Exposure to high concentrations of plastic particles inhibits hatching, decreases growth rates, and alters feeding preferences of European perch larvae, a new study shows, as well as prevents the fish from responding to predatory cues. The results suggest that microplastic particles operate both chemically and physically on larval fish performance and development. Because of the massive use of plastics in modern society, plastic waste is accumulating, often ending up in waterways. Much of this debris is in the form of microplastics, plastic fragments less than five millimeters in all dimensions that are either manufactured that way or break down from larger pieces of debris. While hundreds of studies have demonstrated global microplastic contamination, few have investigated its impacts on animal populations, communities, and ecosystems. "This pattern is not unique," Chelsea M. Rochman says in a related Perspective. "For many chemical contaminants in the environment, widespread contamination is documented, yet little is known about their ecological impacts." The mechanisms by which microplastics impact eggs, embryos, and larvae of aquatic organisms, which are particularly vulnerable to water-borne pollutants, are especially murky.
Here, to provide greater insights into this problem, Oona M. Lo?nnstedt and Peter Eklo?v collected European perch embryos and larvae from the Baltic Sea. In lab aquaria, they exposed these specimens to varying concentrations of polystyrene microplastics, including very high concentrations comparable to those found in nature. Among other results, they observed that exposure of embryos to microplastics decreased hatching success by about 15%. What's more, exposed 2-week-old larvae were much less able to escape predation, leading to reduced survival. Also, fish reared in the highest microplastic concentrations were significantly smaller than fish reared in average concentrations. Studies like this one could guide efforts to mitigate the entry of microplastics into the oceans by determining the types that may be most hazardous and by identifying the most sensitive populations, species, and ecosystems. "With such data in hand," Rochman writes, "practitioners can shift their energy toward prevention and avoid the need for costly recovery and restoration."