入侵种福寿螺的养殖液对水环境及本地种铜锈环棱螺的影响

Impact of aquaculture liquid from invasive species apple snails( pomacea canaliculata) on water quality and indigenous species Bellamya aeruginosa

以大薸(Pistia stratiotes)、凤眼莲(Eichhornia crassipes)和小竹节草(Najas guadelupensis)为福寿螺(Pomacea canaliculata)的食物,养殖数量设置为0、2、4、8、16和32只,分别在养殖的第1、3、5、7和9天测定养殖水体中的温度、pH、溶氧以及铵态氮、亚硝态氮、硝态氮、溶解性磷酸盐的浓度。在此基础上,开展了福寿螺养殖液对福寿螺和铜锈环棱螺(Bellamya aeruginosa)的胁迫实验。结果表明:福寿螺的养殖数量和食物种类对养殖液中的溶氧、铵态氮、硝态氮和溶解性磷酸盐有极显著的影响(P<0.01);溶氧量随着养殖数量的增大和养殖时间的延长显著降低,而铵态氮、硝态氮和溶解性磷酸盐的浓度显著升高(P<0.05);养殖液中亚硝态氮的含量只受养殖数量的显著影响(P<0.05);胁迫实验中,福寿螺养殖液对铜锈环棱螺和福寿螺相对生长率和死亡率的影响存在显著差异(P<0.05);福寿螺表现为减速增长,铜锈环棱螺表现为负增长,并且养殖液浓度越高,对铜锈环棱螺的致死效应越大。本研究表明,福寿螺可以通过养殖液改变养殖水体的理化性质,抑制铜锈环棱螺的生长,并对其具有显著的致死效应,这可能是导致福寿螺入侵的一个重要机制。本研究不仅丰富了入侵生态学的理论,也为福寿螺的生态风险评估提供了实验基础。

Using water lettuce （Pistia stratiotes）, water hyacinth （Eichhornia crassipes） and southern naiad （Najas guadelupensis） as apple snails’ （Pomacea canaliculata） food, we determined the temperature, pH, dissolved oxygen and the concentrations of ammonium nitrogen, nitrite nitrogen, nitrate nitrogen, and soluble phosphate of aquaculture liquid at 1, 3, 5, 7, 9 days when different number snails were bred （0, 2, 4, 8, 16, 32）. Then, a manipulative experiment was carried out to test the effects of aquaculture liquid of apple snails on the growth and mortality of Bellamya aeruginosa and P. canaliculata. It was found that apple snails’ breeding numbers and types of feeding food had very significant influence on dissolved oxygen, ammonium nitrogen, nitrate nitrogen and soluble phosphate （P〈0.01）. Dissolved oxygen was significantly decreased with the increase of breeding numbers and cultivation time, while the concentrations of ammonium nitrogen, nitrate nitrogen and dissolved phosphate increased significantly （P〈0.05）. The nitrite nitrogen concentration was significantly affected only by breeding numbers （P〈0.05）. In the manipulative experiment, on base of relative growth and mortality rate, apple snails’ aquaculture liquid had significantly different influence on P. canaliculata and B. aeruginosa （P〈0.05）; the growth rate of P. canaliculata decreased while B. aeruginosa had negative growth. Furthermore, the mortality rate of B. aeruginosa became greater with the increasing concentration of aquaculture liquid. This study indicates that apple snails can change the physical and chemical properties of breeding water quality through their aquaculture liquid. The aquaculture liquid of P. canaliculata can restrain the growth of B. aeruginosa and hasten its mortality, which may be an important invasive mechanism of apple snails. Our study not only enriches the theory of invasion ecology, but also possibly provides experimental basis for ecological risk assessment of apple snails.