Inventory of Crap on the Ocean Floor

By Elizabeth Preston | May 2, 2014 9:09 am

ocean trash

Going to the bottom of the ocean isn’t such a big deal. Sure, James Cameron generated a lot of fuss last year with his record-breaking descent into the Mariana Trench—but Uncle Ben has been to the deep sea without even using a sub. Yes, that picture shows a packet of Uncle Ben’s microwaveable rice a kilometer deep in the Atlantic Ocean. It’s one of the items an international group of scientists found in their detailed inventory of underwater garbage.

The scientists pooled data from 588 different surveys of the seafloor, covering 32 European sites. The studies had taken place in the Atlantic and Arctic Oceans and the Mediterranean Sea between 1999 and 2011. Some were surveys by remotely operated vehicles, scanning the seabed with video cameras. Others were brute-force sweeps with trawling nets. From all this, a few patterns emerged.

First, surprising no one, was plastic. Forty-one percent of all the trash items found were plastic. And that’s not even counting plastic nets or fishing lines, which were grouped together with fishing gear (34% of items). Glass bottles made frequent appearances, although glass only accounted for 4% of the trash. There was also wood, paper, cardboard, fabric, and some mystery materials.

Coming in at 1% of garbage items was “clinker,” the rocky leftovers of burned coal. Steamships used to dump this material overboard between the 18th and 20th centuries, and it still crisscrosses the Mediterranean in the shadows of old shipping routes. The researchers found especially high amounts of clinker in deep sea basins and continental slopes, though they note that there’s probably even more of it hidden under a century’s worth of sediment on the seafloor.

From plastic bags to used coal to Heineken cans (and more plastic bags), much of the trash was sadly expected. For most sites, “the concentrations were pretty much what we expected to find,” says lead author Christopher Pham, a PhD student at the University of the Azores in Portugal. However, there was more debris in the Arctic than they thought they’d see—something “we are still trying to explain,” he adds.

Looking at sites all around Europe gave the scientists a glimpse of the forces that push and pull debris through the oceans. Some bits of refuse sink right away, while others float for long distances before succumbing. The authors found lots of fishing debris on underwater mountains, ridges, and banks, which are areas targeted by commercial fishers. They also found a general increase in litter closer to shore, but low concentrations on continental shelves, Pham says, as currents presumably push trash off of them and into deeper waters.

It makes sense, then, that ocean canyons held the most garbage. These sites are dead ends for a drifting bit of junk. Pham thinks more hotspots and accumulation patterns will emerge as scientists survey the seafloor across the rest of the world.

One thing scientists probably won’t find is a pristine space. “What was shocking was that all of the sites sampled had debris,” Pham says. Whether they were looking 35 meters or 4500 meters (almost 3 miles) deep, the researchers found trash. Everywhere in the ocean there are tiny grains of plastic waiting to be eaten by tiny organisms; drifting bags that will be gulped down by sea turtles mistaking them for jellyfish; plastics containing toxic chemicals that can gradually travel up the food chain to humans. There are nets wrapped around corals. There are fish killed by “ghost fishing,” the work of discarded fishing gear without a person at the other end.

Still, Pham isn’t too gloomy. “I’m convinced there is still hope!” he says.

“The solution is rather simple,” Pham says; “we need to produce less and recycle more.” That’s simple to say, but not so simple to enact on a global scale. It also doesn’t address the question of cleaning up the trash that’s already in the ocean. Maybe the next time James Cameron goes down there, he can pick some up.

Images: (both) National Oceanography Centre, UK.

Pham, C., Ramirez-Llodra, E., Alt, C., Amaro, T., Bergmann, M., Canals, M., Company, J., Davies, J., Duineveld, G., Galgani, F., Howell, K., Huvenne, V., Isidro, E., Jones, D., Lastras, G., Morato, T., Gomes-Pereira, J., Purser, A., Stewart, H., Tojeira, I., Tubau, X., Van Rooij, D., & Tyler, P. (2014). Marine Litter Distribution and Density in European Seas, from the Shelves to Deep Basins PLoS ONE, 9 (4) DOI: 10.1371/journal.pone.0095839

  • Uncle Al

    A flat sea bottom is biodepauperate. Add texture (e.g., artificial reefs, shipwrecks, dead whales) and life blooms – as pictured. North Atlantic shipping and Nazi U-boats created sustained rich ecological niches. Bottom debris are valuable paleontological and archeological markers for millennia hence. Glass bottles will document mankind’s existence long after the planet is withered.

    Surface flotation is lethal across the biome. Address what is important. As for the turtles…oceans are suffocating in jellyfish plagues. Relocate some turtles where they will do some good.

    • virginia662

      Uncle Jacob got a year 2013 Audi TT RS Coupe by working part time online. imp
      source C­a­s­h­D­u­t­i­e­s­.­ℂ­o­m

  • Dr. Santosh Bhaskaran

    Human extinction would therefore be a great relief to Nature!!

  • Ken

    As to “human extinction being a relief to nature”…….I am not certain why so many place humans outside of nature. The planet spawned an intelligent (more or less) species that uses tools and exploits resources….the very nature of speciation and planetary evolution make us a part of nature – trash, climate change and all.
    As to humans being disastrous…..our planet has survived extinction level events in the past. The planet will always be here, regardless of what man does today. Geologic time is very different than that measured by human lives…..humans may yet go the way of dinosaurs unless we can establish a viable civilization off-planet to hedge our bets against the next asteroid strike.

  • Ken Reed

    Imagine a severe climate change in which all the oceans dry up. You could walk on what was once the bottom, and mostly you would find it like the Sahara. If by chance you come upon a Coke bottle, you are entitled to think “the gods must be crazy.”

  • Kathy

    Shouldn’t the plastic manufacturers start to be held accountable for the clean-up?

    • Lyrusi

      We don’t even know how to do this cleaning up, it’s some incredibly complicated and hard task.
      However if we did know how to, the price of it would likely surpass all of their money, about a trillion times (even a trillion in European scale).
      Also it isn’t the manufacturers who trashed everywhere. It’s the people who bought all this plastic.

      • Kathy

        Agreed. It is our fault for buying the plastic. However, if companies were held accountable for what they produce they might start producing products that have a lower environmental impact.

        And, by the way, it can be done….



Like the wily and many-armed cephalopod, Inkfish reaches into the far corners of science news and brings you back surprises (and the occasional sea creature). The ink is virtual but the research is real.

About Elizabeth Preston

Elizabeth Preston is a science writer whose articles have appeared in publications including Slate, Nautilus, and National Geographic. She's also the former editor of the children's science magazine Muse, where she still writes in the voice of a know-it-all bovine. She lives in Massachusetts. Read more and see her other writing here.


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