Current and Former Members of Aquatic Biogeochemistry Research Unit (ABRU)
Tom Jilbert is Assistant Professor (Tenure Track) within the Ecosystems and Environment Research Program (ECOENV). His Tenure-Track position is co-funded by University of Helsinki and Vesijärvi Foundation. Tom is also Academy of Finland Research Fellow since September 2018. He is specialized in the study of sediment biogeochemistry and phosphorus cycling, in particular in eutrophied and low-oxygen aquatic environments. Tom is involved in various collaborative projects within ABRU, with other research groups in ECOENV, and with national and international partners, including University of Turku, Finnish Geological Survey, University of Utrecht (Netherlands) and Stirling University (UK). In 2018 Tom co-ordinated an international symposium on lake restoration in Lahti, Finland and gave a keynote talk at the Ocean Deoxygenation Conference in Kiel, Germany. In February 2019 he gave an invited presentation at the ASLO Aquatic Sciences meeting in Puerto Rico.
Karoliina Koho is an Academy Research Fellow and the Principal Investigator in two Academy of Finland funded projects. Her work is focused on the interface of ecology and biogeochemistry, investigating how benthic (micro)organisms influence oxygen dynamics, and nutrient and carbon cycling in sediments. Her research to date has focused on understanding of biogeochemical cycles and ecosystem dynamics in low-oxygen settings, such as oceanic Oxygen Minimum Zones (OMZs), as well as survival strategies of single celled eukaryotes (benthic foraminifera) in these hostile environments. In addition to benthic ecology and biogeochemistry, Karoliina's previous projects have included aspects of paleoenvironmental research and development of foraminiferal paleoindicators, or proxies. These aspects of her research background connect her understanding of modern day aquatic biogeochemistry to long-term elemental cycles on Earth.
Karoliina on TUHAT
Eero Asmala is a post-doctoral researcher funded by Academy of Finland, based at Tvärminne Zoological Station. His research covers broadly organic matter biogeochemistry in coastal areas. His current project focuses on short-term variations in river discharge (such as rain events) and their effect on organic matter inputs to coastal areas.
Saija Saarni is a post-doctoral researcher funded by Academy of Finland. She became a member of MERG-ABRU within ECOENV in September 2019 and she is based at Viikki. Her research interests are to study 1) climatic and anthropogenic forcing of lake sedimentation and catchment erosion, and 2) sedimentary processes of micro plastic litter in aquatic environments. The latter field of interest is also the main focus of her current - Academy of Finland funded - project "BaSeMent": Baltic Sea Monitoring on Microplastic sedimentation processes.
Dana Hellemann is a post-doctoral researcher funded by the Walter and Andrée de Nottbeck Foundation, whose background and research interest lie in the field of marine biogeochemistry, with a focus on elemental cycling in coastal systems, biogeochemical responses to anthropogenic pressures, eutrophication dynamics, and, particularly, the nitrogen cycle. In her current project, Dana studies how the specific composition of in situ organic carbon affects benthic nitrate reduction processes in different zones of the Baltic Sea coast along a seasonal cycle from pre- to post-spring bloom conditions. Dana is based both at Viikki campus and Tvärminne Zoological Station.
Dana on TUHAT
JP Myllykangas is a PhD student in the project ´Biogeochemical links between climate change and eutrophication in the Baltic Sea´. He studies methane processes in coastal sediments and water column of the Baltic Sea. His research topics range from large scale disturbances down to specific processes concerning microbial production and consumption of methane. He is especially interested in estuarine environments and learning what are the main drivers behind spatial and temporal changes in methane processes in these systems and how they connect to eutrophication and climate change.
JP on TUHAT
Mari Joensuu is a PhD student studying sediment erodibility and resuspension in coastal areas of the Baltic Sea. She is specifically interested in the environmental drivers behind the spatial and temporal variability of sediment erodibility in natural environments. She is also a member of the Benthic Ecology Team at Tvärminne Zoological Station.
Mari on TUHAT
Iines Salonen is a PhD student specialized in microbiology and focusing on benthic foraminifera and the sedimentary microbial community. It is known that microbes can act as essential symbionts for foraminifera as well as a food source, but the nature and prevalence of these relationships and their importance in marine biogeochemical cycles is understudied. In her research she applies molecular methods such as Next Generation Sequencing to study the identity and activity of microbial communities inside the foraminifera and in the surrounding sediment. Furthermore, Iines conducts isotope labelling experiments to track carbon transfer from microbes to foraminifera. The fieldwork for the project is carried out in intertidal areas (the Netherlands) and in a deep-sea setting (Japan). In addition to this, Iines is studying microeukaryote communities and their temporal variation in Baltic Sea sediments.
