Encyclopedic Entry

Marine debris is rarely this big—or easy to get rid of.

Photograph by Rutger Geerling, MyShot

International Coastal Cleanup
International Coastal Cleanup is the third Saturday in September. The event features beach clean-ups, river clean-ups, and even underwater clean-ups for dive sites. It is the world's largest volunteer effort to clean up the marine environment and collect marine environmental data from both land and underwater sites. Click here to sign up for the annual project.

Trashy Houses
Some sea creatures make homes out of garbage. Researchers from the Sea Education Association in Woods Hole, Massachusetts, found a bucket covered in algae and other organisms. About two dozen triggerfish also used the bucket as a home base. Triggerfish normally live in coral reefs, but this bucket was more than 1,600 kilometers (1,000 miles) from the nearest reef. Sadly, a garbage patch is not a healthy homethe scientists found more than 40 pieces of plastic in one fish's digestive tract.

Marine debris is litter that ends up in oceans, seas, or other large bodies of water.

This manmade debris gets into the water in many ways. People often leave trash on beaches or throw it into the water from boats or offshore facilities, such as oil rigs. Sometimes, litter makes its way into the ocean from land. This debris is carried by storm drains, canals, or rivers. The wind can even blow trash from landfills and other areas into the water. Storms and accidents at sea can cause ships to sink or to lose cargo.

Types of Debris

Any kind of trash can get into the ocean—from glass bottles to aluminum cans to medical waste. The vast majority of marine debris, however, is plastic.

Plastic products can be very harmful to marine life. For instance, loggerhead sea turtles often mistake plastic bags for jellyfish, their favorite food. And many sea animals and birds have become strangled by the plastic rings used to hold six-packs of soda together.

Plastics do not biodegrade quickly. Ironically, some new biodegradable plastics might not break down in oceans at all. These products are designed to break down when they heat up in a landfill or compost pile. Cooler ocean temperatures prevent these products from truly degrading.

Instead, like many other types of plastic, they simply break down into tiny particles called microplastics. Microplastics are pieces of debris between 0.3 and 5 millimeters (0.01 to 0.20 inches) thick, no thicker than a grain of rice. One example of microplastics is “nurdles,” the manmade pellets of raw material used in making plastic products. These tiny pieces of plastic can collect in the stomachs of marine animals, interfering with digestion. When marine animals ingest nurdles, they can feel “full” although they are not getting nutrients. The animals are at risk of malnutrition and starvation.

Floating on the ocean’s surface, nurdles and other small plastic pieces can block the sun’s rays from reaching plants and algae that depend on the sun to create nutrients. When these organisms are threatened, the entire marine food web may be disturbed.

As plastics get smaller and smaller, they release chemicals. One of those chemicals can be bisphenol A (BPA). Bisphenol A can interfere with animals’ reproductive systems. Fish are especially at risk when exposed to bisphenol A. Exposed fish produce fewer healthy offspring.

Bisphenol A and other chemicals build up in the fish’s body through a process called bioaccumulation. Plants or algae may absorb bisphenol A through the water. A fish, already exposed to the chemical, ingests more bisphenol A when it eats the algae. Top predators such as sharks or dolphins, which eat the fish, accumulate the most chemicals.

A reduction in the fish population can impact human activity in the area. Fisheries shrink, weakening the area’s economy. Fish that are harvested may have a high amount of toxins or other marine debris in their system as a result of bioaccumulation. Some of these toxins, such as mercury or bisphenol A, may be harmful to people, putting consumers at risk.

Another type of marine debris that is harmful to sea life comes from fishing gear. Discarded fishing lines and nets don’t stop fishing once humans are done with them. They continue to trap fish, along with marine mammals, turtles, and birds.


The Widening Gyre

Marine debris tends to collect in areas called ocean gyres. A gyre is a circular ocean current formed by the Earth’s wind patterns and the forces created by the rotation of the planet. The area in the center of a gyre tends to be very calm and stable. The circular motion of the gyre draws in debris. The garbage makes its way into the center of the gyre, where it becomes trapped and builds up.

Trash build-ups in the middle of gyres are known as garbage patches. For example, the Great Pacific Garbage Patch exists in the North Pacific Ocean between the U.S. states of California and Hawaii. There is a similar patch in the North Atlantic Ocean.

