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  • 1.
    Ammar, Yosr
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Otto, Saskia A.
    Möllmann, Christian
    Finsinger, Walter
    Blenckner, Thorsten
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    The rise of novelty in marine ecosystems: The Baltic Sea case2021In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 27, no 7, p. 1485-1499Article in journal (Refereed)
    Abstract [en]

    Global environmental changes have accelerated at an unprecedented rate in recent decades due to human activities. As a consequence, the incidence of novel abiotic conditions and biotic communities, which have been continuously emerging in the Earth system, has rapidly risen. Despite growing attention to the incidence and challenges posed by novelty in terrestrial ecosystems, novelty has not yet been quantified in marine ecosystems. Here, we measured for the rate of novelty (RoN) in abiotic conditions and community structure for three trophic levels, i.e., phytoplankton, zooplankton, and fish, in a large marine system - the Baltic Sea. We measured RoN as the degree of dissimilarity relative to a specific spatial and temporal baseline, and contrasted this with the rate of change as a measure of within-basin change over time. We found that over the past 35 years abiotic and biotic RoN showed complex dynamics varying in time and space, depending on the baseline conditions. RoN in abiotic conditions was smaller in the open Central Baltic Sea than in the Kattegat and the more enclosed Gulf of Bothnia, Gulf of Riga, and Gulf of Finland in the north. We found a similar spatial pattern for biotic assemblages, which resulted from changes in composition and stock size. We identified sea-surface temperature and salinity as key drivers of RoN in biotic communities. Hence, future environmental changes that are expected to affect the biogeochemistry of the Baltic Sea, may favor the rise of biotic novelty. Our results highlighted the need for a deeper understanding of novelty development in marine ecosystems, including interactions between species and trophic levels, ecosystem functioning under novel abiotic conditions, and considering novelty in future management interventions.

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  • 2.
    Ammar, Yosr
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Voss, Rudi
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Blenckner, Thorsten
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Quantifying socio-economic novelty in fisheries social-ecological systems2022In: Fish and Fisheries, ISSN 1467-2960, E-ISSN 1467-2979, Vol. 23, no 2, p. 445-461Article in journal (Refereed)
    Abstract [en]

    Socio-economic development has shaped fisheries social-ecological systems (SES) worldwide across different scales. No work has yet undertaken how this development led to novel, not experienced before, systems structure in marine SES. Here, we quantify socio-economic novelty as the degree of dissimilarity relative to a specific spatiotemporal baseline in the Baltic Sea fisheries SES between 1975 and 2015. We used catch by "gears," catch by "commercial groups" and trade ("import" and "export") as respective indicators of novelty at national, regional and international governance levels. We found that socio-economic novelty increased over time nonlinearly in relation to the 1975–1979 baseline. The contribution to total novelty shifted from the dominance of “gears” and “commercial groups” in the late 1990s and early 2000s to “import” and “export” after the mid-2000s, i.e. from national and regional levels to the international level. The fastest increase in novelty occurred with the trade dominance shift, primarily related to monetary value rather than quantity. Spatially, novelty emerged with a large difference across countries, and a major contribution by Sweden, Denmark and Poland. We identified the influence of different management interventions and governance actions on the emergence of novelty in the Baltic SES. The decreasing socio-economic novelty at national and regional levels could indicate reduced variability due to management intervention in recent years which might decrease SES resilience to shocks. Calculating socio-economic novelty and studying its drivers at different scales could provide a better understanding of SES complexity and inform urgently needed adaptation and transformation towards sustainable future pathways. 

  • 3.
    Blenckner, Thorsten
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Ammar, Yosr
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Müller-Karulis, Bärbel
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Arneborg, Lars
    Li, Qiang
    Stockholm University, Faculty of Science, Department of Physical Geography.
    The Risk for Novel and Disappearing Environmental Conditions in the Baltic Sea2021In: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 8, article id 745722Article in journal (Refereed)
    Abstract [en]

    Future climate biogeochemical projections indicate large changes in the ocean with environmental conditions not experienced at present referred to as novel, or may even disappear. These climate-induced changes will most likely affect species distribution via changes in growth, behavior, evolution, dispersal, and species interactions. However, the future risk of novel and disappearing environmental conditions in the ocean is poorly understood, in particular for compound effects of climate and nutrient management changes. We map the compound risk of the occurrence of future novel and disappearing environmental conditions, analyze the outcome of climate and nutrient management scenarios for the world’s largest estuary, the Baltic Sea, and the potential consequences for three charismatic species. Overall, the future projections show, as expected, an increase in environmental novelty over time. The future nutrient reduction management that improves the eutrophication status of the Baltic Sea contributes to large novel and disappearing conditions. We show the consequences of novel and disappearing environmental conditions for fundamental niches of three charismatic species under different scenarios. This first step toward comprehensively analyzing environmental novelty and disappearing conditions for a marine system illustrates the urgent need to include novelty and disappearing projection outputs in Earth System Models. Our results further illustrate that adaptive management is needed to account for the emergence of novelty related to the interplay of multiple drivers. Overall, our analysis provides strong support for the expectation of novel ecological communities in marine systems, which may affect ecosystem services, and needs to be accounted for in sustainable future management plans of our oceans.

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  • 4.
    Blenckner, Thorsten
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Möllmann, Christian
    Stewart Lowndes, Julia
    Griffiths, Jennifer R.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Washington State Department of Fish and Wildlife, USA.
    Campbell, Eleanore
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    De Cervo, Andrea
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Belgrano, Andrea
    Boström, Christoffer
    Fleming, Vivi
    Frazier, Melanie
    Neuenfeldt, Stefan
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Nilsson, Annika
    Ojaveer, Henn
    Olsson, Jens
    Palmlöv, Christine S.
    Stockholm University, Faculty of Science, Department of Environmental Science.
    Quaas, Martin
    Rickels, Wilfried
    Sobek, Anna
    Stockholm University, Faculty of Science, Department of Environmental Science.
    Viitasalo, Markku
    Wikström, Sofia A.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Halpern, Benjamin S.
    The Baltic Health Index (BHI): Assessing the social-ecological status of the Baltic Sea2021In: People and Nature, E-ISSN 2575-8314, Vol. 3, no 2, p. 359-375Article in journal (Refereed)
    Abstract [en]

    1. Improving the health of coastal and open sea marine ecosystems represents a substantial challenge for sustainable marine resource management, since it requires balancing human benefits and impacts on the ocean. This challenge is often exacerbated by incomplete knowledge and lack of tools that measure ocean and coastal ecosystem health in a way that allows consistent monitoring of progress towards predefined management targets. The lack of such tools often limits capabilities to enact and enforce effective governance.

    2. We introduce the Baltic Health Index (BHI) as a transparent, collaborative and repeatable assessment tool. The Index complements existing, more ecological-oriented, approaches by including a human dimension on the status of the Baltic Sea, an ecosystem impacted by multiple anthropogenic pressures and governed by a multitude of comprehensive national and international policies. Using a large amount of social-ecological data available, we assessed the health of the Baltic Sea for nine goals that represent the status towards set targets, for example, clean waters, biodiversity, food provision, natural products extraction and tourism.

    3. Our results indicate that the overall health of the Baltic Sea is suboptimal (a score of 76 out of 100), and a substantial effort is required to reach the management objectives and associated targets. Subregionally, the lowest BHI scores were measured for carbon storage, contaminants and lasting special places (i.e. marine protected areas), albeit with large spatial variation.

