The concept of multi-use of the sea has gained popularity in recent years as a result of ocean space (coastal areas and regions with relatively small sea space in particular) becoming increasingly crowded due to the development of the maritime economy. Competing claims for space can be a source of conflict, however this may also lead to mutual benefits for different users when sustainable combinations are sought. Despite increasing European-wide efforts, on-the-ground knowledge and practice of multi-use are still limited. Therefore, with the aim of investigating opportunities for multi-use development in the European seas, 10 case studies were selected, involving different site-specific contexts. This study analyses the characteristics and development potential for ocean multi-use, integrating results from desk analysis and stakeholder perceptions from different sectors in each of the case study locations. Similarities and differences between various combinations of sea uses are also identified. The results show a high heterogeneity of multi-use opportunities between case studies, with a range of combinations identified. The investigated combinations of maritime uses share an overall balance between factors promoting (drivers) and hindering (barriers) multi-use development. Based on stakeholder opinions, expected benefits (added values) of multi-use implementation outweigh potential negative impacts. Management actions are also proposed to further exploit multi-use potential at a local, regional (sub-national) and national levels.

Ypacaraí Lake is the most renowned lake in landlocked Paraguay and a major source of drinking and irrigation water for neighbouring towns. Beyond its socioeconomic and cultural significance, it has great ecological importance, supporting a rich biodiversity. Rapid growth of human presence and activities within its basin has led to its environmental degradation, a heartfelt matter of high political concern that compels intervention. Here, by reconstructing the history of scientific and management-oriented research on this system, we provide a comprehensive assessment of current knowledge and practice to which we contribute our recent, novel findings. An upward trend in total phosphorus concentration confirms ongoing eutrophication of an already eutrophic system, evidenced by consistently high values of trophic state indices. Downward trends in water transparency and chlorophyll-a concentration support the hypothesis that primary production in this lake is fundamentally light limited. Statistical and other analyses suggest high sensitivity of the system to hydraulic, hydro-morphological and hydro-meteorological alterations arising, respectively, from engineering interventions, land use and climate change. By discussing knowledge gaps, opportunities for research and challenges for management and restoration, we argue that this case is of high scientific value and that its study can advance theoretical understanding of shallow subtropical lakes.

Human pressures on marine ecosystems significantly increased during last decades. Among the intense anthropic activities, industrial fisheries have caused the alteration of habitats, the reduction of biodiversity and the main fish stocks. The aim of this research, carried out in the Adriatic Sea, was to test a repeatable Marine Spatial Planning framework aimed at enhancing fisheries sustainability through the application of Decision Support Tools and the composition of a catalog of possible measures. The use of these tools proved very useful to identify possible criticalities and facilitate an effective exchange with fisheries stakeholders, local authorities, and fishermen, whose involvement was an indispensable step in the process. Tool-based analyses allowed to assess the spatial footprint of a range of anthropogenic pressures from human activities (e.g., fisheries, maritime traffic, and aquaculture). Within this multi-pressure scenario, special attention was paid to fishing-related disturbances and potential conflicts across different fishing métier and with other sectors. Specifically, results highlighted the spatial features of the major fishing pressures (e.g., abrasion from trawling) affecting essential fish habitats, marine mammals and turtles in the study area. A portfolio of possible management measures is identified for the study area. It provides clear evidence that, in order to mitigate emerging conflicts and cumulative impacts, it is necessary to combine and integrate different types of measures: spatial measures modulated over time, monitoring and control, actions to fill knowledge gaps, concertation—involvement—co-management actions, improvement of governance systems, actions to support innovation in the sector, etc. Given the complex set of measures discussed, this work can provide a useful contribution to the management of fisheries both at local and regional level, fostering the transition to sustainable fisheries.