镉质量浓度和鱼尺寸对罗非鱼积累和转移镉的影响

为研究尺寸和镉(Cd²⁺)质量浓度对罗非鱼积累和转移水环境中Cd²⁺的影响,用室内培养的方法,选取4种尺寸的罗非鱼,设置不同质量浓度Cd²⁺的暴露试验,分别测定其半致死率、Cd²⁺积累量和对Cd²⁺的转移系数以及罗非鱼的相对增长率.结果表明:不同尺寸的罗非鱼对Cd²⁺的响应不同,其中,幼龄鱼的LC₅₀浓度最低,体长为31.5±3.4 cm的罗非鱼LC₅₀最高;低质量浓度Cd²⁺(0.5 mg/kg)处理下,罗非鱼尺寸不同,相同鱼组织对Cd²⁺的吸收积累量差异显著(P< 0.05),而高质量浓度Cd²⁺处理时,不同尺寸罗非鱼的同一组织对Cd²⁺的积累量无显著性差异;除体长27.4±2.9 cm罗非鱼外,相同尺寸的罗非鱼Cd²⁺转移系数都是低质量浓度显著大于高质量浓度(P< 0.05);高质量浓度Cd²⁺处理对各种尺寸罗非鱼质量增加的抑制率显著高于低质量浓度Cd²⁺处理的抑制率.此外,不同Cd²⁺质量浓度对相同尺寸的罗非鱼也产生不同的影响.因此,罗非鱼的尺寸和Cd²⁺质量浓度都对罗非鱼积累和转移Cd²⁺产生影响.

Influence of Cd concentration and fish size on Cd accumulation and transfer in Orechromis niloticus

In China,more and more fishes were polluted by waterborne heavy metal.Four sizes of tilapia were cultured to different Cd exposure in order to study the influence of heavy metal concentration as well as the fish size on the Cd accumulation and transfer by the Orechromis niloticus.The median lethal Cd concentration (LC₅₀),Cd accumulation and transfer rate in fish and relative growth rate of the fish are analyzed.The results show that different age of tilapia had different response to Cd contamination.LC₅₀ in the juvenile fish was the lowest while that in 31.5±3.4 cm length fish was the highest.Exposed to low Cd²⁺ concentration (0.5 mg/kg),different size of fishes accumulated significantly different (P<0.05) quantity of Cd²⁺ in the same tissue.While exposed to high Cd²⁺ concentration,the Cd²⁺ accumulation in different size of fishes had no obvious difference.The Cd²⁺ transfer factor was significantly greater in low Cd²⁺ concentration than that in high Cd²⁺ concentration,for all fishes except fish with 27.4±2.9 cm length.High Cd²⁺ concentration inhibits the fish weight increase more than low Cd²⁺ concentration,in all age of fishes.In addition,different Cd²⁺ concentration had different effect on the same age of tilapia.In conclusion,both the fish size of tilapia and the Cd²⁺ concentration affected the Cd²⁺ accumulation and transfer in fish.