鄱阳湖草洲植被与钉螺血吸虫感染性年间变异的分析

目的　探讨鄱阳湖北部湖汊型草洲植被的覆盖度和钉螺的生长发育、钉螺血吸虫感染性年间变异的关系。方法　选定都昌县 6个草洲连续 3年进行植被覆盖度和螺情调查 ,对所获钉螺进行测量、解剖 ,并收集水文资料进行比较分析。结果　 13- 16 m高程的草洲 ,水淹日数越长 ,植被的覆盖度越低 ;同一草洲不同年间钉螺的生长发育与植被的覆盖度呈正相关 ;不同草洲不同年间钉螺血吸虫感染率以钉螺壳长 7.5 m m以上为最高 ,5 .5 - 7.5 mm为其次 ,5 .5 m m以下最低 ;草洲钉螺血吸虫感染性年间变异与植被的覆盖度无关 ,而与传染源的多少和管理措施的力度有关。结论　草洲水淹日数与植被的覆盖度呈负相关 ,钉螺壳长与植被的覆盖度呈正相关 ,感染性钉螺其壳长者感染率较高 ,钉螺血吸虫的感染率与植被的覆盖度无关。

ANALYSIS OF ANNUAL CHANGES OF TOTAL PLANT COVER IN THE POYANG LAKE MARSHLAND AND THE RATE OF SCHISTOSOMA INFECTED SNAILS

Objectives To explore the degree of plant cover in the marshland of the north section of the Poyang Lake; also to explore the annual variation and relationship between snail growth and snail infection. Methods Six marshlands in Duchang County were selected, degree of plant cover and snail condition were investigated for successive years. Snails were measured and dissected. Data on meteorology and hydrology were collected and analyzed. Results In marshlands of height 13-16 m, The longer the date of meadows flooded, The lower the degree of plant cover. Every year, the growth and development of snails were positively correlative with the degree of plant cover in the same meadow. The rate of Schistosoma infected snails was the highest as the length of snail shell was over 7.5 mm, the next was 5.5-7.5 mm, and the lowest was less than 5.5 mm, regardless of what year or which meadow. Degree and variation of infected snails in a meadow was not related with the degree of plant cover yearly, but related with the degree of infective resources and the strength of control measures. Conclusion The degree of plant cover in a meadow was negatively related with the days of the meadow flooded. The shell length of snail was positively related with the degree of plant cover in the meadow. The longer the snail shell length, the higher the snail infected. The infectivity of snails by Schistoeoma was not related with the degree of plant cover.