As the mussels feed, they suck materials in from their surroundings (bacteria, algae and microplastics) into their gills. When they process and excrete waste, microplastics come with it, encased in an outer faeces shell.
One mussel can filter 150,000 litres of water per day.
PML scientists placed 300 mussels (5kg in total) in a flow tank that mimics currents, alongside microplastics, algae and phytoplankton. The experiment showed that the mussels were able to filter out 250,000 microplastics per hour.
What happens once the microplastics are filtered?
The microplastics ended up encased in the mussels faeces which naturally sinks down the water column.
Scientists are now running tests in the ocean with the belief that mussels that are placed near drains, marinas and harbours could potentially filter 20-25% (depending on various variables) of microplastics before they head out into the ocean. They are using nets with receptacles underneath to catch the waste and avoid it floating to the ocean floor (see below).
In future, they hope to use the plastic-filled faeces as a source of biofuel because of their carbon richness.
It's important to mention that plastic is unlikely to cause the mussel any harm. Whilst this solution will not solve the issue of microplastics, it's exciting to see a natural idea. This solution opposed to nets reduces impacts on surrounding marine life.
How you can help as an individual...
Stop plastic at the source by embracing a plastic-free lifestyle, check out our guide to plastic-free living here. Keep spreading the word about products that are better for you and the planet. You've got this!