水体镉暴露对南方鲇仔鱼存活率的影响

Effects of Cadmium Exposure on the Survival Rate of Larval Southern Catfish(Silurus meridionalis Chen)

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 tolerance of 1‐ and 10‐day‐old larval southern catfish to cadmium exposure was examined through exposure to the water‐borne Cd in an acute toxicity experiment .The concentrations of water‐borne Cd was designed as 0 （the control） ,0.04 ,0.08 ,0.16 ,0.32 and 0.64 mg/L for 1‐day‐old larvae ,and as 0 （the control） ,0.075 ,0.15 ,0.3 ,0.6 and 1.2 mg/L for 10‐day‐old larvae .The results showed that surviv‐al rate of 1‐day‐old larvae had no significant difference among all the groups （p〉0.05） after 24 h expo‐sure ;survival rate in the group of 0.64 mg/L was significantly lower than that of other groups （p〈0.05） after 48 h exposure ,and survival rates in the groups of 0.16 mg/L ,0.32 mg/L ,and 0.64 mg/L were sig‐nificantly lower than in other groups （p〈0.05） after 72 h and 96 h exposure .The median lethal concen‐tration in 96 hours （96 h LC50 ） was 0.104 mg/L for 1‐day‐old larvae ,and 0.039 mg/L for 10‐day‐old lar‐vae .Effects of cadmium exposure on survival rate of 10‐day‐old larvae showed a clear dose‐response effect and a time dependent effect .Compared with most fish species reported in relevant literature ,the larvae of southern catfish were more sensitive to Cd exposure ,and its 10‐day‐old larvae were more sensitive to expo‐sure of Cd than the 1‐day‐old larvae .The age of 10 days of southern catfish larvae may be the bottleneck period of water‐borne Cd pollution and ,therefore ,this stage of the development of the fish should given priority in water quality protection work .