碳酸盐碱度和pH对中国林蛙蝌蚪的毒性作用

Toxicity of pH and carbonatealkalinity on tadpoles of frog Rana chensinensis

为了解中国林蛙(Ranachensinensis)蝌蚪对水环境中碳酸盐碱度和pH的适应能力,采用单因子静态急性毒性实验法进行研究。结果表明,在pH7 0～8 5、盐度0 18g/L时,碳酸盐碱度对中国林蛙蝌蚪的24h、48h、72h和96hLC50值分别为14 36、11 83、10 35和7 68mmol/L,安全值(SC)为2 41mmol/L。在相同盐度下,碳酸盐碱度为1 41mmol/L时,中国林蛙蝌蚪的pH为24、48、72和96hLC50值,碱性范围分别为10 33、10 18、10 08和10 02,酸性范围分别为3 92、4 07、4 11和4 16。建议野外蝌蚪养殖水体的pH应控制在6 0～8 0,碳酸盐碱度保持在1 5～3 5mmol/L。

Rana chensinensis is one of the principal wild economic animal of the Changbai Mountain Area in China.As its resource is excessively developed,the amount is decreasing a lot.But it has been increased remarkablely because artificial cultivating and enhacement in recent years.NaCl,CaO,Na(2)CO(3) and NaHCO(3) are widely adopted in tadpole culture to carry out disinfection of waters,and regulation for the alkalinity and the pH of waters.But this can produce great impacts on survival of tadpoles and growth of young frog.In China,technology on artificial enhacement and cultivating of R.chensinensis not only has been researched for a long time,but also the technology systems are taking shape at the moment.Yet,effects of ecological factor of waters on R.chensinensis are researched less than the studies on R.chensinensis ecology.In this experiment,the toxicity of water pH and carbonate-alkalinity to tadpoles of frog was studied in order to understand adaptability of tadpoles on two ecological factors of waters,and provide culture industry of (R.chensinensis) with scientific data. Acute toxicity was determined at water temperatures from 16 to 18℃ in wild by one-way toxicity test.The tadpoles used in the test were cultured by the institute at 37 days of age,body length (14.7±2.2) mm,body weight (347.4±82.7) mg.The water in tadpole pond was used for basic water in test,of which pH was from 7.0 to 8.5,salinity about 0.18g/L and water carbonate-alkalinity 1.41mmol/L.The water carbonate-alkalinity was set from 2.0 to 20.0mmol/L at gradient intervals of 2.0mmol/L,and a control group in the water of tadpole pond,each gradient with two replicates and 15 individuals each.The water carbonate-alkalinity was controlled by Na(2)CO(3) and NaHCO(3),and the water pH of test groups was maintained at 7.0-8.5 (the same as tadpole pond) during the experiment,and was regulated by HCl of 0.1mol/L and NaOH of 0.1mol/L.The water was exchanged by 1/2 volume every 12h.In pH toxicity test,first of all,a pre-test was designed to decide the correct pH range for the normal test.On the basis of the pre-test,the water pH were designed as 3.7,3.9,4.1,4.3,9.5,9.7,10.2,10.5 and 11.0.During the test,the water was exchanged by 50% volume every 8h. The results showed that at water salinity 0.18g/L,water carbonate-alkalinity 1.41mmol/L and pH 4.3-9.7,the 96h survival rate of tadpole was not affected .The 24h,48h,72h and 96hLC(50) of pH to tadpole were 10.33,10.18,10.08 and 10.02 in the upper limit,which were 3.92,4.07,4.11 and 4.16 in the prescribed minimum,respectively.The 24h,48h,72h and 96hLC(0) of pH to the tadpoles were 9.95,9.80,9.70 and 9.70 in the upper limit,of which the prescribed minimum were 4.23,4.45,4.30 and 4.30,respectively.24h,48h,72h and 96hLC(100) of pH to tadpoles were 10.70,10.55,10.45 and 10.33 in the upper limit,which were 3.55,3.70,3.92 and 4.03 in the prescribed minimum,respectively.The 24h,48h,72h and 96hLC(50) of carbonate-alkalinity to tadpoles were 14.36,11.83,10.35,and 7.68mmol/L at water pH 7.0-8.5 and at water salinity 0.18g/L,respectively.The 24h,48h,72h and 96hLC(0) were 8.76,8.51,4.65 and 3.88mmol/L,respectively.The 24h,48h,72h and 96hLC(100) were 19.96,15.14,16.05 and 11.48mmol/L,respectively,and the safe concentration was 2.41mmol/L.The adaptability of tadpole to water carbonate-alkalinity is not so good as that of freshwater fish,but in terms of pH adaptability,both are the same.The survival rate of tadpole dropped with the increase of water pH and water carbonate-alkalinity.For survival and growth of tadpoles,the suitable water carbonate-alkalinity is 1.0-3.0mmol/L,and pH 6.0-8.0.