Clean Ocean Action: Effects

Close-up of wormtubes on the seafloor. Benthic (seafloor) worms are an important prey item for marine predators. The worms can accumulate toxins that are attached to sediment particles that the worms ingest. The toxins are then transferred up the food chain to higher predators such as fish. photo: courtesy of National Ocean Atmospheric Administration (NOAA) OAR/National Underseas Research Program (NURP).

Given the national extent of sediment contamination, and the variety of toxics found, the impact on marine life from exposure to contaminated sediments can be significant.

The presence and disposal of contaminated sediments threaten habitat, and fisheries, shellfisheries, and other marine wildlife. According to the National Research Council, contaminated sediments affect not only individual fish and shellfish, but also entire populations:

"Accumulation of contaminants in marine sediments can cause death, reproductive failure, growth impairment or other detrimental changes in the organisms exposed to these contaminants. Such changes can impact not only individuals but also entire benthic [bottom-living] populations and communities . . . These population-scale impacts include decreased population size, decreased reproduction potential, shorter average lifespans and loss of habitat." (NRC, 1989)

When they are in-place, contaminated sediments threaten the benthic ecosystem, exposing fish and other animals that are the base of the foodchain to harmful contaminants. When they are dredged and dumped, sediments further expose fish, shellfish, and marine wildlife to unknown quantities of toxic materials. The impact on marine resources can be experienced on an individual level, through tumors and other ailments, and also on a population-wide level. For example:

- Contaminant-tolerant species have replaced indigenous bottom-dwelling species in New Bedford Harbor, Massachusetts (Chesapeake Executive Council, 1989.)

- Research in Puget Sound revealed damage to DNA in fish livers from exposure to hydrocarbons, (Varanasi, 1992.)

- Chemicals that act like hormones can upset a natural instinct as ingrained as a salmon’s drive to spawn upstream. A study on embryonic coho salmon that were exposed to the chemical benzo(a)pyrene showed that the baby fish were normal in all regards except that their ability to orient themselves upstream and navigate was significantly compromised (Malins and Ostrander, 1991.)

To read a thorough review of effects to marine wildlife from contaminated sediments, check out COA's paper entitled "Reducing Contaminated Sediments and Their Threats to Marine Resources."