Iines on TUHAT
Sami Jokinen is a PhD student studying the long-term development of eutrophication and oxygen deficiency in the coastal northern Baltic Sea. He uses a wide set of sedimentological and geochemical proxies to probe the effects of climatic oscillations and anthropogenic nutrient inputs on bottom water oxygenation. Furthermore, Sami is working on the Academy of Finland project ´Next Generation Tool for Environmental Assessment´ to assess the mechanisms of trace metal sequestration in coastal sediments.
Sami on Research Gate
Soila Silvonen is a PhD student working with Tom Jilbert on the project 'Optimizing the efficiency of the Kymijärvi hypolimnetic withdrawal filter'. She recently gained her MSc in limnology and also worked within ABRU as a technical assistant in the 'Next Generation Tool for Environmental Assessment' project. She is especially interested in different anthropogenic impacts on aquatic ecosystems, as well as their management, and lake and coastal restoration. In her PhD, Soila will investigate the chemical mechanisms by which the new filter system retains phosphorus, as well as the possible impacts of the system on a nearby wetland. Ultimately, Soila's project aims to determine the viability of hypolimnetic withdrawal and treatment as a restoration measure for larger eutrophic lakes.
Soila on TUHAT
Mareike Paul is a PhD student studying the mechanisms of trace metal enrichment in the sediments of coastal European seas, including the Baltic Sea and Swedish West Coast fjords. Each of the study areas are characterized by varying environmental stress (eutrophication – hypoxia – anoxia/euxinia), salinity and anthropogenic impacts, all of which influence the concentration of trace metals in sediments. Although general ideas of sedimentary concentrations of the trace metals and their potential as proxies for redox conditions exist, many details of sedimentary trace metal chemistry and enrichments are still poorly constrained, which limits the use of trace metals as quantitative recorders of (past) hypoxia. Hence, the aim of this project is to shed light on these ongoing problems. The project is strongly supported by collaborators, such as Prof. Caroline Slomp (Utrecht University), the Baltic Bridge collaboration between Stockholm University and Tvärminne Zoological Station, the FINMARI consortium (Baltic Sea), Dr. Helena Filipsson (Lund University) and Prof. Karline Soetaert (Royal Netherlands Institute for Sea Research; NIOZ). Mareike is funded by the Academy of Finland research fellowship to Tom Jilbert ´Sedimentary trace metals: unlocking the archives of coastal marine hypoxia´.
Mareike on TUHAT
Siqi Zhao is a PhD student working with Tom Jilbert on the new project `Timescales of recovery from eutrophication in Finnish lakes´, where she will study sedimentary phosphorus dynamics in eutrophic lakes in the agricultural areas of southern Finland. Siqi is interested in the effect of internal loading of phosphorus on restoration from lake eutrophication, and especially in the recovery timeline. In her PhD work, she will compare the differences of sedimentary phosphorus processes between lakes with varied lake catchment area/lake surface area ratios, and history of nutrient loading. Furthermore, she will build nutrient cycle models for Finnish lakes to predict their development with the decrease of external phosphorus loading in the future. Siqi is a grant researcher funded by the China Scholarship Council.
Luukas Lintumäki is completing an MSc degree at the University of Helsinki, specializing in hydrogeology and environmental geology. He is carrying out his MSc thesis work with Tom Jilbert, within the project ´Iron and manganese cycling in boreal estuaries´. The project is part of the Baltic Bridge collaboration between Tvärminne Zoological Station and Stockholm University. The goal of Luukas' thesis is to determine how fluxes of organic matter and iron to coastal sediments of the Gulf of Finland have changed due to human activties in recent centuries, and their impact on biogeochemical processes in sediments. Previously in his BSc thesis, Luukas has studied eutrophication mechanisms and remediation techniques in lakes. He is particularly interested in human impact and restoration of aquatic environments.
Susanna Hietanen was Academy Research Fellow (2013-2018) and leader of the "Nutrient cycles in aquatic ecosystems" group within ABRU. She led the project ´Biogeochemical links between eutrophication and climate change in the Baltic Sea´ and was responsible for ABRU work in the project ´BONUS COCOA: Nutrient cocktails in the coastal zone of the Baltic Sea´. She is a specialist in the aquatic nitrogen cycle, having extensively studied denitrification, anammox, nitrification and DNRA in sediments and water columns both in freshwaters and in the Baltic Sea.
