Christina Hoerterer

Coastal social-ecological systems worldwide are strongly affected by climate change and its impacts, such as the intensified occurrence of extreme events. In the marine realm, the increased manifestation and expansion of marine biological hazards, such as harmful cyanobacteria blooms, pathogenic vibrio as well as the occurrence of hypoxia, cause far-reaching socio-economic impacts. Addressing these impacts requires a coordinated response from key actors, implementing strategies that promote sustainable and resilient pathways. In the transdisciplinary research project PrimePrevention this challenge is addressed across the western Baltic Sea. We adopt a systems-view on coastal governance, which includes the rules, institutions and processes that drive a response to prevent and minimise socio-economic impacts of marine extreme events. In this context, we want to understand how different stakeholders influence different governance processes, and how this influence can be characterised. While social capital is already broadly used to investigate stakeholder networks, it is not the only capacity that actors need to influence decision-making or governance processes, and therefore to have agency. For example, technical knowledge and access to critical scientific data are equally crucial in shaping effective policies and interventions. We therefore use the concepts of human agency and a capitals approach while harnessing network analysis as a methodological bridging element. We present and discuss an application of the approach in a living lab at the German Baltic Sea, where we investigate actor networks and decision-making mechanisms for the improved monitoring of biological hazards and the prevention of subsequent socio-economic consequences. The study advances current understandings of how actors intervene in governance systems to ultimately increase the resilience of coastal social-ecological systems to climate change and its associated impacts. Furthermore, the presented approach can be adopted for different problem framings in the context of generating actionable knowledge for the sustainable management of coasts and the ocean.

In today's complex and dynamic society, the integration of science, policy, and society through inclusive interfaces is crucial for the successful co-development and transfer of knowledge that transcends disciplinary boundaries. Under the umbrella of the transdisciplinary project PrimePrevention that applies a living lab approach along the German Baltic Sea, we bring together a broad range of societal users and interest groups to work towards the mitigation of marine biological hazards such as harmful microorganisms and hypoxia. To ensure appropriate supportive processes and conditions of impact creation, we systematically examine and evaluate the effectiveness of various knowledge transfer processes in two living labs, focusing on three key aspects. Firstly, we identify factors that foster active and meaningful involvement of stakeholders in the production and utilization of knowledge. This includes highlighting the role of participatory methods and co-production of knowledge. Secondly, we investigate the mechanisms that ensure accountability of the knowledge transfer process to relevant stakeholders. This involves analyzing the responsibilities and roles of all involved actors, as well as the transparency and traceability of the knowledge transfer process. Thirdly, we evaluate factors that influence stakeholders' perceptions regarding the relevance, credibility, and legitimacy of the knowledge transfer process. This includes trust-building measures, communication strategies, and consideration of cultural and social contexts. The aim of this study is to identify the conditions and practices that enable effective collaboration between science, policy, and society within the living labs with a given problem-focus, in our case the mitigation of marine biohazards. By analyzing these aspects, we formulate recommendations to improve knowledge transfer processes and strengthen inclusive science-society interfaces. Ultimately, this will contribute to informed decision-making and sustainable solutions for societal challenges such as the expected increase in marine biological hazards.

Circular economy driven feed ingredients and emerging protein sources, such as insects and microbial meals, has the potential to partially replace fishmeal in diets of high-trophic fish. Even though growth and feed performance are often unaffected at low inclusion levels, the metabolic effects are unknown. This study examined the metabolic response of juvenile turbot (Scophthalmus maximus) to diets with graded fishmeal replacement with plant, animal, and emerging protein sources (PLANT, PAP, and MIX) in comparison to a commercial-like diet (CTRL). A ¹H-nuclear magnetic resonance (NMR) spectroscopy was used to assess the metabolic profiles of muscle and liver tissue after feeding the fish the experimental diets for 16 weeks. The comparative approach revealed a decrease in metabolites that are associated with energy deficiency in both tissues of fish fed with fishmeal-reduced diets compared to the commercial-like diet (CTRL). Since growth and feeding performance were unaffected, the observed metabolic response suggests that the balanced feed formulations, especially at lower fishmeal replacement levels, have the potential for industry application.

