Instituto do Mar, Department of Life Sciences, University of Coimbra, Coimbra, Portugal.
Environ Toxicol Chem. 2013 Sep;32(9):2144-52. doi: 10.1002/etc.2297. Epub 2013 Jul 18.
Contaminant-driven feeding inhibition has direct and immediate consequences at higher levels of biological organization, by depressing the population consumption and thus hampering ecosystem functioning (e.g., grazing, organic matter decomposition). The present study aimed at developing a short-term laboratory and in situ assay based on the postexposure feeding of the freshwater snail Theodoxus fluviatilis. A method to precisely quantify feeding rates was first developed, consisting of a 3-h feeding period, in darkness, on 150 defrosted nauplii of the brine shrimp Artemia franciscana. Postexposure feeding after a 48-h exposure to cadmium was approximately as sensitive as survival, with the median effective concentration (EC50) and median lethal concentration (LC50) being 85 µg/L and 102 µg/L, respectively, and the 20% effective concentration (EC20) and 20% lethal concentration (LC20) being 41 µg/L and 77 µg/L, respectively. Together, both effects at the LC20 reduced population consumption by 56%. In situ experiments at reference sites covering broad ranges of current velocity, hardness, conductivity, sediment organic matter content, and sediment particle size distribution revealed the influence of these abiotic conditions on postexposure feeding, in the absence of contamination, to be negligible. The effectiveness of the in situ assay was evaluated at 5 sites contaminated with acid mine drainage. Surviving organisms at the single partially lethal site (37% mortality) presented a 54% feeding inhibition relative to the reference, whereas the population consumption would be inhibited by 71%, confirming the integration of survival and feeding to be pertinent for estimating contaminant effects at higher levels of biological organization.
污染物驱动的摄食抑制在更高的生物组织层次上具有直接和即时的影响，通过降低种群的摄食量，从而阻碍生态系统功能（例如，放牧、有机物质分解）。本研究旨在开发一种基于淡水蜗牛（Theodoxus fluviatilis）暴露后摄食的短期实验室和现场测定方法。首先开发了一种精确量化摄食率的方法，该方法包括在黑暗中进行 3 小时的摄食期，摄食 150 只解冻的卤虫（Artemia franciscana）无节幼体。暴露于镉 48 小时后的暴露后摄食与存活率一样敏感，其半数有效浓度（EC50）和半数致死浓度（LC50）分别为 85µg/L 和 102µg/L，20%有效浓度（EC20）和 20%致死浓度（LC20）分别为 41µg/L 和 77µg/L。这两种效应在 LC20 时共同使种群摄食量减少了 56%。在参考地点进行的现场实验涵盖了当前流速、硬度、电导率、沉积物有机质含量和沉积物粒径分布的广泛范围，结果表明，在没有污染的情况下，这些非生物条件对暴露后摄食的影响可以忽略不计。在受酸性矿山排水污染的 5 个地点评估了现场测定的有效性。在单一的部分致死地点（37%死亡率）中，存活的生物相对于参考点表现出 54%的摄食抑制，而种群摄食量将受到 71%的抑制，证实了生存和摄食的整合对于估计更高层次生物组织的污染物效应是相关的。
