Deep sea plastic pollution in the spotlight

Our unsustainable daily habits have put the planet's future at stake, threatening natural habitats - with marine ecosystems at the top of the list.

The picture that won the World Press Photo award in the nature category poignantly highlights the problem. The Spanish photographer Francis Perez's image confronts the viewer with a  sad reality: an endangered sea turtle struggling in a plastic fishing net.

At the same time, a report published in the journal Nature Ecology and Evolution shocked the world with the revelation that pollutants are present even at the deepest point of the world's oceans, the Mariana Trench.

To top it off, researchers from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have found rising levels of litter  in the depths of the remote Arctic Ocean.

At least eight million tons of plastic end up in our oceans every year - and the plastic production is expected to double in the next 20 years. Yet, we still pay little attention to marine pollution.

"Oceans are greatly ignored," Perez told DW in an interview.  "But we all depend on the oceans."

We don't care enough

Perez stresses that only four percent of the ocean is under protection, and the situation is constantly worsening.

"I've been diving for more than 20 years," Perez said. "And I see less fish species every day."

The recent AWI study focused on the Arctic Ocean. It shows that here, too, pollution poses a major challenge. The concentration of marine litter at a deep-sea measuring station in the area is twenty times higher  than a decade ago.

"While the production of plastic has increased, waste management strategies did not develop efficiently enough," Melanie Bergmann, co-author of the study, told DW. 

The recent findings on pollutants in the Mariana Trench back up her claim. Not even the tiniest crustaceans living in such remote places were able to escape highly dangerous man-made toxins such as polychlorinated biphenyl (PCB) and polybrominated diphenyl ethers (PBDE).

Alan Jamieson, lead author of that report, said pollutants were found in every sample they analyzed, regardless of depth and species.  

Plastic, the ocean's worst enemy

Researchers believe the pollutants most probably reached the depths through plastic waste and dead animals sinking to the ocean floor.

However, the use of both pollutants found in the Mariana Trench was banned long ago because of the negative impact on reproductive and immune systems in both humans and wildlife.  

This shows marine pollutants such as plastics have a very long life, further increasing the damage they cause to the ecosystem.

In the case of the Arctic, the litter drifts in from northern European countries. According to a 2016 study, it takes around two years for plastic pollution to drift from the United Kingdom to the southern Arctic Ocean.   

At the same time, while sea ice levels are decreasing in the Arctic, shipping traffic is increasing.

"There has been an increase of ships from touristic cruises and fisheries," Bergmann told DW.

"And where you have ships, you also have litter - even unintended."   

Steady accumulation

Until now, scientists have only been able to observe one percent of the litter that ends up in the oceans. They fear the remaining 99 percent could be lying on the seabed.

Bergmann's analysis over time helps to determine whether litter is accumulating in the ocean, and at what rate. But once a plastic element has been found, the chances are it will still be there at the next count.

"The deep sea has no light, very low temperatures and scarce water movements," Bergmann said. "So materials just sit there and accumulate."

But litter has not only accumulated in the Arctic Ocean. It has also increased.

When Bergmann and her colleague calculated the contamination level in 2011, they found some 5,000 pieces of litter per square kilometer. In 2014, more than 2,000 additional pieces were recorded.

In some areas around the northern station, they found more than 20 times the level found in 2004 .

Time to react

Bergmann believes collecting the litter sitting on the seabed would cause further damage. What's needed is to concentrate on reducing waste and improving waste management. 

"We really need to think about alternative materials such as paper," she said.

"It will just get worse if we don't do anything."

Award-winning nature photographer Perez believes there is a general lack of will to tackle marine pollution. But he hopes images like his will help raise awareness and protect our oceans.

He welcomes the fact that his picture has brought oceans back into the headlines - and he highlights that there is an amazing world full of life under the surface of the sea surfaces - and it badly needs to be protected.