One part of aquaculture sustainability is reducing the environmental footprint of aquaculture feeds. For European aquaculture, this means finding feed ingredients that are produced within the economic community, and that are not in conflict with human consumption. This is especially challenging when formulating diets for carnivorous fish such as turbot with low tolerance to fishmeal replacement that are both nutritious and economically and environmentally sustainable. Therefore, we investigated the effects of two novel and innovative feed formulation concepts on growth and feed performance and the nutritional status of market-sized turbot in a recirculating aquaculture system. In a 16-week feeding trial, 440 turbot (300 ± 9 g) were fed twice a day with a control diet (CTRL), based on a commercial formulation, and four experimental diets. The experimental diets were designed to investigate the effects of two formulations concepts based on sustainable terrestrial plant proteins (NoPAP) or processed animal proteins (PAP) and of 30% and 60% fishmeal replacement with emerging feed ingredients (fisheries by-products, insect meal and fermentation biomass). Turbot from the CTRL group had a similar growth and feed performance than fish fed the NoPAP30 formulation, with a significant decline of performance in the fish fed both PAP formulations and the NoPAP60. Comparing the two formulation concepts with each other the voluntary feed intake and protein efficiency ratio on tank basis as well as the individual weight gain and relative growth rate was significantly higher in the fish from the NoPAP groups than PAP groups. Furthermore, the apparent digestibility of nutrients and minerals was significantly reduced in the fish fed with the diets with 30% and 60% fishmeal replacement level compared to the fish from the CTRL group. In conclusion, the performance of the fish fed the NoPAP30 formulation concept highlights the potential of the used combination of sustainable ingredients, such as fisheries by-products, insect meal, microbial biomass and plant protein for turbot. Furthermore, this study shows that turbot has a higher tolerance to the incorporation of plant and insect protein than of processed animal protein.

There is an increasing need in the aquaculture industry for more sustainable and functional feed concepts for marine finfish. This study provides results for the effect of alternative feed formulations on health status, welfare parameters, sensory analysis, and growth performance in European seabass (Dicentrarchus labrax) over an 83-day feeding trial. Fish were fed twice a day with five experimental diets. A control diet (control) and four different alternative feed concepts rich in processed animal proteins (PAP), other alternative ingredients (NOPAP), and a positive (NOPAP⁺) and negative (PAP⁻) formulation were tested. All alternative formulations contained hydrolysates from aquaculture by-products and macroalgae. The results indicate that the alternative feed concepts are more sustainable alternatives compared with the commercial diet. Equally interesting, the alternative formulations did not affect the sensory analysis of the fillet quality or the animal welfare. These are increasingly important factors in aquaculture products and, accordingly, also in the formulation of new feeds. Feed concepts that are not only more sustainable in their production, have shorter transportation distances, recycle the resources (usage of by-products), and have no adverse effect on growth or welfare parameters are highly needed. Therefore, the experimental diets tested in this study are a win-win concept for future seabass aquaculture production.

In Europe, turbot aquaculture has a high potential for sustainable production, but the low tolerance to fishmeal replacement in the diet represents a big issue. Therefore, this study investigated the effects of more sustainable feed formulations on growth and feed performance, as well as nutritional status of juvenile turbot in recirculating aquaculture systems. In a 16-week feeding trial with 20 g juvenile turbot, one control diet containing traditional fishmeal, fish oil and soy products and two experimental diets where 20% of the fishmeal was replaced either with processed animal proteins (PAP) or with terrestrial plant proteins (PLANT) were tested. Irrespective of diets, growth performance was similar between groups, whereas the feed performance was significantly reduced in fish of the PAP group compared to the control. Comparing growth, feed utilisation and biochemical parameters, the results indicate that the fish fed on PAP diet had the lowest performance. Fish fed the PLANT diet had similar feed utilisation compared to the control, whereas parameters of the nutritional status, such as condition factor, hepato-somatic index and glycogen content showed reduced levels after 16 weeks. These effects in biochemical parameters are within the physiological range and therefore not the cause of negative performance. Since growth was unaffected, the lower feed performance of fish that were fed the PAP formulation might be balanced by the cost efficient formulation in comparison to the commercial and the PLANT formulations. Present study highlights the suitability of alternative food formulation for farmed fish.

Coastal marine environments provide livelihoods as billions of people around the world depend greatly on sustainability efforts in the Blue Economy. In this study, we investigated how stakeholders from important Blue Economy sectors along the German North Sea coast perceive the impacts of climate change on their daily work life and the growth of the Blue Economy. In a two-stage approach we first conducted two stakeholder workshops with representatives from the regional sea food sector, science, NGOs and local authorities, in order to identify important issues linked to climate change affecting environment, society, economy and policy. In the second stage, we conducted semi-structured interviews with key knowledge holders from the Blue Economy, to evaluate and validate the most important issues identified during the first stage, and the impacts on the respective sectors. The workshop participants identified perceptible effects of climate change on their marine environment. Early career scientists showed that they possess a clear focus on measures for climate change adaptation, transdisciplinary approaches and knowledge transfer. The interviews revealed that the climate change effects could be perceived as both negative and positive, depending on the sector. Other issues, especially political decisions and developments are perceived to have a greater immediate impact on the Blue Economy than the slow progress of climate change effects. Additionally, increased human activities, in the form of new or intensified uses like marine renewable energy generation, have a greater influence and lead to conflicts between the Blue Economy sectors. Our study showed that economic and societal stakeholders in Germanys North Sea region are aware of climate change and already perceive its effects on their businesses. Synergies and conflicts between the sectors and political decisions might influence sustainable growth of the Blue Economy in highly contested regions, such as the North Sea basin, much stronger than the effects of climate change. This calls for a more flexible and adaptive approach to policymaking, taking into account the changing environmental, social and economic realities.