Prize winners

Björn Carlsons Östersjöpris is intended to recognise researchers or other individuals who have made valuable contributions to improving the Baltic Sea environment in a broad sense. This may involve independent research findings or projects conducted over a longer period. Consideration will also be given to initiatives to translate research into policy or communicate findings to the wider public.

Winners of the Björn Carlsons Östersjöpris are announced in the early summer each year, with the prize being presented in September/October.

Professors Jacob Carstensen and Daniel Conley

The Björn Carlsons Östersjöpris 2023 is awarded to Jacob Carstensen, Professor in Marine System Management at the Department of Ecoscience, Aarhus University, Denmark and Daniel Conley, Professor in Biogeochemistry, at the Department of Geology, Lund University, Sweden.

The prize motivation is:

The Björn Carlsons Östersjöpris 2023 is awarded to Jacob Carstensen, Professor in Marine System Management at the Department of Ecoscience, Aarhus University, Denmark and Daniel Conley, Professor in Biogeochemistry, at the Department of Geology, Lund University, Sweden.

Jacob Carstensen and Daniel Conley are awarded for playing critical roles in shaping key research on eutrophication, water quality, hypoxia, and underlying biogeochemical processes in the Baltic Sea. Through groundbreaking collaboration, Carstensen and Conley have combined expertise from different fields, and thus, their research has transformed, developed and broadened this field of research.

Introduction to the research area: The Baltic Sea is strongly affected by human activities, including nutrient loading, resulting in eutrophication. One of the most important effects of eutrophication is low oxygen levels or hypoxia. The Baltic Sea is indeed the largest man-induced hypoxic area in the world. Lack of oxygen adversely impacts bottom-living organisms and fish, and alters the breakdown of organic matter and the cycling of important nutrients, such as nitrogen and phosphorus. Actual oxygen levels result from a complex interplay between air, water, sediments and organisms. To understand these processes, advanced biogeochemical analyses and experiments, and huge amounts of data need to be produced, analysed and managed by adequate statistical methods. Deep and extensive knowledge of complex processes, and variability of spatial and temporal scales, is needed, as well as a seamless and innovative collaboration between scientists from different disciplines, such as professor J. Carstensen and professor D. Conley. Such ground-breaking collaboration can only be established through years of collaborative work, where the researchers both challenge and support each other.

Detailed justification for the nomination: Professors Jacob Carstensen and Daniel Conley have played critical roles in shaping key research on eutrophication, water quality, hypoxia, and underlying biogeochemical processes in the Baltic Sea. Their contributions have transformed, developed, and broadened this field of research.

They have jointly, and with other collaborators, produced several highly cited papers, such as Hypoxia related processes in the Baltic Sea (Conley et al. 2009), Deoxygenation of the Baltic Sea during the last century (Carstensen et al. 2014), and Hypoxia is increasing in the coastal zone of the Baltic Sea (Conley et al. 2011).

Their work is interdisciplinary, combining expertise in environmental statistics, biogeochemistry, ecology, and marine biology, and has resulted in ground-breaking scientific publications. Their research, based on e.g. advanced experiments, long-term data sets, modelling and simulations, has shown the long-term effect of nutrient loading and eutrophication in the Baltic Sea and contributed to recommendations on measures for improving its water quality. Those recommendations have been actively communicated to policy makers, both nationally and to the entire Baltic Sea community via HELCOM working groups, contracting parties, and publications. In this way, they have had a direct impact on the management of the Baltic Sea environment, the implementation of the Baltic Sea Action Plan and the development of quantitative targets for the reduction of nutrient loading from water-borne sources to the Baltic Sea.

Description of the awardees’ research: Professor Conley led the work to produce the first comprehensive review of the biogeochemical and physical processes involved in Baltic Sea hypoxia, showing the importance of phosphorus and nitrogen loading for eutrophication in the Baltic Sea, as well as globally. In several papers, Conley has also demonstrated the human impact on the aquatic biogeochemical cycles in nutrient-enriched inland and coastal waters. These papers show how deficiency in essential nutrients may have consequences for nutrient fluxes in and between sediments and water, that control algal blooms both in freshwaters and marine systems. His review from 2002 has been cited as evidence that the current distorted biogeochemical cycles exceed planetary boundaries (Steffen et al. 2015).

