Laboratory survivorship of aerially exposed pond snails (Physella integra) from Illinois Tucker, J. K., F. J. Janzen, and G .L. Paukstis. 1996. Laboratory survivorship of aerially exposed pond snails (Physella integra) from Illinois. Transactions of the Illinois State Academy of Science 89(3 and 4):225 231. Reprinted by U.S. Geological Survey, Environmental Management Technical Center, Onalaska, Wisconsin, August 1997. LTRMP 97-R016. 7 pp. (NTIS #PB98-100860) ABSTRACT Many aquatic snails occupy ephemeral habitats that are occasionally subjected to severe environmental conditions. To investigate the physiological capacity of these animals to resist extreme environmental changes, we aerially exposed pond snails (Physella integra) to temperatures of 5øC and 20øC for 6, 8, 12, 24, 36, 48, and 60 hours. Survivorship varied with temperature and exposure times. At 20øC, survivorship was 0% for snails aerially exposed for 24 hours or longer. At 5øC, 0% survivorship was attained at 60 hours exposure. Sensitivity to aerial exposure was related to shell size of individuals, with larger specimens (shell length greater than 7 mm) significantly more likely to survive exposure than smaller specimens at temperatures and intervals with incomplete mortality. These results suggest that epiphragm development and size-specific survivorship predispose these animals to rapid population recovery following severe, short-term environmental fluctuations. KEYWORDS Aerial exposure, Illinois, laboratory survivorship, Physella integra, pond snails