State Key Laboratory of Eco-hydraulic in Northwest Arid Region of China, Xi'an University of Technology, Xi'an, 710048, Shaanxi, China.
State Key Laboratory of Eco-hydraulic in Northwest Arid Region of China, Xi'an University of Technology, Xi'an, 710048, Shaanxi, China.
J Environ Manage. 2022 Oct 15;320:115885. doi: 10.1016/j.jenvman.2022.115885. Epub 2022 Aug 11.
Lateral hydrological connectivity (LHC) is a key process in maintaining aquatic biodiversity in river floodplain ecosystems. However, the effects of LHC loss on aquatic biodiversity are rarely studied. Here, we evaluated, for the first time, the responses of multiple facets (i.e., taxonomic, functional and phylogenetic) of alpha and beta diversity of freshwater molluscs to the LHC loss in 23 floodplain lakes in the Yangtze River Basin in China. Our results showed that taxonomic and functional alpha diversities were all significantly higher in connected lakes (CLs) than in disconnected lakes (DLs), whereas phylogenetic alpha diversity (Δ) was lower in CLs than in DLs. For beta diversity facets, taxonomic (Tβ) and phylogenetic (Pβ) dissimilarities were slightly more contributed by the turnover component or equally contributed by the turnover and nestedness-resultant components both in CLs and DLs. Instead, functional beta diversity (Fβ), generally showing much lower values than Tβ and Pβ, was mainly contributed by the nestedness-resultant component (76.6-84.0%), especially in DLs. We found that only functional dissimilarities were significantly higher in DLs than CLs, indicating a high level of functional diversity loss without replacement of species possessing traits sensitive to hydrological disconnection (i.e., large body size, lamellibranch body form, filter feeding, ovoviviparity and burrowing habits). In general, lake area, hydrological connectivity, aquatic vegetation coverage and nutrient levels (TN and TP) played important roles in structuring variation in molluscan alpha and beta diversities, although the three diversity facets responded to different environmental factors. Our results suggest that loss of connectivity to the mainstem river has negative impacts on molluscan assemblages in floodplain lakes. More importantly, as taxonomic, functional and phylogenetic diversities responded somewhat differently to the loss of hydrological connectivity, all of these biodiversity facets should be better incorporated into aquatic biodiversity assessment and conservation programs in large river floodplains.
侧向连通性（LHC）是维持河流泛滥平原生态系统水生生物多样性的关键过程。然而，LHC 丧失对水生生物多样性的影响很少被研究。在这里，我们首次评估了 23 个长江流域泛滥平原湖泊中 LHC 丧失对淡水软体动物多样性多个方面（即分类、功能和系统发育）的影响。我们的结果表明，与不连通湖泊（DLs）相比，连通湖泊（CLs）的分类和功能多样性都显著更高，而 CLs 的系统发育多样性（Δ）则较低。对于多样性方面，分类（Tβ）和系统发育（Pβ）差异在 CLs 和 DLs 中均主要由周转率成分贡献，或者由周转率和嵌套结果成分共同贡献。相反，功能多样性（Fβ）通常比 Tβ和 Pβ低得多，主要由嵌套结果成分贡献（76.6-84.0%），尤其是在 DLs 中。我们发现，只有功能差异在 DLs 中明显高于 CLs，这表明在没有替代对水文分离敏感的物种（即大尺寸、双壳类体型、滤食、卵胎生和穴居习性）的情况下，功能多样性丧失程度较高。总体而言，湖泊面积、连通性、水生植被覆盖率和营养水平（TN 和 TP）对软体动物分类和β多样性的变异结构起着重要作用，尽管这三个多样性方面对不同的环境因素有不同的反应。我们的结果表明，与主河道的连通性丧失对泛滥平原湖泊中的软体动物组合有负面影响。更重要的是，由于分类、功能和系统发育多样性对水文连通性丧失的反应有些不同，所有这些生物多样性方面都应该更好地纳入大河泛滥平原的水生生物多样性评估和保护计划中。
