Recent research suggests the tiniest pieces of plastic debris may pose some of the greatest risks for ocean ecosystems - and us.
Each year, tons of plastic find their way from our picnics and recycling bins into the ocean. We've all seen heartbreaking photos of sea turtles disfigured by six-pack rings or seals caught in fishing line. And we've all heard that plastic never goes away.
But, over time, cups, water bottles, cigarette filters, and shopping bags break down into tiny, unidentifiable fragments. The smallest pieces, known as microplastics, are virtually impossible to clean up and pose insidious risks. They may be mistaken for food or accidentally ingested by everything from fish, to turtles, to seabirds, to whales.
Recent research also suggests that some microbes may be digesting plastic. It's unclear whether they are truly biodegrading the plastic - that is, breaking it down completely to simple molecules like carbon dioxide and water - or whether they are just releasing the chemicals that comprise plastic. The latter is concerning because many plastics contain hormone-like chemicals, such as bisphenol A and pthalates.
In addition, plastics can adsorb other toxicants, such as heavy metals or organochlorine compounds. And some of the microbes that tend to be found on plastics are potentially disease-causing organisms. It's unknown what impact the chemicals and microbes coating plastic fragments may have on animals that consume them. It's also unclear how much plastic-derived contamination is working its way through the food chain to top-level consumers, like ourselves.
There are a lot of open questions when it comes to oceanic plastic pollution. What's clear is that there's a lot of plastic out there that isn't going anywhere anytime soon. As appealing as it may be, the idea of vacuuming and filtering the ocean is just that - an idea that incites skepticism from many experts. We'd do better to look to our own daily habits and try to reduce our reliance on disposable plastic.
For more on this topic:
- Sea Education Association's Plastics at SEA Program
- NOAA's Marine Debris Program
- Algalita Marine Research Institute