Departamento de Sistemas Acuáticos, Facultad de Ciencias Ambientales - Centro EULA, Universidad de Concepción, Concepción, Chile.
Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile; Departamento de Ecología, Facultad de Ciencias y Centro de Investigación en Biodiversidad y Ambientes Sustentables (CIBAS), Universidad Católica de la Santísima Concepción, Concepción, Chile.
Sci Total Environ. 2021 Apr 20;766:144323. doi: 10.1016/j.scitotenv.2020.144323. Epub 2020 Dec 25.
Connectivity plays a crucial role in maintaining the structural and functional attributes of river networks. Therefore, the loss of connectivity (fragmentation) alters the functioning and diversity patterns of the biota at local and regional scales. The global hydropower boom is one of the main drivers of river network fragmentation, with significant effects on the diversity of riverine biota. Analyses of beta diversity of fish assemblages in rivers with different degrees of fragmentation can give new insights into mechanisms that contribute to the responses of these assemblages to fragmentation. Here, fish beta diversity within six river networks of central Chile with different levels of fragmentation was studied to assess the responses of fish assemblages to fragmentation. A hypothesis of a significant effect of fragmentation on the beta diversity of native and non-native fish in riffles and pools was tested. This effect is expected to be modulated by both changes in environmental heterogeneity and direct obstruction of natural dispersal routes. Beta diversity based on variation of assemblage structure and environmental heterogeneity showed significant differences among river networks. Fish beta diversity showed a clear response to fragmentation in recently fragmented rivers. Specifically, the beta diversity of native fishes in pools and non-native fishes in riffles decreased with increase of the ratio between the longest non-fragmented sections of the river network to the total length of the network. These effects of fragmentation on fish assemblages were modulated by the biological features of each species, and open-water species were most severely affected. These results have significant implications for planning of the placement of new barriers in river networks subjected to hydropower boom. Planning of the placement of new barriers should consider the maintenance of long, connected sections within river networks in order to minimise the effects of fragmentation on fish biodiversity.
连通性在维持河网的结构和功能属性方面起着至关重要的作用。因此，连通性的丧失（破碎化）改变了生物在局部和区域尺度上的功能和多样性模式。全球水电热潮是河网破碎化的主要驱动因素之一，对河流生物多样性产生了重大影响。对不同破碎化程度的河流中鱼类组合的β多样性进行分析，可以深入了解有助于这些组合对破碎化做出响应的机制。在这里，研究了智利中部六个具有不同破碎化程度的河网中的鱼类组合β多样性，以评估鱼类组合对破碎化的响应。检验了破碎化对急流和缓流中本地和非本地鱼类β多样性产生重大影响的假设。这种影响预计将受到环境异质性变化和自然扩散途径直接阻塞的调节。基于组合结构和环境异质性变化的β多样性在河网之间表现出显著差异。鱼类β多样性对最近破碎化的河流表现出明显的破碎化响应。具体来说，在急流中，非本地鱼类的β多样性和缓流中本地鱼类的β多样性随着河网中最长非破碎段与网络总长度之比的增加而降低。这些破碎化对鱼类组合的影响受到每个物种的生物学特征的调节，而开放性物种受到的影响最为严重。这些结果对于规划在受水电热潮影响的河网中设置新障碍物具有重要意义。在规划河网中新障碍物的位置时，应考虑保持河网内长而连通的河段，以最小化破碎化对鱼类生物多样性的影响。
