State Key Laboratory of Eco-hydraulic in Northwest Arid Region of China, Xi'an University of Technology, Xi'an 710048, Shaanxi, China.
Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
Sci Total Environ. 2021 Apr 1;763:144177. doi: 10.1016/j.scitotenv.2020.144177. Epub 2020 Dec 17.
Hydrological disconnection is increasingly threatening biodiversity in river floodplain ecosystems worldwide, but studies reporting long-term change of aquatic biodiversity in relation to floodplain disconnection are seldom, especially from multifaceted biodiversity perspectives. Here, we examined how loss of river-lake connectivity affected multifaceted (taxonomic, functional and phylogenetic) alpha and beta diversity of fish assemblages in 11 Yangtze River floodplain lakes over the past 70 years. We found that all three facets of alpha diversity significantly decreased through time, but the decrease rate was highest (31.4%) in taxonomic richness, second in functional (26.4%) and lowest in phylogenetic facet (4.7%). Nevertheless, taxonomic, functional and phylogenetic structures of fish fauna all exhibited differentiation. The taxonomic and phylogenetic differentiations were due to the joint increases in their turnover and nestedness-resultant component, whereas the functional differentiation was mainly driven by the increase in its turnover component. Such distinct results were because of the imbalanced extirpations of fish species (especially from species-poor orders and families) in disconnected lakes and connected lakes. With few exceptions of strong correlations between changes in taxonomic dissimilarities and phylogenetic dissimilarities, we generally found weak correlations between changes in different facets of both alpha and beta diversity. This discrepancy highlights that measuring different biodiversity facets offer distinct information about biodiversity dynamics and can enhance our ability to detect and evaluate the impacts of floodplain disconnection on biodiversity. We therefore recommend an integrative approach embracing taxonomic, functional and phylogenetic diversity is essential to effective biodiversity assessment and conservation in large river floodplains.
水文连通性的丧失正日益威胁全球河流漫滩生态系统的生物多样性，但鲜有研究报告与漫滩断流相关的水生生物多样性的长期变化情况，尤其是从多方面生物多样性的角度来看。在这里，我们研究了过去 70 年间，长江漫滩 11 个湖泊中河流-湖泊连通性丧失如何影响鱼类群落的多方面（分类学、功能和系统发育）α和β多样性。我们发现，所有三个方面的α多样性都随时间显著下降，但下降速度最快的是分类丰富度（31.4%），其次是功能（26.4%），最低的是系统发育方面（4.7%）。尽管如此，鱼类动物群的分类学、功能和系统发育结构都表现出分化。分类学和系统发育的分化是由于它们的周转率和嵌套性成分的共同增加所致，而功能的分化主要是由其周转率成分的增加驱动的。这种截然不同的结果是由于在断流湖泊和连通湖泊中鱼类物种（尤其是来自物种较少的目和科的鱼类）的不平衡灭绝。除了分类差异和系统发育差异之间的变化存在强烈相关性的少数例外情况外，我们通常发现 α和β多样性不同方面之间的变化之间存在较弱的相关性。这种差异突出表明，衡量不同的生物多样性方面可以提供有关生物多样性动态的不同信息，并可以增强我们检测和评估漫滩断流对生物多样性影响的能力。因此，我们建议采用综合方法，包括分类学、功能和系统发育多样性，这对于大河流域漫滩的有效生物多样性评估和保护至关重要。