    4. Overall, the likely future status of all goals in the BHI averaged for the entire Baltic Sea is better than the present status, indicating a positive trend towards a healthier Baltic Sea. However, in some Baltic Sea basins, the trend for specific goals was decreasing, highlighting locations and issues that should be the focus of management priorities.

    5. The BHI outcomes can be used to identify both pan-Baltic and subregional scale management priorities and to illustrate the interconnectedness between goals linked by cumulative pressures. Hence, the information provided by the BHI tool and its further development will contribute towards the fulfilment of the UN Agenda 2030 and its Sustainability Development Goals.

  • 5. Daewel, Ute
    et al.
    Hjøllo, Solfrid Saetre
    Huret, Martin
    Ji, Rubao
    Maar, Marie
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Travers-Trolet, Morgane
    Peck, Myron A.
    van de Wolfshaar, Karen E.
    Predation control of zooplankton dynamics: a review of observations and models2014In: ICES Journal of Marine Science, ISSN 1054-3139, E-ISSN 1095-9289, Vol. 71, no 2, p. 254-271Article, review/survey (Refereed)
    Abstract [en]

    We performed a literature review to examine to what degree the zooplankton dynamics in different regional marine ecosystems across the Atlantic Ocean is driven by predation mortality and how the latter is addressed in available modelling approaches. In general, we found that predation on zooplankton plays an important role in all the six considered ecosystems, but the impacts are differently strong and occur at different spatial and temporal scales. In ecosystems with extreme environmental conditions (e.g. low temperature, ice cover, large seasonal amplitudes) and low species diversity, the overall impact of top-down processes on zooplankton dynamics is stronger than for ecosystems having moderate environmental conditions and high species diversity. In those ecosystems, predation mortality was found to structure the zooplankton mainly on local spatial and seasonal time scales. Modelling methods used to parameterize zooplankton mortality range from simplified approaches with fixed mortality rates to complex coupled multispecies models. The applicability of a specific method depends on both the observed state of the ecosystem and the spatial and temporal scales considered. Modelling constraints such as parameter uncertainties and computational costs need to be balanced with the ecosystem-specific demand for a consistent, spatial-temporal dynamic implementation of predation mortality on the zooplankton compartment.

  • 6.
    Griffiths, Jennifer R.
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Kadin, Martina
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Nascimento, Francisco J. A.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Tamelander, Tobias
    Törnroos, Anna
    Bonaglia, Stefano
    Stockholm University, Faculty of Science, Department of Geological Sciences. Lund University, Sweden.
    Bonsdorff, Erik
    Brüchert, Volker
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Gårdmark, Anna
    Järnström, Marie
    Kotta, Jonne
    Lindegren, Martin
    Nordström, Marie C.
    Norkko, Alf
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. University of Helsinki, Finland.
    Olsson, Jens
    Weigel, Benjamin
    Zydelis, Ramunas
    Blenckner, Thorsten
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Winder, Monika
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    The importance of benthic-pelagic coupling for marine ecosystem functioning in a changing world2017In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 23, no 6, p. 2179-2196Article, review/survey (Refereed)
    Abstract [en]

    Benthic-pelagic coupling is manifested as the exchange of energy, mass, or nutrients between benthic and pelagic habitats. It plays a prominent role in aquatic ecosystems, and it is crucial to functions from nutrient cycling to energy transfer in food webs. Coastal and estuarine ecosystem structure and function are strongly affected by anthropogenic pressures; however, there are large gaps in our understanding of the responses of inorganic nutrient and organic matter fluxes between benthic habitats and the water column. We illustrate the varied nature of physical and biological benthic-pelagic coupling processes and their potential sensitivity to three anthropogenic pressures - climate change, nutrient loading, and fishing - using the Baltic Sea as a case study and summarize current knowledge on the exchange of inorganic nutrients and organic material between habitats. Traditionally measured benthic-pelagic coupling processes (e.g., nutrient exchange and sedimentation of organic material) are to some extent quantifiable, but the magnitude and variability of biological processes are rarely assessed, preventing quantitative comparisons. Changing oxygen conditions will continue to have widespread effects on the processes that govern inorganic and organic matter exchange among habitats while climate change and nutrient load reductions may have large effects on organic matter sedimentation. Many biological processes (predation, bioturbation) are expected to be sensitive to anthropogenic drivers, but the outcomes for ecosystem function are largely unknown. We emphasize how improved empirical and experimental understanding of benthic-pelagic coupling processes and their variability are necessary to inform models that can quantify the feedbacks among processes and ecosystem responses to a changing world.

  • 7. Gårdmark, Anna
    et al.
    Lindegren, Martin
    Neuenfeldt, Stefan
    Blenckner, Thorsten
    Stockholm University, Faculty of Science, Stockholm Resilience Centre, Baltic Nest Institute.
    Heikinheimo, Outi
    Müller-Karulis, Barbel
    Stockholm University, Faculty of Science, Stockholm Resilience Centre, Baltic Nest Institute. Institute of Food Safety, Animal Health and Environment BIOR, Latvia.
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre, Baltic Nest Institute.
    Tomczak, Maciej T.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre, Baltic Nest Institute.
    Aro, Eero
    Wikström, Anders
    Moellmann, Christian
    Biological ensemble modeling to evaluate potential futures of living marine resources2013In: Ecological Applications, ISSN 1051-0761, E-ISSN 1939-5582, Vol. 23, no 4, p. 742-754Article in journal (Refereed)
    Abstract [en]

    Natural resource management requires approaches to understand and handle sources of uncertainty in future responses of complex systems to human activities. Here we present one such approach, the biological ensemble modeling approach,'' using the Eastern Baltic cod (Gadus morhua callarias) as an example. The core of the approach is to expose an ensemble of models with different ecological assumptions to climate forcing, using multiple realizations of each climate scenario. We simulated the long-term response of cod to future fishing and climate change in seven ecological models ranging from single-species to food web models. These models were analyzed using the biological ensemble modeling approach'' by which we (1) identified a key ecological mechanism explaining the differences in simulated cod responses between models, (2) disentangled the uncertainty caused by differences in ecological model assumptions from the statistical uncertainty of future climate, and (3) identified results common for the whole model ensemble. Species interactions greatly influenced the simulated response of cod to fishing and climate, as well as the degree to which the statistical uncertainty of climate trajectories carried through to uncertainty of cod responses. Models ignoring the feedback from prey on cod showed large interannual fluctuations in cod dynamics and were more sensitive to the underlying uncertainty of climate forcing than models accounting for such stabilizing predator-prey feedbacks. Yet in all models, intense fishing prevented recovery, and climate change further decreased the cod population. Our study demonstrates how the biological ensemble modeling approach makes it possible to evaluate the relative importance of different sources of uncertainty in future species responses, as well as to seek scientific conclusions and sustainable management solutions robust to uncertainty of food web processes in the face of climate change.

