IMAR - Instituto do Mar, Department of Life Sciences, University of Coimbra, Apartado 3046, 3001-401 Coimbra, Portugal.
Chemosphere. 2012 Mar;87(1):43-8. doi: 10.1016/j.chemosphere.2011.11.052. Epub 2011 Dec 20.
Consumption inhibition in natural populations, namely due to contaminants, may have direct and immediate effects on ecosystems, by hampering ecosystem key functions (e.g., organic matter decomposition, grazing), long before effects at the individual level (e.g., reproduction, growth, emergence) have time-delayed consequences at successively higher levels of biological organization. The present study aimed at developing a cost-effective (short and easy) toxicity test based on the postexposure feeding of a freshwater amphipod present in the Iberian Peninsula and at evaluating the immediate impact of contamination on the population-level consumption rate. First, methodologies to quantify postexposure feeding were developed and optimized, the most important criterion being a feeding period as short as possible to minimize physiological recovery from the contaminant exposure. Second, the sensitivities of 48-h postexposure feeding and 48-h lethality tests were compared, using a reference chemical - copper. Third, the latter responses were integrated in a single parameter, the median population consumption inhibitory concentration. When Echinogammarus meridionalis males were fed on 100 defrosted Artemia franciscana nauplii during 30 min in darkness at 19-21°C, the eaten proportion was approximately 80%, without truncated data distributions. The 48-h median effective copper concentration for postexposure feeding was approximately two times lower than the 48-h LC50 - 91 versus 198 μg L(-1), respectively. Two techniques were used to quantify the median population consumption inhibitory copper concentration, both leading to similar values (75 and 68 μg L(-1)). In conclusion, when contaminant concentrations elicit both lethality and feeding depression, the integration of both responses can provide an ecologically relevant evaluation on the potency of a contaminant to immediately disrupt ecosystem functioning.
自然种群中的消费抑制，即由于污染物的存在，可能会直接且立即对生态系统产生影响，阻碍生态系统的关键功能（例如，有机质分解、放牧），而这些影响在个体水平（例如，繁殖、生长、出现）上的延迟后果在生物组织的更高层次上才会显现。本研究旨在开发一种具有成本效益（简短且简单）的毒性测试方法，该方法基于在伊比利亚半岛存在的淡水端足目甲壳动物的暴露后摄食，并评估污染对种群消费水平的即时影响。首先，开发并优化了量化暴露后摄食的方法，最重要的标准是摄食期尽可能短，以最大限度地减少从污染物暴露中恢复的生理能力。其次，使用参考化学物质 - 铜，比较了 48 小时暴露后摄食和 48 小时致死性测试的敏感性。第三，将后者的反应整合到一个单一的参数中，即种群消费抑制浓度的中位数。当雄性 Echinogammarus meridionalis 在 19-21°C 的黑暗中用 30 分钟时间，喂食 100 只解冻的卤虫无节幼体时，吃掉的比例约为 80%，没有截断的数据分布。暴露后摄食的 48 小时铜中值有效浓度约为 48 小时 LC50 的两倍 - 分别为 91 和 198 μg/L。使用两种技术来量化种群消费抑制铜浓度的中位数，两种技术都得到了相似的值（75 和 68 μg/L）。总之，当污染物浓度既引起致死性又引起摄食抑制时，整合这两种反应可以提供对污染物立即破坏生态系统功能的潜在能力的生态相关评估。
