目平湖洲滩钉螺分布与水位及植被变化的关系

Relationship Between Snail Distribution and Changes of Water Level and Vegetation in Muping Lake

目的探讨目平湖水位和洲滩植被变化对钉螺分布的影响。方法收集目平湖三峡建坝前后两个时段气象水位资料及螺情资料,从2003-2007年,纵向开展春秋螺情调查,比较三峡建坝前后环境变化并分析对钉螺分布的影响。结果目平湖区三峡建坝后比建坝前枯水位升高1m,洪水位降低0.5m,枯洪水位落差缩减了1.5m,年均水位升高0.9m;年均气温升高0.8℃,平均降雨量增加466mm。春秋两季活螺密度及感染螺密度建坝前后无明显变化,但有年间差异。草洲植树后,活螺密度逐年减少,第2年后未发现感染性钉螺。结论三峡工程对目平湖洲滩钉螺分布影响不大,但湖洲钉螺分布与水位及植被变化有明显关系,草洲植树可改造疫源地,降低疫情。

Objective To explore the impact on snail distribution in marshland areas after the alteration of water level and vegetation in Muping Lake areas. Methods Two periods of meteorological and hydrological as well as snail data before and after the establishment of Three Gorges Super Dam were collected in Muping Lake areas. From 2003 to 2007. snails surveillance in Spring and Autumn was longitudinal conducted for 5 successive years in Muping Lake areas. Environmental changes before and after the establishment of Three Gorges Super Dam were compared, and its impacts on snails distribution were analyzed. Results Compared with that prior to the establishment of Three Gorges Super Dam, water level in dry season in Muping Lake areas was elevated for 1 meter, reduced 0.5m in flood season, and reduced 1.5m between dry and flood seasons. Moreover, year mean water level raised 0.9m and year mean temperature increased 0.8℃ respectively, with year average precipitation rising 466mm, after the setting up of Three Gorges Super Dam. Lively snails density and infected snails one in Spring and Autumn were stable. After forestation on grassland, living snails density was decreased year by year. and the infected snails disappeared in the second year after forestation. Conclusions Three Gorges Super Dam has no sig- nificant impact on snails distribution in the Muping Lake areas, yet there is significant relationship between snails distribution and vegetation environmenl in the Lake areas. Forestation on grassland could reclaim the transmission land and reduce endemic situation.