How Poo Spreads Plastic Pollution

We’ve all seen it – an almost perfect pristine beach spoiled by an accumulation of debris washed up on its shore. Fizzy drinks bottles, plastic bags and six-pack rings not only destroy the natural beauty of our planet, they can also seriously upset its ecosystems, as well. However, the consequences of such carelessness could be even farther reaching than previously imagined.

According to a study published in Environmental Science and Technology, microplastics can be ingested and defecated by plankton. This in itself is not a novel discovery, but the fact that the plastics can directly affect the sinking speed and properties of the plankton faeces is and could have complex consequences for marine life.

The Problem of Microplastics

In January of last year, a six-year research mission came to a close and concluded that there is a minimum of 5.25 trillion pieces of plastic in our oceans. 5.25 trillion! It’s an overwhelming figure – and even more concerningly, the majority of that sum is made up of microplastics.

Microplastics refer to pieces of plastic with a diameter of less than a millimetre. Since these are so tiny, they are incredibly hard to recover from the ocean and can easily be mistaken for food by plankton. After eating and ingesting the plastic, plankton then defecates it back into the ocean, where its added density makes it fall to the ocean floor.

However, since plastic is made of less dense material than the food upon which plankton normally feed, it takes a far longer time to travel to the seabed. Therefore, instead of sinking to the bottom of the ocean and circulating and storing both nutrients and carbon as nature intends, the plastic poo pellet is far more likely to be gobbled up by a passing sea creature. In this manner, the microplastics are spread more widely and farther than would be possible otherwise.

“Magnitude of Change”

The study is a joint project between Plymouth Marine Laboratory and the University of Exeter and is the first of its kind to uncover a correlation between plastic pollution and an aberration in the structure, density and sinking rates of animal faecal pellets.

 “The magnitude of change observed here is concerning. We believe the impact of plastic contamination in the ocean deserves more detailed investigation and the team now hope to carry out further work in the natural environment," explained Dr Matthew Cole, who led the study. "As these faecal pellets sink, they take the plastic with them. This could be an important route by which floating plastic litter is removed from the sea surface down to the ocean depths.”

The implications this holds are grave. It means that plastic could be distributed far and wide across the oceans around the world, giving us little to no hope of ever recovering it. As such, it’s more important than ever we take all possible measures to limit the amount of plastics we dump into our oceans – especially if they take the form of microplastics.

With this in mind, it’s no surprise why President Obama banned microbeads last year. The beads are commonly found in beauty and healthcare products but are almost impossible for wastewater treatment plants to filter out and once in the ocean, they are very difficult to recover. Hopefully, a similar ban on this unnecessary and damaging blight on the world’s oceans will come into place in the UK in the near future.