Sedimentation: Potential Biological Effects of Dredging Operations in Estuarine and Marine Environments

摘要

During the process of dredging, sediments are excavated and relocated. At various points in the process some volume of sediment is injected into the water column, either at the dredging site or at the dredged material disposal site. The amounts may be relatively small (e.g., around operating hydraulic cutterheads) or substantial (e.g., unconfined open-water disposal). The fate of these resuspended sediments, even if uncontaminated, is source of concern. Potential detrimental effects generally fall into two categories: water column effects (i.e. exposure to suspended sediments) and sedimentation effects. Potential impacts of suspended sediments on aquatic organisms have previously been reviewed (e.g., Newcombe and Jensen 1996; Wilber and Clarke 2001); however, only recently has the subject of sedimentation in the context of dredging effects received effects of sedimentation focuses on freshwater streams rather than coastal water bodies. This technical note summarizes the current scientific literature with emphasis on effects of uncontaminated, bedded sediments on estuarine and marine organisms. This review consolidates existing information on sedimentation effects, identifies aspects of natural and anthropogenic sedimentation processes that may be problematic, and identifies gaps in the current state of knowledge necessary for prudent dredging project management and resource protection.