Analysis of the preference of two snail species (Physa acuta and Planorbella campanulata) for algae grown in varying nutrient conditions of nitrogen and phosphorous

Abstract

The various interactions within communities can represent a balance that is quickly upset by changes in abiotic factors and we investigated to preference of snails on algae subjected to varying nutrient conditions during growth. We grew algae in 3 varying levels of phosphorus and nitrogen using fertilizer and introduced two species of snails, Physa acuta and Planorbella campanulata, to observe their preference when given the option of all three algae samples. The various algae samples had increasing levels of phosphorus and decreasing levels of nitrogen when grown in increasing levels of phosphorus and nitrogen. The three samples also resulted in differing species composition due to the varied nutrient levels. While not statistically significant, and observed trend was the preference of both snail species for the algae grown in higher nutrient conditions. These results did not support our hypothesis that the algae grown in higher nutrient levels would contain higher levels of both phosphorus and nitrogen, but did support increasing levels of phosphorus only. These results, though not statistically significant, gave some level of support to our hypothesis that both snail species would prefer algae grown in higher nutrient conditions due to nutritional quality and decreased energy used in grazing. This knowledge could be further used to prevent and control algae blooms with the increasing levels of nutrients entering our watersheds from a variety of sources.