Description: Permanent sea-ice cover and low primary productivity in the mostly ice-covered Central Arctic ocean basins result in significantly lower biomass and density of macrobenthos in the abyssal plains compared to the continental slopes. However, little is known on bathymetric and regional effects on the macrobenthos diversity. This study synthesizes new and available macrobenthos data to provide a baseline for future studies of the effects of Arctic change on macrofauna community composition in the Arctic basins. Samples collected during three expeditions (in 1993, 2012 and 2015) at 37 stations on the slope of the Barents and Laptev Seas and in the abyssal of the Nansen and Amundsen Basins in the depth range from 38 m to 4381 m were used for a quantitative analysis of species composition, abundance and biomass. Benthic communities clustered in five depth ranges across the slope and basin. A parabolic pattern of species diversity change with depth was found, with the diversity maximum for macrofauna at the shelf edge at depths of 100–300 m. This deviates from the typical species richness peak at mid-slope depths of 1500–3000 m in temperate oceans. Due to the limited availability of standardized benthos data, it remains difficult to assess if and how the significant sea-ice loss observed in the past decade has affected benthic community composition. The polychaete Ymerana pteropoda and the bryozoan Nolella sp. were found for the first time in the deep Nansen and Amundsen Basins.

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: The German Bight (North Sea) is a centre of development of offshore wind energy. In the near future, windfarms will cover a significant part (about 25%) of the German Exclusive Economic Zone. In order to understand and assess potential effects of the construction and early operational phase of offshore wind turbines on the marine environment, an extensive research programme was carried out at Germany's first offshore windfarm alpha ventus. Here, data are presented on macroinfauna and local sediment characteristics collected as part of this programme. Grab samples were taken annually in autumn in 2008 (baseline), 2009 (construction phase) and 2010 and 2011 (early operational phase). Sampling stations were located along transects between adjacent turbines inside the windfarm and in two reference areas with similar environmental conditions in terms of sediment characteristics and water depth. A total of 336 samples were taken inside the windfarm and 192 samples in the reference areas. Sediment characteristics were described in terms of grain size distribution and organic content. The infauna was taxonomically analysed and quantified in terms of abundance and biomass. One-hundred three infauna taxa were identified, mainly belonging to the polychaetes, crustaceans and bivalves, living in fine to medium sandy soft bottom in water depths ranging from -27 m to -30 m. The data can be useful in meta-analyses of renewable energies impacts. Additionally, the data can support species distribution modelling to gain a better understanding of species' requirements and habitats as a basis for spatial planning scenarios and the evaluation of the ecological status of the marine environment. Moreover, the data can serve as baseline data for future monitoring and management of nearby protected areas where environmental conditions are comparable to those of the present study area.