洞庭湖麻塘垸北闸洲滩地形环境与感染性钉螺的分布特点

目的查明日本血吸虫感染性钉螺在东洞庭湖麻塘北闸洲滩的分布环境，着重分析洲滩离岸距离、地面高程、坡度及优势植被种类等环境因素对感染性钉螺分布的影响。方法查螺段面从堤岸边最高有螺线往下一直查到最低有螺线，同时用水准仪测定地面高程（吴淞零点），并记录植被种类。结果在该洲滩钉螺孳生地中，有感染性钉螺分布的面积占31．48％，主要分布在大堤边和洲滩上部的坡岸地带。结论地势高、坡度陡的环境感染性钉螺较多；地势低、坡度小的平坦环境没有查到感染性钉螺。

Characteristics of infected snail distribution and topographical environment of the islet in Matong Beiza

Objective To investigate environmental distribution of infected snail in the islet of Matang Beiza on the east Dongting Lake, and analyze the environmental factors that influence the distribution of infected snail, such as the distance from the shore, ground elevation, gradient and main vegetation species. Methods The range for snail survey was from the highest snail-ridden area to the lowest snail-ridden area, and the ground elevation was measured using gradienter （Wu Song＇s elevation of zero）, and the vegetation types were recorded. Results The area of infected snail accounted for 31.48% of the snail habitats in the islet, and mainly distributed on the top-slope zone and nearby the embankment. Conelusion The infected snails were mainly observed in the higher altitude and steep slope zone, while no infected snail were found in low altitude and flat slope zone.