Author(s): Wei Xu, Xiaojuan Chen, Jiangping Tao, Xiaoming Zhang, Jianbo Chang
Linked Author(s): Wei Xu
Keywords: Eggs, larvae, abundance, Three Gorges Reservoir, ecological operation
Abstract: The structure of ichthyoplankton community is studied in the Shashi reach during the experimental ecological operation of the Three Gorges Reservoir in the middle mainstream of the Yangtze River, China, from 2012 to 2014. A total of 44 fish species are identified as belonging to 5 orders, 9 families and 36 genera. The dominant species by individual number proportion are Squalidus argentatus, Xenocypris microlepis, Hemiculter bleekeri, Parabramis pekinensis, Pseudolaubuca sinensis and Culter alburnus. The peak of fish spawning season is in May and June, with eggs decreasing and larvae increasing, both markedly in early July. The mean daily drift density of eggs is 95. 93 ind. /1, 000m3 in 2012, 620. 31 ind. /1, 000m3 in 2013, and 250. 98 ind. /1, 000m3 in 2014, with significant differences existing among the years (?2=49. 52, p?0. 05); and of larvae is 880. 44 ind. /1, 000m3 in 2012, 178. 37 ind. /1, 000m3 in 2013, and 561. 75 ind. /1, 000m3 in 2014, with no significant difference existing among the years (?2=0. 26, p?0. 05). Egg and larva relative abundance show opposite fluctuation trends with the drift density of eggs highest and of larvae lowest both in 2013. The absolute abundance of ichthyoplankton increases year by year, from about 69 billion to 78 billion. Community biodiversity analysis shows both eggs and larvae go through a slight decline during the three years, but it remains smooth for the ichthyoplankton. Preliminary analysis which indicates different patterns in hydrological regime along with water temperature might be mainly attributed to the dynamics of ichthyoplankton community. The man-made flood process created by the ecological operation of TGR has a positive effect on ichthyoplankton recruitment by enlarging the reservoir discharge, but its future development is still a matter of concern. Fundamental research should be strengthened by seeking quantitative relations between ichthyoplankton and key environmental factors to promote the TGR's adaptive management with regard to fish recruitment restoration
Year: 2017