Focused Review of Factors Influencing Fish at Underwater Features Created with Dredged Sediments: Path Toward Expanding Beneficial Use?

Abstract

There is a growing recognition that sediments dredged to maintain navigation and port infrastructure are valuable resources that can be placed in the aquatic environment to achieve ecological benefits if managed appropriately. However, specific interactions and long-term influences of placement on local aquatic ecosystems, particularly fisheries, remain to be fully explored. Therefore, the aim of this review was to identify and synthesize key factors influencing the outcomes of stable underwater features (e.g., berms, reefs, mounds) created from open water placement (OWP) of dredged sediments on fish habitat. Emphasizing ecological, biological, and artificial habitat perspectives, the review explored historic OWP techniques and features, their habitat alterations, and identified reported physical, biological, and chemical factors that influence fish. Results from this review suggest that underwater features can influence fish habitat by changing benthic relief, voids, and rugosity while altering hydrology through upwelling, velocity shelters, and lee waves. Additionally, as short-term disturbances to resident benthic fauna and flora can occur, recolonization rate and successional stages are important biological factors to consider at OWP sites aimed at ecological improvement. Collectively, these data provide insight into integrating intentional design features to improve locally diversified and enhanced aquatic habitats beneficial to fish and other organisms, through attributes such as height, shape, side slope, sediment grain size, micro effects on hydrodynamics and benthic prey resources.

Keywords: Beneficial Use; Dredged Sediment; Dredging; Fish; Habitat; Sustainability.