Washington State University, Puyallup, Washington, USA.
Institute of Environmental Toxicology, Huxley College of the Environment, Western Washington University, Bellingham, Washington, USA.
Integr Environ Assess Manag. 2021 Jan;17(1):95-109. doi: 10.1002/ieam.4357. Epub 2020 Nov 24.
The population level is often the biological endpoint addressed in ecological risk assessments (ERAs). However, ERAs tend to ignore the metapopulation structure, which precludes an understanding of how population viability is affected by multiple stressors (e.g., toxicants and environmental conditions) at large spatial scales. Here we integrate metapopulation model simulations into a regional-scale, multiple stressors risk assessment (Bayesian network relative risk model [BN-RRM]) of organophosphate (OP) exposure, water temperature, and DO impacts on Chinook salmon (Oncorhynchus tshawytscha). A matrix metapopulation model was developed for spring Chinook salmon in the Yakima River Basin (YRB), Washington, USA, including 3 locally adapted subpopulations and hatchery fish that interact with those subpopulations. Three metapopulation models (an exponential model, a ceiling density-dependent model, and an exponential model without dispersal) were integrated into the BN-RRM to evaluate the effects of population model assumptions on risk calculations. Risk was defined as the percent probability that the abundance of a subpopulation would decline from their initial abundance (500 000). This definition of risk reflects the Puget Sound Partnership's management goal of achieving "no net loss" of Chinook abundance. The BN-RRM model results for projection year 20 showed that risk (in % probability) from OPs and environmental stressors was higher for the wild subpopulations-the American River (50.9%-97.7%) and Naches (39.8%-84.4%) spring Chinook-than for the hatchery population (CESRF 18.5%-46.5%) and the Upper Yakima subpopulation (21.5%-68.7%). Metapopulation risk was higher in summer (58.1%-68.7%) than in winter (33.6%-53.2%), and this seasonal risk pattern was conserved at the subpopulation level. To reach the management goal in the American River spring Chinook subpopulation, the water temperature conditions in the Lower Yakima River would need to decrease. We demonstrate that 1) relative risk can vary across a metapopulation's spatial range, 2) dispersal among patches impacts subpopulation abundance and risk, and 3) local adaptation within a salmon metapopulation can profoundly impact subpopulation responses to equivalent stressors. Integr Environ Assess Manag 2021;17:95-109. © 2020 SETAC.
人口水平通常是生态风险评估（ERA）中关注的生物终点。然而，ERA 往往忽略了复合种群结构，这使得人们无法理解在大空间尺度上，种群生存力是如何受到多种胁迫因素（如毒物和环境条件）的影响的。在这里，我们将复合种群模型模拟纳入到一种针对有机磷（OP）暴露、水温和 DO 对奇努克鲑鱼（Oncorhynchus tshawytscha）影响的区域多胁迫风险评估（贝叶斯网络相对风险模型[BN-RRM]）中。我们为美国华盛顿雅基马河流域的春季奇努克鲑鱼建立了一个矩阵复合种群模型，包括 3 个具有本地适应性的亚种群和与这些亚种群相互作用的人工养殖鱼类。我们将 3 种复合种群模型（指数模型、上限密度依赖模型和无扩散的指数模型）整合到 BN-RRM 中，以评估种群模型假设对风险计算的影响。风险定义为亚种群数量从初始数量（50 万）下降的百分比概率。这种风险定义反映了普吉特海湾合作伙伴关系实现奇努克鲑鱼数量“零净损失”的管理目标。BN-RRM 模型对 2020 年的预测结果表明，野生亚种群（美国河的奇努克鲑鱼为 50.9%-97.7%，纳奇斯河的奇努克鲑鱼为 39.8%-84.4%）比人工养殖种群（CESRF 为 18.5%-46.5%）和上雅基马亚种群（21.5%-68.7%）面临更高的 OP 和环境胁迫风险。夏季（58.1%-68.7%）的复合种群风险高于冬季（33.6%-53.2%），而且这种季节性风险模式在亚种群水平上是保守的。为了实现美国河春季奇努克鲑鱼亚种群的管理目标，雅基马河下游的水温条件需要降低。我们证明了 1）相对风险会在复合种群的空间范围内发生变化，2）斑块之间的扩散会影响亚种群的数量和风险，3）鲑鱼复合种群中的本地适应性会深刻影响亚种群对同等胁迫因素的反应。《综合环境评估与管理》2021 年；17：95-109。版权所有©2020 SETAC。
