Description: The presented data shows the results of suitability analyses to assess potential restoration grounds for ostrea edulis in the German Bight's marine protected areas (MPA) Borkum Reef Ground and Sylt Outer Reef. We made use of existing marine data from various sources and applied a spatial multicriteria decision analysis (MCDA). Spatial input variables are scored uniformly in order to express their respective ability to improve restoration preconditions. They are summed in a linear combination using expert's judgements founded weights using the analytical hierarchy process (AHP) algorithm. Datasets which describe circumstances to prevent a successful restoration are subtracted from the resulting suitable area. The dataset presented here includes the resulting raster datasets as described in out publication. Detailed metadata on the original raw data (not included here) are listed in Table 1 of the publication. The Analysis was performed in 2021 and modified in 2022.

Description: Understanding the distribution and structure of biotopes is essential for marine conservation according to international legislation, such as the European Marine Strategy Framework Directive (MSFD). The biotope 'Sea Pen and Burrowing Megafuna Communities' is included in the OSPAR list of threatened and/or declining habitats. Accordingly, the MSFD prescribes a monitoring of this biotope by the member states of the EU. In the German North Sea, however, the distribution and spatial extent of this biotope as well as the structuring of its benthic species inventory is unknown. We used an extensive geo-referenced dataset on occurrence, abundance and biomass of the benthic infauna of the south-eastern North Sea to estimate the distribution of the biotope and to characterize the associated infauna assemblages. Sediment preferences of the burrowing megafauna, comprising decapod crustaceans and echiurids, were identified and the core distribution areas of the burrowing megafauna were modelled using Random Forests. Clusters of benthic infauna inside the core distribution areas were identified by fuzzy clustering. The burrowing megafauna occurred on a wide range of sediments with varying mud contents. The core distribution area of the burrowing megafauna was characterized by elevated mud content and a water depth of 25-55 m. The analysis of the benthic communities and their relation to sedimentological conditions identified four infauna clusters of slightly varying species composition. The biotope type 'Sea Pen and Burrowing Megafuna Communities' is primarily located inside the paleo valley of the river Elbe and covers an area of 4980 km2. Dedicated monitoring will have to take into account the spatial extent and the structural variability of the biotope. Our results can provide a baseline for the evaluation of the future development of the environmental status of the biotope. The maps generated herein will facilitate the communication of information relevant for environmental management to authorities and policy makers.

Description: Marine sublittoral sandbanks are essential offshore feeding grounds for larger crustaceans, fish and seabirds. In the southern North Sea, sandbanks are characterized by considerable natural sediment dynamics and are subject to chronic bottom trawling. However, except for the Dogger Bank, sandbanks in the southeastern North Sea have been only poorly investigated until now. We used an extensive, multi-annual dataset covering ongoing national monitoring programmes, environmental impact assessments, and basic research studies to analyse benthic communities on sublittoral sandbanks, evaluating their ecological value against the backdrop of similar seafloor habitats in this region. The analysis revealed complex spatial structuring of sandy seafloor habitats of the southeastern North Sea. Different infauna clusters were identified and could be specified by their composition of characteristic species. The sandbanks shared common structural features in their infauna community composition although they were not necessarily characterized by particularly high biodiversity compared to other sandy habitats. A close association of one of the main bioturbators in the southern North Sea, the sea urchin Echinocardium cordatum, with sandbanks was detected, which may promote the sediment-bound biogeochemical activity in this particular seafloor habitat. This would corroborate the status of sandbanks as sites of high ecological value calling for consideration in marine conservation.

Description: Against the background of the UN decade on ecosystem restoration and the new EU Biodiversity Strategy for 2030, and in the context of marine spatial planning and complex maritime user conflicts, reliable information on habitat suitability for large-scale restoration is an important prerequisite for implementing conservation management and for supporting successful, sustainable, and ecologically efficient restoration measures. In this study, habitat suitability was assessed using multicriteria decision analysis (MCDA) for the restoration of the European oyster, Ostrea edulis, in marine protected areas (MPAs) of the German Bight in the North Sea: Borkum Reef Ground (Borkum Riffgrund, BRG) and Sylt Outer Reef – Eastern German Bight (Sylter Außenriff, SAR). Based on site selection criteria, exclusion and suitability factors for the MCDA were defined. Results were integrated with the available geodata to produce habitat suitability maps for oyster restoration in the area of interest. Suitable as well as unsuitable habitats have been successfully identified for both MPAs: several hundred square kilometres (≥97.2% of BRG) or several thousand square kilometres (≥74.5% of SAR) were classified as ecologically and logistically suitable for oyster restoration measures in the respective MPAs. As oyster restoration is significantly limited by human activities (e.g. bottom trawl fisheries), the management of fisheries is an important prerequisite for successful oyster restoration in both MPAs. Results show that designated fishery management measures will increase the possibilities for oyster restoration. In BRG, our results correspond to the known historical distribution. In SAR, our results significantly exceed the historically known distribution. The habitat suitability analysis will facilitate decision-making regarding ocean use, and will reduce restoration costs through targeted management activities in areas of high suitability and expand species recovery by improving the survival of reintroduced individuals. The habitat suitability analysis procedure is easily adaptable for application to other areas, other species, or other habitat restoration projects, or to other conservation management settings. The software applied is open source and the suitability calculation is described in detail to inform wider applications.