Teachers, scroll down for a quick list of key resources in our Teachers’ Toolkit.
- Startling new analysis reveals that cleaning up plastics near the coast would reduce ocean debris much more dramatically than focusing on the vast “Great Pacific Garbage Patch.” What is the Great Pacific Garbage Patch? Read through our encyclopedic entry and take a look at the nice Nat Geo map above for some help.
- The Great Pacific Garbage Patch is a collection of marine debris in the North Pacific Ocean. It is actually comprised of two patches: the Western Garbage Patch, located near Japan, and the Eastern Garbage Patch, located between the U.S. states of Hawaii and California. Here’s a great NOAA map of the patches.
- Researchers describe the garbage patch as a “relative dead zone.” Why? Read through our short entry on ocean gyres for some help.
- The entire Great Pacific Garbage Patch is bounded by the North Pacific Subtropical Gyre. An ocean gyre is a system of circular ocean currents 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. These calm centers have traditionally been regarded as oligotrophic, or nutrient-poor, because they have few concentrations of the organic chemicals that support producers, such as algae and plankton, in the ocean food web.
- Take a look at the maps above. The top map identifies the set of 29 sink (clean-up) locations for the mass scenario where the objective is to remove the most microplastics. The bottom map identifies the scenario where the objective is to reduce the overlap between microplastic and plankton growth. Where are the most effective sink areas?
- The vast majority of effective sinks would be located along China’s coast. Other effective sink areas are western Japan, the Indonesian archipelago, the eastern Mediterranean, and the south Atlantic Ocean.
- Why do researchers think focusing cleanup efforts near the coasts will be more effective than trying to clean up the garbage patch?
- Most marine debris is deposited in coastal waters, so collection efforts would focus on finding it at the source. “It makes sense to remove plastics where they first enter the ocean around dense coastal economic and population centers where there is a lot of marine life. It also means you can remove the plastics before they have had a chance to do any harm. Plastics in the patch have traveled a long way and potentially already done a lot of harm.”
- In addition to the accumulation of pollutants, researchers also studied areas where microplastics overlapped with phytoplankton. What is phytoplankton? Take a look at our video for some help.
- Phytoplankton are microscopic organisms that live in the ocean and can convert light energy to chemical energy through photosynthesis. Plankton are autotrophs, and different species may be considered plants, algae, or bacteria.
- Phytoplankton are the base of many marine food webs. Organisms from corals to cod, whelks to whales depend on phytoplankton for food.
- Why would oceanographers study the overlap between marine debris and phytoplankton?
- Many marine animals accidentally consume microplastics instead of phytoplankton. This threatens the animal’s health due to lack of nutrition, as well as the accumulation of sometimes-toxic chemicals present in the plastic. One recent study showed that more than 90% of seabirds have swallowed plastics, and these birds are also concentrated around coasts where their food is plentiful.
- Why do researchers think cleanup efforts are so much more effective in areas rich in phytoplankton compared to the garbage patch?
Nat Geo: What is an ocean gyre?
Nat Geo: Plankton Revealed video
(extra credit!) Environmental Research Letters: Modeling marine surface microplastic transport to assess optimal removal locations