| 1. |
- Yletyinen, Johanna, 1977-
(författare)
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The Impact of Multiple Drivers on Marine Systems : Novel approaches for studying structural changes
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Human action is transforming the species composition, biogeochemistry and habitats of the world’s oceans at unprecedented rates. The cumulative effect of natural and anthropogenic drivers is challenging to measure, in part due to indirect effects and the complexity of marine systems. Building on the theory of complex adaptive systems, this thesis aims to increase our understanding of how complex, heterogeneous marine social-ecological systems (SES) may respond to changing conditions. This thesis integrates resilience research with network science and describes change and structural patterns at several SES scales in order to advance our knowledge on the effects of multiple drivers.Paper I proposes a new, quantitative fish stock collapse definition, that accounts for fish stock dynamics and enables standardization and thus comparability across a large number of commercial fish stocks. Recognizing that substantial ecosystem changes are part of SES dynamics, in Paper II we review marine regime shifts worldwide to specify how co-occurring bundles of drivers are related to degraded ecosystem services for management purposes. A more detailed ecological study on regime shifts was performed in Papers III and IV. Paper III describes the late-1980s central Baltic Sea regime shift based on a food-web model. Paper IV uses a novel structural network analysis approach to detect functional shifts in complex food webs. The results of Paper IV imply that the Baltic Sea regime shift may not be a systemwide shift. Paper V uses a network approach to analyze fishing strategy diversification and social-ecological connectivity among Swedish Baltic Sea fishers, indicating that natural resource management evaluations should not be limited only to ecosystem conditions but also take account of social conditions.Overall, this thesis provides empirical evidence for the emerging perspective that marine resource science and management must account for the complexity of system elements in order to ensure the provision of ecosystem services in the future. The first application of Exponential Random Graph Modeling in ecology and an improved fish stock collapse definition provide new advanced tools for studying oceans from an SES perspective in the future.
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| 2. |
- Björkvik, Emma, 1987-
(författare)
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Stewardship in Swedish Baltic small-scale fisheries : A study on the social-ecological dynamics of local resource use
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sustainability scholars frequently advocate for stewardship as a strategy to foster sustainable development. Stewardship broadly refers to the wise and responsible use of nature, and is considered necessary to ensure the long-term wellbeing of humans and that of life in general. In the academic literature local resource users, like hunters, farmers or fishers, are widely acknowledged to act as stewards of the natural environments their livelihoods depend upon. Research shows that this group of people often are able to use natural resources in a sustainable manner, and that their knowledge of how to do so can improve natural resource management. However, research also emphasizes how different local resource users have different potential to steward natural environments. There is thus a need to better understand what stewardship among local resource users entails more concretely as well as when and how it fosters environmental sustainability. In this thesis, I study stewardship in the case of Swedish Baltic small-scale fisheries. I conceptualize stewardship as an interaction between fishers and the social-ecological context in which they are embedded. This conceptualization implies that stewardship does not exist or emerge from within fishers themselves, but is created, formed and realized through fishing practices. I further define and analyze stewardship using a framework composed of three dimensions: care, agency and knowledge. My findings are contained in four papers. Paper I presents a theoretical model of how local resource users respond to social and ecological change, and shows the model’s empirical relevance. Paper II gives an overview of the diversity and development within present-day Swedish Baltic small-scale fisheries. Paper III investigates the historical development of a Swedish fishery that targets the critically endangered European eel (Anguilla anguilla). Paper IV focuses on fishers’ knowledge and assesses how this knowledge can be applied in fisheries science and management. The papers collectively demonstrate the contextual nature of stewardship and showcase how stewardship varies over time as well as between fishers. The findings illustrate the ambiguous link between stewardship and environmental sustainability, they support the notion that fishers’ knowledge can improve fisheries management, while also suggesting that future research needs to pay more attention to how stewardship is empirically manifested. Overall, the thesis advances the understanding of stewardship by highlighting the social-ecological dynamics of local resource use.
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| 3. |
- Bryhn, Andreas Christoffer, 1971-
(författare)
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Quantitative Understanding and Prediction of Lake Eutrophication
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many lakes around the world have been exposed to increased nutrient input from anthropogenic sources such as sewage discharge and runoff from fertilised agricultural areas. This has led to eutrophication, manifested as intensified algal blooms, murky waters, oxygen depleted lake bottoms, and alterations of considerable parts of the foodweb. However, many of these lakes have also recovered, due to improved nutrient abatement techniques and to an improved quantitative scientific understanding of eutrophication and its causes. General, predictive models have played a crucial role in the latter development, as they have made it possible to quantitatively assess expected ecosystem changes from various planned actions against eutrophication. The present thesis has been aimed at improving the domain of validity and predictive power of a general, dynamic total phosphorus (TP) model (LakeMab) and to provide the basis for constructing a similar model for total nitrogen (TN). Among the findings in the thesis is that dissolved nitrogen gas is probably always available in excess for nitrogen fixation and nitrogen modelling in eutrophication contexts. Two papers have laid the ground for improved nutrient modelling in calcareous lakes, where sedimentation is particularly pronounced. Static models for predicting concentrations of particulate phosphorus, nitrogen, and organic carbon have been presented that may be incorporated into sedimentation algorithms in dynamic nutrient models. Boundary conditions for various flux algorithms have made it possible to greatly expand the domain of LakeMab for TP. The typical uncertainty of TP concentration values is 17% when predicted with LakeMab, whereas the uncertainty in predictions using older, static models is about twice as high. LakeMab may be very useful for resolving practical issues such as predicting climate-induced eutrophication and drawing up operational guidelines for achieving good water quality as prescribed by, e.g., the European Water Framework Directive.
