澳洲鳗鲡(Anguilla australis)不同生长阶段的生物学耐受性特征及其演变趋势

BIOLOGICAL TOLERANCE CHARACTERISTICS AND EVOLUTION TREND OF ANGUILLA AUSTRALIS AT DIFFERENT GROWTH STAGES

以不同生长阶段的澳洲鳗鲡为对象,研究澳洲鳗鲡白仔、黑仔、幼鳗和成鳗的耗氧率、窒息点、对水温、非离子氨、亚硝酸盐的耐受性特征及其演变趋势。结果表明,白仔、黑仔、幼鳗和成鳗的昼间与夜间耗氧率都随体质量增大而下降。但昼夜间均存在显著差异(P<0.05)。在15-30℃,耗氧率与水温呈正相关。并得到了白仔、黑仔、幼鳗和成鳗的耗氧率和水温回归方程。在水温25℃,白仔、黑仔、幼鳗和成鳗的窒息点溶解氧浓度随体质量增大而下降。14—29℃为澳洲鳗鲡适温范围。具体来说,25-29℃为白仔和黑仔最适生长温度, 23-29℃为幼鳗和成鳗最适生长温度,随体质量增加对水温的耐受性增强。水中非离子氨对白仔、黑仔、幼鳗和成鳗的半致死浓度分别为2.35、7.96、2.94和2.62 mg/L,安全浓度为0.24、0.80、0.29和0.26 mg/L,可见黑仔的耐受性最强。亚硝酸盐对白仔、黑仔、幼鳗和成鳗的半致死浓度分别为52.07、63.80、691.89和885.12 mg/L,安全浓度为5.21、6.38、69.19和88.51 mg/L。因此,随体质量的增加,澳洲鳗鲡对亚硝酸盐的耐受性增强。

Experiments were conducted to understand the oxygen consumption rate and asphyxiation in tolerance to water temperature,non-ionic ammonia,and nitrite by Anguilla australis at different growth stages from glass eel,fingerling eel,juvenile eel,and yellow eel.The oxygen consumption rates of the eels of different growth stages were measured,and it was found increased in daytime but decreased in nighttime with the increase of individual body mass,showing significant differences in between(P<0.05).At 15—30℃,oxygen consumption rate was positively correlated with water temperature,based on which equations by regressions were established for the eels of different ages.At 25℃,the concentration of dissolved oxygen at the asphyxiation point decreased with the increase of age in terms of individual body mass.The suitable temperature range for A.australis growth was 14—29℃.Specifically,25—29℃ was the optimal growth temperature for the glass eel and fingerling eel,and 23—29℃ was the optimal growth temperature for juvenile eel and yellow eel.With the increase of individual body mass,the thermal tolerance of A.australis increased.The LC50 of non-ionic ammonia in water for glass eel,fingerling eel,juvenile eel,and yellow eel was 2.35,7.96,2.94,and 2.62 mg/L,while the SC(safety concentration)was 0.24,0.80,0.29,and 0.26 mg/L,respectively,indicating that the fingerling eel was most tolerant.The LC50 of nitrite for glass eel,fingerling eel,juvenile eel,and yellow eel was 52.07,63.80,691.89,and 885.12 mg/L,while the SC was 5.21,6.38,69.19,and 88.51 mg/L,respectively,showing that the older the eel,the more tolerant to the stress,and the tolerance of nitrite concentration increased with the increase of individual weight.