In a new study published in Science, researchers found that larval fish exposed to “environmentally relevant” concentrations of microplastics had altered feeding behaviors, lower growth rates, and were easier targets for predators. The larval fish exposed to microplastic particles ignored zooplankton, their natural food source, and preferentially fed only on plastic.
I asked study co-author Peter Eklöv why he thought larval fish would preferentially feed on such a nutrient-poor resource.
“It seems like the plastic triggers a signal in the foraging behavior of the fish,” he said. “A possible evolutionary explanation could be that items that look or act in a strange way are easy targets, and in the absence of pollution this would likely be something nutritious.”
Eklöv and his colleagues exposed larval perch in the lab to concentrations of microplastic particles similar to those found in the Baltic Sea and other marine ecosystems. They found that the exposure not only inhibited hatching and growth, but also made the fish more susceptible to predators because they were slower and ignored olfactory cues that would normally trigger a response.
“Currently, we have no full picture on how serious this threat is in the natural environment,” said Dr. Eklöv. “Our study is the first to have approached the question how microplastics affect ecological systems. We know that microplastics in the environment are abundant and that we have recruitment problems of fish in the Baltic Sea. But with the strong effects we see on behavior, growth and mortality of perch in our experiment, this is a serious threat and we should be concerned.”
Plastic waste, including microplastic particles, enter the environment from a variety of sources. There is growing concern about the environmental impact their accumulation is having on oceans.
“Microplastics have many sources and some of them are probably difficult to control,” said Dr. Eklöv. “For example, about 50% of the microplastic particles are emitted from car tires. Although sewage plants are reducing more than 90% of microplastic particles, this source is still emitting a substantial amount. There could be a ban for microplastic particles in, for example personal care and other consumer products.”
“Whenever possible we could develop alternative material to plastic,” he said. “This problem has to be taken seriously. The government has to initiate mitigation plans to decrease the emission of microplastics. There are some initiatives, but more is required.”