5 Ocean Gyres
Plastic Pollution Hotspots
The oceans are home to an estimated 5 trillion pieces of floating plastic
Much of this buoyant trash is to be found concentrated in the main circular currents, or gyres. These are formed by a combination of the Earth's rotation and winds. Floating particles naturally drift towards their centre.
There are 5 major gyres in the world's oceans:
• North Pacific Gyre
• South Pacific Gyre
• North Atlantic Gyre
• South Atlantic Gyre
• Indian Ocean Gyre
You might get a bundle of fishing net, a washing basket, a chair; then you see bottle tops, toothbrushes, combs – people’s belongings basically. It doesn’t make any sense.
Emily Penn, eXXpedition voyage leader
No doubt you've already heard of the 'Great Pacific Garbage Patch', which covers 1.6 million km2 of the North Pacific Gyre. This contains between 1,100,000,000,000 and 3,600,000,000,000 floating plastic items, 94% of which (by number) are microplastics (less than 5mm).
In the centre of the gyre, the dry mass of plastic exceeds the dry mass of plankton, reportedly reaching densities as high as millions of pieces of plastic per square kilometre!
This is a particular risk to marine life, as filter feeders including whales have been observed within highly polluted areas of the Great Pacific Garbage Patch.
The amount of plastic in the Great Pacific Garbage Patch is now increasing exponentially
Other ocean gyres are accumulating plastic
The Great Pacific Garbage Patch in the North Pacific Gyre was the first to be discovered. However, the events occurring in the Pacific are being mirrored in all the world's oceans.
A region of the Great Atlantic Garbage Patch, in the North Atlantic Gyre, was found to contain an estimated 80 billion pieces of floating plastic, amounting to around 1100 metric tonnes.
Some net tows found as much as 580,000 floating plastic pieces per km2.
Water like this can contain hundreds of thousands of plastic pieces in every square kilometre. It can take as little as 40 days for drifting plastic to go from the coast to the centre of the accumulation zone, highlighting just how powerful these ocean currents can be in concentrating our rubbish.
How is this affecting our marine life?
Midway Atoll, 2000 miles from the nearest landmass, was once a haven for wildlife including seabirds, but now is an island of plastic.
Being in the middle of the North Pacific Gyre, huge amounts of plastic is gathering around this tiny island. Seabirds nesting here also gather plastic floating in the surrounding ocean, much of which is fed to their chicks. The result? Every year thousands of young seabirds on this island die, and a single albatross chick had consumed 450 pieces of plastic.
These gyres have massive potential to concentrate marine plastic debris, and so pose enormous risk to our ocean life
1. Eriksen et al. (2014). Plastic Pollution in the World's Oceans: More than 5 Trillion Plastic Pieces Weighing over 250,000 Tons Afloat at Sea. https://doi.org/10.1371/journal.pone.0111913
2. Law et al. (2010). Plastic Accumulation in the North Atlantic Subtropical Gyre. https://doi.org/10.1126/science.1192321
3. Lebreton et al. (2018). Evidence that the Great Pacific Garbage Patch is rapidly accumulating plastic. https://doi.org/10.1038/s41598-018-22939-w
4. Moore et al. (2001). A Comparison of Plastic and Plankton in the North Pacific Central Gyre. https://doi.org/10.1016/S0025-326X(01)00114-X
5. Law et al. (2014). Distribution of Surface Plastic Debris in the Eastern Pacific Ocean from an 11-Year Data Set. https://doi.org/10.1021/es4053076
6. Gibbs et al. (2019). Cetacean sightings within the Great Pacific Garbage Patch. https://doi.org/10.1007/s12526-019-00952-0
8. Lavers & Bond (2016). Ingested plastic as a route for trace metals in Laysan Albatross (Phoebastria immutabilis) and Bonin Petrel (Pterodroma hypoleuca) from Midway Atoll. https://doi.org/10.1016/j.marpolbul.2016.06.001