The current erosion of biodiversity is a major concern that threatens the ecological integrity of ecosystems and the ecosystem services they provide. Due to global change, an increasing proportion of river networks are drying and changes from perennial to non-perennial flow regimes represent dramatic ecological shifts with potentially irreversible alterations of community and ecosystem dynamics. However, there is minimal understanding of how biological communities respond functionally to drying. Here, we highlight the taxonomic and functional responses of aquatic macroinvertebrate communities to flow intermittence across river networks from three continents, to test predictions from underlying trait-based conceptual theory. We found a significant breakpoint in the relationship between taxonomic and functional richness, indicating higher functional redundancy at sites with flow intermittence higher than 28%. Multiple strands of evidence, including patterns of alpha and beta diversity and functional group membership, indicated that functional redundancy did not compensate for biodiversity loss associated with increasing intermittence, contrary to received wisdom. A specific set of functional trait modalities, including small body size, short life span and high fecundity, were selected with increasing flow intermittence. These results demonstrate the functional responses of river communities to drying and suggest that on-going biodiversity reduction due to global change in drying river networks is threatening their functional integrity. These results indicate that such patterns might be common in these ecosystems, even where drying is considered a predictable disturbance. This highlights the need for the conservation of natural drying regimes of intermittent rivers to secure their ecological integrity.

中文翻译：

---

河流群落对水流间歇性的功能反应的全球视角

当前生物多样性的侵蚀是一个主要问题，威胁着生态系统的生态完整性及其提供的生态系统服务。由于全球变化，越来越多的河流网络正在干涸，从常年流态到非常年流态的变化代表着巨大的生态转变，可能导致群落和生态系统动态发生不可逆转的变化。然而，人们对生物群落如何对干燥做出功能性反应的了解甚少。在这里，我们强调了水生大型无脊椎动物群落对三大洲河流网络间歇性水流的分类和功能反应，以测试基于基础性状的概念理论的预测。我们发现分类学和功能丰富度之间的关系存在一个显着的断点，表明流量间歇性高于 28% 的位点具有更高的功能冗余。多种证据，包括α和β多样性模式以及功能组成员资格，表明功能冗余并不能弥补与间歇性增加相关的生物多样性丧失，这与公认的观点相反。随着流动间歇性的增加，选择了一组特定的功能性状，包括体型小、寿命短和繁殖力高。这些结果证明了河流群落对干旱的功能反应，并表明由于全球干旱河网变化而导致的生物多样性持续减少正在威胁其功能完整性。这些结果表明，即使在干燥被认为是可预测的干扰的地方，这种模式可能在这些生态系统中很常见。这凸显了保护间歇性河流自然干燥状态的必要性，以确保其生态完整性。