In a highly influential paper with Duarte, Conley and Carstensen showed that coastal systems recovering from eutrophication seldom return a state similar to that before the human impact, since shifting baselines and regime shifts hinder ecosystem recovery. The concept and evidence of shifting baselines and regime shifts are very timely now that it appears that the recovery of coastal and marine waters has not proceeded as expected, and takes longer than anticipated to reach target values for nutrient and phytoplankton indicators. Therefore, the message of this paper has current policy implications, as coastal managers need to evaluate how to reach good environmental status under climate change.

Conley, Carstensen and co-authors have also contributed significantly to the discussion of solutions to the hypoxia crisis in the Baltic Sea. They made a convincing case that long-lasting improved water quality can only be achieved by reducing nutrient loads. In other joint work, Conley and Carstensen tackled many additional critical questions regarding water quality in the Baltic Sea, showing the potentially positive role of macrofaunal activity in recovery from hypoxia, quantifying the deoxygenation of the Baltic Sea during the last century, demonstrating the rise in hypoxia in the coastal zone, analysing spatial variation in the efficiency of the coastal zone as a filter for nutrients, and assessing the past, present and future eutrophication status of the Baltic Sea.

Both Carstensen and Conley are extremely productive scientists that have impressive track records using conventional science citation indexes. Jacob Carstensen has published more than 160 peer-reviewed articles in international scientific journals. Daniel Conley has published more than 180 peer-reviewed articles in international scientific journals.

Science to policy: Professor J. Carstensen and professor D. Conley have widely and effectively communicated the results of their research concerning measures to improve water quality in the Baltic Sea, through scientific and popular publications, lectures, interviews, and other outreach.

Their work has been of direct use for HELCOM, for the implementation of the EU Water Framework Directive and the Marine Strategy Framework Directive, as well as for national environmental protection agencies in Sweden and Denmark. Daniel Conley coordinated the scientific work to develop reference conditions, that is the baselines to which the current ecological status is compared in the assessment of the Baltic Sea coastal areas for the EU Water Framework Directive. Together Conley and Carstensen have contributed to the assessment of the eutrophication status of coastal waters and estuaries, where they analysed the long-term trends of oxygen and nutrients in coastal waters, particularly in the southern Baltic Sea.

Jacob Carstensen led the scientific work to develop quantitative ecological targets for eutrophication and the indicators used for the assessment of the eutrophication status of the Baltic Sea. These targets were used to revise and agree on the maximum allowable inputs of nutrients to the Baltic Sea, including the provisional country-wise nutrient reduction figures. This ultimately ensures an appropriate set of measures to improve the eutrophication status of the Baltic Sea.

With many collaborators, Carstensen continues to provide expert advice to HELCOM working groups (latest HELCOM advice in 2020). He participated in a recent comprehensive review for identifying knowledge gaps and future research needs in the field of marine biogeochemistry in the Baltic Sea. This paper summarized the external loads, transformations in the coastal zone, changes in organic-matter production (eutrophication) and remineralization (oxygen availability), and the role of sediments in burial and turnover of carbon, nitrogen, and phosphorus, as well as changes in the marine CO2 system (Kulinski et al. 2022).

The Baltic Sea research by Conley and Carstensen is also used in the global context, to understand the deoxygenation of the global ocean and coastal waters worldwide. The International Oceanographic Commission of UNESCO has launched the UN Decade of Ocean Science for Sustainable Development (2021-2030) and the Ocean Decade programme GOOD – Global Ocean Oxygen Decade – that aims to raise global awareness about ocean deoxygenation and provide knowledge for understanding causes, mitigation, and adaptation. Both Conley and Carstensen contributed to a global overview of drivers of low oxygen in marine systems, ranging from the open ocean, to continental shelves, enclosed seas and coastal environments. This paper addressed the physical and biogeochemical processes and trends of oxygen availability, allowing the identification of causal relationships, and is a priority output from the Global Ocean Oxygen Network (GO2NE) under the GOOD programme.

