INRA, UR1037 SCRIBE, 35042 Rennes, France.
Ecotoxicology. 2012 Jan;21(1):155-64. doi: 10.1007/s10646-011-0775-1. Epub 2011 Aug 30.
Experimental ecosystems such as mesocosms have been developed to improve the ecological relevance of ecotoxicity test. However, in mesocosm studies, the number of replicates is limited by practical and financial constraints. In addition, high levels of biological organization are characterized by a high variability of descriptive variables. This variability and the poor number of replicates have been recognized as a major drawback for detecting significant effects of chemicals in mesocosm studies. In this context, a tool able to predict precisely control mesocosms outputs, to which endpoints in mesocosms exposed to chemicals could be compared should constitute a substantial improvement. We evaluated here a solution which consists in stochastic modelling of the control fish populations to assess the probabilistic distributions of population endpoints. An individual-based approach was selected, because it generates realistic fish length distributions and accounts for both individual and environmental sources of variability. This strategy was applied to mosquitofish (Gambusia holbrooki) populations monitored in lentic mesocosms. We chose the number of founders as a so-called "stressor" because subsequent consequences at the population level could be expected. Using this strategy, we were able to detect more significant and biologically relevant perturbations than using classical methods. We conclude that designing an individual-based model is very promising for improving mesocosm data analysis. This methodology is currently being applied to ecotoxicological issues.
实验生态系统，如中观生态系统，已经被开发出来以提高生态毒性测试的生态相关性。然而，在中观生态系统研究中，由于实际和财务限制，重复的数量是有限的。此外，高水平的生物组织具有描述性变量的高变异性。这种变异性和较差的重复数量已被认为是在中观生态系统研究中检测化学物质显著影响的主要缺点。在这种情况下，能够精确预测对照中观生态系统输出的工具，以及可以与暴露于化学物质的中观生态系统中的终点进行比较的工具，应该构成一个实质性的改进。我们在这里评估了一种解决方案，即对对照鱼类种群进行随机建模，以评估种群终点的概率分布。选择了基于个体的方法，因为它可以生成现实的鱼类长度分布，并考虑到个体和环境的变异性来源。该策略应用于在池塘中观生态系统中监测的食蚊鱼（Gambusia holbrooki）种群。我们选择了作为所谓“胁迫物”的 founders 数量，因为可以预期在种群水平上会产生后续的后果。使用这种策略，我们能够检测到比使用传统方法更显著和更具生物学意义的干扰。我们得出的结论是，设计基于个体的模型对于改进中观生态系统数据分析非常有前景。该方法目前正在应用于生态毒理学问题。
