铜锈环棱螺对铅污染沉积物慢性胁迫的繁殖响应和氧化应激反应敏感性

The reproductive reaction and oxidative stress responses sensitivity of Bellamya aeruginosa to the chronic exposure of lead-contaminated sediments

利用底栖无脊椎动物进行沉积物毒性测试可以为沉积物质量评价提供直接的依据。铜锈环棱螺(Bellamya aeruginosa)在我国淡水水体中分布广泛,具有重要的生态价值。对实验室培养的铜锈环棱螺进行环境相关水平铅加标沉积物(39～433μg.g-1)的42 d暴露,以评价该物种在Pb污染沉积物慢性胁迫下的繁殖响应和氧化应激反应敏感性。结果表明,低浓度的铅对铜锈环棱螺的繁殖力没有影响,当Pb浓度在中度污染水平以上(≥246μg.g-1)时,繁殖力出现显著下降。较低浓度的铅(66μg.g-1)即可诱导肝胰脏抗氧化酶SOD和CAT的氧化应激,但存在明显的性别差异,雄性的敏感性高于雌性。高浓度的铅(433μg.g-1)可致抗氧化酶的损伤。肝胰脏的谷胱甘肽GSH含量仅在最大Pb浓度时才出现显著下降。利用铜锈环棱螺的42 d繁殖测试可以反映中度铅污染沉积物的慢性毒性效应。肝胰脏SOD和CAT均可以作为沉积物中Pb慢性胁迫的潜在有效生物标志物,雄性的SOD和CAT可以用作指示低水平Pb污染沉积物长期污染胁迫的敏感生物标志物,在低浓度Pb胁迫下GSH的应激反应相对不敏感。

Sediment toxicity tests using benthic invertebrates can provide important evidence in the assessment of sediment quality.Bellamya aeruginosa is widely distributed as a dominant community member in aquatic ecosystems in China.In this study,adult B.aeruginosa from lab cultures were exposed for 42 d to sediments artificially spiked with lead（Pb） at environmentally relevant concentrations（39-433 μg g^-1） to evaluate their reproductive reaction and sensitivity of oxidative stress responses.The results showed that no reproductive toxicity was observed at relatively low Pb concentrations,whereas the fecundity was decreased significantly by 246μg Pb g^-1 or above.A relatively low Pb concentration（66μg g^-1） led to significantly increased hepatopancreatic SOD and CAT activities with obvious differences between sexes： the oxidative stress responses of males to lead exposure were more sensitive than that of females.A high Pb concentration（433μg g^-1） caused damage to the antioxidases.In contrast,glutathione（GSH） contents were only decreased significantly by the highest Pb concentration.The reproductive response of B.aeruginosa was indicative of the chronic toxicity of sediments moderately contaminated by Pb.While GSH was insensitive to the chronic stress of low concentrations of sedimental Pb,hepatopancreatic SOD and CAT,especially in males,were potentially effective biomarkers indicating the chronic stress of low concentrations of sedimental Pb.