As the industrial production of nanoplastic and the degradation of microplastic into smaller particles at sea increase, the potential amount of nanoplastics in the marine environment rises. It has been reported that mussels uptake 100-nm polystyrene (PS) beads; to date, however, the effects of this uptake on the organism are unknown. In the present study, the authors investigated the effects of 30-nm PS on the feeding behavior of the blue mussel (Mytilus edulis) by exposing the organism to different nano PS and different algae (Pavlova lutheri) concentrations. The state of nano PS aggregation in the exposure medium was assessed using dynamic light scattering. In all treatments that contained nano PS, M. edulis produced pseudofeces. The total weight of the feces and pseudofeces increased with increasing nano PS and increasing algae concentration. Furthermore, M. edulis reduced its filtering activity when nano PS was present but still caused a decrease in the apparent nano PS concentration in the water. The presence of nano PS around the foot of M. edulis after the bioassay confirmed that the organism removed nano PS from the water. Chronic effect studies are therefore needed to investigate the effects of nanoplastics in M. edulis and possible consequences for its predators, including humans.

Knowledge of aquaculture–environment interactions is essential for the development of a sustainable aquaculture industry and efficient marine spatial planning. The effects of fish and shellfish farming on sessile wild populations, particularly infauna, have been studied intensively. Mobile fauna, including crustaceans, fish, birds and marine mammals, also interact with aquaculture operations, but the interactions are more complex and these animals may be attracted to (attraction) or show an aversion to (repulsion) farm operations with various degrees of effects. This review outlines the main mechanisms and effects of attraction and repulsion of wild animals to/from marine finfish cage and bivalve aquaculture, with a focus on effects on fisheries‐related species. Effects considered in this review include those related to the provision of physical structure (farm infrastructure acting as fish aggregating devices (FADs) or artificial reefs (ARs), the provision of food (e.g. farmed animals, waste feed and faeces, fouling organisms associated with farm structures) and some farm activities (e.g. boating, cleaning). The reviews show that the distribution of mobile organisms associated with farming structures varies over various spatial (vertical and horizontal) and temporal scales (season, feeding time, day/night period). Attraction/repulsion mechanisms have a variety of direct and indirect effects on wild organisms at the level of individuals and populations and may have implication for the management of fisheries species and the ecosystem in the context of marine spatial planning. This review revealed considerable uncertainties regarding the long‐term and ecosystem‐wide consequences of these interactions. The use of modelling may help better understand consequences, but long‐term studies are necessary to better elucidate effects.

Efforts to restore the native oyster Ostrea edulis and its associated habitats are gaining momentum across Europe. Several projects are currently running or being planned. To maximize the success of these, it is crucial to draw on existing knowledge and experience in order to design, plan and implement restoration activities in a sustainable and constructive approach. For the development of best practice recommendations and to promote multidimensional knowledge and technology exchange, the Native Oyster Restoration Alliance (NORA) was formed by partners from science, technology, nature conservation, consultancies, commercial producers and policy-makers. The NORA network will enhance scientific and practical progress in flat oyster restoration, such as in project planning and permitting, seed oyster production, disease management and monitoring. It also focuses on joint funding opportunities and the potential development of national and international regulatory frameworks. The main motivation behind NORA is to facilitate the restoration of native oyster habitat within its historic biogeographic range in the North Sea and other European seas along with the associated ecosystem services; services such as enhancing biodiversity, including enhanced fish stocks, nutrient cycling and sediment stabilization. NORA members agreed on a set of joint recommendations and strongly advise that any restoration measure should respect and apply these recommendations: The Berlin Oyster Recommendation is presented here. It will help guide the development of the field by developing and applying best practice accordingly. NORA also aims to combine the outreach activities of local projects for improved community support and awareness and to provide educational material to increase knowledge of the key ecological role of this species and increase awareness among regulators, permit providers and stakeholders. A synthesis of O. edulis restoration efforts in Europe is provided and underlines the general significance in the field.

Although adapted to different methods of feeding, deposit-and suspension-feeding bivalves in the Wadden Sea (The Netherlands) appear to rely partly on the same limiting food sources. Two conditions for food competition, viz. use of the same food source and simultaneous feeding (in relation to season and tidal cycle), were studied in the field. The algal species composition in the stomachs of 3 suspension feeders (Cerastoderma edule, Mya arenaria and Mytilus edulis) and 2 deposit feeders (Macoma balth~ca and Scrobicularia plana) showed high correlations with the species composition of the water column, but lower correlations with the species composition of the sedment surface. During the phytoplankton spring-bloom penods in April and May, the stomachs of the suspension feeders C. edule, M. arenaria and M. edulis, and the deposit feeder M. balthica contained maximum amounts of algae. During the tidal cycle, the stomachs of the suspension feeders generally contained minimum amounts of algae when the tidal flat was drained and maximum amounts around times of high water. The stomachs of the deposit feeder M. balthica, however, contained relatively high amounts of algae during the entire tidal cycle. These results indicate that, although some difference in feeding behaviour was observed between deposit and suspension feeders, both groups rely on the same food source at the same time, irrespective of type of feeding

The “Dutch Energy Agreement” motivates governments and industries to invest in renewable energy sources, of which offshore wind energy is one of the solutions to meet the agreed target of 16% of the total energy budget from renewable resources by 2023. An option for the multi-use of wind farms is nature-inclusive building, in which the design and construction of wind farms make use of the potential for co-design with oyster bed restoration. This can support the government’s ambitions, for the Dutch North Sea, to achieve biodiversity goals, restore ecosystem functions, and enhance ecosystem services, including future seafood production. For the recovery of flat oyster (Ostrea edulis) beds, knowledge is required about the conditions under which active restoration of this species in the North Sea can be successfully implemented. This paper gives a framework and presents results to determine suitability of wind farms for flat oyster restoration, and provides recommendations for pilot studies. Our analysis showed that a number of wind farms in the Dutch section of the North Sea are suitable locations for development of flat oyster beds. Combining oyster restoration and oyster culture, as a protein source, is a viable option worth investigating.