Humanity's penchant for single-use plastics is beginning to manifest in some truly ugly ways. As we start to really get a grasp on the magnitude of the Great Pacific Garbage Patch, elsewhere in the ocean plastic waste is mounting on the shores of some of the most remote islands, with a new study revealing the true extent of the mess and the threat it poses to local species.

The work was carried out by scientists from the British Antarctic Survey (BAS), who completed four research cruises between 2013 and 2018 investigating the scope of marine plastic pollution in some Atlantic Marine Protected Areas. This involved taking samples of the water surface, water column and seabed in the Southern Atlantic, as well surveying beaches to tally up plastic waste and examining more than 2,000 animals.

Among the findings was a startling rise in the density of plastic waste along the beaches of the East Falkland and St Helena islands. Here, the team recorded up to 300 plastic items per meter (3.2 ft) of shoreline, which is 10 times higher than the figures recorded a decade ago.

"Three decades ago these islands, which are some of the most remote on the planet, were near-pristine," says lead author Dr David Barnes. "Plastic waste has increased a hundred-fold in that time, it is now so common it reaches the seabed. We found it in plankton, throughout the food chain and up to top predators such as seabirds."

Earlier research has previously shown how easy it is for animals to mistake plastic debris for food. One study in 2016 described how seabirds that rely on a distinctive smell to hunt down krill for dinner could easily mistake that for a sulfur compound expelled by floating plastic debris and chow down on that instead. Beyond that, there is also the problem of entanglement, and the BAS scientists raise the issue of non-indigenous and potentially invasive species making their way to these remote islands on these floating plastic "rafts."

This new research calls to mind a similar study published last year, where scientists discovered the Earth's highest density of plastic waste washed up on an uninhabited island in the Pacific Ocean. And new research expeditions carried out by the Ocean Cleanup Project indicate the Great Pacific Garbage Patch covers an area three times the size of continental France and includes 1.8 trillion pieces of plastic, somewhere between four and 16 times higher than previous estimates.

Currently, millions of metric tons of plastic wash into the world's oceans each year, and most of it is broken down into smaller fragments that are hard to track. These visible representations of plastic waste are therefore stark reminders of the magnitude of the problem and the threat it poses to biodiversity, along with the wellbeing of the planet.

"These islands and the ocean around them are sentinels of our planet's health," says study author and biologist at the Royal Society for the Protection of Birds, Andy Schofield. "It is heart-breaking watching Albatrosses trying to eat plastic thousands of miles from anywhere. This is a very big wake up call. Inaction threatens not just endangered birds and whale sharks, but the ecosystems many islanders rely on for food supply and health."

The research was published in the journal Current Biology.