Why are gyres a concern?
Floating plastic and microplastics can be transported by ocean currents for great distances. They can reach ocean gyres, which are circular ocean systems that either trap or repel debris. Converging surface currents in the five subtropical gyres create garbage patches that accumulate microplastics along with other debris suspended below the ocean surface.
Plastics break down into smaller and smaller pieces (microplastics) but don’t disintegrate. Wildlife, such as fish and birds, can eat the microplastics which may harm or kill them. The higher an animal is in the food chain, the greater the potential for a higher concentration of microplastics in that animal species. There is increasing concern about the potential for microplastics to harm human health and marine life as these microplastics move through the marine food web. Microplastics both absorb and leach out chemicals and harmful pollutants into the marine environment. The chemical ingredients of plastics or toxic chemicals absorbed by the plastics may accumulate over time and be persistent in the environment. Scientists are studying the gyre and factors that impact it.
This description is based on the information found in the Web links listed with this topic.
Web Links from MedlinePlus (National Library of Medicine)
Ocean Gyre (National Geographic Society)
Oceans Full of Plastic (Convention on the Conservation of Migratory Species of Wild Animals (CMS)) (PDF — 548.66 KB)
Last Updated: April 20, 2017