Our junk is piling up in the oceans—more than 14 billion pounds of it every year—and as it does, it’s altering parts of the world we haven’t even explored yet. Over the past few months, I seem to be stumbling over one study after another that explores the impact of our trash. Together, they suggest that our garbage alone is physically altering the world’s oceans.
We’re creating superhighways of floating trash and sunken debris–mostly plastic, but also steel and glass and other long-lived materials–that can transport fish, invertebrates, microorganisms and disease to new territories. Once there, the trash, and the marine life it carries, can cause shifts in the populations of plants, animals, and microbes. What’s more, our junk has the potential to affect water chemistry and local currents. It’s even possible this stuff can disrupt the carbon cycle in the ocean—something that plays an important role in climate change.
The spread of plastic is so far reaching, the potential impacts so diverse, and the research so new, that it’s not yet possible to get a comprehensive picture of what’s going on out there. And our trash keeps flowing.
What we know for sure is: the oceans make up 99 percent of all the living space on Earth, and the discarded remains of our daily lives have been found in every corner of the ocean where we’ve looked for it. And yet the flow of this kind of debris is relatively new. Synthetic plastic has only been around for 100 years or so, and modern plastics didn’t come into broad use until after World War II. Modern container shipping didn’t begin until 1956.
In that short period of time we have flooded the ocean with material that will outlive everyone alive today. We have very little understanding of what kind of impact that material is having. There’s a good chance we never will. Our stuff has already begun to accumulate in unexplored territories where we have no baseline to tell us what things were like before it got there.
Human beings have explored just five percent of the ocean. How much will have already changed by the time we’ve explored ten percent?
In some coastal areas, human debris makes up 80 percent of all the stuff floating on the surface of the water. That stuff provides a home for bacteria the minute it hits the water. As small organisms feed on that bacteria and are in turn eaten by bigger organisms, a small community begins to form. The floating debris serves as a raft. Living things can hitch a ride through open water where they wouldn’t normally be able to survive, and because plastic lives on longer than natural debris, it has the potential to carry hitchhikers far from their native waters.
“Some of this debris can go from a coastal region, like here at Woods Hole off into the Sargasso Sea in about a month and a half,” said Dr. Tracy Mincer, a marine chemist at Woods Hole Oceanographic Institution. “That’s relatively quick, so invasive species and other things could be transported that way.”
In 2010, for instance, skeletal eroding band disease appeared for the first time in Hawaii. Although no one can say for sure how this coral-killing disease got there, it’s entirely possible plastic debris carried it there, because the organism that causes the disease has been found on plastic floating in the western Pacific, and such plastic regularly washes onto the beaches in Hawaii.
PLASTISPHERE—a whole new ecosystem
Our plastic debris isn’t just providing taxi service between habitats. In 2013, Mincer and his colleagues announced that patches of floating garbage collecting in the middle of the oceans have developed their own ecosystems. Rotating currents called ocean gyres sweep floating debris into their centers like giant, slow-moving whirlpools. Once there, plastic debris can become trapped for decades, providing a growing surface for bacteria and the things that feed on it. Five major gyres span thousands of miles in each ocean, and the garbage patches they encompass produce a rich microbial reef, ripe with nutrients in places that are normally considered wastelands as far as food for marine life is concerned. The researchers named this new ecosystem the plastisphere, and they’re working to determine exactly what role it’s playing out there.
They’ve named 1,000 species of algae and bacteria growing on the plastic, including certain species of vibrio which show signs of being toxic to fish. Obviously, an explosion in the amount of toxic bacteria can have a major impact on fish populations.
Even more intriguing, however, is what may happen when the plastic breaks down. Although it’s commonly believed that most of the floating plastic that makes it to mid-ocean gyres floats around out there for decades, there’s evidence to suggest it actually sinks—at least partly. According to Mincer, the Sea Education Foundation, which has been surveying garbage in the Sargasso Sea, has discovered that, despite the constant flow of new trash, the total amount of plastic in the gyres isn’t growing. They suspect that microbes help to break it into tiny bits, which may a eaten by animals that are an important part of the mid-ocean ecosystem.
“One of the things we’re very interested in pursuing is these little tiny copepods and other shrimps that make a living out of filtering the water in open ocean,” said Mincer who is collaborating with scientists at the Sea Education Foundation. “As they eat this stuff, they make fecal pellets that are very dense and sink to the bottom of the ocean and are a big part of the carbon pump. They play a role in sequestering carbon dioxide out of our atmosphere. But one of the issues is; what happens if the plastic makes their fecal pellets less dense so they don’t sink as far? There could be a problem with the disturbance of the carbon cycle.”
