Meeting Abstract

83.2  Monday, Jan. 6 10:45  The benefits of high density: Do chemical cues facilitate food location in the gregarious snail, Potamopyrgus antipodarum? HANSEN, B. K.*; FAIR, M. B.; University of Wyoming; Colorado State University buteoblues@raderstudios.com

While a minimum number of individuals is necessary for the continued presence of a species, very high densities often result in increased competition within and among species. Despite this, some invasive species may benefit from seemingly maladaptive densities through increased mating opportunities, predator avoidance and improved foraging. Potamopyrgus antipodarum, the New Zealand mudsnail, is a successful world-wide invader that has established populations in multiple habitat types, where it can maintain very high densities. Recent studies have demonstrated that P. antipodarum benefits from increased conspecific density through increased reproduction and improved foraging. To determine if this increase in foraging is facilitated by an enhanced ability of individual P. antipodarum to locate food resources when others are present, we compared the foraging activity of snails exposed to high or low conspecific density, with the addition of water that was or was not conditioned by feeding conspecifis. Because juvenile and adult snails have different nutritional demands, we tested their behavior separately. Consistent with previous experiments, we found that P. antipodarum were more likely to feed and spent more time feeding in high relative to low conspecific density, and that this appears to be facilitated by chemical cues produced by feeding individuals. We also found that juvenile P. antipodarum are more likely to feed than adults, which may result from increased nutrient demands during growth. While an understanding of Allee effects has long contributed to the maintenance of endangered populations, our results highlight the importance of understanding the effects of density when controlling invasive species.