Arkansas Cooperative and Wildlife Research Unit, Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA.
U.S. Geological Survey, Arkansas Cooperative Fish and Wildlife Research Unit, Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA.
Sci Total Environ. 2024 Oct 1;945:173825. doi: 10.1016/j.scitotenv.2024.173825. Epub 2024 Jun 8.
Understanding the role of hydrologic variation in structuring aquatic communities is crucial for successful conservation and sustainable management of native freshwater biodiversity. Partitioning beta diversity into the additive components of spatial turnover and nestedness can provide insight into the forces driving variability in fish assemblages across stream flow regimes. We examined stream fish beta diversity across hydrologic and anthropogenic disturbance gradients using long-term (1916-2016) site occurrence records (n = 17,375) encompassing 252 species. We assessed total beta diversity (Sørensen dissimilarity), spatial turnover, and nestedness of fish assemblages in contrasting stream flow regimes across a gradient of decreasing flow stability: groundwater stable (n = 77), groundwater (n = 67), groundwater flashy (n = 175), perennial runoff (n = 141), runoff flashy (n = 255), and intermittent (n = 63) streams. Differences in total beta diversity among the stream flow regimes were driven predominantly (>86 %) by spatial turnover (i.e. species replacement) as opposed to nestedness (i.e. species loss or gain). Total fish beta diversity and spatial turnover were highest in streams with intermediate flow stability (groundwater flashy), while more flow-stable streams (groundwater stable and groundwater) had lower turnover and higher nestedness. Species turnover was also strongly associated with seasonal variation in hydrology across all flow regimes, but these relationships were most evident for assemblages in intermittent streams. Distance-based statistical comparisons showed significant correlations between beta diversity and anthropogenic disturbance variables, including dam density, dam storage volume and water withdrawals in catchments of groundwater stable streams, while hydrologic variables were more strongly correlated with beta diversity in streams with runoff-dominated and flashy flow regimes. The high spatial turnover of species implies that fish conservation actions would benefit from watershed-focused approaches targeting multiple streams with wide spatial distribution, as opposed to simply focusing on preserving sites with the greatest number of species.
了解水文变化在构建水生群落结构中的作用，对于成功保护和可持续管理本土淡水生物多样性至关重要。将β多样性分解为空间周转率和嵌套性的附加组成部分，可以深入了解鱼类群落在不同溪流流量状态下变化的驱动力。我们使用长期（1916-2016 年）站点出现记录（n=17375），包括 252 个物种，研究了水文和人为干扰梯度下溪流鱼类的β多样性。我们评估了不同溪流流量状态下鱼类群落的总β多样性（Sørensen 不相似性）、空间周转率和嵌套性，这些溪流的流量稳定性呈梯度下降，分别为：地下水稳定（n=77）、地下水（n=67）、地下水湍急（n=175）、常年径流（n=141）、径流湍急（n=255）和间歇性（n=63）溪流。不同溪流流量状态之间的总β多样性差异主要是由空间周转率（即物种更替）驱动的，而不是嵌套性（即物种损失或增益）。在具有中等流量稳定性（地下水湍急）的溪流中，鱼类总β多样性和空间周转率最高，而更稳定的溪流（地下水稳定和地下水）的周转率较低，嵌套性较高。物种更替也与所有流量状态下的季节性水文变化密切相关，但在间歇性溪流的群落中，这些关系最为明显。基于距离的统计比较显示，β多样性与人为干扰变量（包括大坝密度、大坝储水体积和流域取水量）之间存在显著相关性，而在以径流水为主和湍急水流的溪流中，水文变量与β多样性的相关性更强。物种的高空间周转率意味着鱼类保护措施将受益于以流域为重点的方法，针对具有广泛空间分布的多个溪流，而不是仅仅关注保留物种数量最多的地点。
