Changes in megafaunal benthic communities in different habitats after trawling disturbance

As part of a long-term study to examine the ecological effects of beam-trawling, we investigated the immediate impact of fishing on the megafaunal component of a benthic community and the extent to which it had recovered 6 months later. A quantitative dredge was used to collect megafaunal samples following a replicated, paired control and treatment design to maximize the chances of detecting any effects due to trawling. There were two different habitats with distinct communities in the experimental area, one with stable sediments and a rich fauna, the other with mobile sediment and a relatively impoverished fauna. Immediately after fishing the composition of the community in the stable sediments was significantly altered. While the abundance of some species decreased (e.g. sea mice Aphrodita aculeata), others apparently increased (e.g. hermit crabs Pagurus bernhardus). Variation between samples from the fished areas was higher than those From the control areas. This suggests that the effects of trawling were not uniform, even though the treatment area was entirely swept at least once. The effects of fishing were not delectable in the mobile sediments. Six months later, seasonal changes had occurred in both communities and the effects of the trawling disturbance were no longer evident. :(C) British Crown copyright 1998.