  • 8. Havenhand, Jonathan N.
    et al.
    Filipsson, Helena L.
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Troell, Max
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Royal Swedish Academy of Science, Sweden.
    Crépin, Anne-Sophie
    Jagers, Sverker
    Langlet, David
    Matti, Simon
    Turner, David
    Winder, Monika
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    de Wit, Pierre
    Anderson, Leif G.
    Ecological and functional consequences of coastal ocean acidification: Perspectives from the Baltic-Skagerrak System2019In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 48, no 8, p. 831-854Article, review/survey (Refereed)
    Abstract [en]

    Ocean temperatures are rising; species are shifting poleward, and pH is falling (ocean acidification, OA). We summarise current understanding of OA in the brackish Baltic-Skagerrak System, focussing on the direct, indirect and interactive effects of OA with other anthropogenic drivers on marine biogeochemistry, organisms and ecosystems. Substantial recent advances reveal a pattern of stronger responses (positive or negative) of species than ecosystems, more positive responses at lower trophic levels and strong indirect interactions in food-webs. Common emergent themes were as follows: OA drives planktonic systems toward the microbial loop, reducing energy transfer to zooplankton and fish; and nutrient/food availability ameliorates negative impacts of OA. We identify several key areas for further research, notably the need for OA-relevant biogeochemical and ecosystem models, and understanding the ecological and evolutionary capacity of Baltic-Skagerrak ecosystems to respond to OA and other anthropogenic drivers.

  • 9. Kadin, Martina
    et al.
    Frederiksen, Morten
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Converse, Sarah J.
    Linking demographic and food-web models to understand management trade-offs2019In: Ecology and Evolution, E-ISSN 2045-7758, Vol. 9, no 15, p. 8587-8600Article in journal (Refereed)
    Abstract [en]

    Alternatives in ecosystem-based management often differ with respect to trade-offs between ecosystem values. Ecosystem or food-web models and demographic models are typically employed to evaluate alternatives, but the approaches are rarely integrated to uncover conflicts between values. We applied multistate models to a capture-recapture dataset on common guillemots Uria aalge breeding in the Baltic Sea to identify factors influencing survival. The estimated relationships were employed together with Ecopath-with-Ecosim food-web model simulations to project guillemot survival under six future scenarios incorporating climate change. The scenarios were based on management alternatives for eutrophication and cod fisheries, issues considered top priority for regional management, but without known direct effects on the guillemot population. Our demographic models identified prey quantity (abundance and biomass of sprat Sprattus sprattus) as the main factor influencing guillemot survival. Most scenarios resulted in projections of increased survival, in the near (2016-2040) and distant (2060-2085) future. However, in the scenario of reduced nutrient input and precautionary cod fishing, guillemot survival was projected to be lower in both future periods due to lower sprat stocks. Matrix population models suggested a substantial decline of the guillemot population in the near future, 24% per 10 years, and a smaller reduction, 1.1% per 10 years, in the distant future. To date, many stakeholders and Baltic Sea governments have supported reduced nutrient input and precautionary cod fishing and implementation is underway. Negative effects on nonfocal species have previously not been uncovered, but our results show that the scenario is likely to negatively impact the guillemot population. Linking model results allowed identifying trade-offs associated with management alternatives. This information is critical to thorough evaluation by decision-makers, but not easily obtained by food-web models or demographic models in isolation. Appropriate datasets are often available, making it feasible to apply a linked approach for better-informed decisions in ecosystem-based management.

  • 10.
    Kininmonth, Stuart
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. University of Queensland, Australia; University of the South Pacific, Fiji.
    Blenckner, Thorsten
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Watson, James
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Oregon State University, USA.
    Orio, Alessandro
    Casini, Michele
    Neuenfeldt, Stefan
    Bartolino, Valerio
    Hansson, Martin
    Is Diversity the Missing Link in Coastal Fisheries Management?2022In: Diversity, E-ISSN 1424-2818, Vol. 14, no 2, article id 90Article in journal (Refereed)
    Abstract [en]

    Fisheries management has historically focused on the population elasticity of target fish based primarily on demographic modeling, with the key assumptions of stability in environmental conditions and static trophic relationships. The predictive capacity of this fisheries framework is poor, especially in closed systems where the benthic diversity and boundary effects are important and the stock levels are low. Here, we present a probabilistic model that couples key fish populations with a complex suite of trophic, environmental, and geomorphological factors. Using 41 years of observations we model the changes in eastern Baltic cod (Gadus morhua), herring (Clupea harengus), and Baltic sprat (Sprattus sprattus balticus) for the Baltic Sea within a Bayesian network. The model predictions are spatially explicit and show the changes of the central Baltic Sea from cod- to sprat-dominated ecology over the 41 years. This also highlights how the years 2004 to 2014 deviate in terms of the typical cod–environment relationship, with environmental factors such as salinity being less influential on cod population abundance than in previous periods. The role of macrozoobenthos abundance, biotopic rugosity, and flatfish biomass showed an increased influence in predicting cod biomass in the last decade of the study. Fisheries management that is able to accommodate shifting ecological and environmental conditions relevant to biotopic information will be more effective and realistic. Non-stationary modelling for all of the homogeneous biotope regions, while acknowledging that each has a specific ecology relevant to understanding the fish population dynamics, is essential for fisheries science and sustainable management of fish stocks.

  • 11.
    Lade, Steven J.
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. The Australian National University, Australia.
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Generalized modeling of empirical social-ecological systems2017In: Natural Resource Modeling, ISSN 0890-8575, E-ISSN 1939-7445, Vol. 30, no 3, article id e12129Article in journal (Refereed)
    Abstract [en]

    Modeling social-ecological systems is difficult due to the complexity of ecosystems and of individual and collective human behavior. Key components of the social-ecological system are often over-simplified or omitted. Generalized modeling is a dynamical systems approach that can overcome some of these challenges. It can rigorously analyze qualitative system dynamics such as regime shifts despite incomplete knowledge of the model's constituent processes. Here, we review generalized modeling and use a recent study on the Baltic Sea cod fishery's boom and collapse to demonstrate its application to modeling the dynamics of empirical social-ecological systems. These empirical applications demand new methods of analysis suited to larger, more complicated generalized models. Generalized modeling is a promising tool for rapidly developing mathematically rigorous, process-based understanding of a social-ecological system's dynamics despite limited knowledge of the system. Recommendations for Resource Managers Understanding empirical social-ecological dynamics requires integrating quantitative and qualitative data Generalized modeling can analyze qualitative dynamics, such as regime shifts, by integrating both qualitative and quantitative data Generalized modeling is well-suited to use in participatory or collaborative settings

  • 12.
    Lade, Steven J.
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Hentati-Sundberg, Jonas
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Blenckner, Thorsten
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Boonstra, Wiebren J.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Orach, Kirill
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Quaas, Martin F.
    Österblom, Henrik
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Schlüter, Maja
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    An empirical model of the Baltic Sea reveals the importance of social dynamics for ecological regime shifts2015In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 112, no 35, p. 11120-11125Article in journal (Refereed)
    Abstract [en]

    Regime shifts triggered by human activities and environmental changes have led to significant ecological and socioeconomic consequences in marine and terrestrial ecosystems worldwide. Ecological processes and feedbacks associated with regime shifts have received considerable attention, but human individual and collective behavior is rarely treated as an integrated component of such shifts. Here, we used generalized modeling to develop a coupled social-ecological model that integrated rich social and ecological data to investigate the role of social dynamics in the 1980s Baltic Sea cod boom and collapse. We showed that psychological, economic, and regulatory aspects of fisher decision making, in addition to ecological interactions, contributed both to the temporary persistence of the cod boom and to its subsequent collapse. These features of the social-ecological system also would have limited the effectiveness of stronger fishery regulations. Our results provide quantitative, empirical evidence that incorporating social dynamics into models of natural resources is critical for understanding how resources can be managed sustainably. We also show that generalized modeling, which is well-suited to collaborative model development and does not require detailed specification of causal relationships between system variables, can help tackle the complexities involved in creating and analyzing social-ecological models.

