Beschreibung: This study examines whether or not biogeographical and/or managerial divisions across the European seas can be validated using soft-bottom macrobenthic community data. The faunal groups used were: all macrobenthos groups, polychaetes, molluscs, crustaceans, echinoderms, sipunculans and the last 5 groups combined. In order to test the discriminating power of these groups, 3 criteria were used: (1) proximity, which refers to the expected closer faunal resemblance of adjacent areas relative to more distant ones; (2) randomness, which in the present context is a measure of the degree to which the inventories of the various sectors, provinces or regions may in each case be considered as a random sample of the inventory of the next largest province or region in a hierarchy of geographic scales; and (3) differentiation, which provides a measure of the uniqueness of the pattern. Results show that only polychaetes fulfill all 3 criteria and that the only marine biogeographic system supported by the analyses is the one proposed by Longhurst (1998). Energy fluxes and other interactions between the planktonic and benthic domains, acting over evolutionary time scales, can be associated with the multivariate pattern derived from the macrobenthos datasets. Third-stage multidimensional scaling ordination reveals that polychaetes produce a unique pattern when all systems are under consideration. Average island distance from the nearest coast, number of islands and the island surface area were the geographic variables best correlated with the community patterns produced by polychaetes. Biogeographic patterns suggest a vicariance model dominating over the founder-dispersal model except for the semi-closed regional seas, where a model substantially modified from the second option could be supported.

Beschreibung: We provide an overview of the role of biological processes in the Benthic boundary layer (BBL) and in sediments on the cycling of particulate organic material in the Goban Spur area (Northeast Atlantic). The benthic fauna, sediment and BBL characteristics were studied along a transect ranging from 208 to 4460 m water depth in different seasons over 3 years. Near-bottom flow velocities are high at the upper part of the slope (1000–1500 m), and high numbers of filter-feeding taxa are found there such that organic carbon normally passing this area during high flow conditions is probably trapped, accumulated, and/or remineralised by the fauna. Overall metabolism in shelf and upper slope sediments is dominated by the macrofauna. More than half of the organic matter flux is respired by macrofauna, with a lower contribution of metazoan meiofauna (4%) and anoxic and suboxic bacterial mineralisation (21%); the remainder (23%) being channelled through nanobiota and oxic bacteria. By its feeding activity and movement, the macrofauna intensely reworks the sediments on the shelf and upper slope. Mixing intensity of bulk sediment and of organic matter are of comparable magnitude. The benthos of the lower slope and abyssal depth is dominated by the microbiota, both in terms of total biomass (〉90%) and carbon respiration (about 80%). The macrofauna (16%), meiofauna (4%) and megafauna (0.5%) only marginally contribute to total carbon respiration at depths below 1400 m. Because large animals have a lower share in total metabolism, mixing of organic matter within the sediments is reduced by a factor of 5, whereas mixing of bulk sediment is one to two orders of magnitude lower than on the shelf. The food quality of organic matter in the sediments in the shallowest part of the Goban Spur transect is significantly higher than in sediments in the deeper parts. The residence time of mineralisable carbon is about 120 d on the shelf and compares well with the residence time of the biota. In the deepest station, the mean residence time of mineralisable carbon is more than 3000 d, an order of magnitude higher than that of biotic biomass.

Beschreibung: The pan-European MacroBen database was used to compare the AZTI Marine Biotic Index (AMBI) and the Benthic Quality Index (BQIES), 2 biotic indices which rely on 2 distinct assessments of species sensitivity/tolerance (i.e. AMBI EG and BQI E[S50]0.05) and which up to now have only been compared on restricted data sets. A total of 12 409 stations were selected from the database. This subset (indicator database) was later divided into 4 marine and 1 estuarine subareas. We computed E(S50)0.05 in 643 taxa, which accounted for 91.8% of the total abundances in the whole marine indicator database. AMBI EG and E(S50)0.05 correlated poorly. Marked heterogeneities in E(S50)0.05 between the marine and estuarine North Sea and between the 4 marine subareas suggest that sensitivity/tolerance levels vary among geographical areas. High values of AMBI were always associated with low values of BQIES, which underlines the coherence of these 2 indices in identifying stations with a bad ecological status (ES). Conversely, low values of AMBI were sometimes associated with low values of BQIES resulting in the attribution of a good ES by AMBI and a bad ES by BQIES.This was caused by the dominance of species classified as sensitive by AMBI and tolerant by BQIES. Some of these species are known to be sensitive to natural disturbance, which highlights the tendency of BQIES to automatically classify dominant species as tolerant. Both indices thus present weaknesses in their way of assessing sensitivity/tolerance levels (i.e. existence of a single sensitivity/tolerance list for AMBI and the tight relationship between dominance and tolerance for BQIES). Future studies should focus on the (1) clarification of the sensitivity/tolerance levels of the species identified as problematic, and (2) assessment of the relationships between AMBI EG and E(S50)0.05 within and between combinations of geographical areas and habitats.

Beschreibung: A large-scale database concerning benthic copepods from the Arctic, Baltic Sea, North Sea, British Isles, Adriatic Sea and Crete was compiled to assess species richness, biodiversity, communities, ecological rangesize and biogeographical patterns. The Adriatic showed the highest evenness and the most species-rich communities. Assemblages from the North Sea, British Isles, Baltic and Crete had a lower evenness. The British Isles were characterised by impoverished communities. The ecological specificity of copepod species showed two diverging trends: higher specificity of species in more diverse assemblages was observed in the Adriatic, North Sea and Baltic. A uniformly high species specificity disregarding sample diversity was found on Crete and in the British Isles. Benthic copepod communities showed distinct patterns that clearly fit the predefined geographical regions. Communities were distinguishable and b-diversity was found to be high around Europe, indicating a high species turnover on the scale of this investigation. The British Isles and the North Sea were found to be faunistic links to the Baltic and the Arctic.