Invasive Species Find a New Way to Sail the Seven Seas

Floating ocean plastic allows alien bacteria to infect new waterways.
Massive oceanic garbage patches are actually made of billions of tiny plastic particles, like the ones shown here. (Photo: 5 Gyres Institute/Facebook)
Jul 6, 2013· 1 MIN READ
A six-time grantee of the National Geographic Expeditions Council, Jon writes about all things ocean.

Aquatic Invasive Species (AIS) love to latch themselves onto the hulls of boats, go for long rides across oceans, and take up new lives in foreign waters, where they are usually very unwelcome. The global spread of Asian carp, zebra mussels and thousands of other species that have hitched themselves around the world in just such a manner have proven themselves unwanted guests, impossible to disinvite.

These pests are not usually picky about the vessel, attaching themselves to everything from tankers moving petroleum, cars, or containers, to rubber Zodiacs delivering tourists to remote Antarctic and deserted island shores.

Now a new form of transport has been identified for the world’s wandering bugs: those giant, floating plastic patches that have created dead zones in each of the five oceans. Defined as being “as big as Texas or New Jersey,” these floating plastic trash heaps trapped in gyres of ocean current are proving to be perfect ways for ever smaller microbacteria to move around the globe.

Scientists at Woods Hole Oceanographic Institution in Massachusetts have identified a variety of microorganisms using floating plastic trash as rafts; a recent study found at least 1,000 different species of microbes attached to millimeter-sized scraps of plastic afloat in the North Atlantic.

The Woods Hole report identified a rash of diverse members of the microbial community hitching rides—including “heterotrophs, autotrophs, predators and symbionts”—and has dubbed the new ecosystems created by these floating trash heaps as “the plastisphere.”

Different from carp and mussels, these hitchhikers don’t need much surface to attach to. Tiny pieces of plastic are found to be carrying bacteria that can cause intestinal diseases, including cholera. One concern is that as these bacteria are transported into new environments they will forever alter ecosystems, as well as make people sick.

While the problem of AIS has been long known, and cargo boats and pleasure craft are aggressively warned to keep hulls scraped clean, there’s no chance to scrub these tiny bits of floating plastic. Because plastic lives so long, it offers a new and different kind of home to bacteria than the natural substances they’re used to latching on to.

Previously, a similar study undertaken by some of the same team from Woods Hole investigated if certain “specialist” bacteria might not help rid the problem of plastic eating it.

In the same North Atlantic waters where they recently discovered the hitchhiking bacteria, scientists found evidence that certain microbes appeared to not just be hitching a ride but to be munching on plastic, ranging from fishing lines to plastic bags and nurdles.

In some landfills, microbes have been found to successfully digest plastic, but it’s uncertain how that will go down in the marine world. The biggest concern is that rather than help eliminate plastic, the process will just pass toxins up the food chain, eventually making their way into human diets.