  • 13. Lotze, Heike K.
    et al.
    Tittensor, Derek P.
    Bryndum-Buchholz, Andrea
    Eddy, Tyler D.
    Cheung, William W. L.
    Galbraith, Eric D.
    Barange, Manuel
    Barrier, Nicolas
    Bianchi, Daniele
    Blanchard, Julia L.
    Bopp, Laurent
    Buchner, Matthias
    Bulman, Catherine M.
    Carozza, David A.
    Christensen, Villy
    Coll, Marta
    Dunne, John P.
    Fulton, Elizabeth A.
    Jennings, Simon
    Jones, Miranda C.
    Mackinson, Steve
    Maury, Olivier
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Oliveros-Ramos, Ricardo
    Roy, Tilla
    Fernandes, José A.
    Schewe, Jacob
    Shin, Yunne-Jai
    Silva, Tiago A. M.
    Steenbeek, Jeroen
    Stock, Charles A.
    Verley, Philippe
    Volkholz, Jan
    Walker, Nicola D.
    Worm, Boris
    Global ensemble projections reveal trophic amplification of ocean biomass declines with climate change2019In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 116, no 26, p. 12907-12912Article in journal (Refereed)
    Abstract [en]

    While the physical dimensions of climate change are now routinely assessed through multimodel intercomparisons, projected impacts on the global ocean ecosystem generally rely on individual models with a specific set of assumptions. To address these single-model limitations, we present standardized ensemble projections from six global marine ecosystem models forced with two Earth system models and four emission scenarios with and without fishing. We derive average biomass trends and associated uncertainties across the marine food web. Without fishing, mean global animal biomass decreased by 5% (+/- 4% SD) under low emissions and 17% (+/- 11% SD) under high emissions by 2100, with an average 5% decline for every 1 degrees C of warming. Projected biomass declines were primarily driven by increasing temperature and decreasing primary production, and were more pronounced at higher trophic levels, a process known as trophic amplification. Fishing did not substantially alter the effects of climate change. Considerable regional variation featured strong biomass increases at high latitudes and decreases at middle to low latitudes, with good model agreement on the direction of change but variable magnitude. Uncertainties due to variations in marine ecosystem and Earth system models were similar. Ensemble projections performed well compared with empirical data, emphasizing the benefits of multimodel inference to project future outcomes. Our results indicate that global ocean animal biomass consistently declines with climate change, and that these impacts are amplified at higher trophic levels. Next steps for model development include dynamic scenarios of fishing, cumulative human impacts, and the effects of management measures on future ocean biomass trends.

  • 14. MacKenzie, Brian R.
    et al.
    Meier, H. E. Markus
    Lindegren, Martin
    Neuenfeldt, Stefan
    Eero, Margit
    Blenckner, Thorsten
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Tomczak, Maciej T.
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Niiranen, Susa
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Impact of Climate Change on Fish Population Dynamics in the Baltic Sea: A Dynamical Downscaling Investigation2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 6, p. 626-636Article in journal (Refereed)
    Abstract [en]

    Understanding how climate change, exploitation and eutrophication will affect populations and ecosystems of the Baltic Sea can be facilitated with models which realistically combine these forcings into common frameworks. Here, we evaluate sensitivity of fish recruitment and population dynamics to past and future environmental forcings provided by three ocean-biogeochemical models of the Baltic Sea. Modeled temperature explained nearly as much variability in reproductive success of sprat (Sprattus sprattus; Clupeidae) as measured temperatures during 1973-2005, and both the spawner biomass and the temperature have influenced recruitment for at least 50 years. The three Baltic Sea models estimate relatively similar developments (increases) in biomass and fishery yield during twenty-first century climate change (ca. 28 % range among models). However, this uncertainty is exceeded by the one associated with the fish population model, and by the source of global climate data used by regional models. Knowledge of processes and biases could reduce these uncertainties.

  • 15. Meier, H. E. Markus
    et al.
    Andersson, Helen C.
    Arheimer, Berit
    Donnelly, Chantal
    Eilola, Kari
    Gustafsson, Bo G.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre, Baltic Nest Institute.
    Kotwicki, Lech
    Neset, Tina-Simone
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Piwowarczyk, Joanna
    Savchuk, Oleg P.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre, Baltic Nest Institute.
    Schenk, Frederik
    Weslawski, Jan Marcin
    Zorita, Eduardo
    Ensemble Modeling of the Baltic Sea Ecosystem to Provide Scenarios for Management2014In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 43, no 1, p. 37-48Article in journal (Refereed)
    Abstract [en]

    We present a multi-model ensemble study for the Baltic Sea, and investigate the combined impact of changing climate, external nutrient supply, and fisheries on the marine ecosystem. The applied regional climate system model contains state-of-the-art component models for the atmosphere, sea ice, ocean, land surface, terrestrial and marine biogeochemistry, and marine food-web. Time-dependent scenario simulations for the period 1960-2100 are performed and uncertainties of future projections are estimated. In addition, reconstructions since 1850 are carried out to evaluate the models sensitivity to external stressors on long time scales. Information from scenario simulations are used to support decision-makers and stakeholders and to raise awareness of climate change, environmental problems, and possible abatement strategies among the general public using geovisualization. It is concluded that the study results are relevant for the Baltic Sea Action Plan of the Helsinki Commission.

  • 16.
    Meier, Markus
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Andersson, Helen C.
    Arheimer, Berit
    Blenckner, Thorsten
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Chubarenko, Boris
    Donnelly, Chantal
    Eilola, Kari
    Gustafsson, Bo G.
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Hansson, Anders
    Havenhand, Jonathan
    Hoglund, Anders
    Kuznetsov, Ivan
    MacKenzie, Brian R.
    Müller-Karulis, Barbel
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Neumann, Thomas
    Niiranen, Susa
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Piwowarczyk, Joanna
    Raudsepp, Urmas
    Reckermann, Marcus
    Ruoho-Airola, Tuija
    Savchuk, Oleg P.
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Schenk, Frederik
    Schimanke, Semjon
    Vali, Germo
    Weslawski, Jan-Marcin
    Zorita, Eduardo
    Comparing reconstructed past variations and future projections of the Baltic sea ecosystem first results from multi model ensemble simulations2012In: Environmental Research Letters, E-ISSN 1748-9326, Vol. 7, no 3, p. 034005-Article in journal (Refereed)
    Abstract [en]

    Multi-model ensemble simulations for the marine biogeochemistry and food web of the Baltic Sea were performed for the period 1850-2098, and projected changes in the future climate were compared with the past climate environment. For the past period 1850-2006, atmospheric, hydrological and nutrient forcings were reconstructed, based on historical measurements. For the future period 1961-2098, scenario simulations were driven by regionalized global general circulation model (GCM) data and forced by various future greenhouse gas emission and air-and riverborne nutrient load scenarios (ranging from a pessimistic 'business-as-usual' to the most optimistic case). To estimate uncertainties, different models for the various parts of the Earth system were applied. Assuming the IPCC greenhouse gas emission scenarios A1B or A2, we found that water temperatures at the end of this century may be higher and salinities and oxygen concentrations may be lower than ever measured since 1850. There is also a tendency of increased eutrophication in the future, depending on the nutrient load scenario. Although cod biomass is mainly controlled by fishing mortality, climate change together with eutrophication may result in a biomass decline during the latter part of this century, even when combined with lower fishing pressure. Despite considerable shortcomings of state-of-the-art models, this study suggests that the future Baltic Sea ecosystem may unprecedentedly change compared to the past 150 yr. As stakeholders today pay only little attention to adaptation and mitigation strategies, more information is needed to raise public awareness of the possible impacts of climate change on marine ecosystems.