Adjunct Professor Petra Tallberg is an expert on the biogeochemical cycling of silicon who worked in the "Nutrient cycles in aquatic ecosystems"-group of Susanna Hietanen. She is currently involved in the international research projects “Marine primary producers under thinning ice - past responses and future projections for high Arctic Greenland” (at the Geological Survey of Denmark) and “Promoting phosphorus mobilization in soils using silicon fertilization” (at University of Evora, Portugal). Former projects and research interests include biogenic silica analysis, the Si cycle in the Baltic Sea, silicon-phosphorus interactions, terrestrial Si cycling, diatom sedimentation dynamics, phytoplankton ecology and aquatic food web restoration. She is also active in the field of environmental education.
Jesse Harrison is a postdoctoral researcher working on the Academy of Finland ´Next Generation Tool for Environmental Assessment´ project, focusing on the applications of high-throughput sequencing in benthic monitoring surveys. Previously he worked as a postdoc at the Universities of Vienna (Division of Microbial Ecology) and Edinburgh (UK Centre for Astrobiology), where his research topics included single-cell microbiology and the habitability of extreme ecosystems. Jesse also has a continuing interest in research into the environmental impacts and fate of microplastics. His wider roles have included serving on the European Commission-funded AstRoMap European Astrobiology Roadmap Panel, a Defra Technical Advisory Group focusing on the biodegradability of plastic waste, and collaborating on the NASA BASALT (Biologic Analog Science Associated with Lava Terrains) project.
Myrsini Chronopoulou was a postdoctoral researcher working on the role of benthic foraminifera and their endobionts in key biogeochemical processes, as well as the application of Next Generation Sequencing as a biomonitoring tool. Her PhD research (University of Essex) focused on the impact of crude oil on microbial communities and the role of nitrogen fixing bacteria in oil impacted marine environments. During her previous postdoctoral projects (Queen Mary, University of London & University of Essex) she studied important aspects of the nitrogen cycle (e.g. production of nitrous oxide and nitrogen gas) and the carbon cycle (methanogenesis and methane oxidation) in the ocean, as well as in freshwater ecosystems. Her research is characterised by a dual approach, a) looking at the processes occurring in the ecosystem by applying chemical and stable isotope analysis and, b) targeting the microbial communities involved in these processes by in-depth molecular analysis (e.g. high throughput sequencing techniques) and subsequent bioinformatics/data analysis.
Antti Rissanen joined ABRU for the month of November 2018 to consolidate collaborations with Tom Jilbert and JP Myllykangas, studying methane-related processes in lake and estuarine sediments. Rissanen has previously worked as an Academy of Finland postdoctoral researcher at Tampere University of Technology and as a postdoctoral researcher at University of Eastern Finland and University of Jyväskylä. He is specialized in the microbiology of sediments and water columns.
Pirita Anttila was a University of Helsinki MSc student working on her thesis “Effects of heavy metals on benthic macrofaunal communities” within the larger project ´Next Generation Tool for Environmental Assessment´. She focused on identifying species in sediment macrofaunal samples and combining the results with sediment heavy metal and organic content analysis results.
Gunnar Jakobs was a post-doctoral guest researcher in Susanna Hietanen's team. He is a specialist in the pelagic methane turnover in the central Baltic Sea, including the determination of methane oxidation rates using 14C labeling experiments, analysis of dissolved methane in seawater and identification of microorganisms involved. He has studied the seasonal and spatial variability in water column methane distribution as well as the methanotrophic response to changing environmental conditions. In addition he has investigated the links between denitrification and methanotrophic processes in the marine environment using bioreactor based enrichment experiments. He currently works at Center for Nuclear Technologies, Technical University of Denmark.
Anni Jylhä-Vuorio worked as a technical assistant in 2015 in Susanna Hietanen's project ´Biogeochemical links between eutrophication and climate change´, in 2016 for Tom Jilbert within the project ´Phosphorus burial in Lake Vesijärvi´, and in 2017 with Karoliina Koho within the project ´Next Generation Tool for Environmental Assessment´.
Peter Petros completed a research project at ABRU in 2017 studying the particle size dynamics of suspended particulate matter (SPM) in Pohjanpitäjänlahti estuary using data gathered from a LISST-100X particle size analyzer. Peter will return to his native Australia to graduate from his MCEng at the University of Melbourne before coming back to Finland to begin a PhD position studying drained peatland hydrology, up north at the University of Oulu.
Rosa Tiihonen completed her MSc research project in ABRU in 2016 studying the factors conrolling the distribution of iron and manganese in coastal sediments of the Gulf of Finland (supervisors Tom Jilbert and Susanna Hietanen). She then worked with Karoliina Koho as a technical assistant in the project ´Next Generation Tool for Environmental Assessment´.