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Marine debris, also called marine trash, is any human-made solid material that is disposed of or abandoned on beaches, in waterways that lead to the ocean, or in the ocean itself, regardless of whether disposal occurred directly, indirectly, intentionally or unintentionally.
Dead seaweed, shells, carcasses or other naturally-produced materials are not included.
Marine debris, including plastics, paper, wood, metal and other manufactured materials is found on beaches worldwide and at all depths of the ocean. About 60%-80% of all marine debris is composed of plastic (Rios et al 2007) and Ocean Conservancy's Trash Free Seas Alliance estimates that 8 million metric tons of plastic enters the ocean each year.

About 80% of marine debris originates from sources on land  and the other 20%, about 636,000 tons per year, comes from ocean vessels (US Department of Commerce 1999; Ramirez-Llodra et al. 2011). Cruise ships represent only 1% of marine vessels, but produce about 25% of ship-sourced waste; on average, a single cruise passenger produces 3.5 kg of waste per day (Butt 2007).

A useful general overview of marine trash pollution is found here.

Top Marine Debris Items Found in Cleanups Over the Last 25 Years ย 

How Was It Measured?

The Clean Water goal is unusual because its four components--Trash Pollution, Nutrient Pollution, Chemical Pollution and Pathogen Pollution--indicate both Status and Pressure.  Low levels of those factors produce a high goal score, but high levels produce a low score.  For example, perfectly clean water has no trash pollution, so Status for this component is expressed as 1 - Trash Pollution. Status for the other components is similarly expressed.  Beginning in 2015 input data for Trash was obtained from Eriksen et al. (2014). Input sources for data used to calculate Status and Pressure scores for the other components are listed in Table S23 of Halpern et al. 2015.  The overall goal score is the geometric mean of the scores for the four components, which are weighted equally.    

Use of the geometric mean magnifies the importance of a very bad score for any one of the components, matching public perception that very high levels of a single pollutant would make waters seem โ€˜too dirtyโ€™ to enjoy for recreational or aesthetic purposes.

All pressures, including marine  trash, have different affects on different goals. For each goal, the affect of each pressure is weighted 'low' (1), 'medium' (2) or 'high' (3). The actual data-derived value of the pressure is then multiplied by the weight assigned to it for that goal. That process is repeated for each pressure-goal combination.  The sum of those values divided by 3 (the (the maximum pressure-goal value) expresses the total affect of that pressure on the goal.

Marine trash is a pressure for several of the Ocean Health Index goals. Marine trash has high effect (weight = 3) on Tourism & Recreation, Coastal Livelihoods and Economies (Tourism), Sense of Place (Lasting Special Places), and Clean Waters. It has low effect (weight = 1) on Coastal Livelihoods and Economies (Marine Cetacean Watching), Sense of Place (Iconic Species), and Biodiversity (Species).  

What Are The Impacts?


Floating marine debris often accumulates in particular regions because of wind patterns and currents known as gyres. The oceanโ€™s five largest gyres are the North Pacific Gyre, the South Pacific Gyre, the North Atlantic Gyre, the South Atlantic Gyre and the Indian Ocean Gyre. The North Pacific Gyre has received most attention as the โ€˜Great Pacific Garbage Patchโ€™, but floating trash accumulates in all of the major gyres as well as in many smaller ones worldwide.

Seabirds, turtles, marine mammals and fish can mistake floating trash for food; if ingested, it can choke them or block their digestive systems. Large debris, such as old fishing gear and nets, can kill animals by strangulation or prevent them from performing vital activities such as swimming or diving. Plastic trash smaller than 5mm (microplastic) poses an additional threat because it adsorbs toxic chemicals, including DDT and PCBs, which can cause cancers, weaken the immune system and make animals more susceptible to diseases and other infections.

More than 260 species are known to have ingested or been entangled by plastic debris (STAP 2011).

Of the 120 marine mammal species listed on the IUCN Red List, 54% are known to have ingested or been entangled in plastic debris (STAP 2011).


Ingestion of plastic trash and the consequent uptake of toxins adsorbed on its surface can transfer harmful chemicals through the food web into species eaten by humans; these can include molecules known to increase the risk of birth defects and cancer.

Careless or unlawful disposal of syringes and other medical waste products can spread diseases and pose risks to beach-goers.


Marine debris decreases the economic value and productivity of coastal regions, particularly in the tourism, recreation, and seafood industries, and creates additional costs.

In the United States, 85% of tourism revenue comes from coastal ocean states.

Economic activity directly related to the ocean generated $138 billion in 2004, and contiributed 47 million jobs in 2007 (Dorfman and Rosselot  2010).

What Has Been Done?

For the past 25 years, the Ocean Conservancy has organized ocean clean-ups in 152 countries. Local volunteers walk beaches to collect trash, SCUBA divers collect debris from the ocean floor, and volunteers in boats collect floating debris, yielding staggering amounts of trash. Data from these cleanups are used by ocean scientists, and can help inform policymakers.

5Gyres and LUSH Cosmetics teamed up to launch โ€œBan the Beadโ€, a campaign to help clean the ocean. 5Gyres initially set out to research plastics in the oceans across the world, but wanted to learn more about the sources of plastic pollution. In water samples from the Great Lakes between the US and Canada, the team found spherical pieces of plastic that were less than a millimeter in diameter. Quickly, they realized that these plastic spheres were the microbeads advertised in facial scrubs as exfoliating agents. The Ban the Bead campaign urges corporations to eliminate the use of microbeads in cosmetics, toothpaste and other products. An impressive list of corporations that have already removed microbeads from their products, or pledged to do so quickly, is available here.


Get More Information

United States National Oceanic and Atmospheric Administration (NOAA): Marine Debris Program

Educational and informative source regarding the impact of marine debris.

Ocean Conservancy: International Coastal Cleanup

A report detailing results of the 2014 International Coastal Cleanup

Ocean Conservancy: Trash Free Seas Program

International Coastal Cleanup for collecting and recording marine debris.

Marine Debris Solutions

An organization providing information on the causes of marine debris and potential solutions. 


Boerger,C. M. et al. 2010. Plastic ingestion by planktivorous fishes in the NorthPacific Central Gyre. Marine Pollution Bulletin 60:2275โ€“2278.

Butt,N. 2007. The impact of cruise ship generated waste on home ports and ports ofcall: A study of Southampton.  MarinePolicy 31:591โ€“598.

Ramirez-Llodra, E. et al.2011. Man and the last great wilderness: human impact on the deep sea. PLoS ONE6(8): e22588. doi:10.1371/journal.pone.0022588

Rios,L. M., C. Moore and P.R. Jones. 2007. Persistent organic pollutants carried by synthetic polymers in the oceanenvironment. Marine Pollution Bulletin 54:1230โ€“1237.