Biodiversity and marine ecosystems Threats to marine biodiversity Destructive fishing practices, such as the use of sodium cyanide pictured here, and overexploitation are two of the top threats to the coastal environment that WRI is addressing through its Global Marine Strategy . There are many causes loss of marine biodiversity, especially in the coastal waters of industrialized countries. As a consequence, the productivity of fisheries and such important ecosystems as mangroves and coral reefs has been depressed, an local communities have suffered. Even in Antarctica, penguins far from any agriculture contain DDT, shorelines have been fouled by oil spills, and blue whales are critically endangered. The species and ecosystems suffering most, however, are in the coastal waters closes to humankind.
Many marine organisms release their eggs into the surface waters of the sea.
Planktonic larvae can disperse hundreds, even thousands, of kilometers, and because of this widespread dispersal marine fishes, invertebrates, and plants might seem to be a low risk of extinction. So are the exceptionally large species favored by people for food and other products, who have decimated once-sizable populations of giant clams, king crabs, bluefin tunas, and the great whales. Preventing extinctions is essential but not sufficient. Maintaining the integrity of the sea and, hence, its sustained production of resources and services requires attention to whole ecosystems as well as to their component species. Estuaries and salt marshes, mangrove forests, and seagrass beds near cities and towns are severely degraded worldwide.