Japanese medaka fish, also known as the Japanese rice fish, is a model organism and is extensively used in areas of biological research, most notably in toxicology. A team of scientists from Duke University has found that when those fish are subject to high concentrations of microplastic fibers, it can experience severe effects on their respiratory and reproductive systems.
Microplastics have also been found to cause life at the bottom of lakes to decline, and those that find their way into humans’ food cause their immune cells to die three times faster. There’s a lot of plastic pouring into the marine environment every day, and so much we don’t know about the damage it causes. However, these scientists are determined to find out.
Melissa Chernick, the study author, said:
Microplastic pollution is an environmental threat that poses increasing risks for species and ecosystems worldwide. Until now, most studies have focused primarily on looking for the presence of plastics in animals, without identifying what the effects on various tissues might be. But that’s exactly where our study suggests the science needs to go.
Most microplastic fibers that end up in the ocean come from the laundry, breaking off of synthetic clothes we wash, seeping through wastewater treatment facilities, and releasing into the sea. “Even if they are released miles from the ocean, they can work their way down there. So, they affect both freshwater and marine organisms,” study author, David E. Hinton added.
The team conducted some tests involving 27 breeding pairs of Japanese rice fish, which were placed inside tanks filled with high levels of microplastic fibers for three weeks. Throughout this time, the team observed how much fiber the fish consumed and excreted the fishes’ weight, along with their egg production, and published their findings in the journal PLoS ONE.
The fish experienced high levels of mucus production in their gills and aneurysms, which is the growth of an artery caused by weakness in the artery wall. The fish also had profound changes to the epithelial cells lining their gills, along with an indication that chemicals from the plastic were entering their bloodstream. The female fish that were exposed to microplastics produced more eggs, which suggests that chemicals seeping from the materials might be disrupting their endocrine system.
Chernick explained:
There were severe changes and a lot of them. And each change can affect respiration. If you’re a fish in the wild with gill damage and you’re in a low-oxygen environment or being chased by a predator, you’re in trouble. The same goes if you’re competing with other fish for food. Just having these damages would cause you to be less competitive.
Fish aren’t the only marine creatures eating microplastics. Coral are consuming the tiny plastic particles as if they were zooplankton. However, scientists aren’t sure yet of the consequences of this.
