氨氮对软体动物生长的影响:以铜锈环棱螺为例

为探究氨氮对底栖动物的毒性效应,在位于湖北保安湖的近自然生态系统(单个水域面积约600 m²,水深约1.5 m)中开展了为期1年的模拟实验,分析了6个不同氨氮浓度N25>N20>N15>N10>N5>N0(对照);0.2—33.7 mg/L]条件下,大型底栖动物(软体动物)群落特征的差异。结果表明:(1)实验系统中采集的软体动物主要为铜锈环棱螺(Bellamya aeruginosa);(2)从B. aeruginosa密度来看, N0、N5、N10和N15处理相差不大28(0—85) ind./m²],均显著高于N20和N25处理5(0—29) ind./m²](P<0.05);(3)从B. aeruginosa生物量来看,N0、N5、N10、N15和N20处理相差不大40.0(0—85.5) g/m²],均显著高于N25处理0.8(0—4.0) g/m²](P<0.05);(4)从B. aeruginosa壳长、壳宽和带壳...

AMMONIA ON THE GROWTH OF MOLLUSC: A CASE STUDY OF BELLAMYA AERUGINOSA

Ammonia nitrogen, as one of the main pollutants, have toxicity to organisms under high concentration in aquatic ecosystem. It has been widely reported about the negative impacts of ammonia on the behavior, growth and reproduction of organisms. However, the previous studies were mainly focused on fish, rarely studies were conducted with zoobenthos and limited to small scale experiments. To explore the toxicity of ammonia on zoobenthos, we conducted a one-year semi-natural experiment in 6 ponds (ca. 600 m2 in surface area; ca. 1.5 m in depth) located in Hubei Province and analyzed the difference of zoobenthos (mollusc) community under 6 ammonia concentrations N25>N20>N15>N10>N5>N0 (control; 0.2—33.7 mg/L]. The result showed that: (1) the mollusc identified during the experiment was mainly Bellamya aeruginosa; (2) N0, N5, N10 and N15 treatments had similar B. aeruginosa density 28(0—85) ind./m2], which were significantly higher than that in N20 and N25 treatments 5(0—29) ind./m2] (P<0.05); (3) N0, N5, N10, N15 and N20 treatments had similar B. aeruginosa biomass 40.0(0—85.5) g/m2], which were significantly lower than that in N25 treatment 0.8(0—4.0) g/m2] (P<0.05); (4) shell length, shell width and body mass of B. aeruginosa were the lowest in N0 treatment, while which were the highest in N20 or N25 treatment; (5) B. aeruginosa density and biomass were negatively correlated with ammonia concentration significantly (P<0.05), and decreased with the increasing non-ionized ammonia concentration; (6) shell length, shell width and body mass of B. aeruginosa were positively correlated with non-ionized ammonia concentration significantly (P<0.05), and increased with the increasing nonionized ammonia concentration. The results suggested that ammonia concentration higher than 21.7 mg/L and non-ionized ammonia concentration higher than 0.18 mg/L (annual mean value in N15 treatment) had significantly negative impact on mollusc, especially for its reproduction, while no negative impact was found on the growth of individuals. More phytoplankton induced by ammonia loading may provide more food for mollusc which was advantageous for the accumulation of carbohydrate and help to detoxify the body. The shelter from sediments might have released B. aeruginosa from ammonia exposure as the non-ionized ammonia concentration was lower at the bottom layer near the water-sediment interface compared with that at the surface layer. This study could help to develop the understanding of ammonia toxicity to mollusc and may improve scientific basis for nitrogen management in aquatic ecosystems to a certain extent.