Scientists have shown for the first time that krill can break down plastic through digestion. But what might sound like a solution to marine plastic pollution is actually very concerning, says the study's co-author.
Krill are tiny crustaceans that look a little like shrimpImage: picture-alliance/blickwinkel/A. Hartl
Advertisement
DW: Krill are among the smallest creatures in the ocean. But your study shows that they have an unexpected feature: They can digest plastic. How does that work?
Willa Huston: What we found is that Antarctic krill actually eat microplastics. The krill takes that in and digests it through their normal digestive processes, converting the microplastics into nanoplastics.
This is the first time that we've understood that krill actually degrade plastic down to smaller sizes — that was a real surprise to us.
How did you come across these findings?
We fed the krill plankton mixed with plastic. The more plastic they were exposed to, the more fragmentation of plastic we found. We actually completely fragmented the krill, and then captured every bit of tissue. We were then able to develop an algorithm to measure the nanoparticles of plastic all throughout their bodies.
Willa Huston co-authored the study and teaches at University of Technology in SydneyImage: privat
There have been several studies touching on plastic digestion. Why do you consider your findings to be groundbreaking?
Feeding studies in the past have thought that the plastic just passes through, and is excreted or just translocated through organs.
The new side is that the krill physically breaks down the plastic into smaller particles. They do excrete some of those fragmented microplastics, but they also do end up [staying] inside the krills' bodies and their organs.
Which means that any creature that then feeds on krill is taking up microplastics that are broken into nanoplastics.
Plastic is very long-lasting in the ocean. The plastics break up into smaller pieces, mainly by physical processes like light exposure and physical drift in the ocean.
But what we're showing is that, unfortunately, the krill are also breaking it up. That's actually problematic because that means that little tiny bits of plastic could be accumulating in tissues of [ocean] animals that we're all eating.
Sqid are among the marine animals that eat krillImage: Fotolia/Mara Zemgaliete
And the plastic could end up in the human tissue as well?
We have absolutely no evidence for that. But this certainly is something that the study points to as being a possibility.
So the krill fragmenting plastic is not a solution, but rather an additional problem?
It's very problematic; it certainly is not good news at all.
It adds another dimension to how we need to think about the biochemical cycling of plastic in the ocean. It is yet another complexity in the serious problem that we have with plastics in the world's oceans. Antarctic krill are a keystone feature in that ecosystem. The fact that krills might be taking in plastics in their bodies could be quite serious for plastics then accumulating up the food chain in the Antarctic. It's a really important thing that we think everyone needs to consider in their studies going forward.
The study "Turning microplastics into nanoplastics through digestive fragmentation by Antarctic krill" was published in Nature Communications.
Microplastics: Our daily companions
Tiny pieces of plastic, or microplastics, are everywhere — despite potentially harmful effects on the environment and human health. Here are just a few of the products in our day-to-day life that contain microplastics.
Image: picture alliance/JOKER/A. Stein
Plastic in your mouth
Microplastics are defined as smaller than 5 milimeters in diameter. But these tiny particles accumulate in the sea, can enter the food chain, and are even found in the air. Personal care products containing microplastics, such as toothpaste, represent one of the most common intentional uses of microplastics in our daily lives.
Image: picture-alliance/dpa/S. Sauer
Cleaning your skin with plastic
Some cosmetic products can contain as much plastic added as the amount of plastic in which they are packaged, experts indicate. Exfoliating daily washes very often use of microplastics, often termed "micro-beads," which then get flushed into the household wastewater stream.
Image: picture-alliance/empics/Y. Mok
Mmm, plastic
Via wastewater, microplastics reach the oceans, where they move enter the food chain through feeding zooplankton. In 2017, researchers found that 25 percent of marine fish tested in markets in Indonesia and California had plastic and textile fibers in their guts. Research is still lacking as to whether consuming microplastics through fish harms humans.
Image: picture-alliance/dpa/Anka Agency International
Plastic condiment
Several studies published in 2017 showed that microplastics have also been found in sea salt from the United States, Europe and China. It's not surprising, considering how plastic debris represent between 60 to 80 percent of the total marine waste, and that up to 12 million tons of plastic waste ends up in the ocean every year.
Image: picture alliance/Bildagentur-online/Tetra
No way to escape
Beside microplastics in seafood like fish, shrimp and mussels, scientists point to other foods, such as honey. In the recently adopted European Union plastics strategy, honey was mentioned as one of the food products containing microplastics — to motivate a push toward a ban.
Image: Colourbox
Wearing plastics
Aside from micro-beads in hygiene products, synthetic textiles also release a vast amount of tiny plastic fibers into wastewater. Researchers found that a typical 6-kilogram (13-pound) washing load of acrylic-fabric items (like fluffy blankets) generates more than 700,000 individual fibers. Synthetic fabrics account for around a third of ocean microplastics.
Image: Imago/Mint Images
Dirty wheels
Vehicles tires are also a main source releasing microplastics into the environment. Tires are made of synthetic polymers mixed with rubber, which grinds down when used. This generates microplastics that are either blown around by the wind or washed away by rain. Norwegian and Swedish researchers agree that a large proporation of particles found in the sea come from car tires.
Image: Colourbox/Akhararat
Open the tap, and ... microplastics
Microplastics have also been found in tap water. In an analysis of tap water samples from countries around the world, more than 80 percent were contaminated with some amount of plastic fibers. If synthetic fibers are in tap water, they are also likely to be in a number of other basic foodstuffs, like bread.
Image: Imago/Westend61
No, not my beer!
And yes, if tap water contains microplastics, beer could very well also be contaminated. A 2014 study found plastic particles in a total of 24 German beers - but variability in the results was high, and further research would needed for verification, the German Environment Agency has pointed out. In any case, cheers for now.
Image: picture alliance/PIXSELL/Z. Basic
9 images1 | 9
The interview was conducted by Lisa Hänel and has been edited and condensed for clarity.
