Of all ecosystems, freshwaters support the most dynamic and highly concentrated biodiversity on Earth. These attributes of freshwater biodiversity along with increasing demand for water mean that these systems serve as significant models to understand drivers of global biodiversity change. Freshwater biodiversity changes are often attributed to hydrological alteration by water‐resource development and climate change owing to the role of the hydrological regime of rivers, wetlands and floodplains affecting patterns of biodiversity. However, a major gap remains in conceptualising how the hydrological regime determines patterns in biodiversity's multiple spatial components and facets (taxonomic, functional and phylogenetic). We synthesised primary evidence of freshwater biodiversity responses to natural hydrological regimes to determine how distinct ecohydrological mechanisms affect freshwater biodiversity at local, landscape and regional spatial scales. Hydrological connectivity influences local and landscape biodiversity, yet responses vary depending on spatial scale. Biodiversity at local scales is generally positively associated with increasing connectivity whereas landscape‐scale biodiversity is greater with increasing fragmentation among locations. The effects of hydrological disturbance on freshwater biodiversity are variable at separate spatial scales and depend on disturbance frequency and history and organism characteristics. The role of hydrology in determining habitat for freshwater biodiversity also depends on spatial scaling. At local scales, persistence, stability and size of habitat each contribute to patterns of freshwater biodiversity yet the responses are variable across the organism groups that constitute overall freshwater biodiversity. We present a conceptual model to unite the effects of different ecohydrological mechanisms on freshwater biodiversity across spatial scales, and develop four principles for applying a multi‐scaled understanding of freshwater biodiversity responses to hydrological regimes. The protection and restoration of freshwater biodiversity is both a fundamental justification and a central goal of environmental water allocation worldwide. Clearer integration of concepts of spatial scaling in the context of understanding impacts of hydrological regimes on biodiversity will increase uptake of evidence into environmental flow implementation, identify suitable biodiversity targets responsive to hydrological change or restoration, and identify and manage risks of environmental flows contributing to biodiversity decline.

中文翻译：

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扩大对水文制度的生物多样性响应

在所有生态系统中，淡水支持地球上最具活力和高度集中的生物多样性。淡水生物多样性的这些属性以及对水需求的增加意味着这些系统可以作为了解全球生物多样性变化驱动因素的重要模型。由于河流、湿地和洪泛区的水文状况对生物多样性模式的影响，淡水生物多样性的变化通常归因于水资源开发和气候变化引起的水文变化。然而，在概念化水文制度如何决定生物多样性的多个空间组成部分和方面（分类、功能和系统发育）的模式方面仍然存在重大差距。我们综合了淡水生物多样性对自然水文状况的反应的主要证据，以确定不同的生态水文机制如何影响当地、景观和区域空间尺度的淡水生物多样性。水文连通性影响当地和景观生物多样性，但响应因空间尺度而异。地方尺度的生物多样性通常与连通性的增加呈正相关，而景观尺度的生物多样性随着地点之间的碎片化程度的增加而增加。水文干扰对淡水生物多样性的影响在不同的空间尺度上是可变的，并取决于干扰频率以及历史和生物特征。水文在确定淡水生物多样性栖息地方面的作用也取决于空间尺度。在局部尺度上，栖息地的持久性、稳定性和大小均会影响淡水生物多样性的模式，但构成整体淡水生物多样性的生物群之间的反应各不相同。我们提出了一个概念模型，将不同生态水文机制对跨空间尺度的淡水生物多样性的影响结合起来，并制定了四项原则，以将淡水生物多样性对水文制度的反应的多尺度理解应用到。淡水生物多样性的保护和恢复既是全球环境水资源分配的基本理由，也是核心目标。在理解水文制度对生物多样性的影响的背景下更清晰地整合空间尺度的概念将增加对环境流量实施的证据的吸收，