Microplastics Increase Animals’ Appetite

Predators can learn to prefer prey that is contaminated with microplastics, even when cleaner options are available. This behavior can impact the dietary habits and health of the entire ecosystem, including humans.

Researchers identified this preference for plastic by studying the dietary choices of small roundworms known as nematodes (caenorhabditis elegans) over multiple generations. Initially, first-generation nematodes opted for a cleaner diet when offered the usual bacteria and the same microorganisms tainted with microplastics. However, after repeated exposure to plastic-laden food across generations, their preferences shifted.

“They start to prefer contaminated foods,” notes Song Lin Chua from Hong Kong Polytechnic University.

Why did the worms develop a taste for plastic? As creatures without vision, nematodes depend on other senses to locate food, such as olfactory cues. “Plastics may influence those odors,” explains Chua. After enduring prolonged exposure, they might start to perceive microplastics as “food-like” and subsequently choose to consume them. He theorizes that other small species which rely heavily on scent for locating prey may also be similarly perplexed.

Chua emphasizes that this behavior could potentially be reversed since it “mirrors a learned response” rather than being a genetic alteration. “It’s akin to a taste preference,” he states. In theory, this could be undone in future generations, though further research is necessary.

As one of the most prevalent animal types globally, the dietary choices of nematodes could have far-reaching implications for ecosystem health. “The interactions of organisms consuming one another are crucial for the recycling and transformation of various forms of matter and energy,” asserts Lee Demi from Allegheny University in Pennsylvania, who describes this finding as a source of “anxiety.”

“This could move up the food chain,” Chua warns. “Ultimately, we might be affected too,” he concludes.