Macroinvertebrate Biodiversity Trends and Habitat Relationships within Headwater Rivers of the Qinghai-Tibet Plateau

Mengzhen Xu,Baozhu Pan,Zhaoyin Wang,Na Zhao,Wei Liu,Shimin Tian,Xiongdong Zhou

doi:10.3390/w10091214

Abstract

Highland running-water biodiversity has gained growing interest around the world, because of the more pristine conditions and higher sensitivity to environmental changes of highland rivers compared to the lowland rivers. This study presents the findings of systematic investigations and analyses on running-water biodiversity of macroinvertebrate assemblages in the most important headwater streams in the Yalutsangpo and Sanjiangyuan River basins in the Qinghai-Tibet Plateau and the lowland headwaters of the Songhua River, Juma River, and East River during the non-flood seasons of 2012 to 2016. The results indicated that the headwaters on the plateau had a higher regional biodiversity compared to the lowland rivers with the similar flow and substrate conditions. Even though the local diversity of the highland rivers was not significantly different at each single site, the taxonomic composition was significantly different with several rarely seen species scattering among the different sites, resulting in a high regional biodiversity. The biodiversity and composition of macroinvertebrates were strongly affected by the altitude gradient and the environmental variables associated with altitude. To be specific, for the Yalutsangpo River, canonical correspondence analyses of the macroinvertebrate assemblages and their environmental variables indicated that altitude, stream condition (represented by river pattern, riverbed structures, substrate composition), and water temperature influence macroinvertebrate taxa composition. Because of the restrictive plateau conditions including low water temperature, poor aquatic and riparian vegetation, and low runoff, the macroinvertebrate assemblages showed low biodiversity and were vulnerable to potential human disturbance/climate change. Therefore, it is essential to conserve suitable conditions of the determinative environmental variables to protect the unique and high regional biodiversity of the headwaters on the Qinghai-Tibet Plateau.

Highlights

Studying and protecting highland running-water biodiversity has gained growing interest over the world, because of more pristine conditions and higher sensitivity to environmental changes in highland rivers than in lowland rivers [1]
This study indicated that the local biodiversity may not be significantly affected by altitude, while the high regional biodiversity of highland rivers was obviously associated with the high altitudes, and especially the high altitude gradients, which created the high habitat heterogeneity
Following the Yalutsangpo, as the altitude descended from 4000–5000 m to 3000–4000 m and to 2000 m, the riparian vegetation changed from cold desert to arid steppe and to deciduous scrub, which resulted in changes in taxa composition and the formation of a high regionally diverse macroinvertebrate community

Summary

Introduction

Studying and protecting highland (i.e., high altitude) running-water biodiversity has gained growing interest over the world, because of more pristine conditions and higher sensitivity to environmental changes in highland rivers than in lowland rivers [1]. Its environmental and ecological conditions have been the focus of attention for decades owing to its unique geographical location and ecological functions including water resource conservation and biodiversity protection [3]. Climate change and anthropogenic activities have significantly influenced the physical and ecological conditions of the headwaters on the plateau [6]. Understanding the aquatic biodiversity, especially the relationships of biodiversity with major geographical and other environmental variables of the plateau is important for protecting the highland ecology and the headwater ecosystem functions of large

Results

Discussion

Conclusion