The effects of microplastic on freshwater Hydra attenuata morphology & feeding

Microplastic pollution has been a growing concern in the aquatic environment for a number of years. It’s abundance in the environment has invariably lead them to come into contact with a variety of different aquatic species. With many capable of ingesting these plastics, the impact of which is not fully understood. The majority of research studying microplastic pollution has focused upon the marine environment and species with little attention paid to the freshwater. Here we examine the effect of microplastics on a freshwater cnidarian, Hydra attenuata. Hydra play a vital role in the planktonic make up of slow moving water bodies which they inhabit and are sensitive environmental indicators. Hydra were exposed to polyethylene particles (<400 µm) extracted from facewash at different concentrations (Control, 0.01, 0.02, 0.04, 0.08 g/mL). The ingestion rate of prey (Artemia) and microplastics were recorded every 30 min for 120 min. The preliminary results of this study show that H. attenuata are capable of ingesting microplastics. After 60 min of exposure the Hydra ingested a lower amount of Artemia in all concentrations compared to the control. This became even more evident at the 90 and 120 min mark. No Artemia were ingested at the highest concentration used (0.08 g/mL) after the 90 min mark. This shows that the presence of microplastics can interfere with the feeding of Hydra, either by reducing the amount of prey ingested or by preventing feeding completely. Exposure to the microplastics caused significant changes to the morphology of the Hydra, however these changes were nonlethal. This study demonstrates that freshwater Hydra are cable of ingesting microplastics and that microplastic can impact the feeding of freshwater organisms.