Laboratory of Environmental Toxicology and Aquatic Ecology, Environmental Toxicology Unit (GhEnToxLab), Ghent University, Gent, Belgium.
Environ Toxicol Chem. 2018 Jun;37(6):1668-1678. doi: 10.1002/etc.4115. Epub 2018 Apr 23.
Under natural conditions, organisms can experience a variety of abiotic (e.g., temperature, pH) and biotic (e.g., species interactions) factors, which can interact with toxicant effects. By ignoring species interactions conventional ecotoxicological studies (i.e., single-species tests) oversimplify the actual field situation. We investigated whether temperature and interspecific competition affected the effects of zinc (Zn) on a Daphnia longispina population. The D. longispina populations were exposed in a full factorial design to 3 different Zn treatments (background, 29, and 110 μg Zn/L), 2 different temperature regimes (cold, 17-18 °C; warm, 21-22 °C), and 2 interspecific competition levels (no interspecific Brachionus competition = no Brachionus calyciflorus added; interspecific Brachionus competition = B. calyciflorus added). Interspecific Brachionus competition and temperature by itself had a limited effect on the Daphnia abundance but significantly interacted with the highest Zn concentration. Without Brachionus competition the D. longispina juvenile and adult abundances under warm conditions were up to 5.5 and 21 times lower, respectively, in the high Zn treatment in comparison with the Zn control, whereas under cold conditions no significant Zn effect was observed. However, with Brachionus competition the highest Zn treatment was on average 2.2 times less toxic to the D. longispina juvenile abundance at higher temperatures. Under cold conditions the highest Zn treatment affected the juvenile abundance sooner and up to 9 times more negatively when simultaneously faced with Brachionus competition. It is possible that the competition for food reduced the amount of energy that could be used by D. longispina for reproduction, and the metabolic costs increased as a result of Zn stress. The present study clearly illustrated the influence of temperature and competition on the effects of a chemical stressor. Thus, not considering such factors in ecological risk assessment may underestimate or overestimate risks in aquatic ecosystems when extrapolating data from standard single-species tests to the field. Environ Toxicol Chem 2018;37:1668-1678. © 2018 SETAC.
在自然条件下，生物体会经历各种非生物（例如，温度、pH 值）和生物（例如，物种相互作用）因素，这些因素可能会与毒物效应相互作用。通过忽略物种相互作用，传统的生态毒理学研究（即单一物种测试）过于简化了实际的现场情况。我们研究了温度和种间竞争是否会影响锌（Zn）对长额溞（Daphnia longispina）种群的影响。长额溞种群在完全析因设计中暴露于 3 种不同的 Zn 处理（背景、29 和 110μg Zn/L）、2 种不同的温度条件（冷，17-18°C；暖，21-22°C）和 2 种种间竞争水平（无种间桡足类竞争=不添加桡足类 calyciflorus；种间桡足类竞争=添加桡足类 calyciflorus）。种间桡足类竞争和温度本身对溞类丰度的影响有限，但与最高 Zn 浓度显著相互作用。没有桡足类竞争，温暖条件下高 Zn 处理下长额溞幼体和成虫的丰度分别比 Zn 对照低 5.5 倍和 21 倍，而在寒冷条件下则没有观察到显著的 Zn 效应。然而，在有桡足类竞争的情况下，高温下最高 Zn 处理对溞类幼体丰度的毒性平均降低了 2.2 倍。在寒冷条件下，当同时面临桡足类竞争时，最高 Zn 处理对幼体丰度的影响更早，幅度高达 9 倍。这可能是因为对食物的竞争减少了溞类用于繁殖的能量，并且由于 Zn 胁迫导致代谢成本增加。本研究清楚地说明了温度和竞争对化学胁迫因子影响。因此，在将从标准单一物种测试中获得的数据外推到现场时，如果在生态风险评估中不考虑这些因素，可能会低估或高估水生生态系统的风险。Environ Toxicol Chem 2018;37:1668-1678。 © 2018 SETAC。
