Data from: Increased habitat connectivity homogenizes freshwater communities: historical and landscape perspectives

1. Increases in habitat connectivity can have consequences for taxonomic, functional, and genetic diversity of communities. Previously isolated aquatic habitats were connected with canals and pipelines in the largest water development project in US history, the Columbia Basin Project (eastern Washington, USA), which also altered environmental conditions; however, the ecological consequences are largely unknown. 2. Using a historical dataset, we examined long-term patterns in zooplankton communities, water chemistry and clarity, testing the hypothesis that increased connectivity will result in taxonomic homogenization. Further, we tested contemporary drivers of communities using a comprehensive set of environmental and landscape variables. 3. Waterbodies were sampled for zooplankton community composition as well as physical and chemical variables inside and outside the Columbia Basin Project using methods consistent with historical studies. 4. We found significant declines in salinity inside the Columbia Basin Project, whereas changes in water clarity were prevalent across all waterbodies. Increased connectivity via canals homogenized zooplankton communities over time, as well as increasing regional richness. Other long-term changes in zooplankton communities may be related to climate change, invasive species, and land-use changes. 5. Synthesis and applications. Though canals may offer species spatial refugia, homogenization may decrease resilience to environmental stressors. These new hybrid aquatic landscapes, or hydroscapes, should be considered carefully in future water development, including specific plans for monitoring of species and environmental conditions, as well as mitigation of undesirable conditions and/or non-native species.

1. 栖息地连通性的提升会对群落的分类学、功能学与遗传多样性产生相应影响。美国历史上规模最大的水利开发工程——哥伦比亚盆地工程（美国华盛顿州东部）通过运河与管道将此前相互隔离的水生栖息地连通，同时也改变了当地的环境条件；但其带来的生态后果在很大程度上仍未明确。
2. 本研究依托历史数据集，分析了浮游动物群落、水化学特征与水体透明度的长期变化模式，验证了“连通性提升将导致分类学同质化”这一假说。此外，本研究通过涵盖环境与景观的多维度变量，探究了当前驱动群落结构变化的因素。
3. 研究采用与历史研究一致的方法，对哥伦比亚盆地工程内外的水体开展采样，分析浮游动物群落组成以及水体的物理、化学变量。
4. 研究结果显示，哥伦比亚盆地工程内部的盐度显著下降，而所有采样水体的透明度均出现了普遍变化。随着时间推移，通过运河实现的连通性提升使得浮游动物群落出现分类学同质化，同时也提升了区域物种丰富度。浮游动物群落的其他长期变化可能与气候变化、外来入侵物种以及土地利用变化相关。
5. 综合分析与应用启示。尽管运河可为物种提供空间避难所，但群落同质化可能会降低其应对环境胁迫的恢复力。未来的水利开发活动中，应审慎考量这类新型混合水生景观——或称水景观（hydroscapes），相关规划需包含针对物种与环境条件的专项监测方案，以及针对不良环境状况和/或非本地物种的防控措施。