三峡工程运行后水位变化对安徽和县陈桥洲滩地钉螺孳生分布的影响

目的 探讨三峡工程运行后水位变化对长江安徽段下游滩地钉螺孳生分布的影响。方法 收集1990-2016年间和县陈桥洲长江日均水位数据、滩地螺情与药物灭螺资料，并结合滩地现场调查了解滩地开发利用情况，分析大坝启用前后水位变化特点，探讨其与滩地开发利用和钉螺孳生分布的关系。结果 三峡大坝启用后，陈桥洲长江水位总体有所下降，滩地年淹水天数中位数由大坝启用前的59 d减少至21 d（Z=2.440，P=0.015）；圩外滩地开垦面积由大坝启用前的0.95 km2上升为4.55 km2，目前已达到圩外滩地面积的85.0%；药物灭螺覆盖率降低，年覆盖率中位数由大坝启用前的33.0%降为0.0%（Z=4.116，P<0.001）；钉螺面积下降缓慢，年面积中位数由大坝启用前的317.6 hm2下降为264.6 hm2（Z=1.744，P=0.081）；钉螺密度下降迅速，年中位数由大坝启用前的0.84只/0.11 m2下降为0.27只/0.11 m2（Z=3.779，P<0.001）。结论 三峡大坝启用后长江安徽段下游水位下降有利于滩地开发利用，不利于钉螺的孳生和扩散，这对血吸虫病控制起到了积极作用。

Water level changes caused from the Three Gorges Dam impact on the breeding and distribution of Oncomelania snails in the marshland of Chenqiaozhou,Hexian County,Anhui Province

Objective To explore the effect of water level changes caused by the Three Gorges Dam on the breeding and distribution of Oncomelania snails in the marshland of Chenqiaozhou of Hexian County, Anhui Province. Methods From 1990 to 2016, the daily average water level of the Yangtze River in Chenqiaozhou area, the area and density of Oncomelania snails, and data of snail control with molluscicide in the marshland of Chenqiaozhou were collected, field study was also conducted to understand the development and utilization of the marshland. By comparing the changes of various indicators before and after the operation of the project, this study tried to analyze the relationship between water lever and utilization of marshland as well as breeding of snails. Results After the completion of the Three Gorges Project, the water level of the Yangtze River in Chenqiaozhou was generally declined, the median value of annual flooding days of the marshland was reduced from 59 d to 21 d (Z=2.440, P=0.015), the reclamation area had been increased from 0.95 km2 to 4.55 km2, which had reached 85.0% of the total area of marshland. The coverage rate for snail controlled with molluscicide was significantly reduced, and the median value of annual coverage rate was reduced from 33.0% to 0.0% (Z=4.116, P<0.001).The snail area decreased slowly, and median value of annul snail area was reduced from 317.6 hm2 to 264.6 hm2 (Z=1.744, P=0.081). The average density of live snails decreased rapidly, and median value of annul snail density was reduced from 0.84 number/0.11 m2 to 0.27 number/0.11 m2 (Z=3.779, P<0.001). Conclusions After completion of the Three Gorges Project, the change of water level in the lower reaches of the Yangtze River in Anhui area and its influence on the exploitation and utilization of the marshland affect negatively on the breeding and spreading of snails, playing a positive role in the control of schistosomiasis.