Department of Ecology, Evolution, and Behavior, College of Biological Sciences, University of Minnesota, St. Paul, MN, USA.
Department of Ecology, Evolution, and Behavior, College of Biological Sciences, University of Minnesota, St. Paul, MN, USA.
Sci Total Environ. 2019 Nov 25;693:133295. doi: 10.1016/j.scitotenv.2019.07.101. Epub 2019 Jul 26.
In this paper, we applied an individual-based model to study the population-level impacts of sub-lethal stressors affecting the metabolic pathways of three closely related trout species: Oncorhynchus mykiss (rainbow trout, RT), Salmo trutta (brown trout, BT) and Oncorhynchus calrki stomias (greenback cutthroat trout, GCT). Both RT and BT are well-studied species, and the former is widely used as a standard cold-water test species. These species are known to outcompete GCT, which is listed as threatened under the US Endangered Species Act. Our goal was to understand the extent to which stressor effects, which are often measured at the individual level, on taxonomically-related (i.e., surrogate) species can be informative of impacts on population dynamics in species that cannot be tested (e.g., listed species). When comparing stressor effects among species, we found that individual-level responses to each stressor were qualitatively comparable. Individual lengths and number of eggs decreased by similar percentages with respect to baseline, even if small quantitative differences were present depending on the physiological mode of action of the stressor. Individual-level effects in GCT were slightly greater when ingestion efficiency decreased, whereas effects in GCT and RT were greater when maintenance costs increased, and effects in BT were slightly greater when costs of growth increased. In contrast, results at the population level differed markedly among species with GCT the most impacted by sub-lethal stress effects on individual metabolism. Our findings suggest that using non-listed species to assess the risks of stressors to listed species populations may be misleading, even if the species are closely related and show similar individual-level responses. Mechanistic population models that incorporate species life history and ecology can improve inter-species extrapolation of stressor effects.
在本文中，我们应用个体基础模型来研究影响三种密切相关的鳟鱼物种（虹鳟鱼、褐鳟鱼和金鳟鱼）代谢途径的亚致死胁迫对种群水平的影响。虹鳟鱼和褐鳟鱼都是研究得很好的物种，前者被广泛用作冷水测试标准物种。这些物种被认为会与金鳟鱼竞争，后者被列为美国濒危物种法案下的受威胁物种。我们的目标是了解在多大程度上，通常在个体水平上测量的胁迫效应，对于不能进行测试的物种（例如，列入名单的物种）的种群动态影响具有信息性。在比较物种之间的胁迫效应时，我们发现，个体对每种胁迫的反应在定性上是可比的。个体长度和卵的数量相对于基线减少了相似的百分比，即使存在取决于胁迫生理作用模式的小的定量差异。当摄入效率降低时，金鳟鱼个体水平的影响略大，而当维持成本增加时，金鳟鱼和虹鳟鱼的影响更大，当生长成本增加时，褐鳟鱼的影响略大。相比之下，种群水平的结果在物种之间差异显著，金鳟鱼受到亚致死胁迫对个体代谢的影响最大。我们的研究结果表明，即使物种密切相关且表现出相似的个体水平反应，使用未列入名单的物种来评估胁迫对列入名单的物种种群的风险也可能具有误导性。纳入物种生活史和生态学的机制种群模型可以提高胁迫效应的物种间外推。
