东洞庭湖区钉螺密度影响因素研究

Identification of factors affecting Oncomelania hupensis density in Eastern Dongting Lake regions

目的探索东洞庭湖水体污染物、水位和气象因素等对钉螺密度的影响,为血吸虫病防控提供科学依据。方法选择2007—2014年东洞庭湖区有螺洲滩,以系统抽样法查螺,同时收集水体污染、水位和气象等因素资料,计算水淹天数和开始水淹时间。首先对钉螺密度及各影响因素进行描述性分析,并建立钉螺密度与各因素间的线性混合模型,以探索钉螺密度主要影响因素,最后拟合钉螺密度与其主要影响因素的平滑曲线。结果 2007-2014年东洞庭湖钉螺密度呈波动变化,密度最高值出现在2010年10月(52.79只/0.1 m^(2)),最低值出现在2009年1月(2.15只/0.1 m^(2))。拟合线性混合模型发现钉螺密度主要影响因素有高锰酸盐指数、总磷和开始水淹时间(t=6.386、-2.920和-3.892,P均<0.01)。拟合平滑曲线发现钉螺密度与高锰酸盐指数和总磷的关系呈近似二次曲线,且在4月底后开始水淹时间越早、钉螺密度越高。结论东洞庭湖区高锰酸盐指数、总磷和开始水淹时间对钉螺密度有一定影响。

Objective To evaluate the impact of water pollutants, water levels and meteorological factors on the Oncomelania hupensis density in Eastern Dongting Lake regions, so as to provide insights into schistosomiasis control.Methods O. hupensis snails were surveyed using a systematic sampling method in snail-infested marshlands in Eastern Dongting Lake regions from2007 to 2014, and data pertaining to water pollutants, water levels and meteorological factors were collected. The duration of submergence and the date of the start of submergence were calculated. The snail density and its influencing factors were descriptively analyzed, and a linear mixed model was generated to examine the impacts of variables on the snail density. In addition, smooth curves were fitted to investigate the relationship between snail density and variables.Results The snail density appeared a fluctuation in Eastern Dongting Lake regions during the period from 2007 to 2014, with the highest density on October, 2010(52.79 snails/0.1 m^(2)) and the lowest density on January 2009(2.15 snails/0.1 m^(2)). Linear mixed-model analysis showed that permanganate index, total phosphorus and the date of the start of submergence affected the snail density(t = 6.386,-2.920 and-3.892, all P values < 0.01). Smooth curve analysis revealed that the associations of the snail density with the permanganate index and total phosphorus appeared an approximately quadratic curve. After the end of April, the earlier date of the start of submergence resulted in a higher snail density.Conclusion Permenganate index, total phosphorus and the date of the start of submergence affect the O. hupensis snail density in Eastern Dongting Lake regions.