsinki 3 year research grant, Walter and Andrée de Nottbeck Foundation