  • 17. Neuenfeldt, Stefan
    et al.
    Bartolino, Valerio
    Orio, Alessandro
    Andersen, Ken H.
    Andersen, Niels G.
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Bergström, Ulf
    Ustups, Didzis
    Kulatska, Nataliia
    Casini, Michele
    Feeding and growth of Atlantic cod (Gadus morhua L.) in the eastern Baltic Sea under environmental change2020In: ICES Journal of Marine Science, ISSN 1054-3139, E-ISSN 1095-9289, Vol. 77, no 2, p. 624-632Article in journal (Refereed)
    Abstract [en]

    Five decades of stomach content data allowed insight into the development of consumption, diet composition, and resulting somatic growth of Gadus morhua (Atlantic cod) in the eastern Baltic Sea. We show a recent reversal in feeding level over body length. Present feeding levels of small cod indicate severe growth limitation and increased starvation-related mortality. For young cod, the low growth rate and the high mortality rate are manifested through a reduction in size-at-age. The low feeding levels are likely the result of a decrease in benthic prey abundance due to increased hypoxic areas, while decreasing abundances of pelagic species in the area of cod distribution have prevented a compensatory shift in diet. Our study emphasizes that environmental forcing and the decline in pelagic prey caused changes in consumption and growth rates of small cod. The food reduction is amplified by stunted growth leading to high densities of cod of smaller size competing for the scarce resources. The average growth rate is negative, and only individuals with feeding levels well above average will survive, though growing slowly. These results suggest that the relation between consumption rate, somatic growth and predatorprey population densities is strongly environmentally mediated.

  • 18.
    Niiranen, Susa
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Baltic Sea food web dynamics and response to environmental change2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Baltic Sea ecosystem is subject to a combination of external pressures such as fishery, changing climate and land-based nutrient inputs. In combination with internal food web mechanisms these external forces can lead to changes in the food web structure and function. In this licentiate thesis a new Baltic Sea Ecopath with Ecosim food web model for the open Baltic Proper (BaltProWeb) is introduced as a tool to study the past (1974-2006) food web dynamics (paper 1) and the sensitivity of this model to data uncertainties is analyzed (paper 2).

    BaltProWeb includes 22 functional groups from phytoplankton to top-predators, is calibrated with biomass data across trophic levels and can accommodate external forcing such as fishery and environmental change. The model can reproduce the main trends observed in the biomass development of most Baltic Proper functional groups as well as the late 1980s ecosystem reorganization, or regime shift, from the cod (Gadus morhua) dominated state into the sprat (Sprattus sprattus) dominated one. In addition to changes in the functional group biomasses, changes in ecosystem flows were observed. For example the energy flow from the benthic system into the pelagic one (via cod diet) was large during the pre-regime shift period, but decreased in importance after the sharp post-regime shift increase in the sprat biomass. The proportions of both clupeid and zooplankton production required to support the Baltic Sea fisheries were large throughout the model run suggesting that fisheries have potential to be an ecosystem structuring actor in the Baltic Proper. Successful reproduction of the past biomass dynamics required the inclusion of fishery and environmental forcing together with appropriate trophic control during the calibration process. This finding motivates to develop ecosystem models that can incorporate both external pressures as well as internal ecosystem dynamics.

    The BaltProWeb model turned out to be sensitive to uncertainty in both model input data (1974 biomasses) as well as environmental forcing functions used. The functional groups the parameterization of which the model was most sensitive to were, in decreasing order of importance, (i) 2-3 year old cod, (ii) adult sprat, (iii) macrozoobenthos, (iv) Pseudocalanus sp. and (v) other mesozooplankton. Changing the initial biomass values of these groups within the boundaries of input data uncertainty (measured as coefficients of variation) together with model recalibration resulted in a set of new Ecosim models with a rather large range in model fit, biomass projections and trophic control. When future (2007-2100) fishery and climate change scenarios were run using the different models, and by this way taking the uncertainties in the input data into account, the range of model outcomes was yet larger than observed during the calibration period (1974-2006). This indicates that model uncertainties cannot be ignored when modeling results are used as basis for ecosystem management. Further, the results highlight that evaluating the model only based on the model fit with data is not sufficient, but also studying the realized trophic control of different models is crucial and that sensitivity analysis can actually be one tool to study possible trophic control mechanisms with. This sensitivity study gave valuable information about both the model sensitivity and the need to communicate the uncertainties when the BaltProWeb model is used in the project ECOSUPPORT to project the future climate change effects on the Baltic Sea ecosystem.

  • 19.
    Niiranen, Susa
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Multiple forces drive the Baltic Sea food web dynamics and its response to environmental change2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Understanding the interaction of multiple drivers and their compounded effects on ecosystem dynamics is a key challenge for marine resource management. The Baltic Sea is one of the world’s seas most strongly impacted by effects from both human activities and climate. In the late 1980’s changes in climate in combination with intensive fishing initiated a reorganization of the Central Baltic Sea (CBS) food web resulting in the current sprat-dominated state. In the future, climate change is projected to cause drastic changes in hydrodynamic conditions of the world oceans in general, and the Baltic Sea in particular.  

    In this thesis, CBS food web responses to the combined effects of fishing, nutrient loads and climate were tested for the past (1974-2006) and projected into the future (2010-2098). A new food web model for the CBS (BaltProWeb) was developed using extensive monitoring data across trophic levels. This model described the past food web dynamics well, and was hence also used for future (2010-2098) projections. Different ensemble modeling approaches were employed when testing the food web response to future scenarios.

    The results show that regardless the climate change, the management of nutrient loads and cod fishing are likely to determine the food web dynamics and trophic control mechanisms in the future Baltic Sea. Consequently, the variation in the food web projections was large, ranging from a strongly eutrophied and sprat-dominated to a cod-dominated CBS with eutrophication levels close to today’s values. The results also suggest a potential risk of abrupt ecosystem changes in the future CBS, particularly if the nutrient loads are not reduced. Finally, the studies illustrate the usefulness of the ensemble modeling approach, both from the perspective of ecosystem-based management as well as for studying the importance of different mechanisms in the ecosystem response.

