鱼毒性微藻小定鞭藻对海洋青鳉鱼的急性致毒效应研究

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0.9×108~11.2×108/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LC₅₀分别为5.62×108、1.58×108和1.44×108/L。当小定鞭藻浓度分别为1.87×108和2.8×108/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0.9×108/L,推测小定鞭藻藻华对鱼类的安全阈值为9×106/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。

Acute toxicity of Oryzias Melastigma exposed to ichthyotoxic microalgae Prymnesium Parvum

Prymnesium parvum is one of the ichthyotoxic microalgae, causing mass mortality of cultured fish.To understand the safety threshold and the poisoning patheway of P.parvum to fish, the research on the acute toxicity and the changes of superoxide dismutase (SOD) activity, catalase (CAT) activity and malondialdehyde (MDA) content of Oryzias melastigma exposed to P.parvum was carried out.The results showed that there was a dose-effect relationship between P.parvum cell density and the toxicity on O.melastigma when the cell density of P.parvum ranged from 0.9×108 to 11.2×108/L.The LC₅₀ in 3 h, 24 h and 48 h were 5.62×108, 1.58×108 and 1.44×108/L, respectively.The LT₅₀ of O.melastigma exposed to the P.parvum cell density of 1.87×108 and 2.8×108/L were 41.75 h and 6.5 h.The maximum ineffective concentration of P.parvum was 0.9×108/L, from which we speculated cell density of 9×106/L could be the safety threshold of P.parvum to fish.Activity of SOD decreased when O.melastigma exposed to lower cell density of P.parvum, but it didn't show a dose-effect relationship between SOD activity of O.melastigma and cell density of P.parvum.O.melastigma exposed to higher cell densities of P.parvum had a higher activity of CAT.A higher content of MAD in O.melastigma was detected when they exposed to lower cell densities of P.Parvum, it implied that a lower cell density of P.parvum could lead to lipid peroxidation in O.melastigma, which could be one of the poisoning pathways of P.parvum to fish.