Trophic Transfer and Biomagnification Potential of Contaminants in Aquatic Ecosystems

The potential ecological effects of sediment-associated contaminants are of concern, particularly in the context of dredged materials management. Sediments may serve as sinks by binding and sequestering contaminants that are entering aquatic systems where they can accumulate to much higher concentrations than in the overlying water. Sediments may then serve as secondary sources for transport of and biotic exposure to these materials, particularly when sediments are disturbed by physical perturbations such as storm events, bioturbation, or dredging and aquatic placement of dredged material. Sediment-sorbed contaminants may accumulate sufficiently in the tissues of prey organisms to elicit direct adverse effects, and they may be transferred to consumers through dietary intake or by increased concentrations in the water column. Aquatic organisms that bioaccumulate contaminants from water or sediment may transfer these contaminants to predators that forage on them. The extent to which these sediment-associated contaminants can move through aquatic food webs and thus potentially affect organisms at higher trophic levels is a crucial issue for environmental decision-making. The potential transfer of contaminants from one trophic level to another through aquatic food webs has not been thoroughly investigated. This trophic transfer potential must be known in order to evaluate the environmental significance of bioaccumulation of sediment-associated materials in aquatic organisms.