Shellfish often accumulate contaminants from the environment. Eating contaminated shellfish, especially when raw or partially cooked, poses considerable health risk to humans. Since the early 1920s the U.S. Public Health Service has been monitoring the nation s shellfish harvest for bacterial contamination. Today the harvest of shellfish is restricted or prohibited in approximately 30 percent of all shellfish growing waters because of poor water quality. Untreated sewage discharge from boats accounts for about 13 percent of those restrictions.
Coral reefs are one of the most spectacular and diverse ecosystems on earth.
U.S. coral reef communities can be found in the Florida Keys, the southern Atlantic, the Gulf of Mexico, the Caribbean, and the western Pacific. Coral reef tourism provides significant income to Florida, Hawaii, and the U.S. Virgin Isands. Home to more than 1 million species, coral reefs also support valuable commercial and recreational fisheries. Vessel sewage discharges increase bioerosion of coral reefs, making them more susceptible to collapse. Coral reefs protect nearby coastal areas.