Impact of Microplastic Fiber Pollution on Ramshorn Snail (Panorbella campanulata) Reproduction and Mortality

Microplastic pollution is an emerging problem in aquatic environments becoming a global challenge. Many studies have shown impacts of microplastics on marine organisms, but less is known about the impact of exposure to microplastics on freshwater organisms. Mollusks are one group of organisms that appear to be especially sensitive to exposure to microplastics. We explored how snail mortality and reproduction were impacted by exposure to polyester microfibers. The polyester microfibers were obtained by grinding small pieces of a blue fleece jacket. We exposed freshwater snails (Planorbella campanulata) to these microfibers for a seven week period in individual 1.1L laboratory mesocosms. The mortality of parent snails, along with the amount of eggs sacs, eggs, and offspring were recorded in both experimental and control treatments. We found a higher rate of mortality in adult snails during the experiment. At any given time the fiber treatment group was recorded to have 0.33 more adult deaths in each mesocosm. The fiber treatment group also had significantly more offspring per adult by the end of the experiment. To test for the effects of competition in the mesocosms, we repeated the experiment with fewer initial adult snails, and found the same result in reproductive behavior and mortality. We concluded that exposure to polyester microfibers stimulated reproduction, possibly by hormonal stimulation from the microfibers or blue dye in the original fleece material. It is also possible that reproduction and mortality are linked through increased stress caused by reproduction. Our results suggest that microplastic pollution can be having negative effects on freshwater organisms.