For many people, the idea of a “garbage patch” conjures up images of an island of trash floating on the ocean. In reality, these patches are usually made up of microplastics that can’t always be seen by the naked eye. Satellite imagery of the oceans do not reveal a giant patch of garbage. Even so, scientists have found up to 750,000 bits of plastic in a single square kilometer (or 1.9 million bits per square mile) in the Great Pacific Garbage Patch. They have found more then 200,000 pieces of trash per square kilometer (520,000 bits per square mile) in areas of the Atlantic garbage patch.

No one knows exactly how much marine debris is in the oceans. Ocean gyres are too vast for scientists or volunteers to trawl the entire surface scooping up trash. In addition, not all of the trash floats. Denser debris can sink to the middle or bottom of the water. We have no way to measure this unseen marine debris.

What We Can Do About Marine Debris

Cleaning up marine debris is not as easy as it sounds. Many pieces of debris are the same size as small sea animals, so nets designed to scoop up trash would catch these creatures as well. Even if we could design nets that would just catch garbage, the size of the oceans makes this job too time-consuming to consider. And no one can reach trash that has sunk to the ocean floor.

Because of these difficulties, most environmentalists focus on preventing more garbage from entering the oceans. Since people became aware of the problem, governments and international organizations have passed laws against ocean dumping to try to reduce marine debris.

Many organizations, like the National Geographic Society, are working to educate people about the dangers of littering oceans. Through the Mission Blue program, National Geographic is working with other organizations, such as the Ocean Conservancy and Sea Web, to educate the public about threats to the ocean.

National Geographic Emerging Explorer David de Rothschild often collaborates with the Algalita Marine Research Foundation. Algalita’s founder, Charles Moore, discovered the Great Pacific Garbage Patch while sailing from Hawaii to California. De Rothschild’s organization, Adventure Ecology, and Algalita both work to reduce the amount of marine debris, especially plastics.

Everyone can help reduce the problem. The most important rule—don’t litter! Don’t leave trash on the beach, toss it from a boat, or litter anywhere else. Remember, even trash dumped on land can make its way into bodies of water. In addition, remember to reduce, reuse, and recycle. The less trash we produce, the less that will end up in the ecosystem.

Vocabulary

Term Part of Speech Definition Encyclopedic Entry

absorb

Verb

to soak up.

algae

Plural Noun

(singular: alga) diverse group of aquatic organisms, the largest of which are seaweeds.

beach

Noun

narrow strip of land that lies along a body of water.

Encyclopedic Entry: beach

bioaccumulation

Noun

process by which chemicals are absorbed by an organism, either from exposure to a substance with the chemical or by consumption of food containing the chemical.

biodegradable

Adjective

able to decompose naturally.

bisphenol A (BPA)

Noun

chemical used to make some types of plastic that may be unsafe for people, especially infants.

canal

Noun

artificial waterway.

cargo

Noun

goods carried by a ship, plane, or other vehicle.

chemical

Noun

molecular properties of a substance.

compost

Noun

mixture of decaying organic material, such as food waste and plants.

conjure

Verb

to imagine or bring to mind.

consumer

Noun

person who uses a good or service.

current

Noun

steady, predictable flow of fluid within a larger body of that fluid.

Encyclopedic Entry: current

debris

Noun

remains of something broken or destroyed, waste, or garbage.

degrade

Verb

to lower the quality of something.

dense

Adjective

having parts or molecules that are packed closely together.

digest

Verb

to convert food into nutrients that can be absorbed.

discard

Verb

to throw away.

economy

Noun

system of production, distribution, and consumption of goods and services.

ecosystem

Noun

community and interactions of living and nonliving things in an area.

Encyclopedic Entry: ecosystem

Emerging Explorer

Noun

an adventurer, scientist, innovator, or storyteller recognized by National Geographic for their visionary work while still early in their careers.

environmentalist

Noun

person who studies or works to protect the Earth's ecosystems.

facility

Noun

a building or room that serves a specific function.

fishery

Noun

industry or occupation of harvesting fish, either in the wild or through aquaculture.

food web

Noun

all related food chains in an ecosystem. Also called a food cycle.

Encyclopedic Entry: food web

government

Noun

system or order of a nation, state, or other political unit.

grain

Noun

harvested seed of such grasses as wheat, oats, and rice.