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| 4. |
- Kadin, Martina, 1981-
(författare)
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Seabirds as food for thought : An integrative study on seabird ecology and ecosystem services in changing marine systems
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The importance of the benefits that humans obtain from the oceans is increasingly recognized, along with the rapid decline in marine resources that threatens these benefits. Studying seabirds – top predators in marine ecosystems, can provide insights about multiple pressures and the state of the oceans. The thesis links studies of seabirds through the lens of ecosystem services with an ecological case study. Paper I reviews ecosystem services, finding that seabirds contribute to provisioning, regulating, supporting and cultural services. Seabirds serve as mobile links in marine and terrestrial ecosystems, through regulating and supporting services. Further, scientific knowledge and indicators based on seabirds can be seen as an ecosystem service as they facilitate management. Papers II-IV proceed to build such knowledge about the importance of food quality and quantity for breeding seabirds, in particular common murres Uria aalge in the Baltic Sea. Here, there is a negative relationship between quantity (sprat Sprattus sprattus abundance) and quality (sprat weight-at-age). Quality, but not quantity, was positively related to common murre fledging success while parental foraging trips had shorter duration when quantity was higher, but showed no relationship with food quality (paper II). Paper III describes foraging behaviour of adults and found indications of good foraging conditions at sea. Parents made efforts to adjust provisioning of food according to the needs of the chicks (paper IV), but the adjustments did not seem to be enough to counteract the impact of lower food quality. Paper V explores ecosystem services obtained from seabirds over time identifying a shift from provisioning to cultural services, where current cultural services are often connected. The integration of ecosystem services with seabird ecology shows that seabirds are illustrative of changes in marine resources and provide ways to help people reconnect with the health of marine systems.
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| 5. |
- Niiranen, Susa, 1982-
(författare)
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Baltic Sea food web dynamics and response to environmental change
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 6. |
- Niiranen, Susa, 1982-
(författare)
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Multiple forces drive the Baltic Sea food web dynamics and its response to environmental change
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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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| 7. |
- Orach, Kirill, 1987-
(författare)
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Understanding interest politics in social-ecological systems : Mechanisms behind emergent policy responses to environmental change
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Environmental policymaking is embedded in social-ecological systems (SES) that continuously evolve and change, often in unexpected and non-linear ways. Such challenges call for responsive policymaking that adjusts policy when new information and knowledge about social-ecological change is available. However, policy adaptation can be difficult as policies often emerge as an outcome of multiple interactions between state and non-state actors that pursue their different interests, aim to achieve their individual and shared goals and make sense of information and knowledge. Complexities inherent in SES can be better captured through diverse types of information and knowledge, while adaptation to social-ecological change can occur through innovation and learning. Research has emphasized the contribution of non-state actors or interest groups in realizing such processes in policymaking. However, interest group participation can also be a source of conflict or result in dominance of powerful interests and resistance to learning and policy change. This thesis aims to shed light on the dynamics of the policy process in social-ecological systems to better understand some of the mechanisms that drive its responsiveness to social-ecological change. It focuses on interest groups and their properties as well as the social and ecological conditions of their participation in the policy process to investigate how responsive and sustainable policies can emerge out of the “messy” political struggle. The thesis first explores the case of 2013 EU Common Fisheries Policy (CFP) reform to trace the mechanism of interest group influence and identify their contribution to the flow of information from SES. Further it applies the empirical mechanism in an agent-based model to: 1) test the scope conditions of the mechanism; 2) extend it to include interest group responses to change in the managed SES. Paper I of the thesis analyses theoretical frameworks of the policy process originating in public policy research to assess their suitability for capturing political complexity in SES governance research. Paper II looks at the CFP reform case, using process tracing to understand how interest groups have been able to achieve influence on the reform. Paper III further investigates the case to find the role of interest groups in shaping information flows within the policy process. Paper IV uses empirical findings in Papers II and III, along with frameworks analyzed in Paper I to develop an agent-based model that explores how individual characteristics of political actors in interaction with political conditions and issue characteristics influence the responsiveness of the policy process and result in sustainable outcomes. I find that through interest group participation policies can better respond to change in the managed SES; however structural factors (such as presence of institutional ‘window of opportunity’, issue salience and beliefs of policymakers) can make the response adverse or weaken it. Interest groups also engage in transmitting and interpreting diverse information about policy impacts, social and ecological context of the issue and use framing to convey information that better supports their proposals.
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