Awkerman Jill A, Greenberg Cathryn H
Gulf Ecosystem Measurement and Modeling Division, US EPA, One Sabine Island Drive, Gulf Breeze, FL 32561, USA.
USDA Forest Service, Southern Research Station, Bent Creek Experimental Forest, 1577 Brevard Rd., Asheville, NC 28806, USA.
Ecologies (Basel). 2022 Jun 17;3(2):235-248. doi: 10.3390/ecologies3020018.
Amphibian populations are threatened globally by stressors, including diminishing availability of suitable wetland breeding sites, altered hydroregimes driven by changing weather patterns, and exposure to contaminants. Ecological risk assessment should encompass spatial and temporal scales that capture influential ecological processes and demographic responses. Following the PopGUIDE framework of population model development for risk assessment, we used matrix population models, in conjunction with existing hydroregime predictions, under a climate change scenario to evaluate the effects of environmental stochasticity and aquatic pesticide exposure on amphibians that are dependent on ephemeral wetlands. Using southern toads () as an example, we simulated population dynamics with breeding success dependent on hydroregime suitability. Years were defined as optimal, marginal, or insufficient for successful toad recruitment, based on the duration of their potential breeding season and rate of larval development to metamorphosis. We simulated both probabilistic and chronologically specific population projections, including variable annual fecundity, based on hydroregime suitability and reduced larval survival from carbaryl exposure. In our simulations, populations were more negatively impacted by prolonged drought, and consequently multiple sequential years of reproductive failure, than by aquatic pesticide exposure. These results highlight the necessity of reliable climate projections to accurately represent the effects of altered hydroregimes on amphibian populations. Risk assessment approaches could be improved with flexible modifications that allow inclusion of various extrinsic stressors and identification of demographic and ecological vulnerabilities when precise data are lacking.
两栖动物种群在全球范围内受到多种压力因素的威胁，包括适宜湿地繁殖地的可用性不断减少、天气模式变化导致的水文状况改变以及接触污染物。生态风险评估应涵盖能够捕捉有影响的生态过程和种群统计学响应的空间和时间尺度。遵循用于风险评估的种群模型开发的PopGUIDE框架，我们结合现有的水文状况预测，在气候变化情景下使用矩阵种群模型来评估环境随机性和水生农药暴露对依赖临时性湿地的两栖动物的影响。以南方蟾蜍（）为例，我们模拟了繁殖成功率取决于水文状况适宜性的种群动态。根据潜在繁殖季节的持续时间和幼体发育至变态的速率，将年份定义为蟾蜍成功繁殖的最佳、边缘或不足年份。我们基于水文状况适宜性和西维因暴露导致的幼体存活率降低，模拟了概率性和按时间顺序特定的种群预测，包括可变的年繁殖力。在我们的模拟中，长期干旱以及因此导致的连续多年繁殖失败对种群的负面影响比水生农药暴露更大。这些结果凸显了可靠的气候预测对于准确反映水文状况改变对两栖动物种群影响的必要性。当缺乏精确数据时，通过灵活修改允许纳入各种外部压力因素并识别种群统计学和生态脆弱性，可以改进风险评估方法。
