小定鞭藻(Prymnesium parvum)藻华通常会使养殖的鱼类大量死亡,是一种常见的鱼毒性藻类。本文以海洋青鳉鱼(Oryzias melastigma)为受试生物,研究小定鞭藻胁迫对海洋青鳉鱼的急性毒性效应及抗氧化酶活性变化,以期揭示小定鞭藻对鱼类的安全阈值及致毒作用方式。研究结果表明,在浓度0.9×10~8~11.2×10~8/L范围内,随着小定鞭藻浓度的增加,其对海洋青鳉鱼的毒性越强,呈明显的剂量-效应关系。3、24、和48 h的半致死浓度LC_(50)分别为5.62×10~8、1.58×10~8和1.44×10~8/L。当小定鞭藻浓度分别为1.87×10~8和2.8×10~8/L时,半致死时间LT50分别为41.75 h和6.5 h,最大无作用浓度为0.9×10~8/L,推测小定鞭藻藻华对鱼类的安全阈值为9×10~6/L。低浓度小定鞭藻胁迫可使海洋青鳉鱼的过氧化物歧化酶(SOD)活性降低,但不呈剂量-效应关系,高浓度小定鞭藻可诱导过氧化氢酶(CAT)活性升高,低浓度小定鞭藻可使海洋青鳉鱼丙二醛(MDA)含量升高,提示低浓度小定鞭藻胁迫可导致海洋青鳉鱼脂质过氧化,这可能是小定鞭藻对鱼类致毒作用的方式之一。 Prymnesium parvum algae blooms often cause large-scale death of cultured fish, which is a common fish toxic algae. In this paper, Oryzias melastigma (Oryzias melastigma) was used as the tested organism to study the acute toxic effects and the changes of antioxidant enzyme activities on the marine catfish, Way of toxic effect. The results showed that the toxicity of Penaeus albacter increases with the concentration of Penaeus gladioli in the concentration range of 0.9 × 10 ~ 8 ~ 11.2 × 10 ~ 8 / L, showing a significant dose-effect relationship . The LC 50 values ​​at 3, 24, and 48 h were 5.62 × 10 -8, 1.58 × 10 -8 and 1.44 × 10 -8 / L, respectively. The results showed that the median lethal time (LT50) was 41.75 h and 6.5 h, respectively, and the maximum no-effect concentration was 0.9 × 10 ~ 8 / L when the concentration of Pinillaria nivalis were 1.87 × 10-8 and 2.8 × 10-8 / L respectively The safety threshold of fusarium algae bloom to fish is 9 × 10 ~ 6 / L. The low concentration of small-scale B. punctatus could decrease the activity of superoxide dismutase (SOD) but not the dose-effect, while the high concentration of small-scale dinoflagellate could induce the activity of catalase (CAT) High and low concentrations of small dinoflagellates can increase the content of malondialdehyde (MDA) in marine catfish, suggesting that the stress of low concentration of small paniclespond can lead to lipid peroxidation in marine catfish, One of the ways of toxic effects on fish.