Long-term records of hard-bottom communities and related environmental predictors in the southwestern Baltic Sea (2005-2015)

Seven stations along the SW Baltic coast were selected for an annual monitoring of hard-bottom communities between 2005 and 2015. At each station, eight concrete slabs (50 x 50 cm) equipped with two vertical threaded stainless steel bars were deployed at 3 m depth. These constructions served as the basis for horizontally oriented settlement panels (PVC, 12 x 12 cm), which were fixed on the steel bars 30 cm above the seafloor. Every September, panels were exchanged for new ones, thus, all collected communities were 12 months old and in the same seasonal stage. Directly after collection, the communities were fixed with buffered formaldehyde to a final concentration of 4%. Collected panels were analyzed in the laboratory for species composition to the lowest possible taxonomic level and the relative coverage (%) was estimated to the nearest 5%. In case organisms were exceeding the margins of the panel or settled and grew in multiple layers, the coverage of a single species could exceed 100%. The presented data comprise average taxonomic and functional composition of the communities for each station and year. Functional groups were categorized according to adult body size, growth form, trophic type and modularity, assigning a four letters code to each genus (see related article for further details). In addition, related environmental predictors were modeled for each station and year. Data for sea surface temperature (SST), sea surface salinity (SSS), current direction and current speed were extracted from the Kiel Baltic Sea Ice-Ocean Model (BSIOM). Furthermore, the BSIOM was used to determine the spatial extension of particle (resembling planktonic larvae and propagules of benthic organisms) release areas by calculating the dispersal kernels.