We know that most of the waste in the ocean is plastic. And while that in itself is shocking, researchers are now coming up with even more disturbing news. Indeed, a new study underlines that we have rigorously underestimated the amount of plastic in the Atlantic. It turns out that there is at least ten times more plastic in this ocean than previously thought.

Plastic waste is a major threat to all life in the sea. This plastic ends up in the ocean via multiple ways, plastic bottles, fishing nets, etc. But also via some products containing small plastic particles that flow through showers or rainwater to the sewer and end up in the sea.

During an expedition in 2016, the researchers sampled different parts in the Atlantic Ocean for four months. This happened at three different depths, up to about 200 meters below the water surface. Using state-of-the-art spectroscopic imaging techniques, they took a thorough look at the water. And the findings are not encouraging. In this upper layer alone up to 200 meters deep, there is a mind-boggling 12 to 21 million tons of plastic.

The researchers also stress that this includes only three of the most common and most polluting types of plastic: polyethylene, polypropylene and polystyrene. In addition, the total amount of plastic throughout the Atlantic is probably many times higher.

It means there’s a lot more plastic floating around in the ocean than thought. And that’s worrying. “Previously, we failed to match the mass of visible floating plastic with the mass that had been estimated to have entered the ocean since 1950,” said study leader Katsiaryna Pabortsava. “This is because previous studies have not measured the concentration of ‘invisible’ microplastics below the ocean surface. Our research is the first to do so across the Atlantic, from the UK to the Falklands.

Microplastics are small (often microscopic) pieces of plastic. They are created by the fact that larger pieces of plastic are broken down into smaller and smaller pieces. Microplastics pose a global threat to the environment, with harmful effects on the health of animals, people and ecosystems. The also absorb pollutants as they glide through the water. They then release these dangerous substances when eaten by animals. As a result, they accumulate in the food chain. Experiments have also shown that microplastics cause behavioral changes in fish after they have entered their brain.

The researchers assume that the Atlantic ocean is home to about ten times more plastic than previously thought. “If we assume that the concentration of microplastics we measured up to 200 meters deep is representative of the entire body of water, it means that the Atlantic ocean contains about 200 million tons of plastic litter,” said researcher Richard Lampitt. “To determine the dangers of all this waste to the environment and humans, we need good estimates of the quantity and properties of this material, how exactly it ends up in the ocean, how it is broken down and how toxic it is at the observed concentrations. Our study now shows that scientists have a totally inadequate understanding of these factors. It seems that previous estimates of the quantities of plastic dumped in the ocean have been vastly underestimated.”

The consequences of all this plastic are not yet well known. Researchers hope to better understand the extent and potential harm it can cause. What we do know is that some of the microplastics that end up in the ocean manage to make their way back to the mainland: filter feeders absorb the microplastics, are themselves consumed by fish, which in turn are caught and end up on our plates. In this way, microplastics not only come back to the country, but can also end up in the human body. It is estimated that – by consuming fish and shellfish, but also (tap) water, salts and added sugars and even inhaling microplastics-filled air – we receive more than 74,000 tiny pieces of plastic annually. The health implications of this are still unclear. In the meantime, there is no doubt that plastic poses a major danger to the health of animals in the sea. For example, researchers have shown that one piece of plastic can kill a sea turtle . Cleaning up all that wandering plastic isn’t so easy. The sparse cleanup efforts usually focus on the plastic that roams the surface. And even that is difficult to catch, as evidenced by the work of, for example, The Ocean Cleanup, although in the meantime they seem to be becoming more and more successful.

Joseph Mandell

Mandell is currently working towards a medical degree from the University of Central Florida. His main passions include kayaking, playing soccer and tasting good food. He covers mostly science, health and environmental stories for the Scientific Origin.