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Marine debris on the Hawaiian coast
The problem is global. This is Msasani Beach in Dar es Salaam, the capital of Tanzania, on the Indian Ocean

Marine debris, also known as marine litter, is human-created waste that has deliberately or accidentally become afloat in a lake, sea, ocean or waterway. Oceanic debris tends to accumulate at the centre of gyres and on coastlines,[1] frequently washing aground, when it is known as beach litter or tidewrack.

Deliberate disposal of wastes at sea is called ocean dumping.

Some seeming forms of marine debris, such as driftwood, occur naturally, and human activities have been discharging similar material into the oceans for thousands of years. Recently however, with the increasing use of plastic, human influence has become an issue as many types of plastics do not biodegrade. Waterborne plastic is both unsightly and dangerous, and poses a serious threat to fish, seabirds, marine reptiles, and marine mammals, as well as to boats and coastal habitations.[2] Ocean dumping, accidental container spillages, and wind-blown landfill waste are all contributing to this problem.


Types of debris

Debris collected from beaches on Tern Island in the French Frigate Shoals over one month

A wide variety of anthropogenic artifacts can become marine debris; plastic bags, balloons, buoys, rope, medical waste, glass bottles and plastic bottles, cigarette lighters, beverage cans, styrofoam, lost fishing line and nets, and various wastes from cruise ships and oil rigs are among the items commonly found to have washed ashore. Six pack rings, in particular, are considered a poster child of the damage that garbage can do to the marine environment.[3]

Studies have shown that eighty percent of marine debris is plastic – a component that has been rapidly accumulating since the end of World War II.[4] Plastics accumulate because they don't biodegrade as many other substances do; although they will photodegrade on exposure to sunlight, they do so only under dry conditions, as water inhibits photolysis.[5]


Ghost nets

Fishing nets left or lost in the ocean by fishermen – ghost nets – can entangle fish, dolphins, sea turtles, sharks, dugongs, crocodiles, seabirds, crabs, and other creatures. Acting as designed, these nets restrict movement, causing starvation, laceration and infection, and, in animals that need to return to the surface to breathe, suffocation.[6]

Nurdles and plastics bags

A handful of nurdles, spilt from a train in Pineville, Louisiana

Nurdles, also known as mermaids' tears, are plastic pellets typically under five millimetres in diameter, and are a major component of marine debris. They are used as a raw material in plastics manufacturing, and are thought to enter the natural environment after accidental spillages. Mermaids' tears are also created by the physical weathering of larger plastic debris. Nurdles strongly resemble fish eggs. [7]

Plastic shopping bags may clog digestive tracts when consumed[8] and may cause starvation through restricting the movement of food, or by filling the stomach and tricking the animal into thinking it is full. A 1994 study of the seabed using trawl nets in the North-Western Mediterranean around the coasts of Spain, France and Italy reported a particularly high mean concentration of debris; an average of 1,935 items per square kilometre. Plastic debris accounted for 77%, of which 93% was plastic bags.[8]

Source of debris

Travel of the Friendly Floatees

It has been estimated that container ships lose over 10,000 containers at sea each year (usually during storms).[9] One famous spillage occurred in the Pacific Ocean in 1992, when thousands of rubber ducks and other toys went overboard during a storm. The toys have since been found all over the world; Curtis Ebbesmeyer and other scientists have used the incident to gain a better understanding of ocean currents. Similar incidents have happened before, with the same potential to track currents, such as when Hansa Carrier dropped 21 containers (with one notably containing buoyant Nike shoes).[10] In 2007, MSC Napoli was beached in the English Channel, and dropped hundreds of containers, most of which washed up on the Jurassic Coast, a World Heritage Site.[11]

Though it was originally assumed that most oceanic marine waste stemmed directly from ocean dumping, it is now thought that around four fifths[12] of the oceanic debris is from rubbish blown seaward from landfills, and urban runoff washed down storm drains.[2] In the 1987 Syringe Tide, medical waste washed ashore in New Jersey after having been blown from the Fresh Kills Landfill.[13][14]. Even on the remote sub-Antarctic island of South Georgia fishing related debris comprising of approximately 80% plastics have been found washed up and are responsible for the entanglement of large numbers of Antarctic fur seals.[15]

Legality of ocean and river dumping

Ocean dumping is controlled by international law:

European law

In 1972 and 1974, conventions were held in Oslo and Paris respectively, and resulted in the passing of the OSPAR Convention, an international treaty controlling marine pollution in the north-east Atlantic Ocean around Europe.[18] A similar Barcelona Convention exists to protect the Mediterranean Sea. The Water Framework Directive of 2000 is a European Union directive committing EU member states to make their inland and coastal waters free from human influence.[19] In the United Kingdom, the proposed Marine Bill is designed to "ensure clean healthy, safe, productive and biologically diverse oceans and seas, by putting in place better systems for delivering sustainable development of marine and coastal environment".[20]

A sign above a sewer in Colorado Springs warning people to not pollute the local stream by dumping. Eighty percent of marine debris reaches the sea via rivers.

