In some parts of the world, bodies of water, such as lakes, have a significant amount of microplastics. Areas with highly concentrated pollution are reducing numbers of certain animals vital to the ecosystems at the bottom of ponds, lakes, and canals.
A study, published in Science Advances, has found that when a family of worms called Naididae was exposed to high concentrations of microplastics, nearly half of them didn’t make it. Study author, Paula Redondo-Hasselerharm from Wageningen University, said that losing the Naididae worms would matter. “The worms have an important role in the ecosystem: they incorporate the organic matter, they participate in the nutrient cycling of the system,” she adds.
For the study, Redondo-Hasselerharm and her team set up an experiment that mimicked plastic pollution in the Rhine river. They set up trays containing fresh water with a layer of sediment at the bottom that included worms. The sediments in each tray varied on how much microplastics it contained, between 0 and 5%.
After fifteen months, the worms in the sediment containing the highest concentrations of plastics had experienced a significant amount of adverse effects. The researchers are not exactly sure how the microplastics harm the worms. However, Redondo-Hasselerharm believes they might be ingesting the microplastic, and it remains inside of them, reducing their ability to grow and eat, and eventually kills them.
The trays with lower concentrations of plastic, between 0.005 and 0.05%, didn’t harm the worms. These low concentrations are the levels that are more similar to the Rhine, but some harmful levels of 5% microplastics may be found elsewhere in some polluted parts of the world. Redondo-Hasselerharm predicts that in the future high concentrations of microplastics may be found more often in freshwater.
Alice Horton, of the UK National Oceanography Centre in Southampton, said their current knowledge about the dangers posed by microplastics is based on studies of short-term exposure. However, organisms are more likely going to be exposed to microplastics in the long-term. “This study gives the first evidence that long-term exposure can lead to different and more severe ecosystem effects than the short-term exposures usually studied,” she explained.
Microplastics are not only affecting minuscule worms at the bottom of lakes and canals but also in ocean slicks, coral, and many more.
