Understanding the ecological dimensions of drought is critical for predicting how humans and nature will be affected by the expected increased prevalence of drought in the future. We tested life-history-based predictions for fish assemblage responses to drought using retrospective analysis of long-term (1986–2003) fish surveys from two streams in the Appalachian Mountains of North America. We hypothesised that (1) fish assemblage composition would correlate with wet and dry hydrologic conditions as assemblages fluctuated within a loose equilibrium and (2) life-history traits of fishes would correlate with dry versus wet periods such that opportunistic life-history strategists would dominate during drought. Results showed fish assemblage changes in Little River and Cataloochee Creek correlated with drought severity measured one year prior to fish surveys. Fish assemblages at all three sampling sites in Little River and two sites in Cataloochee Creek fluctuated within a loose equilibrium, while the remaining two sites in Cataloochee Creek indicated directional change. Life-history traits for fishes in Cataloochee Creek correlated with one-year time lag fluctuations in drought caused by opportunistic species being dominant during drought and periodic/equilibrium species dominant during wet periods. Time series plots of fish abundances aggregated by life-history strategy revealed dominance of opportunistic species emerged at the onset of a multi-year drought spanning 1998–2004, particularly for the two sites undergoing directional change. Our work provides empirical evidence for theoretical linkages between life history and environmental fluctuations and can ultimately be used to predict stream fish community response to future drought regimes.

中文翻译：

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昔日高而干燥：生命史理论预测历史干旱期间阿巴拉契亚山脉溪流鱼类群落的转变

了解干旱的生态维度对于预测人类和自然将如何受到预期未来干旱发生率增加的影响至关重要。我们使用对北美阿巴拉契亚山脉两条溪流的长期（1986-2003 年）鱼类调查的回顾性分析，测试了基于生活史的鱼类组合对干旱反应的预测。我们假设（1）鱼类组合组成将与潮湿和干燥的水文条件相关，因为组合在松散的平衡中波动，（2）鱼类的生活史特征将与干燥期和潮湿期相关，因此机会主义生活史战略家将占主导地位在干旱期间。结果显示，Little River 和 Cataloochee Creek 的鱼类群落变化与鱼类调查前一年测量的干旱严重程度相关。Little River 的所有三个采样点和 Cataloochee Creek 的两个采样点的鱼群在松散的平衡内波动，而 Cataloochee Creek 的其余两个采样点则显示出方向变化。Cataloochee Creek 鱼类的生活史特征与干旱期间的一年时间滞后波动相关，这是由机会性物种在干旱期间占主导地位和周期性/平衡物种在潮湿期间占主导地位引起的。通过生活史策略汇总的鱼类丰度时间序列图显示，在 1998 年至 2004 年的多年干旱开始时出现了机会性物种的优势，特别是对于正在发生方向变化的两个地点。