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Yellow perch can eject microplastics, but it comes at a cost

As plastics enter the environment, they often break down through natural processes into microplastics, which are particles less than 5 millimeters in length. These microplastics end up in rivers, lakes and the ocean. There is growing concern about the impact of microplastics on the environment as well as wildlife and human health, yet little is still known about the effect of these plastic particles on fish.

Recent research, carried out in Professor Dong-Fang Deng’s lab at the University of Wisconsin-Milwaukee, looked at the impact of microplastics on farm raised yellow perch. 

The fish were given food contaminated with high density polyethylene (HDPE). The scientists found that although the perch could expel the microplastics, it came at the cost of lower nutritional value in the fish as well as changed liver function, and different microbiomes in their gut. 

Yellow perch were used in this study because of their popularity as a food item. This is especially true as they are becoming increasingly raised in farms as wild caught fish become less common in the Great Lakes region, where the study was carried out. 

“What we found is that the yellow perch not only survived the nine-week exposure, they also expelled all the microplastics from their bodies,” said Professor Deng. “However, the nutritional quality of the fish was reduced – we saw lower body protein and mineral (ash) levels than in fish fed the control diet with no HDPE added.” 

“We also discovered that exposure to HDPE altered their liver function – they had a heavier liver enriched with glycogen (sugar) and bile acids, but lower lipid (fat) levels and enlarged hepatocytes, the cells involved in metabolism, detoxification and nutrient synthesis.  We also saw some disturbance in the gut structure and microbiota community associated with immunity, nutrient digestion and absorption.”

The researchers emphasized that these results were from one particular type and size of microplastic, while various sizes, shapes and types of plastics could yield different results. 

The study is published in the journal Animal Nutrition.

By Zach Fitzner, Staff Writer

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