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  • 20.
    Niiranen, Susa
    et al.
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Blenckner, Thorsten
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Hjerne, Olle
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Tomczak, Maciej T.
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Uncertainties in a Baltic Sea Food-Web Model Reveal Challenges for Future Projections2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 6, p. 613-625Article in journal (Refereed)
    Abstract [en]

    Models that can project ecosystem dynamics under changing environmental conditions are in high demand. The application of such models, however, requires model validation together with analyses of model uncertainties, which are both often overlooked. We carried out a simplified model uncertainty and sensitivity analysis on an Ecopath with Ecosim food-web model of the Baltic Proper (BaltProWeb) and found the model sensitive to both variations in the input data of pre-identified key groups and environmental forcing. Model uncertainties grew particularly high in future climate change scenarios. For example, cod fishery recommendations that resulted in viable stocks in the original model failed after data uncertainties were introduced. In addition, addressing the trophic control dynamics produced by the food-web model proved as a useful tool for both model validation, and for studying the food-web function. These results indicate that presenting model uncertainties is necessary to alleviate ecological surprises in marine ecosystem management.

  • 21.
    Niiranen, Susa
    et al.
    Stockholm University, Stockholm Resilience Centre.
    Blenckner, Thorsten
    Stockholm University, Stockholm Resilience Centre.
    Yletyinen, Johanna
    Stockholm University, Stockholm Resilience Centre.
    Otto, Saskia
    Stockholm University, Stockholm Resilience Centre.
    Meier, H. E. Markus
    Stockholm University, Faculty of Science, Department of Meteorology .
    Hjerne, Olle
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Tomczak, Maciej T
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    The potential risk of regime shifts and changes in ecosystem dynamics in the future Baltic SeaArticle in journal (Refereed)
  • 22.
    Niiranen, Susa
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Orio, A.
    Bartolino, V.
    Bergström, U.
    Kallasvuo, M.
    Neuenfeldt, S.
    Ustups, D.
    Casini, M.
    Predator−prey body size relationships of cod in a low-diversity marine system2019In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 627, p. 201-206Article in journal (Refereed)
    Abstract [en]

    How predators select their prey largely defines ecosystem trophic structure, function and dynamics. In aquatic systems, organism body size is an important trait explaining predator− prey interactions. Here, we used a unique Atlantic cod Gadus morhua stomach content dataset with diet information from over 100 000 individuals collected from the Baltic Sea in 1963−2014, to explore prey size distribution and predator−prey mass ratios in the diet of Eastern Baltic cod. Maximum and average prey sizes increased with predator size, as for cod in other systems. However, the prey size spectra found in Eastern Baltic cod stomachs reflect the low species diversity in the Baltic Sea. In general, Eastern Baltic cod feed on smaller prey in relation to their body size than other cod populations. Due to the truncated prey size distribution in the Baltic Sea, cod cannibalism functions as a compensatory mechanism that allows Baltic cod to reach their prey size potential. On the other hand, small- and intermediate-sized cod prey mainly on a few invertebrate prey species, potentially making them vulnerable to changes in these prey populations. Our results encourage further studies disentangling the relative effects of prey preference and prey availability on cod trophodynamics in species-poor systems such as the Baltic Sea. 

  • 23.
    Niiranen, Susa
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Richter, A.
    Blenckner, Thorsten
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Stige, L. C.
    Valmarn, Matilda
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Eikeset, A. -M.
    Global connectivity and cross-scale interactions create uncertainty for Blue Growth of Arctic fisheries2018In: Marine Policy, ISSN 0308-597X, E-ISSN 1872-9460, Vol. 87, p. 321-330Article in journal (Refereed)
    Abstract [en]

    The Arctic faces high expectations of Blue Growth due to future projections of easier access and increased biological productivity. These expectations are, however, often based on global and regional climate change projections and largely ignore the complexity of social-ecological interactions taking place across different temporal and spatial scales. This paper illustrates how such cross-scale interactions at, and across, different dimensions (e.g., ecological, socioeconomic and governance) can affect the development of Arctic fisheries; and potentially create uncertainties for future Blue Growth projections. Two Arctic marine systems, The Barents Sea and the Central Arctic Ocean (CAO), are used as focus areas. The former hosts productive fisheries and is mostly covered by the EEZs of Norway and Russia, while the latter is still mainly covered by sea-ice and is a high seas area with no multilevel governance system in place. The examples show that, both systems are affected by a number of processes, beyond the environmental change, spanning a wide range of dimensions, as well as spatial and temporal scales. To address the complexity of the Arctic marine systems calls for an increase in holistic scientific understanding together with adaptive management practices. This is particularly important in the CAO, where no robust regional management structures are in place. Recognizing how cross-scale dynamics can cause uncertainties to the current fisheries projections and implementing well-functioning adaptive management structures across different Arctic sub-systems can play a key role in whether the Blue Growth potential in Arctic fisheries is realized or lost.

  • 24.
    Niiranen, Susa
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Yletyinen, Johanna
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. University of Olso, Norway.
    Tomczak, Maciej T.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre, Baltic Nest Institute.
    Blenckner, Thorsten
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Hjerne, Olle
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    MacKenzie, Brian R.
    Müller-Karulis, Bärbel
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre, Baltic Nest Institute.
    Neumann, Thomas
    Meier, H. E. Markus
    Stockholm University, Faculty of Science, Department of Meteorology . Swedish Meteorological and Hydrological Institute, Sweden.
    Combined effects of global climate change and regional ecosystem drivers on an exploited marine food web2013In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 19, no 11, p. 3327-3342Article in journal (Refereed)
    Abstract [en]

    Changes in climate, in combination with intensive exploitation of marine resources, have caused large-scale reorganizations in many of the world's marine ecosystems during the past decades. The Baltic Sea in Northern Europe is one of the systems most affected. In addition to being exposed to persistent eutrophication, intensive fishing, and one of the world's fastest rates of warming in the last two decades of the 20th century, accelerated climate change including atmospheric warming and changes in precipitation is projected for this region during the 21st century. Here, we used a new multi-model approach to project how the interaction of climate, nutrient loads and cod fishing may affect the future of the open Central Baltic Sea food web. Regionally downscaled global climate scenarios were, in combination with three nutrient load scenarios, used to drive an ensemble of three regional biogeochemical models (BGMs). An Ecopath with Ecosim food web model was then forced with the BGM results from different nutrient-climate scenarios in combination with two different cod fishing scenarios. The results showed that regional management is likely to play a major role in determining the future of the Baltic Sea ecosystem. By the end of the 21st century, for example, the combination of intensive cod fishing and high nutrient loads projected a strongly eutrophicated and sprat-dominated ecosystem, while low cod fishing in combination with low nutrient loads resulted in a cod-dominated ecosystem with eutrophication levels close to present. Also, non-linearities were observed in the sensitivity of different trophic groups to nutrient loads or fishing depending on the combination of the two. Finally, many climate variables and species biomasses were projected to levels unseen in the past. Hence, the risk for ecological surprises needs to be addressed, particularly when the results are discussed in the ecosystem-based management context.

