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Pacific Voyage Reveals Depth of Plastic Pollution Crisis

The discovery of microplastics in deep water means scientists may have underestimated the extent to which plastic trash is contaminating the ocean – and its impact on fish, marine mammals and seabed dwellers.

Written by Erica Cirino Published on Read time Approx. 5 minutes
A scientist about the SY Christianshavn with marine debris gathered from the middle of the Pacific Ocean.Erica Cirino

I’m sitting on the back of an old steel sailboat called the SY Christianshavn that is cruising through the middle of the eastern Pacific Ocean, 1,000 miles (1,600km) from land in any given direction, when I spot my first piece of ocean plastic.

It’s a large chunk of an orange laundry basket, and I snap a few photos of it as it floats by the starboard side of the ship. Soon after, I spot a large orange fishing buoy, a few fist-sized plastic flakes, a pink dustpan and a green condiment bottle colonized by barnacles. And then – nothing. The sapphire blue water around the ship appears clean and clear until another pile of plastic debris – a huge tangle of nets and rope, a hunk of Styrofoam and a fishing trap – materializes about 20 minutes later.

It may be called “the Great Pacific Garbage Patch,” but this stretch of the ocean appears less like an overflowing landfill site and more like a lightly littered road.

Yet the people I sailed with last November – a group of seven sailors and scientists affiliated with a Danish nonprofit organization called Plastic Change, plus American artist Chris Jordan – have found a potentially huge and constant presence of plastic lurking below the surface. On this trip they pulled microplastic from the depths, something that had not been done before in the Pacific. The presence of the substance in deep water could mean scientists have been underestimating both the volume of plastic in the ocean and its effects on the marine life that feeds in the middle layers of the ocean and on the seabed.

“New research suggests that large pieces of plastic collect on some parts of the ocean floor, and tiny particles can be suspended in the water column,” said Kristian Syberg, associate professor of environmental risk at Denmark’s Roskilde University, who sailed across the Pacific with Plastic Change.

It is possible that algae and chemicals also weigh down small bits of microplastic, he added, sending them deeper into the water column. A 2016 study found that hermit crabs, lobsters, sea cucumbers – which can live at depths of up to 6,000ft (1,800m) – have eaten microplastic.

Plastic never decomposes; it only breaks down into smaller pieces over time. This means that big plastic items – such as bottles, toys, tires, bags and ropes – that enter the oceans will eventually disintegrate into tiny bits. Plastic pieces smaller than one-fifth of an inch (5mm) in diameter pose the most danger to marine life, according to scientists.

“Microplastics are more jagged and porous than large pieces of plastic, making them like little sponges that soak up toxins from the seas,” said Malene Møhl of the Danish Ecocouncil, who also sailed aboard SY Christianshavn. “When animals mistake microplastic for food – like fish eggs or plankton – they also ingest the chemicals the plastic contains. If the plastic doesn’t stop up their digestive systems and cause starvation, the chemicals in the plastic kill them slowly over time.”

A vertical trawl collects microplastic-contaminated water samples. (Erica Cirino)

Some toxins commonly absorbed by ocean microplastics include pesticides, industrial chemicals and heavy metals. That alarms scientists as plastic can now be found in the bodies of at least 50 percent of all sea turtles. Researchers also estimate that 90 percent of all seabirds have ingested plastic after being attracted by its smell. Plastic is killing significant numbers of Laysan albatrosses on Midway Atoll in the Pacific and whales have been found with quantities of it in their digestive tracts. Fish are also known to eat it in large amounts, and it has been found in fish sold in markets – meaning terrestrial life could also be at risk.

There is definitely more plastic in the oceans than meets the eye; it’s just too tiny to spot as it passes beneath our ship. But it was easy to see when captured below the surface and brought aboard. When the weather was calm enough to sail at a low speed, Syberg and Møhl performed their sampling on deck with Plastic Change’s founder, Henrik Beha Pedersen, an environmental biologist.

The first place the team looked for plastic was on the surface, using a common type of plastic-sampling equipment called a manta trawl. The metal device – named after the ray that its shape emulates – skims the ocean’s surface for tiny pieces of plastic, collecting them in a net as it is dragged through the water for four hours at a time. The first time Syberg, Pedersen and Møhl showed me the contents of the manta trawl’s net, it was filled with handfuls of small, colorful plastic beads and flakes. Systematic research like this led by ocean NGO 5 Gyres prompted scientists to estimate that there were more than 5.25 trillion plastic pieces, weighing more than 250,000 tons, floating throughout the ocean in 2014. But in February 2017, the United Nations’ Clean Seas campaign raised that estimate almost tenfold to 51 trillion pieces.

To determine how much plastic was below the surface, Syberg, Pedersen and Møhl collected microplastic samples using a device called a vertical trawl, which is dragged by a rope tied to a spinnaker boom beside the ship. The trawl is made of 11 tube-nets suspended at specific depths in the first 66ft (20m) of the top ocean layer. That allows scientists to compare the concentrations of plastic at each of 11 depths. They also used a tubelike contraption to collect water samples at varying depths that would be tested for the presence of chemicals and microplastic.

Some of the plastic trash collected on the voyage across the Pacific. (Erica Cirino)

Final results are pending, but there appeared to be tiny bits of microplastic present in the samples, suggesting the scientists did find plastic deeper in the water column than expected. That is consistent with what other researchers have found in the Atlantic, which they believe is due to the turbulence caused by wind and wave. That causes vertical mixing of plastic and water and sends plastic to greater depths. New research suggests climate change is one driver of microplastic distribution in the oceans, as it influences ocean currents.

Plastic Change’s journey across the Great Pacific Garbage Patch is the last leg of a two-year sailboat-based science expedition from Denmark. The vessel has sailed through the Mediterranean, across the Atlantic and the Caribbean, through the Panama Canal and around the Galápagos Islands, up to Los Angeles and, finally, to Honolulu. So far, the team has calculated the concentration of plastic debris in the southwest Mediterranean at 20,717 particles per square kilometer. The composition of the debris – mostly transparent microplastic pieces – suggested that water bottles and packaging comprise a significant amount of plastic pollution in that part of the ocean.

“We set sail to not only bring attention to plastic pollution in the oceans, but to add to the pool of scientific knowledge about it,” said Pedersen. “What we’re finding isn’t good news, but it can hopefully help push forward efforts such as legislation curbing plastic use and restrictions on plastic manufacturers to stop the problem from getting worse.”

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