United States law

In 1972, the United States Congress passed the Ocean Dumping Act, giving the Environmental Protection Agency power to monitor and regulate the dumping of sewage sludge, industrial waste, radioactive waste and biohazardous materials into the nation's territorial waters.[21] The Act was amended sixteen years later to include medical wastes.[22] It is illegal to dispose of any plastic in all US waters.[2] In 2008, the California State Legislature considered several bills aimed at reducing the sources of marine debris, following the recommendations of the California Ocean Protection Council.[23]

Ownership of debris

Property law, admiralty law, and the law of the sea may be of relevance when lost, mislaid, and abandoned property is found at sea. Salvage law has as a basis that a salvor should be rewarded for risking his life and property to rescue the property of another from peril. On land the distinction between deliberate and accidental loss led to the concept of a "treasure trove". In the United Kingdom, shipwrecked goods should be reported to a Receiver of Wreck, and if identifiable, they should be returned to their rightful owner.[24]

The Great Pacific Garbage Patch

The currents of the North Pacific Gyre spiral inwards, depositing debris in the convergence zone

Once waterborne, debris is far from immobile. Flotsam can be blown by the wind, or follow the flow of ocean currents, often ending up in the middle of oceanic gyres where currents are weakest. The Great Pacific Garbage Patch is one such example of this, comprising of a vast region of the North Pacific Ocean rich with anthropogenic wastes. Estimated to be double the size of Texas, the area contains more than 3 million tons of plastic [25]. This means that there are approximately six pounds of plastic for every pound of plankton per cubic meter of seawater [26]. The mass of plastic in our oceans may be as high as one hundred million tons.[12]

Islands situated within gyres frequently have their coastlines ruined by the waste that inevitably washes ashore; prime examples are Midway[27] and Hawaii.[28] Clean-up teams around the world patrol beaches to clean up this environmental threat.[27]

Environmental impact

Remains of an albatross containing ingested flotsam

Many animals that live on or in the sea consume flotsam by mistake, as it often looks similar to their natural prey.[29] Plastic debris, when bulky or tangled, is difficult to pass, and may become permanently lodged in the digestive tracts of these animals, blocking the passage of food and causing death through starvation or infection.[30] Tiny floating particles also resemble zooplankton, which can lead filter feeders to consume them and cause them to enter the ocean food chain. In samples taken from the North Pacific Gyre in 1999 by the Algalita Marine Research Foundation, the mass of plastic exceeded that of zooplankton by a factor of six.[4][31]

A turtle trapped in a ghost net, an abandoned fishing net

Toxic additives used in the manufacture of plastic materials can leach out into their surroundings when exposed to water. Waterborne hydrophobic pollutants collect and magnify on the surface of plastic debris,[12] thus making plastic far more deadly in the ocean than it would be on land.[4] Hydrophobic contaminants are also known to bioaccumulate in fatty tissues, biomagnifying up the food chain and putting great pressure on apex predators. Some plastic additives are known to disrupt the endocrine system when consumed; others can suppress the immune system or decrease reproductive rates.[31]

Not all anthropogenic artefacts in the oceans are harmful however. Iron and concrete do little damage to the environment as they are generally immobile, and can even be used as scaffolding for the creation of artificial reefs, increasing the biodiversity of a coastal region. Entire ships have been deliberately sunk in coastal waters for that purpose.[32] Some organisms have adapted to live on mobile plastic debris,[33] which has allowed the inhabitants to disperse all over the world and become invasive species in remote ecosystems.[34]

Debris removal

Two boats engaged in the collection of floating debris from the surface of the Pearl River in Guangzhou, keeping them from drifting into South China Sea

A variety of techniques are used to collect and remove marine (or riverine) debris by concerned jurisdictions or volunteer organizations. Besides collection by hand, Some cities operate special Beach cleaner machines that collect trash deposited by the sea along the coast line. Other places (e.g. Baltimore[35]) arrange for picking debris while it is still floating; such activities are often undertaken regularly where floating debris are perceived to pose danger to navigation. For example, the US Army Corps of Engineers reports removing 90 tons of "drifting material" from San Francisco Bay shipping lanes etc. every month. The Corps has been doing this work since 1942, when a seaplane carrying Admiral Chester W. Nimitz collided with a piece of floating debris and sank, resulting in the death of its pilot.[36]

Elsewhere, various kinds of "trash traps" are installed on small rivers flowing into the sea, to capture waterborne debris before it reaches the sea. For example, South Australia's Adelaide operates a number of such traps, known as "trash racks" or "gross pollutant traps" on the Torrens River, which flows (during the wet season) into Gulf Saint Vincent.[37]

