摘要:
甲氨基阿维菌素苯甲酸盐(简称甲维盐)是一种广泛应用于农业和水产养殖业的高效抗生素杀虫剂，会进入近海海洋环境从而对海洋生物造成影响。为初步探讨甲维盐对海洋桡足类产生的生物效应，研究了甲维盐对日本虎斑猛水蚤(Tigriopus japonicus Mori)的死亡率、摄食率、滤水率、神经传导关键性酶和抗氧化防御系统中多种酶活性以及生殖、发育的影响。结果显示，甲维盐对于日本虎斑猛水蚤有显著的急性毒性影响，雌性成体和雄性成体的96 h-LC50分别为7 156 μg·L-1和3 637 μg·L-1；雌性成体的24 h-EC50为3.5 μg·L-1。暴露在不同甲维盐浓度(0.5、1、2、3.5和5 μg·L-1)条件下24 h后，日本虎斑猛水蚤的摄食率和滤水率随甲维盐浓度升高逐渐降低，乙酰胆碱酯酶(AchE)活性、抗氧化酶超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GPx)活性均随甲维盐浓度的升高先升高后趋于平稳，而过氧化氢酶(CAT)活性无显著变化。日本虎斑猛水蚤连续暴露2个世代，随着甲维盐浓度的升高，发育率逐渐降低；当甲维盐浓度达到0.5 μg·L-1时，10 d产卵量受到显著抑制，这说明甲维盐对其种群繁衍能力产生了显著影响。将第3代无节幼虫置于海水中进行恢复培养后发现，高浓度甲维盐暴露(0.5 μg·L-1)对日本虎斑猛水蚤发育和生殖均造成了不可逆的影响，毒性可能具有不可恢复性。本文可为评估甲维盐对海洋桡足类的潜在影响提供基础数据和依据。
Abstract:
Emamectin benzoate (EMB) is an effective pesticide widely used in agriculture and aquaculture, which could enter the coastal environment and potentially affect marine organisms. To investigate the effects of EMB on the marine copepods, the acute and the chronic toxicity of EMB were studied on Tigriopus japonicus Mori, of which the mortality, ingestion and the activities of enzymes related to antioxidation and neurotransmission were measured. Acute toxicity assay of EMB showed that, the 96 h-LC50 was 7 156 μg·L-1 and 3 637 μg·L-1 for adult females and males respectively, and 24 h-EC50 was 3.5 μg·L-1 for adult females. Upon the 24 h exposure to EMB at concentrations of 0.5, 1, 2, 3.5 and 5 μg·L-1, the feeding and filtration rate of T. japonicus decreased with increasing EMB concentration. The activities of antioxidant enzymes, i.e., superoxide dismutase (SOD) and glutathione peroxidase (GPx), and the activity of the enzyme related to neurotransmission acetylcholinesterase (AchE) increased with increasing EMB concentration, peaked at 3.5 μg·L-1, 1 μg·L-1 and 3.5 μg·L-1 respectively and remained stable afterwards. However, the activity of antioxidant enzyme catalase (CAT) showed no significant change with EMB concentrations. For chronic toxicity test, T. japonicus were exposed to different sublethal concentrations of EMB for two successive generations (F1 and F2) and subsequently all the treatments were recovered in seawater for one generation (F3). The developmental rate decreased with increasing EMB concentrations and 10 day fecundity was significantly reduced at the highest tested concentration (0.5 μg·L-1), which failed to recover in the third generation (F3) raised in seawater. The results shed light on the effects of EMB on marine benthic copepods and provided basic information for the ecological risks assessment of EMB.
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