Hydrothermal Regime Variation and Ecological Effects on Fish Reproduction in the Yangtze River.

Wenxian Guo,Gaofei Dou,Jianwen Hu,Ning He,Hongxiang Wang

doi:10.3390/ijerph182212039

Abstract

Water temperature, as one of the important water environment impact factors, has a significant impact on the survival and development of aquatic organisms. We selected water temperature data (1959–2017) from four key hydrological stations in the Yangtze River: Cuntan, Yichang, Hankou, and Datong. We analyzed the characteristics and variability of the Yangtze River hydrothermal regime by the Mann-Kendall method, wavelet analysis, and by the IHA-RVA method to analyze hydrothermal regime variations of the Yangtze River, and the response mechanisms of fish to variations in hydrothermal regimes were explored. The results show that (1) The annual average water temperature of the Yangtze River is warming, and Cuntan Station, Yichang Station, Hankou Station, and Datong Station have a sudden increase in temperature in 2002, 1995, 2003, and 2004, and the periodicity analysis demonstrates that Cuntan, Yichang, and Datong stations all have main periods of 24~32 years; (2) The overall variations of 32 hydrothermal indicators at Cuntan Station and Yichang Station reached 65% and 61%, which are close to the height variation; (3) With the construction of the Three Gorges Dam, the stagnant cooling effect caused the arrival date of the upper reproduction water temperature of “The four major fish species” to be delayed by about 23 days, and the stagnant heat effect caused the arrival date of the Chinese sturgeon reproduction upper limit water temperature to be delayed by about 30 days.

Highlights

Hydrothermal regime affects the energy exchange, metabolism, and habitat of biological communities in river ecosystems, which restricts the healthy development of river ecosystems [1,2]
The Yangtze River basin is one of the regions most affected by the anomalous temperature field of upper and high altitude in China, and it is the birthplace of economic fish, such as “The four major fish species“, and the gene pool of fish in China [4], at the same time, the construction of the Three Gorges Dam (TGD)
The results show that the water temperatures of the main hydrological stations of the Yangtze River presents a significant warming trend, and through comparative analysis, it was found the water temperature at Cuntan showed abrupt points in 2002, Yichang in 1995, and Hankou and Datong in 2003 and 2004, among them, Yichang station has the earliest abrupt points in water temperature, and the other three stations have abrupt points around 2003, which may be affected by multiple factors such as the climate and the operation of the Gezhouba Dam and the TGD

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Water temperature is one of the important influencing factors of water enthusiasm. If it is too high or too low, it will threaten the safety of aquatic organisms and seriously affect the normal survival and reproduction of aquatic organisms [3]. The Yangtze River basin is one of the regions most affected by the anomalous temperature field of upper and high altitude in China, and it is the birthplace of economic fish, such as “The four major fish species“, and the gene pool of fish in China [4], at the same time, the construction of the Three Gorges Dam (TGD)

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Discussion

Conclusion