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Marine debris and litter has become both a significant coastal and open ocean problem. Considerable portions of this debris is made of persistent synthetic materials such as plastics, and is not biodegradable as past product waste has been. Surveys have indicated that nearly 80 percent of marine debris originates from land-based activities. The increasing influx of people into coastal zones (nearly 50 percent of the U.S. population now lives within 100 miles of the oceans boarding the country or along the shores of the Great Lakes) has exasperated the problem. This trend has increased dependence on processed, manufactured and packaged goods. Marine debris not only is an aesthetic problem, but has become a serious threat to marine life, a marine transportation hazard, and can threaten human healthy and safety as well as inflict serious economic loss. Estimates of marine life endangered by debris included most of the world's turtle species, 25 percent of marine mammal species, and more than 15 percent of seabird species. Plastic in water appears as food to many varieties of marine life resulting in often fatal ingestion. For boats, both commercial and recreational, debris entanglement in motors or water intake valves can prove costly. Human activities such as swimming, diving and simple walks along the beach can also result in injury or entanglement. Debris , especially plastic film and sheeting, can settle over immobile plants and animals including valuable ecosystem habitats such as coral reefs, effectively smothering them and rendering them uninhabitable and unproductive. Reducing waste, promoting recycling, public education efforts, and volunteer coastal monitoring are major means of addressing coastal sources of marine debris.
The threat and impacts of marine debris have long been ignored. Perhaps it is the perceived vastness of ocean and lack of visibility of marine debris to most people that has allowed society to dismiss the problem as a serious threat. However, recent research demonstrates that quantities and impacts of marine debris are significant and increasing.
The Algalita Marine Research Foundation’s investigation of plastic in the North Pacific Central Gyre of the Pacific Ocean showed that the abundance of plastic pieces was six times greater than zooplankton floating on the water’s surface. This study is one of many that demonstrate that our oceans have become the virtual garbage can for the developed and developing world.
Most of the marine debris in the world is comprised of plastic materials. The average proportion varies between 60 to 80% of total marine debris. In many regions, plastic materials constitute as much as 90 to 95% of the total amount of marine debris. Nearly 80% of marine debris comes from land-based sources. Most of the land-based debris is conveyed to oceans via urban runoff through storm drains. The main sources of plastic and other types of anthropogenic (human-made) debris in urban runoff include: litter (mostly bags, packaging and single-use disposable products), industrial discharges, garbage transportation, landfills, construction debris, and debris from commercial establishments and public venues.
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