Feeding types of the benthic community and particle transport across the slope of the NW European Continental Margin (Goban Spur)

Densities and biomass of feeding guilds of benthic foraminifera, macrofauna and megafauna were estimated at seven stations ranging from 208 m to 4460 m water depth along the OMEX-transect at the continental margin of the Goba n Spur N.E. Atlantic. At the same stations flow velocities in the Bottom Bo undary Layer (BBL) were measured at 30 cm height above the bottom. Overall densities of all three faunal groups decreased with increasing water depth, but a peak in density and biomass of suspension-feeding taxa was observed in all groups at similar to 1000-1500 m water depth. At these depths the hi ghest how velocities were measured in all seasons of the year. At station I I at 1470 m flow velocities of similar to 35 cm s(-1) were measured during autumn/winter, but in spring/summer flow velocities did not exceed 10 cm s( -1), but were still highest at this station. At this station a very high bi omass of suspension feeders was found within the megafauna (mainly sponges) , high densities of Astrorhizid foraminifera and high densities of hydrozoi ds, sponges and tunicates within the macrofauna. At all other stations depo sit feeders predominate and much lower flow velocities occurred. It was con cluded that a high load of (re)suspended material at similar to 1470 m wate r depth provide good feeding conditions for suspension feeders and hence th at flow velocities are important in structuring the benthic community. Thes e high numbers of suspension feeders, on the other hand, actively capture p articles that would otherwise have been transported past this highly energe tic region and the relative high numbers of surface- and interface-feeding infauna then bury them in the sediment. Feeding and tube structures seen on the sediment surface can locally change the flow velocities and cause resu spension and passive biodeposition of particles. (C) 1998 Published by Else vier Science Ltd. All rights reserved.