Contamination
Dumping and discharging of
pollutants into the sea, oil spills, nutrient- and silt-laden
runoff from land and rivers, fallout of chemicals carried
by the wind from land-based sources, and noise from ships
and other machinery are some of the major contaminants affecting
marine species and ecosystems. Air pollution and runoff and
point discharges from the land (and rivers) account for some
three fourths of the pollutants entering marine ecosystems.
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Contaminants
affect marine biodiversity in a number of ways. Untreated
sewage, oil, heavy metals, and other wastes may be directly
toxic to some marine organisms. Oil has lethal and almost
immediate effects on a wide range of marine life resulting
in death through asphyxiation, poisoning, and, among mammals
and birds, loss of the insulating functions of feathers and
fur, causing hypothermia. Eggs and larvae are particularly
sensitive to the toxic effects of pollutants, as are organisms
living at the ocean surface and on the seabed, where wastes
tend to accumulate.
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