Benthic community impacts from sediment dredging and disposal: A comparison of sampling gear

The effect of sediment dredging and disposal work on benthic communities was compared according to two sampling strategies, grab (1-mm mesh) and dredge (1-cm mesh). Nine subtidal, sandy sites were selected in Arcachon Bay (French Atlantic coast), where these operations were performed during winter. Fauna was sampled several months before and one year after the dredging or disposal work. The sediments were fine to medium sands and their characteristics were not modified. In dredging sites, abundance, diversity and community structure of grab sampled fauna were minimally affected by the activities, while abundance and community structure displayed significant changes for dredge sampled fauna. In disposal sites, there was no work effect on fauna, although environmental conditions changed, especially when initial sediments were covered by mussels or seagrass. This study suggests that dredge sampling can be an alternative to grab sampling for monitoring changes related to dredging in sandy shallow channels.