U.S. Geological Survey, Arkansas Cooperative Fish and Wildlife Research Unit, Department of Biological Sciences, University of Arkansas, Fayetteville, AR, 72701, USA.
Arkansas Cooperative Fish and Wildlife Research Unit, Department of Biological Sciences, University of Arkansas, Fayetteville, AR, 72701, USA.
Sci Rep. 2021 May 21;11(1):10704. doi: 10.1038/s41598-021-89632-3.
Hydrologic variation can play a major role in structuring stream fish assemblages and relationships between hydrology and biology are likely to be influenced by flow regime. We hypothesized that more variable flow regimes would have lower and more variable species richness, higher species turnover and lower assemblage stability, and greater abiotic environment-fish relationships than more stable flow regimes. We sampled habitats (pool, run, and riffle) in three Runoff/Intermittent Flashy streams (highly variable flow regime) and three Groundwater Flashy streams (less variable flow regime) seasonally (spring, early summer, summer and autumn) in 2002 (drought year) and 2003 (wet year). We used backpack electrofishing and three-pass removal techniques to estimate fish species richness, abundance and density. Fish species richness and abundance remained relatively stable within streams and across seasons, but densities changed substantially as a result of decreased habitat volume. Mixed model analysis showed weak response variable-habitat relationships with strong season effects in 2002, and stronger habitat relationships and no season effect in 2003, and flow regime was not important in structuring these relationships. Seasonal fish species turnover was significantly greater in 2002 than 2003, but did not differ between flow regimes. Fish assemblage stability was significantly lower in Runoff/Intermittent Flashy than Groundwater Flashy streams in 2002, but did not differ between flow regimes in 2003. Redundancy analysis showed fish species densities were well separated by flow regime in both years. Periodic and opportunistic species were characteristic of Runoff/Intermittent Flashy streams, whereas mainly equilibrium species were characteristic of Groundwater Flashy streams. We found that spatial and temporal variation in hydrology had a strong influence on fish assemblage dynamics in Ozark streams with lower assemblage stability and greater fluctuations in density in more hydrologically variable streams and years. Understanding relationships between fish assemblage structure and hydrologic variation is vital for conservation of fish biodiversity. Future work should consider addressing how alteration of hydrologic variation will affect biotic assemblages.
水文学变化在构建溪流鱼类群落结构方面起着重要作用，而水文学与生物学之间的关系可能受水流状态的影响。我们假设，更具变异性的水流状态将具有更低和更具变异性的物种丰富度、更高的物种周转率和更低的群落稳定性以及更大的非生物环境与鱼类关系，而更稳定的水流状态则不然。我们在 2002 年（干旱年）和 2003 年（湿润年），在三个径流式/间歇性湍急溪流（高变流水文状态）和三个地下水流湍急溪流（低变流水文状态）中，按季节（春季、初夏、夏季和秋季）采集生境（池、流和急流）样本。我们使用背包式电捕鱼和三次去除技术来估计鱼类物种丰富度、丰度和密度。鱼类物种丰富度和丰度在溪流内和整个季节内相对稳定，但由于栖息地体积减少，密度发生了重大变化。混合模型分析表明，2002 年变量-生境关系较弱，季节效应较强，2003 年生境关系较强，季节效应较弱，而水流状态对这些关系的结构不重要。2002 年的季节性鱼类物种周转率明显高于 2003 年，但在不同的水流状态下没有差异。2002 年，径流式/间歇性湍急溪流的鱼类群落稳定性明显低于地下水流湍急溪流，但 2003 年不同水流状态之间没有差异。冗余分析表明，在这两年中，鱼类物种密度都很好地被水流状态分开。周期性和机会性物种是径流式/间歇性湍急溪流的特征，而主要是平衡物种是地下水流湍急溪流的特征。我们发现，在奥扎克溪流中，水文学的时空变化对鱼类群落动态有强烈影响，在更具水文变异性的溪流和年份中，群落稳定性较低，密度波动较大。了解鱼类群落结构与水文学变化之间的关系对于保护鱼类生物多样性至关重要。未来的工作应该考虑解决水文学变化的改变将如何影响生物群落。