See also


  1. ^ Gary Strieker (28 July 1998). "Pollution invades small Pacific island". CNN. Retrieved 2008-04-01. 
  2. ^ a b c "Facts about marine debris". US NOAA. Retrieved 2008-04-10. 
  3. ^ Cecil Adams (16 July 1999). "Should you cut up six-pack rings so they don't choke sea birds?". The Straight Dope. Retrieved 2008-08-11. 
  4. ^ a b c Alan Weisman (2007). The World Without Us. St. Martin's Thomas Dunne Books. pp. 112–128. ISBN 0312347294. 
  5. ^ Alan Weisman (Summer 2007). "Polymers Are Forever". Orion magazine. Retrieved 2008-07-01. 
  6. ^ "'Ghost fishing' killing seabirds". BBC News. 28 June 2007. Retrieved 2008-04-01. 
  7. ^ "Plastics 'poisoning world's seas'". BBC News. 7 December 2006. Retrieved 2008-04-01. 
  8. ^ a b "Marine Litter: An analytical overview" (PDF). United Nations Environment Programme. 2005. Retrieved 2008-08-01. 
  9. ^ Janice Podsada (19 June 2001). "Lost Sea Cargo: Beach Bounty or Junk?". National Geographic News. Retrieved 2008-04-08. 
  10. ^ Marsha Walton (28 May 2003). "How sneakers, toys and hockey gear help ocean science". CNN. Retrieved 2008-04-08. 
  11. ^ "Scavengers take washed-up goods". BBC News. 22 January 2007. Retrieved 2008-04-08. 
  12. ^ a b c "Plastic Debris: from Rivers to Sea" (PDF). Algalita Marine Research Foundation. Retrieved 2008-05-29. 
  13. ^ Alfonso Narvaez (8 December 1987). "New York City to Pay Jersey Town $1 Million Over Shore Pollution". The New York Times. Retrieved 2008-06-25. 
  14. ^ "A Summary of the Proposed Comprehensive Conservation and Management Plan". New York-New Jersey Harbor Estuary Program. February 1995. Retrieved 2008-06-25. 
  15. ^ Walker, T.R., Reid, K., Arnould, J.P.Y., Croxall, J.P. (1997) Marine debris surveys at Bird Island, South Georgia 1990-1995. Marine Pollution Bulletin. 34(1): 61-65.
  16. ^ "London Convention". US EPA. Retrieved 2008-05-29. 
  17. ^ "International Convention for the Prevention of Pollution from Ships, 1973, as modified by the Protocol of 1978 relating thereto (MARPOL 73/78)". International Maritime Organization. Retrieved 2008-05-29. 
  18. ^ "The OSPAR Convention". OSPAR Commission. Retrieved 2008-05-29. 
  19. ^ "Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy". EurLex. Retrieved 2008-05-29. 
  20. ^ "Marine Bill". UK Defra. Retrieved 2008-07-29. 
  21. ^ "Marine Protection, Research, and Sanctuaries Act of 1972" (PDF). US Senate. 29 December 2000. Retrieved 2008-05-29. 
  22. ^ "Ocean Dumping Ban Act of 1988". US EPA. 21 November 1988. Retrieved 2008-05-29. 
  23. ^ "Stopping the Rising Tide of Marine Debris Pollution". Californians Against Waste. Retrieved 2008-04-01. 
  24. ^ "Can you keep ship-wrecked goods?". BBC News. 22 January 2007. Retrieved 2008-05-29. 
  25. ^ "Congress acts to clean up the ocean - A garbage patch in the Pacific is double the size of Texas". The Christian Science Monitor. Retrieved 2008-10-10. 
  26. ^ >. "Great Pacific garbage patch: Plastic turning vast area of ocean into ecological nightmare". Santa Barbara News-Press.>.. Retrieved 2008-10-13. 
  27. ^ a b "New 'battle of Midway' over plastic". BBC News. 26 March 2008. Retrieved 2008-04-01. 
  28. ^ "Plastic blights Hawaii's beaches". BBC News. 11 June 2007. Retrieved 2008-04-01. 
  29. ^ Kenneth R. Weiss (2 August 2006). "Plague of Plastic Chokes the Seas". Los Angeles Times. Retrieved 2008-04-01. 
  30. ^ Charles Moore (November 2003). "Across the Pacific Ocean, plastics, plastics, everywhere.". Natural History. Retrieved 2008-04-05. 
  31. ^ a b "Plastics and Marine Debris". Algalita Marine Research Foundation. 2006. Retrieved 2008-07-01. 
  32. ^ "Chapter 5: Reefing" (PDF). Disposal Options for Ships. Rand Corporation. 2 August 2006. Retrieved 2008-05-03. 
  33. ^ "Ocean Debris: Habitat for Some, Havoc for Environment, Experts Say". National Geographic. 23 April 2007. Retrieved 2008-08-01. 
  34. ^ "Rubbish menaces Antarctic species". BBC News. 24 April 2002. Retrieved 2008-08-01. 
  35. ^ "Baltimore Stormwater Debris Removal". MARCOR. Retrieved 2009-02-07. 
  36. ^ "Debris collection onsite after Bay Bridge struck". US Army Corps of Engineers. Retrieved 2009-02-07. 
  37. ^ "Trash Racks". Adelaide and Mount Lofty Ranges Natural Resources Management Board. Retrieved 2009-02-07. 

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