Tolerance of Ciliated Protozoan Paramecium bursaria (Protozoa, Ciliophora) to Ammonia and Nitrite
許恒龍(Heng-Long Xu)；宋微波(Wei-Bo Song)；路璐(Lu Lu)；Warren Alan
toxicology ； ecotoxicology ； toxicity ； ammonia ； nitrite ； ciliate protozoa ； Paramecium bursaria
Chinese Journal of Oceanology and Limnology
|Volume or Term/Year and Month of Publication||
23卷3期（2005 / 08 / 01）
349 - 353
The tolerance to ammonia and nitrites in freshwater ciliate ”Paramecium bursaria” was measured in a conventional open system. The ciliate was exposed to different concentrations of ammonia and nitrites for 2h and 12h in order to determine the lethal concentrations. Linear regression analysis revealed that the 2h-LC50 value for ammonia was 95.94 mg/L and for nitrite 27.35mg/L using probit scale method (with 95% confidence intervals). There was a linear correlation between the mortality probit scale and logarithmic concentration of ammonia which fit by a regression equation y=7.32x-9.51 (R^2=0.98; y, mortality probit scale; x, logarithmic concentration of ammonia), by which 2h-LC50 value for ammonia was found to be 95.50mg/L. A linear correlation between mortality probit scales and logarithmic concentration of nitrite is also followed the regression equation y=2.86x+0.89 (R^2=0.95; y, mortality probit scale; x, logarithmic concentration of nitrite). The regression analysis of toxicity curves showed that the linear correlation between exposed time of ammonia-N LC50 value and ammonia-N LC50 value followed the regression equation y=2 862.85e^-0.08ⅹ (R^2=0.95; y, duration of exposure to LC50 value; x, LC50 value), and that between exposed time of nitrite-N LC50 value and nitrite-N LC50 value followed the regression equation y = 127.15eOl3v (R^2=0.91; y, exposed time of LC50 value; x, LC50 value). The results demonstrate that the tolerance to ammonia in ”P. bursaria” is considerably higher than that of the larvae or juveniles of some metozoa, e.g. cultured prawns and oysters. In addition, ciliates, as bacterial predators, are likely to play a positive role in maintaining and improving water quality in aquatic environments with high-level ammonium, such as sewage treatment systems.