Pacific Garbage Patch becomes its own ecosystem


“Life, uh, finds a way.” Jeff Goldblum lounging across a chair in sunglasses may seem an unlikely symbol of evolutionary prescience, but he was right. Or the character he was playing in Jurassic Park was, anyway.

Words: Nathan Hill

It often feels like we humans have done all we can to turn this planet into one huge pile of slurry. There’s one patch in particular, out there in the vastness of the oceans, that’s especially gacky. We call it the Great Pacific Garbage Patch, and it lives up to its name.

Swirl a teacup, or the dregs of a cereal bowl, and you’ll see a kind of vortex, with everything solid pulled to the middle. The swirling gyre of the Pacific Ocean has been doing the same thing on a global scale, bringing together more than a few Coco Pops. Gathered up into an area around twice the size of Texas—some 620,000 square miles total—is one colossal testament to human littering. Admittedly, a moderate chunk (maybe as much as 20%) of that appeared as a result of the 2011 tsunami that hit Japan. But still. Plastic straws and all that. Estimates put the collective weight of the rubbish here at 80,000 tonnes, or 1.8 trillion individual objects.

It's no surprise that such a vast tract of trash is on many scientists’ radars. What was less expected, yet subsequently discovered, is that it appears to have formed its own ecosystem. Flipping off our efforts at wanton ecocide, life has indeed found a way.

The rafts

Rafting is generally thought of as hurtling down white-water rivers in a colourful helmet. In scientific parlance, the term refers to an association between organisms and floating debris. That’s not a new concept, and nature has been doing it for as long as things have floated: Sargassum, an alga that floats without tethering, acts as a complex bobbing biome, feeding and sheltering numerous fish and inverts. Other naturally occurring materials, such as pumice from volcanic eruptions, can act as focal points for rafting.

Man-made flotsam and jetsam have for some time provided another type of raft: the anthropogenic raft. Of these anthropogenic rafts, some are relatively impermanent. Drifting wood soaks and sinks. Abandoned boats leak and capsize. Others have a lifespan that will likely outlast human civilisation. Plastics persist.

While collecting and surveying plastic chunks from the Garbage Patch, scientists discovered that some 80% of what they were hauling from the water carried life. Between November 2018 and January 2019, 105 different plastic items were retrieved, and across them, they had become home to 484 marine inverts from 46 different species. That might not seem too surprising; things in the sea gather organisms from the sea. What was unusual was that 80% of these organisms were normally coastal dwellers that were cruising on the life pelagic. Open ocean species like gooseneck barnacles sat shoulder to shoulder with comparative landlubbers like rockpool anemones. Worse, the non-pelagic species outnumbered them, by a factor of three to one.

As with all such discoveries, more questions are raised than are resolved. The first is how the creatures found themselves so far from home, adrift on cola bottles. Were these items seeded during a shoreline stage and then carried to sea? Or did pelagic invert larvae simply colonise what happened to be the only hard surface available at the time?

We also have no idea what ecological impact this might have on species that would never usually meet. What happens, for instance, to the young of migratory shoaling species as they swim through millions of bobbing islands, expansive neopelagic communities, packed with anemones they've never encountered before?

And perhaps most worryingly, what about the transfer of organisms between environments? Some scientists fear that such mobile islands could act as an organic armada, taking coastal invertebrates far from their origins and across to pastures new as invasive, ecologically threatening outbreaks. A similar concern was raised between 2012 and 2017 across North America and Hawaii. In those five years, researchers discovered that over 380 Japanese coastal invertebrate species had landed on the shores, carried primarily on plastic debris from the 2011 tsunami. If nothing else, it confirmed that nominally coastal species can survive the conditions of the open oceans for at least six years.

And if you're wondering what type of plastic debris favoured coastal species the most, the top three items (in order) for species richness were rope, net, and bottle. "Life, uh, finds a way."

You can read the full article from the journal Nature Ecology & Evolution right here: