Microplastics are ubiquitous on Earth. Particles have been found in the deepest and most isolated parts of the ocean, and we shouldn’t be surprised that they are not only in our foods and bodies; they are even in the air we breathe.
Plastic particles have been found to be part of one species’ diet in the most isolated ocean: the Antarctic krill. These are tiny, shrimp-like creatures that primarily feed on algae originally found on ice caps. Animals such as whales feed on krill as part of their diets, but these tiny, microplastic-contaminated species are not only causing disruption to our food web, but to a global rise in temperature.
So how are such small particles, found in such small creatures, increasing the release of carbon dioxide into our atmosphere?
Antarctic krill are the species with the largest biomass in the Antarctic Ocean, an ocean that accounts for 20 per cent of global CO₂ uptake. Krill are essential to the health of our oceans due to their large numbers. What is most striking about them, however—is their faeces. Their dense and fast-sinking faeces trap and export carbon to the deep ocean, a crucial process known as carbon sequestration.
However, in recent studies, krill have been found to break down microplastics. From a study conducted by Dr Amanda Dawson of Griffith University, the digested fragments of microplastics were “on average 78 per cent smaller than the original fragments.”
Krill’s egestion of microplastic-filled faeces has affected the faeces’ structures, reducing their density and therefore their sinking rate. Because of this, the faeces are degrading more quickly, meaning that carbon is being released more rapidly back into the atmosphere. Scientists have measured an alarming loss of carbon-sequestered faeces of around 27 per cent.
When we think of plastics in the ocean, the first image that comes to mind might be the islands of floating plastic waste bags and straws. But we might not stop to think about the more invisible forms of plastic such as plastic fibres. Niko Zlotnik’s article on the same topic highlights that “plastic fibres are shed from clothing, curtains, carpets, and other textiles all the time. And washing and drying makes the problem far worse: over a million microplastic fibres can be released in a single load of laundry.”
As students, we might feel helpless against the big disruption caused by such small particles. However, if animals as small as krill can have such a big impact on our planet, consider how your actions can contribute to addressing the issue too.
Photo by Naja Bertolt Jensen on Unsplash