ASSESSING THE DIETARY HABITS OF SLUGS FROM A DECIDUOUS FOREST IN SE OHIO USING STABLE ISOTOPE ECOLOGY

Land snails play an important role in the ecosystem as organic matter decomposers through their diet. However, the dietary habits of most species are virtually unknown because snails exhibit small sizes and nocturnal habits, which complicate their study through field observations alone. Moreover, snails that live in forests are likely to follow a complex and varied diet because the high diversity of potential food resources in such environments. It is also unclear if different snail species that coexist in space and time compete for same resources or partition foods to reduce competition. To address these questions, this study evaluates introduced (Arion subfusucs) and native (Deroceras laeve) species of slugs from East Fork Lake Park, a deciduous forest about 27 miles east of Cincinnati, using carbon and nitrogen stable isotopes of snail body tissues and surrounding foods. Isotopic results reveal that the analyzed slug species consumed a varied diet incorporating multiple foods from the environment. However, analyzed species appear to have followed significantly different diets. The native species consumed a more diverse diet including an array of foods like vascular plants, moss, fungi, lichen, and soil organics. In contrast, the introduced species ingested mostly moss. This seemly dietary difference between species suggests that slugs may be partitioning the resources to minimize competition. This work reinforces that the use of both carbon and nitrogen isotopes of snail organic tissues is a useful tool to make semiquantitative estimates of snail diet.