Plastic-Eating Microbes Might Be Evolving in Our Oceans

Will organisms eventually need to evolve to eat plastic?. Andrew/Flickr

No where is plastic pollution a greater problem than in our oceans, where it accumulates in ocean gyres, gets broken down into microplastics, and can re-enter the food chain. There's even a designated zone in the Pacific Ocean known as the Great Pacific Garbage Patch where plastics are collecting in alarming concentrations.

The problem is so dire that it might be altering the evolution of life in our oceans in profound new ways. In fact, scientists now suspect that newly evolved microbes that eat plastic could be secretly emerging from this synthetic soup, reports New Scientist.

As worrisome as the plastic problem is, recent attempts to measure the amount of plastic in our oceans actually came up short of expectations. Given the rate of plastic production and predicted models of how it should accumulate, there should be hundreds of thousands of tons of floating plastic that we aren't detecting. That might sound like a good thing, but think again. We know how much plastic gets produced, and we know the rate at which it biodegrades. So just because we can't find it doesn't mean it isn't there.

But where is it? There are several explanations, most of which carry frightening consequences of their own. For example, it's possible that plastics are being broken down into microscopic bits of debris that are too small to measure. Of course, that will also make it nearly impossible to clean up and even more likely to re-enter the food chain. It's also possible that it's accumulating, just not in the places we have thought to look. Maybe more of it is sinking to the bottom of the ocean than predicted, or maybe there are garbage patches in unexpected places, like in the Arctic.

Or maybe it's being eaten by new, undiscovered organisms that have evolved in this synthetic environment to consume plastic.

It's a possibility that researchers are beginning to investigate. In fact, plastics are so radically changing our environment that some scientists have even proposed a whole new ecosystem called the "plastisphere." It makes sense that nature would find a way to colonize and make use of this unnatural resource.

Studies by Linda Amaral-Zettler of the Netherlands Institute for Sea Research show that the microbes colonizing floating plastic are quite distinct from those in the surrounding water, and suggest some are feeding on the pollutants. Though a DNA sweep of the biome surrounding some of this plastic debris in the North Atlantic failed to find any microbes known to break down plastic, that might just be because it's full of new, as-of-yet undiscovered plastic-eating microbes. After all, only a fraction of the world's microbes have been catalogued or studied, and evolution can happen quickly at the smallest biological levels.

Again, while the existence of plastic-eating microbes might seem like a natural solution to the plastic problem, reality is probably far more complicated than that. It could be toxic at higher levels in the food chain, where animals (like humans) can't evolve quite so fast. Adding to this concern, plastics also contain various toxic additives that could get released during the process of biodegrading.

Ultimately, the only real solution to the problem of plastic pollution is for us to stop producing it.

“We need to look at prevention and reduction at the start," warned Amaral-Zettler.