Sure, we all know pollution destroys ecosystems, but, for better or for worse, pollution can create ecosystems too. The billions of tiny pieces of plastic that are now floating in our oceans are exactly that: a novel ecosystem humans have unwittingly made by throwing away too much plastic. Microbes and insects that might have no business thriving in the middle of the ocean suddenly have found a new home amidst all that drifting plastic.
If you took a boat out to the so-called Pacific garbage patch — a swirling region of the ocean where plastic is trapped by wind and ocean currents — you won't find anything resembling a "garbage patch". The water would actually look quite pristine — until you drag a net through it to reveal floating flecks of plastic, mostly glitter-sized or smaller. The amount of plastic in the region has grown 100 fold in the last 40 years, but it still really doesn't look like much. Yet these barely visible pieces of plastic are completely remaking the ocean.
Sea skaters, for example, have found a plastic breeding ground paradise. The water insect skims across the ocean surface eating plankton and laying its eggs on the hard surfaces of flotsam, which is now in abundance as plastics have taken over our world. A 2012 study found that skater eggs increased with microplastic pieces in the ocean. Occasionally, bigger pieces of plastic will show up enveloped in thousands of sea skater eggs, like a one-gallon plastic jug covered with 70,000 of them, 15 layers thick.
The effects of a sea skater explosion will ripple out through the food chain, possibly benefitting some organisms but not others. Is it good? Is it bad? All we can say for sure is that the balance of the ocean ecosystem will likely change. The open ocean suddenly has a lot more hard, durable surfaces for organisms like the sea skater and barnacles — artificial islands of a sort for these tiny, landless creatures.
Sea skater. Courtesy of Scripps Institution of Oceanography
Microbes, too, have found a new home in all the plastic debris. What's more, microbes can hitch a ride on their floating plastic home, making an otherwise unlikely journey from land to the middle of the sea. A study earlier this year cataloged some of the microbes living in the plastisphere, many of them new to science; especially abundant were Vibrio, a group of bacteria including those that cause cholera. But scientists are still working to figuring out the role of all these bacteria. "Each one of these plastic bits is a circle of life — one microbe's waste is another microbe's dinner," one of the study's authors told the LA Times.
The microbes may even be breaking down the plastic, making microscopic pits that the team found in the plastic pieces. To look on the cheery side, perhaps this means we could find microbes to help degrade otherwise long-lasting plastic. But this points toward something else, too: The plastic itself is interacting with the environment.
Plastic pieces are like tiny sponges that soak up toxins such as pesticides from the water and leach them out again when broken down. Animals that eat the microplastics, like gooseneck barnacles, for example, can pass the plastics and the toxins up the food chain. A similar problem is happening in the Great Lakes, which have been contaminated by microbeads from exfoliating soap.
When it comes to individual species, though, there are winners and losers in the new plastisphere, which makes telling tidy story about ocean plastics hard. Certainly it makes sense to stop pouring plastics into the water, but how far should we go to reverse it? Plastic-capture schemes may do more harm than good, scooping up zooplankton, an important source of food for many creatures, along with plastic. Humans might just have to learn to live with the plastisphere we've inadvertently made. [LA Times — Nautilus]