Abstract:

 Pomacea canaliculata is one of the first 16 vicious invasive species in China. It causes serious adverse effects on the survival and continuation of native species through direct (feeding and competition) and indirect ways (ecological disturbance). In order to explore whether the native bioturbator, such as Limnodrilus hoffmeisteri and larvae of chironomus sp., can alleviate the ecological extrusion of Pomacea canaliculata on the native near niche species,Bellamya purificata, we carried out three experiments. The 15day survival rate, relative change rate of body weight and relative change rate of individual body weight of the two snails were observed after the addition of Limnodrilus hoffmeisteriorlarvae of chironomus sp. in the separated and co-cultured system ofPomacea canaliculataand Bellamya purificata. We examined the effects caused by different density and distribution of Limnodrilus hoffmeisteri and larvae ofchironomus sp. on the stress of Bellamya purificata after the invasion of Pomacea canaliculata. The results showed that the survival rate of Pomacea canaliculatawas significantly higher than that of Bellamya purificata in the absence of bioturbator, whereas the survival rate of Pomacea canaliculata was significantly reduced (P<0.05) and that of Bellamya purificata was significantly increased (P<0.05) after adding bioturbators, with higher body weight loss of Bellamya purificata(P<0.05). Regardless of the density of Limnodrilus hoffmeisteri, the survival rate ofPomacea canaliculatawas significantly reduced (P<0.05), and that of Bellamya purificata was significantly increased (P<0.05) after adding Limnodrilus hoffmeisteri. Such effect was the greatest at high density, which significantly reduced the survival rate of Pomacea canaliculata(P<0.01). From the distribution of bioturbator in the water, it was the most favorable for the survival of Bellamya purificatawhen Limnodrilus hoffmeisteri was evenly distributed. Although the addition of both Limnodrilus hoffmeisteri and larvae of chironomus sp. was beneficial to the survival of Bellamya purificata and weakened the invasive influence of Pomacea canaliculata, the effect of Limnodrilus hoffmeisteri was better than that of larvae of chironomus sp.

Key words: Pomacea canaliculata, Bellamya purificata, larvae of chironomid, Limnodrilus hoffmeisteri, bioturbation, invasion mechanism.