LAUSR

Climate change has dramatically altered freshwater ecosystems and will continue to affect them further. As water-level fluctuations increase in frequency and intensity, the tolerance of aquatic organisms to abiotic stressors will become critical determinants of survival. Apple snail species in the genus Pomacea (Ampullariidae) live in freshwater throughout the tropics and subtropics, but deposit egg clutches on terrestrial substrates. Two species, Pomacea canaliculata and Pomacea maculata, are amongst the world’s most invasive species and are expanding their invasive ranges. To evaluate their survival during extreme dry-down conditions in their native range, we collected 156 apple snails (Pomacea spp.) from 4 permanent water bodies in Uruguay and buried them in dry sand to simulate drought. We placed the snails outside, sheltered from sun and rain (ambient temperature: 15.2–28.1°C, ambient humidity: 44.9–100.6% below sand surface, 34.2–98.7% in outside air), and checked survival daily. Genetic identification confirmed the presence of P. canaliculata, P. maculata, and a morphologically indistinguishable undescribed congeneric among these snails. Thirty-six percent of snails survived the entire period (47 d) buried in the sand. Fewer males survived than females. Median lethal exposure time (LT50) was 33 d for the total group of Pomacea species. After re-immersion in water, 93% of survivors resumed normal activities, including feeding, within 24 h and mated during later observations, indicating resistance to drying conditions and resilience during recovery. Offspring from 1 clutch laid after recovery survived >1 y after this experiment. We found high tolerance to prolonged drying and rapid recovery after re-immersion for 3 Pomacea species. As drought frequency increases with climate change, tolerance to these conditions and rapid restoration of normally high reproductive rates after dry-down may confer an advantage to these species, contribute to long-term persistence in their native range, and facilitate continued invasions.