Acute Exposure to Polyethylene Microbeads and Effects on the Water Flea Moina Macrocopa

Microplastics merit attention as they can be ingested by lower trophic organisms, transferred to the food web, and pose potential risks to higher trophic levels. This study investigated the accumulation and effects of polyethylene microbeads (PEMBs, 63-75 μm) on adult water flea Moina macrocopa (600-800 μm), an order-magnitude difference in size, as a result of acute exposure. The organisms were exposed to PEMBs in four treatments of 0 (the Control), 5, 50, and 500 mg PEMB/L for examining PEMB accumulation, survival and reproduction of the organisms after the 24- and 48-h exposures. In general, M. macrocopa ingested PEMBs within 24-h exposure and reached the cumulative PEMB accumulation value of 0.17 ± 0.21 beads/adult after 48-h exposure in the 500 mg PEMB/L treatment. Exposure to PEMBs resulted in a statistically significant decrease of the cumulative survival rates, from 93 ± 12% in the Control to 37 ± 21% in the 500 mg/L treatment. Nevertheless, exposure to PEMBs did not significantly reduce the cumulative reproduction (p > 0.05), although a decrease was observed. This study suggests that the relatively large-size PEMBs could be ingested by the relatively small-size M. macrocopa and pose potential risks to these organisms.