A seafloor crater in the German Bight and its effect on the benthos
In 1963 a deep crater was formed about 65 m below sea level in the western part of the German Bight, due to a gas eruption caused by drilling carried out from the platform ŽMr. LouieŽ. The study area is situated in a sandy to muddy bottom area inhabited by an Amphiura-filiformis-association (sensu Salzwedel et al., 1985). The crater, sometimes called ŽFigge-MaarŽ, functions as a sediment-trap, concentrating particles and organisms from the water column, thus leading to extreme sedimentation rates of about 50 cm, on an average per year. Crater stations compared with stations situated in the vicinity, show enrichments of juveniles. Echinoderms, especially the sub-surface dwelling heart urchin Echinocardium cordatum and ophiuroids are responsive to enrichment. Other species that are typical for the Amphiura-filiformis-association are shown to be unable to cope with the special conditions in the crater.