Influence of water temperature on the activity of the freshwater snail Pomacea canaliculata (Caenogastropoda: Ampullariidae) at its southernmost limit (Southern Pampas, Argentina)

1.The effect of temperature on the activity of the freshwater snail Pomacea canaliculata was investigated through field surveys and laboratory trials.2.During winter most snails in the field were inactive but not in a deep lethargic state; the temperature at which half of the snails were active was 13–15 °C.3.The time spent active and feeding increased with temperature between 10 and 30 °C, exposure time being unimportant except in foul water at 35 °C, while time spent crawling remained constant above 10 °C.4.Activity decreased above 30 °C but no heat coma was observed with temperatures raised to 36.2 °C.5.Under fluctuating temperatures, the rate of change in the percentage of active snails during cooling was higher than during warming, whereas the temperature at which half of the snails were active was lower.