Reaction Difference And The Related Mechanism Between Invasive Golden Apple Snails And Local Snails Under Different Habitat Stresses

Pomacea canaliculata is a widely distributed invasive species in China and the other Asian countries, and has caused incalculable agricultural and ecological problems in invaded areas. Pomacea canaliculata was listed among the 100 worst invasive alien species by the World Conservation Union. Escaped from the original natural enemies, and with wide ecological amplitude, strong feeding capability, fast reproductive growth, it has been becoming the dominant species in invaded habitats. With stronger competition ability than the other creatures, it will further change the ecological environment and biodiversity. In this paper, we selected Cipangopaludina chinesis and Sinotaia quadrata, common freshwater snail in south China, to represents the native snails to investigate the competition reaction between P. canaliculata and native snails under different stresses and difference of alarm response among P. canaliculata and native freshwater snails under the exposure of enemy related habitat, and explore the responses under different stresses(acid and alkali,high temperature, low temperature, predator). The main results are as follows:1. The survival rate of P. canaliculata in the treatments of p H 4.5?6.5?8.5?10.5 were higher than the two native snails; but in the treatments of p H 2.5, all the P. canaliculata died rapidly which may be due to the thinner shell of P. canaliculata. The determination of water showed that P. canaliculata can adjust the p H by secreting mucus in weak acidity or weak alkaline conditions. The electron scanning map for the head and liver of three snails showed that the related organ surface of P. canaliculata appeared injures such as crack,flaw and fracture,but the total structure of the surface remains intact. The related organ surface of the two local snails appeared a lot of filiform fragments, and already were unrecognizable.2. In the drought stress experiment, we found that the survival rate of P. canaliculata and Cipangopaludina chinensis were higher than that of Sinotaia quadrata. The activities of superoxide dismutase(SOD), catalase(CAT) and total antioxidant capacity(T-AOC) of P. canaliculata was significantly higher than those of the local snails in 3 and 7 days ofdrought treatment. P. canaliculata showed strong control ability of body moisture in decreasing the free water, increasing the bend water, and then leading the decrease in the ratio of free water to bound water.3. For the temperature stress, the results showed that P. canaliculata and S. quadrata had higher survival rate than C. chinensis under 35 ?. But under the low temperature treatment(5?), all the P. canaliculata were dead within 7 days, however survival rate of S.quadrata and C. chinensis were more than 50% after 21 days. In conclusion, P.canaliculata were frigolabile but could endure high temperature, C. chinensis could not endure high temperature, S. quadrata had the most wide temperature tolerance among the three snails. P. canaliculata in 25 ? had higher activities of SOD, CAT than the other treatments..4. The difference in alarm response among the invasive snail P. canaliculata and two representative freshwater snails to complicate alarm cue released from their predator turtle Trachemys scripta elegans and injured conspeci?cs was studied by simulation experiments and calculating the displacement. The results showed that both juvenile and adult P.canaliculata's exhibited higher alarm response to predator cue by increasing their displacement and alarm cue released from injured P. canaliculata could strengthenthen S.quadrata The juvenile S. quadrata, juvenile and adult C. chinesis didn't show alarm response to the alarm cue. Adult S. quadrata exhibited alarm response to alarm cue released from injured P. canaliculata's and it's response was weaker than the invasive snail. This result suggested that compared with native freshwater snail, P. canaliculata showed stronger alarm response when they met the alarm cue under the enemy exposure habitat.This finding would provide some references for further investigation of the difference among invasive snail, P. canaliculata, and native freshwater snails in antipredator behavior.