Benthic metazoan biomass, community structure and bioturbation at three contrasting deep-water sites on the northwest European continental margin

摘要: Size structure, taxonomic composition and bioturbation potential of benthic metazoan communities were examined at three contrasting sites on the northwest European continental margin as part a wider study biogeochemical cycling in deep-sea boundary layer. Sampling was conducted Hatton–Rockall Basin (1100 m depth), North Feni Ridge (1920 m) South Rockall Trough (3580 two cruises bracketing expected 1998 spring phytodetrital flux. Density biomass epibenthic megafauna declined with depth consistent previous data from deep northeast Atlantic. Aggregations hexactinellid sponge Pheronema carpenteri occurred 1100 m. The percentage contribution suspension-feeders to megafaunal lower slope much higher than for these depths. Macrofauna (sensu stricto) consistently undersampled by box corer relative an hydraulically damped multiple corer. Estimated macrofaunal densities depth. Polychaete trophic group structure very different sites, more small carnivores m, surface deposit interface-feeders 1920 representation subsurface deposit-feeders 3580 Meiofaunal low comparison published comparable depths numbers increased all May July 1998. increase statistically significant associated greatest accumulation observed during period. mega-, macro- meiofauna did not vary depth, no trend apparent review other studies Depth-related patterns community size recorded Atlantic replicated, suggesting importance local hydrodynamics environmental factors. There obvious link between faunal parameters biodiffusion coefficients or mixing modes estimated radiotracer profiles. Diffusion-analogue 210Pbexcess profiles resulted combination sediment mixing, some it advective. At subduction near-surface concentration feeding activity produced peaks. poorly known burrowing probably play role sites.