Sample unit size effects of spatial pattern of Oncomelania hupensis population in marshland schistosomiasis epidemic areas

Abstract

To explore the sample unit size effects of spatial pattern of Oncomelania hupensis population in the marshland schistosomiasis epidemic areas. The push-broom method was performed to survey the snails in the study site in a basic unit size of 0.33 m×0.33 m in Poyang Lake region of Jiangxi Province. After combining different amount of survey cells, the aggregation indicators, regression models and aggregating factor index were employed to study the spatial distribution pattern. The snail population was in aggregation pattern and the smaller sampling unit could produce higher degrees of aggregation. The regression models showed that the snails distributed in the form of individual groups with attraction with each other and the aggregation was related with the snail density. The clustering factor index demonstrated that the aggregation was introduced by aggregating behavior habit of the snails and environmental factors, or only by snail habit itself, and the aggregating habit of snails could be expressed better by the smaller sampling unit. The spatial pattern of O. hupensis population in the marshland schistosomiasis epidemic areas is in aggregation pattern, and the sample unit size can affect the calculation results of the related biological indices.