• 研究报告:动物多样性 •

### 人为干扰对溪流鱼类功能多样性及其纵向梯度格局的影响

1. 安徽师范大学生态与环境学院, 省部共建皖江流域退化生态系统修复与重建协同创新中心, 安徽芜湖 241000
• 收稿日期:2020-11-20 接受日期:2021-02-09 出版日期:2021-07-20 发布日期:2021-03-09
• 通讯作者: * 严云志 E-mail: yanyunzhi@ahnu.edu.cn
• 作者简介:# 共同第一作者
• 基金资助:
国家自然科学基金(31500452);国家自然科学基金(31372227);安徽省水产产业技术体系项目(皖农科)(〔2016〕84号);重要生物资源保护与利用研究安徽省省级重点实验室经费

### Anthropogenic disturbances affect the functional diversity of stream fishes and its longitudinal patterns in China

Jiayun He#, Dong Zhang#, Ling Chu, Yunzhi Yan*()

1. School of Ecology and Environment, Anhui Normal University, and Collaborative Innocation Center of Reconstruction of Degraded Ecosystem in Wanjiang Basin Co-founded by Anhui Province and Ministry of Education, Wuhu, Anhui 241000
• Received:2020-11-20 Accepted:2021-02-09 Online:2021-07-20 Published:2021-03-09
• Contact: * Yunzhi Yan E-mail: yanyunzhi@ahnu.edu.cn
• About author:# Co-first authors

Abstract

Aims: The distribution and abundance of stream fishes are influenced by historical events as well as abiotic and biotic factors. Due to the high spatial heterogeneity and temporal differentiation of stream environmental characteristics, the composition and abundance of stream fish communities vary on spatial and temporal scales. On this basis, longitudinal patterns in the diversity and distribution of stream fish along upstream-downstream gradients have garnered the widespread attention of ecologists. Previous studies relevant to the longitudinal patterns in stream fish diversity along the upstream-downstream gradient mostly focused on taxonomic α diversity, while taxonomic β diversity and functional diversity have been given less attention. Therefore, this study aimed to (1) determine the effects of anthropogenic disturbances on species composition of fishes by comparing diversity across three streams, and determine the key species contributing to the between-stream variation in fish assemblages; (2) examine the influences of anthropogenic disturbances on functional diversity, and examine if differences in functional diversity relate to α and β diversity; (3) to assess whether the between-stream variations in functional diversity show dependence on the spatial positions along the river continuum or not, and further assess the effects of anthropogenic disturbances on the longitudinal patterns in the functional α and β diversities of stream fishes.
Methods: In this study, we focused on the functional diversity of fishes, which is an effective measure for assessing the response of communities to environmental changes and predicting changes in ecosystem functioning. Using data collected in three headwater streams of the Qingyi River, China, that experience different extents of anthropogenic disturbances, we examined the effects of anthropogenic disturbances on the longitudinal patterns in the functional α and β diversities of streams fishes. We considered multiple metrics of the α diversity, including the functional richness, evenness and divergence, which measure different aspects of functional space and abundance distribution. This work also analyzed β diversity, including its turnover and nestedness components, which can provide additional insights into the processes of community changing.
Results: We found that in the less disturbed stream, functional richness increased but divergence decreased downstream, and functional β diversity decreased downstream. On the other hand, in heavily disturbed streams functional richness was higher in the upstream-midstream but lower in the downstream, and functional divergence decreased in the upstream-midstream and β diversity increased in the downstream. Anthropogenic disturbances significantly altered species compositions and functional diversity of fishes in the heavily disturbed streams, and the mode and degree to which functional diversity varied related to both the metrics of functional diversity and the spatial position along river continuum. As a result, anthropogenic disturbances caused a shift in the longitudinal patterns of functional diversity, from linear variation in less disturbed streams to unimodal distribution in heavily disturbed streams. Similarly, variations in the functional β diversity of fishes mainly occurred in the lower segments, but not in the upper segments, and were derived by the turnover component. We found anthropogenic disturbances caused the endemic species to be replaced by the native-invasive species. Heavy land use and polluting emission could increase the environmental discontinuity, leading to community turnover and nestedness changing. Although functional β diversity was dominated by the nestedness component, the proportion of the turnover component increased significantly compared with less disturbed streams.
Conclusion: Our results highlight the need for a multifaceted approach, including spatial scale and diversity metrics, in assessing the diversity changes of stream fishes under anthropogenic pressure.