Visviki Ioanna, Judge Michael L
Department of Biology, College of Mount Saint Vincent, Bronx, NY, United States of America.
Department of Biology, Manhattan College, Bronx, NY, United States of America.
PeerJ. 2020 Mar 3;8:e8645. doi: 10.7717/peerj.8645. eCollection 2020.
Arsenate (As V) is the predominant inorganic species of arsenic in oxic aquatic environments. Chronic water quality criteria for arsenate have not been established due to the scarcity of relevant studies on its impact on aquatic biota. We examined the acute and chronic effects of arsenate on the benthic amphipod , an important test organism for ecotoxicological studies. We determined that a concentration of 1,971 µg/L arsenate induced 50% mortality (LC) in juveniles in 96-hr water only exposure. Subsequently, we tested the efficacy of a 42-day sediment bioassay to determine chronic population-level effects. Specifically, we analyzed the survivorship, size distribution, reproduction and offspring sex ratio of this amphipod to a sublethal concentration of arsenate. The sublethal concentration was determined based on the results of the acute tests. Arsenate (500 µg/L) was added to seawater (20 psu) overlying natural sediments (particle sizes < 250 µm). Fifteen replicate chambers per treatment were employed, each stocked with 20 stage-sorted juvenile amphipods (500-600 µm). Five replicates per treatment were destructively sampled on week 3 and ten replicates were sampled on week 6. Arsenate exposure did not affect the survivorship of parental amphipods, as expected, but it decreased significantly the number of offspring in the largest size classes. By week 6, arsenate-exposed replicates had statistically fewer sexually mature offspring compared to controls, likely because the overall reproduction was suppressed. Arsenate exposed amphipods had significantly fewer offspring than controls by week 6 (9.3 vs. 19.1 per parent), but the sex ratio of the offspring was not altered. Our results indicate that size distribution and reproduction may be more sensitive endpoints than survivorship for the chronic effects of arsenate in oxic systems. The extended 42-day bioassay with is a very promising tool to study the effects of toxicants on population dynamics.
砷酸盐（As V）是有氧水生环境中砷的主要无机形态。由于缺乏关于其对水生生物群影响的相关研究，尚未制定砷酸盐的慢性水质标准。我们研究了砷酸盐对底栖双壳类动物的急性和慢性影响，底栖双壳类动物是生态毒理学研究的重要受试生物。我们确定，在仅水暴露96小时的情况下，1971 µg/L的砷酸盐浓度可导致幼体50%的死亡率（LC）。随后，我们测试了为期42天的沉积物生物测定法的有效性，以确定慢性种群水平的影响。具体而言，我们分析了这种双壳类动物在亚致死浓度砷酸盐作用下的存活率、大小分布、繁殖情况和后代性别比例。亚致死浓度是根据急性试验结果确定的。将砷酸盐（500 µg/L）添加到覆盖天然沉积物（粒径<250 µm）的海水（20 psu）中。每个处理使用15个重复试验箱，每个试验箱中放入20只按大小分类的幼体双壳类动物（500 - 6
