Hochiminh City University of Technology, Vietnam National University - Hochiminh City, 268 Ly Thuong Kiet Street, District 10, Hochiminh City, Vietnam.
University of Science, Vietnam National University - Hochiminh City, 227 Nguyen Van Cu Street, District 5, Hochiminh City, Vietnam.
Sci Total Environ. 2017 Jan 1;574:1360-1370. doi: 10.1016/j.scitotenv.2016.08.049. Epub 2016 Aug 12.
Metal contamination is one of the major issues to the environment worldwide, yet it is poorly known how exposure to metals affects tropical species. We assessed the sensitivity of a tropical micro-crustacean Daphnia lumholtzi to three trace metals: copper (Cu), zinc (Zn) and nickel (Ni). Both, acute and chronic toxicity tests were conducted with metals dissolved in in situ water collected from two sites in the lower part of the Mekong River. In the acute toxicity test, D. lumholtzi neonates were exposed to Cu (3-30μgL), Zn (50-540μgL) or Ni (46-2356μgL) for 48h. The values of median lethal concentrations (48h-LC) were 11.57-16.67μg Cu L, 179.3-280.9μg Zn L, and 1026-1516μg Ni L. In the chronic toxicity test, animals were exposed to Cu (3 and 4μgL), Zn (50 and 56μgL), and Ni (six concentrations from 5 to 302μgL) for 21days. The concentrations of 4μg Cu L and 6μg Ni L enhanced the body length of D. lumholtzi but 46μg Ni L and 50μg Zn L resulted in a strong mortality, reduced the body length, postponed the maturation, and lowered the fecundity. The results tentatively suggest that D. lumholtzi showed a higher sensitivity to metals than related species in the temperate region. The results underscore the importance of including the local species in ecological risk assessment in important tropical ecosystems such as the Mekong River to arrive at a better conservational and management plan and regulatory policy to protect freshwater biodiversity from metal contamination.
金属污染是全球环境面临的主要问题之一，但人们对金属暴露如何影响热带物种知之甚少。我们评估了一种热带小型甲壳动物——多刺裸腹溞（Daphnia lumholtzi）对三种痕量金属（铜、锌和镍）的敏感性。急性毒性和慢性毒性试验均使用原位采集的河水溶解金属进行，采集地点为湄公河下游的两个位点。在急性毒性试验中，将多刺裸腹溞的幼体暴露于 Cu（3-30μg/L）、Zn（50-540μg/L）或 Ni（46-2356μg/L）中 48 小时。48 小时 LC 的中值浓度（48h-LC）分别为 11.57-16.67μg Cu/L、179.3-280.9μg Zn/L 和 1026-1516μg Ni/L。在慢性毒性试验中，动物暴露于 Cu（3 和 4μg/L）、Zn（50 和 56μg/L）和 Ni（6 个浓度范围为 5-302μg/L）中 21 天。4μg Cu/L 和 6μg Ni/L 浓度提高了多刺裸腹溞的体长，但 46μg Ni/L 和 50μg Zn/L 导致了高死亡率、降低了体长、推迟了成熟并降低了繁殖力。结果初步表明，多刺裸腹溞对金属的敏感性高于温带地区的相关物种。这些结果强调了在湄公河等重要热带生态系统中，包括当地物种进行生态风险评估的重要性，以便制定更好的保护和管理计划以及监管政策，以防止金属污染对淡水生物多样性造成影响。