  • 25. Otto, Saskia A.
    et al.
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Blenckner, Thorsten
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Tomczak, Maciej T.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Müller-Karulis, Bärbel
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Rubene, Gunta
    Möllmann, Christian
    Life Cycle Dynamics of a Key Marine Species Under Multiple Stressors2020In: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 7, article id 296Article in journal (Refereed)
    Abstract [en]

    Identifying key indicator species, their life cycle dynamics and the multiple driving forces they are affected by is an important step in ecosystem-based management. Similarly important is understanding how environmental changes and trophic interactions shape future trajectories of key species with potential implications for ecosystem state and service provision. We here present a statistical modeling framework to assess and quantify cumulative effects on the long-term dynamics of the copepod Pseudocalanus acuspes, a key species in the Baltic Sea. Our model integrates linear and non-linear responses to changes in life stage density, climate and predation pressure as well as stochastic processes. We use the integrated life cycle model to simulate copepod dynamics under a combination of stressor scenarios and to identify conditions under which population responses are potentially mitigated or magnified. Our novel modeling approach reliably captures the historical P. acuspes population dynamics and allows us to identify females in spring and younger copepodites in summer as stages most sensitive to direct and indirect effects of the main environmental stressors, salinity and temperature. Our model simulations furthermore demonstrate that population responses to stressors are dampened through density effects. Multiple stressor interactions were mostly additive except when acting on the same life stage. Here, negative synergistic and positive dampening effects lead to a lower total population size than expected under additive interactions. As a consequence, we found that a favorable increase of oxygen and phosphate conditions together with a reduction in predation pressure by 50% each could counteract the negative effect of a 25% decrease in salinity by only 6%. Ultimately, our simulations suggest that P. acuspes will most certainly decline under a potential freshening of the Baltic Sea and increasing temperatures, which is conditional on the extent of the assumed climate change. Also the planned nutrient reduction strategy and fishery management plan will not necessarily benefit the temporal development of P. acuspes. Moving forward, there is a growing opportunity for using population modeling in cumulative effects assessments. Our modeling framework can help here as simple tool for species with a discrete life cycle to explore stressor interactions and the safe operating space under future climate change.

  • 26. Pedreschi, Debbi
    et al.
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Skern-Mauritzen, Mette
    Reid, David G.
    Operationalising ODEMM risk assessment for Integrated Ecosystem Assessment scoping: Complexity vs. manageability2023In: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 9, article id 1037878Article in journal (Refereed)
    Abstract [en]

    Integrated Ecosystem Assessments (IEA) require consideration of the full suite of pressures and impacts affecting ecosystems. However, capacity limitations often severely limit our ability to do everything that we want or 'should' do, outside of short-term fully-funded focused research projects. In order to make IEA a reality in many contexts, priority consideration has to be given to how to achieve such comprehensive assessments. Ecoregions and Large Marine Ecosystems (LMEs) have been identified as potential management units, however these large areas encompass diverse habitats, and multiple nations with diverse human communities and use of marine environments, and a multitude of different management strategies. In this context, how can we make IEA an operational tool that can be applied at such high-level in a comparable, yet regionally-relevant adaptable approach? This paper outlines the demonstration and adaptation of an established risk assessment approach (Options for Delivering Ecosystem-Based Marine Management: ODEMM) to a rapid risk scoping tool, and how this approach has been applied using open source common analytical tools to improve operationality in both the Mission Atlantic project and the International Council for the Exploration of the Seas (ICES) Integrated Ecosystem Assessment Working Groups. Furthermore, a hierarchical approach is detailed that allows the integration of different levels of detail into a common format. The resulting assessments are then ground-truthed with stakeholders to identify issues, omissions, potential conflicts, and key areas of interest for the next steps of the IEA process.

  • 27. Planque, Benjamin
    et al.
    Mullon, Christian
    Arneberg, Per
    Eide, Arne
    Fromentin, Jean-Marc
    Heymans, Johanna Jacomina
    Hoel, Alf Håkon
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Ottersen, Geir
    Sandø, Anne Britt
    Sommerkorn, Martin
    Thébaud, Olivier
    Thorvik, Thorbjørn
    A participatory scenario method to explore the future of marine social-ecological systems2019In: Fish and Fisheries, ISSN 1467-2960, E-ISSN 1467-2979, Vol. 20, no 3, p. 434-451Article in journal (Refereed)
    Abstract [en]

    Anticipating future changes in marine social-ecological systems (MSES) several decades into the future is essential in the context of accelerating global change. This is challenging in situations where actors do not share common understandings, practices, or visions about the future. We introduce a dedicated scenario method for the development of MSES scenarios in a participatory context. The objective is to allow different actors to jointly develop scenarios which contain their multiple visions of the future. The method starts from four perspectives: fisheries management, ecosystem, ocean climate, and global context and governance for which current status and recent trends are summarized. Contrasted scenarios about possible futures are elaborated for each of the four single perspectives before being integrated into multiple-perspective scenarios. Selected scenarios are then developed into storylines. Focusing on individual perspectives until near the end allows actors with diverse cultures, interests and horizons to confront their own notions of the future. We illustrate the method with the exploration of the futures of the Barents Sea MSES by 2050. We emphasize the following lessons learned: first, many actors are not familiar with scenario building and attention must be paid to explaining the purpose, methodology, and benefits of scenarios exercises. Second, although the Barents Sea MSES is relatively well understood, uncertainties about its future are significant. Third, it is important to focus on unlikely events. Fourth, all perspectives should be treated equally. Fifth, as MSES are continuously changing, we can only be prepared for future changes if we collectively keep preparing.

  • 28.
    Scharin, Henrik
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Swedish Environmental Protection Agency, Sweden.
    Ericsdotter, Siv
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Elliott, Michael
    Turner, R. Kerry
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Blenckner, Thorsten
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Hyytiäinen, Kari
    Ahlvik, Lassi
    Ahtiainen, Heini
    Artell, Janne
    Hasselström, Linus
    Söderqvist, Tore
    Rockström, Johan
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Processes for the sustainable stewardship of marine environments2016In: Ecological Economics, ISSN 0921-8009, E-ISSN 1873-6106, Vol. 128, p. 55-67Article in journal (Refereed)
    Abstract [en]

    Sustainable stewardship of the marine environment necessitates a holistic approach encompassing all the relevant drivers, activities and pressures causing problems for the natural state of the system and their impact on human societies today and in the future. This article provides a framework as well as a decision support process and tool that could guide such an approach. In this process, identifying costs and benefits of mitigation is a first step in deciding on measures and enabling instruments, which has to be accompanied by analyses regarding distributional effects (i.e. who gains or loses) related to different targets and policy instruments. As there are risks of future irreversible regime shifts and even system collapses, the assessments have to be broadened to include scenarios on possible future developments as well as ethical considerations. In particular, a deeper sustainable management strategy may be needed to respond to possible future increases in the rate of environmental change, amongst growing evidence of external pressures, interactions and non-linear dynamics. This adaptive management strategy should focus on building the resilience required to cope with and adapt to change.

  • 29.
    Snoeijs-Leijonmalm, Pauline
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Flores, Hauke
    Volckaert, Filip
    Niehoff, Barbara
    Schaafsma, Fokje L.
    Hjelm, Joakim
    Hentati-Sundberg, Jonas
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Crépin, Anne-Sophie
    Österblom, Henrik
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Review of the research knowledge and gaps on fish populations, fisheries and linked ecosystems in the Central Arctic Ocean (CAO)2020Report (Other academic)
    Abstract [en]

    This report presents a review of the research knowledge and gaps on fish populations, fisheries and linked ecosystems in the Central Arctic Ocean (CAO). The CAO comprises the deep basins of the Arctic Ocean beyond the shelf break, which largely overlap with the High Seas of the Arctic Ocean, i.e. the marine areas outside the Exclusive Economic Zones (EEZs) of the Arctic coastal nations. The authors of the report are members of the European Fisheries Inventory in the Central Arctic Ocean (EFICA) Consortium. This study was funded by the European Commission as an EU contribution to the international cooperation within the Agreement to Prevent Unregulated High Seas Fisheries in the Central Arctic Ocean.

