Overall effects can range from increased coastal erosion because of reduced sediment input to reductions in commercial fishery species because of increases in estuarine salinity. By destroying spawning grounds, dams have been a major factor in the loss of many distinct races of salmon. Toxic chemical pollution from, among other sources, industry, agriculture and urban run-off can cause a variety of effects, including the development of cancer, lesions, genetic and developmental deformities, behavioral abnormalities, reproductive failures, sex change and death in marine animals. Commercial shipping continues to pose a serious hazard to endangered east coast right whales, is an important vector for the transfer of non-indigenous marine organisms and is a major cause of marine debris and oil spills. Recreational boating continues to kill the endangered manatees of Florida.
Some fisheries continue to reduce fish and shellfish populations and damage bottom habitat.
It is estimated that, by the year 2025, three out of every four Americans will live within an hour's drive of the shoreline. Management programs that do not take into account these, and other, driving forces run the risk of being reactive and, ultimately, ineffectual. Important steps in this process include such current initiatives as the EPA's National Estuary Program or the Fish and Wildlife Service program to restore habitat through cooperative voluntary arrangements with landowners. Also, local initiatives to place caps on coastal development are beginning to show up on ballots.