Student Research Projects

Nutrient Excretion by Freshwater Snails: Effect of Body Mass and Feeding

Student David McGuire ‘14
Faculty Mentor(s)
Department Biology
Course Biology 489: Research Methods in the Natural Sciences


The physiological processes of the organisms living in any environment can have an impact on its chemical composition. Two elements that are essential for nutrient cycling in aquatic environments are phosphorus and nitrogen. As such, the rates of excretion of NH4-N and PO4-P by animals can impact the levels of nutrients in the environment. Few studies have examined the role of freshwater snails in consumer-mediated nutrient cycling. The factors that influence this process were examined by comparing excretion rates among different sized snails and fed versus unfed snails. No significant effect was found for the differences in size between snails and the rate of excretion, but this study did conclude that unfed snails excreted almost no phosphates, and only a small amount of ammonia, whereas fed snails excreted significantly more P, but we did not detect a significant difference in N excretion with feeding history. Therefore, the snail’s contribution to the environmental levels of these compounds is reliant on the amount of food they eat, especially for P.