An article published by Chinese scientists shows changes in fish species assemblages along Yellow river during last 50 years due to dams diversions and invasive species
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From the beginning of the 1960s in China, 32 large and medium-size dams in the main stem and hundreds of smaller ones in the tributaries have been constructed or impounded in the 5,464-km-long Yellow River.
Authors assessed changes in fish assemblages by comparing the species presence in historical and contemporary fish data in the Yellow River from 1965 to 2015. The temporal change in species assemblages was found with increased non-endemic species and fewer natives. Fish species richness of the river declined 35.4% over the past fifty years. In the upper Yellow River, higher species richness due to more invasive species were found than those in the historical record, while the lower reaches experienced significant species loss and less invasions.
The number of fish species decreased from 164 to 106 species over the past 50 years, and the number of native species decreased from 163 to 80 species. The proportions of alien fishes in three periods of the 1960s, the 1980s, and the 2000s were 0.6%, 13.1% and 24.5% of the total species, respectively. Dam constructions, exotic fish invasions, and flow reductions played the vital role in structuring the temporal fish assemblages in the Yellow River. Upper reaches where the majority of dams were built experienced higher infestation by non-native fish , which now account for 40-50% of species richness in Upper Yellow River and complete majority by weight in fish catches.
|
Period |
Number of orders |
Number of families |
Number of genera |
Number of fish species |
Number of native fishes |
Number of exotic fishes |
% native fishes lost |
|
The 1960s |
15 |
28 |
92 |
164 |
163 |
1 |
na |
|
The 1980s |
13 |
26 |
83 |
129 |
112 |
17 |
25 |
|
The 2000s |
7 |
18 |
63 |
106 |
80 |
26 |
51 |
TABLE : Statistics in the taxonomic level of fishes
In conclusion, as anthropogenic environmental alterations and human-assisted dispersal of exotic species have sparked widespread changes in the distribution of biota at global scales, species assemblages of the Yellow River basin also face decreased fish species richness, increased exotic species, and increased fish species similarity (between different localities\reaches).
Read full article: Xie JY, Tang WJ, Yang YH.
Fish assemblage changes over half a century in the Yellow River,
China. Ecol Evol. 2018;00:1–10. https://doi.org/10.1002/ece3.3890
The paper adds solid contribution to the growing scientific evidence of detrimental effects of dams and other water infrastructure on aquatic biodiversity and shows urgency for protection of free flowing Amur-Heilong River – the last remaining stronghold of freshwater biodiversity in temperate regions of East Asia.
Source: Wiley Publishers