An important area for further research: The input of excess nutrients over the last century has altered the balance between oxygen supply and consumption in the Baltic Sea, and hypoxia is now widespread in its bottom waters. An increase in temperature, due to climate change, will increase the problem, as warmer waters can hold less oxygen. The situation may be temporarily improved by storms and influx of deep, cold water, but this is not expected to counteract the effects of anthropogenic pollution in the long run. The work of professor Carstensen and professor Conley shows the importance of applying modelling and simulation approaches to big data sets to gain insights into the dynamics of complex environmental systems, influenced by multiple stressors, such as the Baltic Sea.

Contact details of the Prize Recipients:

Jacob Carstensen
Professor in Marine System Management
Department of Ecoscience, Aarhus University, Denmark
Frederiksborgvej 399, Building 7411, B1.17, 4000 Roskilde, Denmark
Phone: +45 87 15 85 96

Daniel Conley
Professor in Biogeochemistry, in particular aquatic and marine systems
Department of Geology, Lund University, Sweden
Sölvegatan 12, 223 62 Lund, Sweden
Phone: +46 46 222 04 49

Professors Jacob Carstensen and Daniel Conley are awarded the 2023 Björn Carlsons Östersjöpris.

Professor Maren Voss

The 2022 Björn Carlsons Östersjöpris is awarded to Professor Maren Voss of the Leibniz Institute for Baltic Sea Research in Warnemünde, Germany.

Professor Maren Voss is being awarded the prize for her groundbreaking research on the importance of marine nitrogen, particularly in the Baltic Sea. Professor Voss realised early on that nitrogen plays a vital role in Baltic eutrophication and has used advanced isotope analyses to map the transformation processes and sources of nitrogen in the Sea. Her research has increased the focus on nitrogen in efforts to counteract Baltic Sea eutrophication.

The prize motivation is:

The Björn Carlsons Östersjöpris 2022 is awarded to Prof. Dr. Maren Voss, Leibniz Institute for Baltic Sea Research Warnemünde (IOW), Rostock, Germany

The prize is given for her pioneering research on the importance of nitrogen as a nutrient in the ocean, and especially the Baltic Sea. Professor Voss realized early the central role nitrogen plays in the eutrophication of the Baltic Sea, and has used advanced isotope analyses to map the sources and cycling of nitrogen in the ocean. Her research has led to greater emphasis on nitrogen abatement in the management of Baltic Sea eutrophication.

Introduction to the research area: Eutrophication results from an excess of nutrients, particularly nitrogen and phosphorus, entering lakes and oceans. The sources of excess nutrients are human activities, such as the use of fertilizers in agriculture or release of untreated wastewater. Nutrients stimulate plant growth, and too much can lead to massive blooms of algae, including toxic cyanobacteria. These blooms can adversely affect the ecosystem, either directly, or indirectly, when they decompose and strip the water of oxygen. In this way eutrophication can push the sea over its ecological thresholds, resulting in a disturbed ecosystem.

Detailed justification for the nomination: Maren Voss was the first in the Baltic Sea region to use the method of measuring stable isotopes in water and organic matter, to decipher processes and identify the origin of nutrients. Her laboratory is still a leader in the application of this method to identify sources of eutrophication and to understand critical processes of the nitrogen cycle. For the Baltic Sea, for example, she has described for the first time that eutrophication from rivers leaves a clearly detectable signal in the biota of the Baltic Sea. Similarly, she and her colleagues were first to describe that not only the large colonial cyanobacteria fix nitrogen, but also unicellular species.

