The widening gyre

Many of the world’s plastics escape the waste management process and wind up with a second coming in the open ocean – turning into subtropical gyres, falling apart and damaging ecosystems as they do. Libby Peake reports

The widening gyre - Image 1The Age of Discovery, when European ships sailed the oceans in search of new trading routes and partners, finding previously unknown lands along the way, ended in the 17th century. By the early 1900s, intrepid explorers had mapped out the remote interiors of Australia, Africa and Antarctica, and these days, even the most rotund of tourists can waddle around what were once remote wildernesses. Modern technology has 
made the world a very small place indeed.

How surprising, then, that a mere 12 years ago, American sea captain Charles Moore should ‘discover’, in the North Pacific, a previously uncharted region twice the size of France.

Moore didn’t stumble upon some amazing (Pacific) Atlantis, but a more sinister byproduct of modern technology: the ‘Great Pacific Garbage Patch’. He wrote: “There were shampoo caps and soap bottles and plastic bags and fishing floats as far as I could see. Here I was in the middle of the ocean, and there was nowhere I could go to avoid the plastic.” The phenomenon is commonly thought of as an ‘island’ stretching 500 nautical miles, but the label is a misnomer. The North Pacific Subtropical Gyre is more of a ‘soup’, the ocean saturated with countless bits of plastic that look like confetti (or, if you’re a marine animal, plankton), along with occasional larger objects. On their research visit last year, the crew of Captain Moore’s ship explained on their blog: “It really is difficult to comprehend the vastness of this phenomenon. There is still a common public misconception that the gyre is a ‘place’, a detectable spot, when rather it is an enormous, extremely diffuse region.”

The widening gyre - Image 2Debris converges in the gyre because of a slowly moving spiral of currents formed by a high-pressure air system. Estimates suggest that 80 per cent of the rubbish originates on land and 90 per cent of it is plastic. And though plastics on solid ground appear stable – even eternal – in the ocean they’re anything but. For one thing, they’re subject to ‘photodegradation’, a process where ultraviolet radiation breaks polymer molecules into shorter segments and weakens their strength, resulting in the tiny bits of plastic that constitute most of the ‘soup’. Moreover, scientists have recently discovered that in open ocean conditions, plastics degrade relatively quickly and release potentially toxic chemicals, including bisphenol A, linked with hormone disruption, and styrene monomer, a potential carcinogen. And that’s not all there is to worry about: Plastics absorb hydrophobic substances like fertilizers and herbicides, which can enter the food chain when marine life mistakes plastic for sustenance.