College of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4QD, UK.
Global Safety, Health and Environment Astrazeneca, Cambridge, CB2 0SL, UK.
Aquat Toxicol. 2020 Jul;224:105483. doi: 10.1016/j.aquatox.2020.105483. Epub 2020 May 1.
The potential environmental impacts of chemical exposures on wildlife are of growing concern. Freshwater ecosystems are vulnerable to chemical effects and wildlife populations, including fish, can be exposed to concentrations known to cause adverse effects at the individual level. Wild fish populations are also often subjected to numerous other stressors simultaneously which in temperate climates often include sustained periods of food limitation. The potential interactive effects of chemical exposures and food limitation on fish populations are however difficult to establish in the field. Mechanistic modelling approaches can be employed to help predict how the physiological effects of chemicals and food limitation on individuals may translate to population-level effects. Here an energy budget-individual-based model was developed and the control (no chemical) model was validated for the three-spined stickleback. Findings from two endocrine active chemical (EAC) case studies, (ethinyloestradiol and trenbolone) were then used to investigate how effects on individual fecundity translated into predicted population-level effects for environmentally relevant exposures. The cumulative effects of chemical exposure and food limitation were included in these analyses. Results show that effects of each EAC on the population were dependent on energy availability, and effects on population abundance were exacerbated by food limitation. Findings suggest that chemical effects and density dependent food competition interact to determine population responses to chemical exposures. Our study illustrates how mechanistic modelling approaches might usefully be applied to account for specific chemical effects, energy budgets and density-dependent competition, to provide a more integrated evaluation of population outcomes in chemical risk assessments.
化学物质暴露对野生动物的潜在环境影响日益受到关注。淡水生态系统容易受到化学物质的影响，野生动物种群，包括鱼类，可能会接触到已知在个体水平上会产生不利影响的浓度。野生鱼类种群也经常同时受到许多其他胁迫因素的影响，在温带气候下，这些因素通常包括持续的食物限制期。然而，在野外很难确定化学物质暴露和食物限制对鱼类种群的相互作用效应。机制模型方法可用于帮助预测化学物质和食物限制对个体的生理影响如何转化为种群水平的影响。在这里，开发了一个能量预算个体基础模型，并对三刺鱼的对照（无化学物质）模型进行了验证。然后，利用两项内分泌活性化学物质（EAC）案例研究的结果（乙炔雌二醇和群勃龙），研究了个体生育力的变化如何转化为与环境相关暴露的预测种群水平效应。这些分析包括了化学暴露和食物限制的累积效应。研究结果表明，每种 EAC 对种群的影响都取决于能量的可利用性，而食物限制加剧了对种群丰度的影响。研究结果表明，化学物质的影响和密度依赖的食物竞争相互作用，决定了种群对化学物质暴露的反应。我们的研究说明了如何利用机制模型方法来考虑特定的化学物质效应、能量预算和密度依赖的竞争，以更全面地评估化学风险评估中的种群结果。
