Symposium Abstract: Changes in the Benthic Invertebrate Assemblage following the Establishment of a Protected Area, the “Plaice Box”
G. J. Piet, J. A. Craeymeersch, and A. D. Rijnsdorp
The ecosystem in the south-eastern North Sea is affected considerably by various sources of both natural and anthropogenic origin. The effect of a reduced beamtrawling effort on the benthic invertebrate assemblage could be studied from changes in the assemblage following the establishment of a protected area, the ‘plaice box’. This area was established in 1989 and closed for all vessels with an engine power over 300 Hp, which constitutes the main part of the beamtrawling fleet. At first it was only effective part of the year but since 1995 the box was closed during the whole year. In order to be able to distinguish between this effect and that of potentially confounding influences from natural origin relevant environmental variables were incorporated in the analyses. The observed effects of the closure of an area on the benthic assemblage are discussed in the context of potential management measures and how to predict and assess their effectiveness and possible side effects.