Freshwater ecosystems are vital for biodiversity and human well-being, but remain amongst the most degraded globally. Nature-based Solutions (NbS) offer a promising pathway to restoration, yet implementation remains fragmented and often limited in scale. This paper synthesises insights from 18 demonstration cases across Europe, carried out under the EU Horizon 2020 MERLIN project, to identify key factors enabling the systemic upscaling of freshwater restoration through NbS. Drawing on practical experiences, five interdependent “building blocks” are proposed: (1) comprehensive status review; (2) narratives of the future; (3) evidence-informed approach; (4) resource management and (5) stakeholder engagement. These dimensions reflect cross-cutting challenges and capacities — such as context-sensitive planning, adaptive learning, financing strategies and inclusive governance. While grounded in diverse local contexts, the framework offers a strategic orientation for scientists, practitioners and policy-makers working to align restoration efforts with the ambitions of the European Green Deal and Nature Restoration Regulation. Rather than prescribing uniform solutions, the paper provides practice-informed guidance for embedding restoration in complex social–ecological systems. Highlights Synthesises lessons from 18 diverse freshwater restoration cases across Europe under the MERLIN project;Proposes five strategic building blocks for scaling Nature-based Solutions: system understanding, shared vision, evidence use, resource management and stakeholder engagement;Emphasises the interdependence of ecological, institutional and societal dimensions in upscaling restoration;Demonstrates the value of transdisciplinary collaboration, adaptive planning and embedded implementation;Offers practice-orientated insights aligned with the European Green Deal and Nature Restoration Regulation.
Plastic pollution monitoring programs use a wide array of methods, protocols, and analytical approaches, making it difficult for researchers and practitioners to determine which techniques to apply, where, and how. This lack of harmonisation across environmental compartments and plastic size classes has led to inconsistent data and limited comparability across studies. To address this, a systematic review of monitoring methods from 1960 to 2021 was conducted, encompassing both peer-reviewed and grey literature. Techniques were categorised into Reproducible Analytical Pipelines (RAPs), each comprising six core steps: survey design, sample collection, sample preparation, analytical detection, quantification, and data reporting. Each RAP was assessed using Technological Readiness Levels (TRLs) to evaluate maturity and suitability for standardised monitoring. The review revealed that while robust and repeatable methods exist, they are inconsistently applied. At the time of this review, atmospheric plastics was underrepresented, highlighting a critical gap in monitoring efforts. The findings underscore the urgent need for a global, objective framework to guide the selection and implementation of plastic pollution monitoring methodologies. This paper lays the foundation for such a framework by presenting a methodology to identify mature, reproducible methods and prioritise areas for further development. Future work should focus on harmonising protocols across compartments and size classes, improving transparency in data reporting, and building consensus around standardised practices to enable global comparability and policy relevance.
Accumulation of total suspended solids (TSS) in recirculating aquaculture systems (RAS) may be harmful to fish and biofilter functionality, and there is a link between particulate organic matter and heterotrophic bacteria proliferation in RAS. In this study, the chronic effects of high total suspended solids (HTSS, n = 3) in RAS were assessed on water quality, biofilter performance, and microbiota, compared to RAS with low levels of suspended solids (LTSS, n = 3), during a 128 day-trial following smoltification procedures on Atlantic salmon. Higher TSS concentration (1 vs 7 mg/L) was accompanied by increased organic matter, particle concentration, surface area, and volume, and bacterial concentration and activity in the water and the biofilter. Furthermore, high TSS systems exhibited higher mean levels of ammonia and nitrite, and lower levels of nitrate. Fish biomass increase after 128 days was 14 % lower in HTSS systems. The microbiota composition in the water and biofilterbiofilm was altered by TSS load, and competition from heterotrophic bacteria may have reduced the nitrifying capacity of the biofilter. A combined nutritional-hydrobiological model was developed to assess the effect of commercially-relevant C/ N ratios on biofilter performance. Nitrification was not affected by calculated C/N ratios between 4.0 and 5.4, but the dynamics of nitrification were influenced by nitrogen load and source (fish or bacteria). This model is a promising tool for biofilter assessment studies in commercially-relevant scenarios but requires further development and validation. The results indicate the potential impacts of accumulating organic matter on RAS water quality, microbiota, and fish performance.
Local fisheries risk marginalization in the blue economy. This study explores fishers' views on sustainability challenges for local fisheries in Northern-Norway through a social survey approach. We asked: "What are the three greatest challenges for fisheries in your municipality today?" and "In 30 years, what will be the greatest challenges?" Fishers' concerns were compared to recent scientific literature on fishers 'challenges globally to identify issues not emphasized by our respondents (non-issues). These are issues that may be silenced, considered non-problematic or that fishers lack knowledge of. Data from 360 fishers showed that challenges identified by the fishers broadly pertained to nine domains - competition for space and resources, access to infrastructure, workforce, economy, environment, governance, local communities, illegal activity and recognition of fisheries, fishers and fishing culture. Aquaculture, competition within fisheries, access to landing sites, and recruitment were frequently mentioned as specific challenges under these domains. Recruitment and depopulation of local communities were mentioned by a higher proportion of fishers as a future challenge than a present day one. Surprisingly, non-issues included challenges with known local relevance and high saliency, such as safety in fisheries, destructive fishing practices, climate-change adaptation, environmental toxins in seafood and gender equality. To sum up, challenges tied to the blue economy, particularly aquaculture, along with the current downward trends within fisheries when it comes to number of fishers and local fishing industry are key challenges facing local fisheries. Alternative visions for the blue economy that holds space for local fishing activity, are called for.
The complex relationships among ecological sustainability, economic viability, and employment opportunities within the fishing industry emphasize the importance of adopting a holistic analytical framework for fishery management. The evaluation of a comprehensive fisheries management policy becomes increasingly critical when an ecosystem, such as the eastern Mediterranean Sea, undergoes large changes. In this study, we analyzed the fishery sector in the Mediterranean region of Israel using the Ecopath with Ecosim (EwE) suite of ecological models, which are influenced by climate change and the influx of nonindigenous species (NIS) both, which alter the ecological and economic balance in the region. We identified key components within the fish supply chain that contribute significantly to the national economy and assessed their performance under several scenarios involving changes in the biomass of NIS within the ecosystem. Our findings indicate that while NIS contributes considerably to the local economy, most of the revenue is derived from native species, particularly large pelagics. Furthermore, the fishery sector in Israel exhibits a financial multiplier of four; that is, for every Israeli Shekel (ILS) earned by fishers, three additional ILS are generated through subsequent transactions along the fish supply chain. Within the supply chain, the restaurant sector is the primary employer, accounting for 41% of all employment. Furthermore, a considerable proportion of those engaged in fishing are recreational fishers who, despite not usually selling their catch, contribute indirectly to local economies and community well-being while deriving substantial cultural, psychological, and recreational value. The results of this study reveal the structure of the Israeli fisheries value chain, which is mostly determined by the moderately small scale of local commercial fisheries. However, the economic contribution of the value chain to the local economy is substantial and should not be overlooked when defining fishery management measures. This study emphasizes the need to examine the entire value chain, from fishing practices to the end consumer, to understand the broader implications of management actions on employment and income distribution, and to inform sustainable policymaking.
