The distribution and effects of microbeads on host-parasite interactions of Ontario wetland fauna: tadpoles, snails and trematodes

Abstract

Plastic microbeads pose an environmental problem as they easily enter into waterbodies, take a long time to break down, and their ingestion can have negative effects on aquatic organisms. I found that microbead consumption had a significant negative effect on the growth of northern leopard frog (Lithobates pipiens) tadpoles, as well as their susceptibility to trematode parasite (Echinostoma trivolvis) infection, but minimal effects on leukocyte profiles and infection tolerance. Freshwater snails (Stagnicola elodes) given microbead diets exhibited a non-monotonic response in their production of trematode (Haematolechus parviplexus) infectious stages, with those in the highest microbead treatment tending to exhibit greater growth and shorter longevity. I also found that algae (Chlorella pyrenoidosa) and microbeads created density-dependent aggregations that could be a potential ingestion pathway for herbivorous fauna. Lastly, I found many particles in Ontario wetlands and ponds that may be used for controlled pesticide release, thus potentially posing a threat.