Preliminary Study On Key Eco-Hydrological Indicators And Thresholds In The Spawning Period Of Coreius Heterodon In National Reserve

As the Xiangjiaba and Xiluodu Hydropower Stations began their impoundment test operations respectively,the hydrological situation in the national protected areas of rare and endemic fishes in the upper reaches of the Yangtze River has changed to some extent,the spawning and breeding activities of fish,especially those that produce floating eggs,require certain flow conditions.Therefore,the study of the hydrological conditions required for spawning activities of spawning egg-laying eggs during the spawning period can provide scientific basis for fish conservation and rational scheduling of water conservancy projects in National Reserve.This paper selects Coreius heterodon,an important economic fish,as a representative fish for the production of floating eggs in National Reserve.Through analysis,the key eco-hydrological indicators and their appropriate thresholds in the spawning period of Coreius heterodon in National Reserve were determined,which provided technical reference for the determination of the ecological flows in National Reserve and the ecological control of reservoirs in the later period.This papper is based on the spawning data of Creius heterodon from the Jiangjin section of National Reserve and the flow data of the Zhuyu station during the period2009-2016,in combination with the biological characteristics of Creius heterodon laying eggs,which needs the stimulation of the rising water and the spawning during falling water,this papper selects the continuous rising water process and the high-flow pulse process defined by IHA software as the ecological hydrological indicators.The software SPSS22.0 was used to count the Pearson correlation between the spawning situation of Coreius heterodon and the continuous rising water process and the high-flow pulse process,according to the biger of the correlation coefficient,the key eco-hydrological indicators in the spawning period of Creius heterodon in National Reserve was determined,and the threshold values for the spawning of Creius heterodon in the key eco-hydrological indicator were statistically analyzed.The results of the study showed that the Pearson correlation coefficients between the Creius heterodon spawning events with the continuous water rising process and the high-flow pulse process were compared,and the Pearson correlation coefficients between the spawning scale of Creius heterodon and the rate of flow change of the continuous water rising process and high-flow pulse process were compared.The key eco-hydrological indicators that determine the occurrence of laying eggs and the scale of spawning for Creius heterodon is high flow pulse.Therefore,this paper believes that high-flow pulse is the key eco-hydrological indicator in the spawning period of Creius heterodon in National Reserve.The statistical indicators(initial flow,peak flow,occurrence time of peak flow,and average increase rate)of the high-flow pulse process during spawning were calculated,find out the high-flow pulse process with better spawning scale and observe the characteristics of the flow process.The appropriate threshold value for the high-flow pulse of Creius heterodon spawning was found to be 5 days,initial flow within4990-8040m~3/s,peak flow within 7840-10800m~3/s,and continuous 2-3d rising water after the start of high flow pulse,the average rate of increase is 15-20%,and the time is one each in May and June.