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Weird Science: Marine Debris and Oceanic Gyres

NGSS Disciplinary Core Ideas

Human-generated marine debris is a global problem. Common debris items include plastic and glass bottles, shopping bags, balloons, Styrofoam, and abandoned fishing nets and lines. They come from a variety of sources such as ocean trash dumping, fishing boats, cruise ships, lost shipping containers, littering, and wind-blown coastal landfills. Marine debris can be harmful to ocean life through ingestion or ensnarement. Seabirds have been known to fatally ingest marine debris, and some marine mammals can become entangled in abandoned fishing nets. Most forms of plastic do not degrade readily and can float in the ocean for years. Ocean winds and surface currents can move this floating debris across entire ocean basins until they either wash ashore or collect inside the middle of oceanic gyres (SF Fig. 3.3 A).


SF Fig. 3.3. (A) Brown boobies (Sula leucogaster) sitting on a pile of marine debris on Green Island, Kure Atoll.

Image courtesy of Claire Fackler, National Oceanic and Atmospheric Administration (NOAA)

SF Fig. 3.3. (B) A green sea turtle is entangled in an abandoned fishing net.

Image courtesy of Doug Helton, National Oceanic and Atmospheric Administration (NOAA)

In addition to plastic, fishing gear is often discarded at sea when it becomes damaged. These nets can continue to float around in the ocean where they entangle marine life (SF Fig. 3.3 B). The entanglement of animals is known as ghost fishing, as the nets continue to carry out their designated purpose long after they’ve been abandoned. In shallow seas nets can also become biofouled and sink onto coral reefs, where they damage corals and fish habitat.


In 2014, a scientific research study reported more than 250,000 tons and 5,000,000,000,000 pieces of floating plastic debris in the gyres of the ocean. The “Great Pacific Garbage Patch” is one such marine debris field, found in the middle of the North Pacific gyre. It contains mostly small plastic particles and discarded fishing lines. Similar oceanic gyre marine debris fields are found in the Indian and North Atlantic ocean basins.

Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawaii, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.