THE TRASH TRAIL—deep sea debris
While human trash represents the majority of floating debris, there’s even more of it at the bottom of the ocean. It’s been reported by various conservation and research institution sites that 70 to 80 percent of the plastic litter flowing into the ocean actually sinks to the bottom fairly quickly. It tends to accumulate bacteria, algae and fouling organisms that eventually become heavy enough to drag it down. A recent survey of the European seafloor found that littler was distributed throughout the Mediterranean, and all the way from the continental shelf of Europe to the Mid-Atlantic Ridge 1,000 miles from land. “This survey has shown that human litter is present in all marine habitats, from beaches to the most remote and deepest parts of the oceans,” said Dr. Kerry Howell in a press release. Howell is a marine scientist who participated in the survey.
Much of the debris tends to pile up where rivers and bays empty into the ocean, but some of it ends up flowing down into underwater canyons, which eventually funnel the plastic straight into the deepest parts of the ocean. Once there, as deep sea organisms feed on the debris, whatever toxins they contain may accumulate up the food web. In addition, the large amount of coastal marine life the debris carries with it may be changing the nature of the ecosystem in the deep oceans. In a phone interview, one of the study authors Christopher Phram agreed that it is possible species are being transported through the seafloor as the litter items are being moved from one area to another by currents. Some of them may become invasive or damaging in their new environment.
STEPPING STONES—Fallen Sea Containers
Shipping containers are regularly lost from cargo ships, tossed overboard by winds and stormy seas. No one is keeping very good records, and estimates vary wildly depending on who you ask — 675 per year according to the World Shipping Council or 10,000 containers a year if you’re quoting conservation scientists. Whatever the number, international shipping lanes are like superhighways crisscrossing the world’s oceans thousands of times a week. Beneath these highways, there’s bound to be a dotted line of containers marking their passage overhead. Could they eventually provide a stepping-stone-like pathway for marine animals to move from one part of the world to another?
“As far as being some kind of attachment point for animals all the way across oceans, it’s definitely feasible,” said Josi Taylor, researcher at the Monterey Bay Aquarium Research Institute. Taylor is the lead author on a recent article detailing the first survey of marine life on one of these lost sea containers in Monterey Bay. Discovered in 2004, the container has been resting beneath 4,200 feet of water for 10 years.
Taylor and her colleagues used an ROV (remotely operated vehicle) to take video footage of marine life on the container. They also collected samples of the muddy seafloor beside the container and then a third of a mile away. Not surprisingly, the container had become a home for scallops, snails, tubeworms, and other marine life commonly found on rocky reefs in the area. Those organisms were mostly absent from the surrounding muddy seafloor. As you might expect, Taylor found more fish, crabs, and other predators near the containers than she found farther away. The container may be providing more food and a little cover for those predators.
What they didn’t find were sponges and soft corals that also tend to colonize the rocky reefs in the area. Taylor and her colleagues are interested in finding out why. Perhaps those organisms simply need more time, or maybe the paint or coating on the container is toxic to them. The researchers are planning more studies to figure it out, but what it all boils down to is that this hunk of shipping trash is causing definite shifts in the neighborhood.
The container Taylor surveyed was still in very good condition with few signs of rust or deterioration, which means it will likely be around for many years to come. And many, many more will be piling up on the bottom alongside it. It’s not hard to imagine that the busiest shipping lanes, may be laying a pathway across the oceans, like stepping stones. Of course, that’s just conjecture. It can’t be said until more containers are found, and until species are turning up where they aren’t expected, but Taylor agrees it’s worth considering.
And let’s not forget about what’s in those containers. In this case its tires, but everything humans have ever shipped is probably sitting in a lost container somewhere on the bottom of the ocean.
“I think probably the most worrisome container cargo would be things like fertilizers that are transported quite often in large quantities,” Taylor said. “Although the effects of one container may seem small, the thousands of shipping containers lost on the seafloor each year could eventually become a significant source of pollution for deep-sea ecosystems.”
WHAT CAN WE DO?
There’s very little chance humans are going to figure out how to remove all the garbage that’s already in the oceans (in fact, there’s probably no chance anyone will even try). But it’s not too late to stem the tide. We can reduce the flow. Simply understanding the impact of our actions might inspire us to try.
1. Cut disposable plastics out of your routine. Simple alternatives include bringing your own bag to the store, choosing reusable items wherever possible, and purchasing plastic with recycled content.
2. Recycle. When you need to use plastic, be sure that you recycle it after you’ve reused it. Each piece of plastic recycled is one less piece of waste that could end up in our oceans.
3. Take Responsibility. Whether you represent yourself, a business, or a government, know how much you are contributing to the problem of plastic pollution.
- Conduct a waste audit and share the information.
- Set specific goals to reduce or eliminate your plastic waste generation.
4. Clean up your beach. Many organizations host clean-up days where you can volunteer to pick up trash at your local beach. A few hours of your time can make a big difference.
5. Support NRDC’s work. Go to the NRDC‘s website to learn more.