Effects of salinity on survival, growth and reproduction of the invasive aquatic snailPomacea canaliculata(Gastropoda: Ampullariidae)

Pomacea canaliculata, a freshwater snail native to tropical and temperate South America, has become an important invader and agricultural pest throughout tropical and subtropical regions around the world. Colonization of various aquatic habitats byP. canaliculatain coastal regions of South China and its establishment potential in estuaries have raised great concern, yet little is known about the biological response of the snail and its tolerance under saline environments. We first examined the salinity tolerance ofP. canaliculatausing a total of 30 experimental juvenile snails exposed to eight salinity levels (from 0 to 14 psu in 2 psu steps). Daily survival of the snails was measured for each salinity treatment over 30 days. Based on salinity exposure test, influence of salinity on snail reproduction was investigated for a period of 30 days using 30 adult snails exposed to four salinity treatments (0, 2, 4 and 6 psu). Each salinity test replicated three times.Pomacea canaliculatacould tolerate salinity levels ranging from 0 to 6 psu in which probability of survival was greater than 72% during a 30 days exposure. Lethal time leading to 50% mortality (LT50) of the snail declined from 71 days at 0 psu to 27 days at 6 psu.Pomacea canaliculatacould ingest and reproduce normally at salinities ranging from 0 to 4 psu. Average mass daily gain, specific growth rate, and the hatching of egg clutches decreased significantly with elevated salinities. Results show a general threshold response ofP. canaliculatato salinity. This freshwater snail falls into "2nd degree" euryhaline limnobionts tolerating salinities of 3-8 parts per thousand.