Her continued work at the highest scientific level has led to a better perception of the problems of the Baltic Sea also in the international context. She has pointed out in various media interviews and publications that a lower meat consumption is an effective means of reducing nitrogen inputs to the Baltic Sea. She has also made important contributions to several very successful EU projects and trained young scientists who are still working for a healthier Baltic Sea today.

Description of the awardee’s research: Maren Voss has worked on the nitrogen cycle of the Baltic Sea for over 25 years and published close to 70 studies on this topic. The measurement of microbial rates and their extrapolation to construct budgets as well as important method developments (e.g nitrogen fixation measurements) were central elements of her work.

Her early work showed that 15N values are elevated in the Baltic Sea, demonstrating that eutrophication by river-borne nutrients is indeed detectable in the Baltic Sea. She also showed that in addition to rivers, precipitation and nitrogen-fixing microorganisms are important nutrient sources for the Baltic Sea. Based on these results, the Swedish Environment Protection Agency invited her as one of five experts to write a report on “Eutrophication of the Seas along Sweden’s West Coast”. The report stressed the essential role of nitrogen for eutrophication in this marine area, modifying a previous focus on phosphorus. She also participated in a workshop that proposed that internal ecosystem feedbacks described as a “vicious circle” complicate management of Baltic Sea eutrophication, and require reduction of the external loads of both nitrogen and phosphorus. With her Baltic Sea expertise, she also collaborated in the European Nitrogen Assessment, which stressed the problematic role of pollution by nitrogen compounds in the environment and the need to regulate them, both in the Baltic Sea area, and for all of Europe.

Much of Maren Voss’ research has focussed on the role of nitrogen-fixing cyanobacteria in the Baltic Sea, to answer fundamental questions such as: How much do they fertilize the Baltic Sea? How can fixation rates for entire basins be better quantified? How can new nitrogen-fixing organisms in the Baltic Sea be identified? How is fixed nitrogen transferred through the food chain? Answers to these questions were provided in numerous publications, and her research group was first to detect nitrogen fixation by singe-cell cyanobacteria in the Baltic Sea.

Maren Voss and her collaborators have shown that the nitrogen balance of the Baltic Sea is still far from understood. A hypothesis they developed suggests that the Baltic Sea nitrogen cycle differs between the coastal regions and the open sea, with most of the combined nitrogen emanating from land in coastal regions, but from nitrogen fixation by cyanobacteria in the open sea. One reason for this is efficient denitrification in the coastal zone that removes much combined nitrogen before it can reach the open sea.

Influence of Maren Voss’ work on the Baltic Sea environment: Her work has become a cornerstone in our understanding of Baltic Sea eutrophication and how to combat it. Her continued cooperation with Baltic Sea colleagues in many EU projects has produced recommendations for EU and HELCOM that have influenced Baltic Sea eutrophication management. Based on her pioneering work on river-borne nitrogen isotopes, 15N values are used today as a standard indicator of eutrophication.

A further contribution by Maren Voss is her important work educating students on the complexity of the nutrient cycling and the potential of stable isotopes for the quantification of nutrient inputs. These activities include teaching at her home University of Rostock, as well as international courses, and an engagement in major initiatives for interdisciplinary education of doctoral students on Baltic Sea issues. With her focus on teaching next generation scientists on the ecology of the Baltic Sea, she has laid the knowledge foundations for tackling future environmental problems of the Baltic Sea.

An important area for further research: Eutrophication remains a major environmental problem in the Baltic Sea, but would have been much worse without the ambitious ongoing international efforts to reduce the nutrient loads. Indeed, improvements have been noted in several areas of the Baltic Sea. Research to better quantify nutrient sources and sinks, like that by Maren Voss, is a necessary and crucial support for this important management process.

Contact details of the Prize Recipient:

Prof. Dr. Maren Voss
Professor for Marine Biogeochemistry
Department of Biological Oceanography
Leibniz Institute for Baltic Sea Research Warnemünde, Germany
Tel: +49-381-5197209

Click here for short CV of Maren Voss, Prof. Dr.

Professor Maren Voss is awarded the 2022 Björn Carlsons Östersjöpris.