Encyclopedic Entry: grain

Great Pacific Garbage Patch

Noun

area of the North Pacific Ocean where currents have trapped huge amounts of debris, mostly plastics.

Encyclopedic Entry: Great Pacific Garbage Patch

harvest

Noun

the gathering and collection of crops, including both plants and animals.

ingest

Verb

to take material, such as food or medicine, into a body.

interfere

Verb

to meddle or prevent a process from reaching completion.

international organization

Noun

unit made up of governments or groups in different countries, usually for a specific purpose.

Encyclopedic Entry: international organization

island

Noun

body of land surrounded by water.

Encyclopedic Entry: island

jellyfish

Noun

type of marine animal, not a fish, with a soft body and stinging tentacles.

landfill

Noun

site where garbage is layered with dirt and other absorbing material to prevent contamination of the surrounding land or water.

litter

Noun

trash or other scattered objects left in an open area or natural habitat.

loggerhead sea turtle

Noun

reptile native to non-polar oceans.

malnutrition

Noun

lack of a balanced diet.

marine

Adjective

having to do with the ocean.

marine debris

Noun

garbage, refuse, or other objects that enter the coastal or ocean environment.

Encyclopedic Entry: marine debris

medical waste

Noun

material thrown away from healthcare facilities such as hospitals, including blood, tissue, and medical instruments.

mercury

Noun

chemical element with the symbol Hg.

microplastic

Noun

piece of plastic between 0.3 and 5 millimeters in diameter.

National Geographic Society

Noun

(1888) organization whose mission is "Inspiring people to care about the planet."

nurdle

Noun

small pellet of plastic that is eventually melted and molded into a plastic product.

nutrient

Noun

substance an organism needs for energy, growth, and life.

Encyclopedic Entry: nutrient

ocean

Noun

large body of salt water that covers most of the Earth.

Encyclopedic Entry: ocean

ocean gyre

Noun

an area of ocean that slowly rotates in an enormous circle.

Encyclopedic Entry: ocean gyre

offshore

Adjective

having to do with facilities or resources located underwater, usually miles from the coast.

offspring

Noun

the children of a person or animal.

oil rig

Noun

complex series of machinery and systems used to drill for oil on land.

particle

Noun

small piece of material.

pellet

Noun

small, rounded object.

planet

Noun

large, spherical celestial body that regularly rotates around a star.

Encyclopedic Entry: planet

plastic

Noun

chemical material that can be easily shaped when heated to a high temperature.

reduction

Noun

lowering.

reproductive system

Noun

organs involved in an organism's reproduction.

river

Noun

large stream of flowing fresh water.

Encyclopedic Entry: river

rotation

Noun

object's complete turn around its own axis.

Encyclopedic Entry: rotation

satellite imagery

Noun

photographs of a planet taken by or from a satellite.

sea

Noun

large part of the ocean enclosed or partly enclosed by land.

Encyclopedic Entry: sea

starvation

Noun

dying from lack of food.

storm

Noun

severe weather indicating a disturbed state of the atmosphere resulting from uplifted air.

storm drain

Noun

system to empty streets of excess rainwater. Storm drains flow into local creeks, rivers, or seas.

strangle

Verb

to choke, or cause death by preventing breathing.

temperature

Noun

degree of hotness or coldness measured by a thermometer with a numerical scale.

Encyclopedic Entry: temperature

top predator

Noun

species at the top of the food chain, with no predators of its own. Also called an alpha predator or apex predator.

toxin

Noun

poisonous substance, usually one produced by a living organism.

trawl

Verb

to fish by dragging a large net along the bottom of the body of water.

vast

Adjective

huge and spread out.

wind

Noun

movement of air (from a high pressure zone to a low pressure zone) caused by the uneven heating of the Earth by the sun.

Credits

Media Credits

The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.

Writers

Kim Rutledge
Melissa McDaniel
Diane Boudreau
Tara Ramroop
Santani Teng
Erin Sprout
Hilary Costa
Hilary Hall
Jeff Hunt

Illustrators

Tim Gunther
Mary Crooks, National Geographic Society

Editors

Kara West
Jeannie Evers

Educator Reviewer

Nancy Wynne

Producer

Caryl-Sue, National Geographic Society

Sources

Dunn, Margery G. (Editor). (1989, 1993). "Exploring Your World: The Adventure of Geography." Washington, D.C.: National Geographic Society.

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