Human Impacts:
Threats to the Health of the Oceans

Following is a description of some of the causes for the pollution of our oceans.  Providing this information is part of our conservation mission.

• Oil spills account for only about five percent of the oil entering the oceans. The Coast Guard estimates that for United States waters sewage treatment plants discharge twice as much oil each year as tanker spills.
• Each year industrial, household cleaning, gardening, and automotive products pollute water. About 65,000 chemicals are used commercially in the United States today, with about 1,000 new ones added each year. Only about 300 have been extensively tested for toxicity.
• It is estimated that medical waste that washed up onto Long Island and New Jersey beaches in the summer of 1988 cost as much as $3 billion in lost revenue from tourism and recreation.
• The most frequently found item in beach cleanups is pieces of plastic. The next four items are plastic foam, plastic utensils, pieces of glass and cigarette butts.
• Lost or discarded fishing nets keep on fishing. Called "ghost nets," this gear entangles fish, marine mammals, and sea birds, preventing them from feeding or causing them to drown. As many as 20,000 northern fur seals may die each year from becoming entangled in netting.
• Air pollution is responsible for almost one-third of the toxic contaminants and nutrients that enter coastal areas and oceans.
• When nitrogen and phosphorus from sources such as fertilizer, sewage and detergents enter coastal waters, oxygen depletion occurs. One gram of nitrogen can make enough organic material to require 15 grams of oxygen to decompose. A single gram of phosphorus will deplete one hundred grams of oxygen.
• The Mississippi River drains more than 40 percent of the continental United States, carrying excess nutrients into the Gulf of Mexico. Decay of the resulting algal blooms consumes oxygen, kills shellfish and displaces fish in a 4,000 square mile bottom area off the coast of Louisiana and Texas, called the "dead zone."
• In 1993, United States beaches were closed or swimmers advised not to get in the water over 2,400 times because of sewage contamination. The problem is even worse than the numbers indicate: there are no federal requirements for notifying the public when water-quality standards are violated, and some coastal states don't monitor water at beaches.
• The zebra mussel is the most famous unwanted ship stowaway, but the animals and plants being transported to new areas through ship ballast water is a problem around the world. Poisonous algae, cholera, and countless plants and animals have invaded harbor waters and disrupted ecological balance.
• There are 109 countries with coral reefs. Reefs in 90 of them are being damaged by cruise ship anchors and sewage, by tourists breaking off chunks of coral, and by commercial harvesting for sale to tourists.
• One study of a cruise ship anchor dropped in a coral reef for one day found an area about half the size of a football field completely destroyed, and half again as much covered by rubble that died later. It was estimated that coral recovery would take fifty years.
• Egypt's High Aswan Dam, built in the 1960s to provide electricity and irrigation water, diverts up to 95 percent of the Nile River's normal flow. It has since trapped more than one million tons of nutrient rich silt and caused a sharp decline in Mediterranean sardine and shrimp fisheries.
• The United Nations Food and Agriculture Organization estimates that of the seventeen major fisheries areas in the world, four are depleted and the other thirteen are either fished to capacity or overfished.
• Commercial marine fisheries in the United States discard up to 20 billion pounds of non-target fish each year-- twice the catch of desired commercial and recreational fishing combined.
• Almost half of all construction in the United States during the 1970s and 1980s took place in coastal areas.
• Within thirty years a billion more people will be living along the coasts than are alive today.
• With only 4.3 percent of the world population, Americans. We use about one-third of the world's processed mineral resources, and about one-fourth of the world's non-renewable energy sources, like oil and coal.

Source:  Smithsonian Institution's Ocean Planet exhibition and from the book Ocean Planet: Writings and Images of the Sea, by Peter Benchley and Judith Gradwohl