Cd^(2+)、Hg^(2+)、Cr^(6+)和Pb^(2+)对黑点青鳉(Oryzias melastigma)早期生活阶段的毒性效应研究

Toxic Effects of Cadmium, Mercury, Chromium and Lead on the Early Life Stage of Marine Medaka (Oryzias melastigma)

近岸海域重金属污染不容乐观,作为"一种潜在的海洋模式鱼种"黑点青鳉(marine medaka,Oryzias melastigma)对不同重金属胁迫的响应水平却鲜有报道。为探究并比较海水鱼种黑点青鳉早期生活阶段对Cd2+、Hg2+、Cr6+和Pb2+等不同重金属胁迫的响应,在实验室通过半静态方式,对黑点青鳉受精卵和初孵仔鱼分别进行了14d短期毒性和96h急性毒性实验。结果显示:当Cd2+、Hg2+、Cr6+和Pb2+浓度分别高于147μg·L-1、24μg·L-1、235μg·L-1和200μg·L-1时,4种重金属离子对黑点青鳉胚胎发育具有显著的毒性效应,可显著降低胚胎的孵化能力和心脏跳动,并导致初孵仔鱼的发育畸形;Cd2+、Hg2+、Cr6+和Pb2+对黑点青鳉初孵仔鱼的96h-LC50分别为1.12(0.496～2.306)mg·L-1、0.097(0.042～0.196)mg·L-1、1.456(0.547～3.242)mg·L-1和>20mg·L-1;与其他海洋鱼种相比,4种重金属离子对黑点青鳉初孵仔鱼的LC50相对较低,表明该鱼种对重金属胁迫具有较强的敏感性。此外,该鱼种具有个体小,易于实验室长期培养,世代周期短和对内分泌干扰物敏感等多项优势,因此,笔者推荐将黑点青鳉作为潜在的海洋模式鱼种用于生态毒理学研究。

The situation of heavy metal pollution in coastal waters in China is not optimistic. However, few studies have reported the toxic effects of heavy metal on marine medaka （Oryzias melastigma） as a new marine test fish. In order to explore and compare the toxicity responses of marine medaka at its early life stage under the exposure of Cd2＋, Hg2＋, Cr6＋ and Pb2＋, static-renewal acute toxicity tests （96 h） on the embryo and short-term toxicity tests （14 d） on the larvae were investigated. Results showed that, when the concentrations of Cd2＋, Hg2＋, Cr6＋ and Pb2＋ were higher than 147 μg·L-1, 24 μg·L-1, 235 μg·L-1 and 200 μg·L-1, respectively, these metal ions caused significant toxic effects on the hatchability and heartbeat of the embryos, and caused the deformity of the larvae. The 96 h-LC50 values for marine medaka larvae exposed to Cd2＋, Hg2＋, Cr6＋ and Pb2＋ were 1.12 （0.496 - 2.306） mg·L-1, 0.097 （0.042 - 0.196） mg·L-1, 1.456 （0.547 - 3.242） mg·L-1 and 20 mg·L-1, respectively. Compared with other marine fish species, the LC50 values of the four metal ions to the marine medaka larvae were relatively low, indicating that the fish species has relatively high sensitivity to heavy metal stress. Additionally, this fish species has many other advantages including a small size, easy cultivation in the laboratory, a short generation cycle and relatively high sensitivity to endocrine disrupting chemicals. Based on these results, marine medaka is highly recommended as a marine test fish for ecotoxicological tests and researches.