  • 30. Tittensor, Derek P.
    et al.
    Eddy, Tyler D.
    Lotze, Heike K.
    Galbraith, Eric D.
    Cheung, William
    Barange, Manuel
    Blanchard, Julia L.
    Bopp, Laurent
    Bryndum-Buchholz, Andrea
    Buechner, Matthias
    Bulman, Catherine
    Carozza, David A.
    Christensen, Villy
    Coll, Marta
    Dunne, John P.
    Fernandes, Jose A.
    Fulton, Elizabeth A.
    Hobday, Alistair J.
    Huber, Veronika
    Jennings, Simon
    Jones, Miranda
    Lehodey, Patrick
    Link, Jason S.
    Mackinson, Steve
    Maury, Olivier
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Oliveros-Ramos, Ricardo
    Roy, Tilla
    Schewe, Jacob
    Shin, Yunne-Jai
    Silva, Tiago
    Stock, Charles A.
    Steenbeek, Jeroen
    Underwood, Philip J.
    Volkholz, Jan
    Watson, James R.
    Walker, Nicola D.
    A protocol for the intercomparison of marine fishery and ecosystem models: Fish-MIP v1.02018In: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 11, no 4, p. 1421-1442Article in journal (Refereed)
    Abstract [en]

    Model intercomparison studies in the climate and Earth sciences communities have been crucial to building credibility and coherence for future projections. They have quantified variability among models, spurred model development, contrasted within- and among-model uncertainty, assessed model fits to historical data, and provided ensemble projections of future change under specified scenarios. Given the speed and magnitude of anthropogenic change in the marine environment and the consequent effects on food security, biodiversity, marine industries, and society, the time is ripe for similar comparisons among models of fisheries and marine ecosystems. Here, we describe the Fisheries and Marine Ecosystem Model Intercomparison Project protocol version 1.0 (Fish-MIP v1.0), part of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP), which is a cross-sectoral network of climate impact modellers. Given the complexity of the marine ecosystem, this class of models has substantial heterogeneity of purpose, scope, theoretical underpinning, processes considered, parameterizations, resolution (grain size), and spatial extent. This heterogeneity reflects the lack of a unified understanding of the marine ecosystem and implies that the assemblage of all models is more likely to include a greater number of relevant processes than any single model. The current Fish-MIP protocol is designed to allow these heterogeneous models to be forced with common Earth System Model (ESM) Coupled Model Intercomparison Project Phase 5 (CMIP5) outputs under prescribed scenarios for historic (from the 1950s) and future (to 2100) time periods; it will be adapted to CMIP phase 6 (CMIP6) in future iterations. It also describes a standardized set of outputs for each participating Fish-MIP model to produce. This enables the broad characterization of differences between and uncertainties within models and projections when assessing climate and fisheries impacts on marine ecosystems and the services they provide. The systematic generation, collation, and comparison of results from Fish-MIP will inform an understanding of the range of plausible changes in marine ecosystems and improve our capacity to define and convey the strengths and weaknesses of model-based advice on future states of marine ecosystems and fisheries. Ultimately, Fish-MIP represents a step towards bringing together the marine ecosystem modelling community to produce consistent ensemble medium- and long-term projections of marine ecosystems.

  • 31.
    Tomczak, Macief
    et al.
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Niiranen, Susa
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute. Stockholm University, Faculty of Science, Department of Systems Ecology.
    Hjerne, Olle
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Blenckner, Thorsten
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Ecosystem flow dynamics in the Baltic Proper-Using a multi-trophic dataset as a basis for food-web modelling2012In: Ecological Modelling, ISSN 0304-3800, E-ISSN 1872-7026, Vol. 230, p. 123-147Article in journal (Refereed)
    Abstract [en]

    The Baltic Proper is a semi-enclosed, highly productive basin of the Baltic Sea with a low biodiversity, where only a few key species drive the system's dynamics. Recently, an ecosystem regime shift was described having pronounced changes at all trophic levels, driven by changes in fishery and climate and leading to a food-web reorganisation. An Ecopath with Ecosim Baltic Proper food-web model (BaltProWeb) was developed to simulate and better understand trophic interactions and their flows. The model contains 22 functional groups that represent the main food-web components. BaltProWeb was calibrated to long-term monitoring data (1974-2006), covering multiple trophic levels and is forced by fisheries and environmental drivers. Our model enables the quantification of the flows through the food-web from primary producers to top predators including fisheries over time. The model is able to explain 51% of the variation in biomass of multiple trophic levels and to simulate the regime shift from a cod dominated to a sprat dominated system. Results show a change from benthic to more pelagic trophic flows. Before the reorganisation macrozoobenthos was identified as an important functional group transferring energy directly from lower trophic levels to top predators. After the regime shift, the pelagic trophic flows dominated. Uncertainties and limitations of the modelling approach and results in relation to ecosystem-based management are discussed.

  • 32.
    Tomczak, Maciej T.
    et al.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre, Baltic Nest Institute.
    Heymans, Johanna J.
    Yletyinen, Johanna
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Nordic Centre for Research on Marine Ecosystems and Resources under Climate Change ((NorMER).
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Otto, Saskia A.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Blenckner, Thorsten
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Ecological Network Indicators of Ecosystem Status and Change in the Baltic Sea2013In: PLOS ONE, E-ISSN 1932-6203, Vol. 8, no 10, article id e75439Article in journal (Refereed)
    Abstract [en]

    Several marine ecosystems under anthropogenic pressure have experienced shifts from one ecological state to another. In the central Baltic Sea, the regime shift of the 1980s has been associated with food-web reorganization and redirection of energy flow pathways. These long-term dynamics from 1974 to 2006 have been simulated here using a food-web model forced by climate and fishing. Ecological network analysis was performed to calculate indices of ecosystem change. The model replicated the regime shift. The analyses of indicators suggested that the system's resilience was higher prior to 1988 and lower thereafter. The ecosystem topology also changed from a web-like structure to a linearized food-web.

  • 33. Uusitalo, Laura
    et al.
    Korpinen, Samuli
    Andersen, Jesper H.
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Valanko, Sebastian
    Heiskanen, Anna-Stiina
    Dickey-Collas, Mark
    Exploring methods for predicting multiple pressures on ecosystem recovery: A case study on marine eutrophication and fisheries2016In: Continental Shelf Research, ISSN 0278-4343, E-ISSN 1873-6955, Vol. 121, p. 48-60Article in journal (Refereed)
    Abstract [en]

    Efforts to attain good environmental status in the marine realm require decisions which cannot be done without knowledge of effects of different management measures. Given the wide diversity of marine ecosystems, multitude of pressures affecting it and the still poor understanding on linkages between those, there are likely no models available to give all the required answers. Hence, several separate approaches can be used in parallel to give support for management measures. We tested three completely different methods - a spatial impact index, a food web model and a Bayesian expert method. We found that a large uncertainty existed regarding the ecosystem response to the management scenarios, and that the three different modelling approaches complemented each other. The models indicated that in order to reach an improved overall state of the ecosystem nutrient reductions are the more effective of the two management variables explored, and that cumulative effects of the management of nutrient inputs and fishing mortality are likely to exist.

1 - 33 of 33
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