以南方鲇Silurus meridionalis Chen初孵仔鱼、10日龄仔鱼为对象,采用水体染毒法进行急性镉暴露实验,研究了南方鲇仔鱼对镉暴露的耐受程度.初孵仔鱼实验设置一个对照组和5个镉处理组(0.04 mg/L,0.08 mg/L,0.16mg/L,0.32mg/L,0.64mg/L);10日龄仔鱼实验设置一个对照组和5个镉处理组(0.075mg/L,0.15mg/L,0.3mg/L,0.6mg/L,1.2mg/L).结果表明:随镉暴露质量浓度升高,初孵仔鱼存活率在暴露24h各组间差异不具有统计学意义(p>0.05);暴露48h存活率仅在0.64mg/L组显著低于其余各组(p<0.05);暴露72h,96h存活率在0.16mg/L,0.32mg/L和0.64mg/L组显著低于其余各组(p<0.05).初孵仔鱼96hLC50为0.104mg/L,10日龄仔鱼96hLC50为0.039mg/L.镉暴露对10日龄仔鱼存活率的影响呈剂量依赖效应和时间依赖效应.与文献报道的多数鱼类相比,南方鲇仔鱼对镉暴露相对较敏感;而10日龄仔鱼对镉暴露的敏感程度高于初孵仔鱼.10日龄可能是南方鲇仔鱼发育受水体镉污染影响的瓶颈期,因此南方鲇生境水质保护工作应重点考虑到10日龄仔鱼的发育.
The eggs of Pelteobagrus vachelli were fertilized artificially at 23℃,from parental fish collected in the Jialing River,on May 23,2004.The embryonic development was observed at nine experimental temperatures,i.e.eight constant temperatures(17,19,21,23,25,27,29 and 31℃)and a varying temperature(from the blastoderm to the blastula stage at 23℃,from gastrulae to the neural plate stage at 25℃,from organogenesis to hatching at 27℃).The results showed that the hatching rate,incubation duration and survival rate in each developmental stage changed significantly with temperature.At 17℃,the fertilized eggs did not develop,and all of them died.Hatching rate increased with temperature from 19 to 25℃,then decreased with as temperatures rose further from 27 to 31℃.Hatching rate was highest(76.92%±1.07%)at 25℃.At the different constant temperatures,the best survival rates in the three stages of blastodem-blastula,gastrulae-neural plate and organogenesis-hatching were obtained at 23,25 and 27℃,respectively.The hatching rate(93.69%±0.57%)with the varying temperature regime was significantly higher than those at each constant temperature,while its incubation duration and accumulated temperature were close to those at the constant 25℃.The results showed that the embryos could develop adequately with temperature of 21-29℃ and optimally at 25℃ in constant temperature regimes.
