United States Geological Survey (USGS) Patuxent Wildlife Research Center, Laurel, Maryland, United States of America.
PLoS One. 2012;7(3):e34170. doi: 10.1371/journal.pone.0034170. Epub 2012 Mar 28.
Large-scale inter-basin water transfer (IBWT) projects are commonly proposed as solutions to water distribution and supply problems. These problems are likely to intensify under future population growth and climate change scenarios. Scarce data on the distribution of freshwater fishes frequently limits the ability to assess the potential implications of an IBWT project on freshwater fish communities. Because connectivity in habitat networks is expected to be critical to species' biogeography, consideration of changes in the relative isolation of riverine networks may provide a strategy for controlling impacts of IBWTs on freshwater fish communities.
METHODS/PRINCIPAL FINDINGS: Using empirical data on the current patterns of freshwater fish biodiversity for rivers of peninsular India, we show here how the spatial changes alone under an archetypal IBWT project will (1) reduce freshwater fish biodiversity system-wide, (2) alter patterns of local species richness, (3) expand distributions of widespread species throughout peninsular rivers, and (4) decrease community richness by increasing inter-basin similarity (a mechanism for the observed decrease in biodiversity). Given the complexity of the IBWT, many paths to partial or full completion of the project are possible. We evaluate two strategies for step-wise implementation of the 11 canals, based on economic or ecological considerations. We find that for each step in the project, the impacts on freshwater fish communities are sensitive to which canal is added to the network.
CONCLUSIONS/SIGNIFICANCE: Importantly, ecological impacts can be reduced by associating the sequence in which canals are added to characteristics of the links, except for the case when all 11 canals are implemented simultaneously (at which point the sequence of canal addition is inconsequential). By identifying the fundamental relationship between the geometry of riverine networks and freshwater fish biodiversity, our results will aid in assessing impacts of IBWT projects and balancing ecosystem and societal demands for freshwater, even in cases where biodiversity data are limited.
大规模跨流域调水（IBWT）项目通常被提议作为解决水资源分配和供应问题的方案。在未来人口增长和气候变化情景下，这些问题可能会加剧。由于淡水鱼类分布的数据稀缺，通常限制了评估 IBWT 项目对淡水鱼类群落潜在影响的能力。由于生境网络的连通性预计对物种的生物地理学至关重要，因此考虑河流网络相对隔离的变化可能为控制 IBWT 对淡水鱼类群落的影响提供一种策略。
方法/主要发现：利用印度半岛河流淡水鱼类生物多样性的当前模式的经验数据，我们展示了在一个典型的 IBWT 项目下，仅空间变化将如何（1）降低整个系统的淡水鱼类生物多样性，（2）改变当地物种丰富度模式，（3）扩大广泛分布物种在半岛河流中的分布范围，以及（4）通过增加流域间相似性（导致观察到的生物多样性减少的一种机制）来降低群落丰富度。鉴于 IBWT 的复杂性，许多部分或全部完成项目的途径都是可能的。我们根据经济或生态考虑，评估了分步实施 11 条运河的两种策略。我们发现，对于项目的每一步，对淡水鱼类群落的影响都取决于添加到网络中的运河。
结论/意义：重要的是，通过将运河的添加顺序与链路的特征相关联，可以减少生态影响，除了 11 条运河同时实施的情况（在这种情况下，运河添加的顺序无关紧要）。通过确定河流网络的几何形状与淡水鱼类生物多样性之间的基本关系，我们的结果将有助于评估 IBWT 项目的影响，并平衡生态系统和社会对淡水的需求，即使在生物多样性数据有限的情况下也是如此。
