title: [Influence regarding micro-ecological environment of snail habitats in lake area on the distribution of snails].
abstract: OBJECTIVE
  To explore the relationships between micro-ecological environmental factors and the density of Snails so as to provide information for the elimination of Snails and control of Schistosomiasis disease, under ecological methods.
  
  
  METHODS
  A bottomland close to Junshan Park in Yueyang city, Hunan province was selected as the field for survey during 10, 2007 - 10, 2008, and a systematic sampling method was applied to determine the specific sites of Snail investigation. All the Snails in each frames were collected and the soil surface temperature and vegetation coverage in several frames were measured. 30 g soil sample in each selected frames were also collected simultaneously. The number of live Snails in each frame was counted by dissection, and soil measured pH value and soil moisture were tested in the laboratory. The distribution of Snails and microecological environmental factors, fitted general additive model for the relationship of these factors and the Snail density were described.
  
  
  RESULTS
  104 frames were surveyed, with pH value as between 4.70 - 7.92, vegetation coverage as in 1% to 96%, soil surface temperature as in 14.5 - 32.7°C, the soil moisture as in 0.07 - 2.00. Under General additive model, data showed that there was no significant difference for vegetation coverage. However, other factors were all significantly different (P < 0.001). It was found that a nonlinear relationship was existing between these factors and the Snail density.
  
  
  CONCLUSIONS
  Smoothing function relationship was noticed between the Snail density and micro-ecological environmental factors. It's suggested to fit general additive model to study the relationship between the distribution of Snails and its influencing factors, so as to adopt appropriate measures to change the related ecology to control the diffusion and reproduction of Snails.
authors.affiliation: Department of Epidemiology, School of Public Health, Fudan University, Shanghai 200032, China.
authors.forename: Yuan-pei
authors.initials: YP
authors.lastname: Li
authors.forename: Hai-yin
authors.initials: HY
authors.lastname: Wang
authors.forename: Yi-biao
authors.initials: YB
authors.lastname: Zhou
authors.forename: Zhong
authors.initials: Z
authors.lastname: He
authors.forename: Wei
authors.initials: W
authors.lastname: Wan
authors.forename: Jie
authors.initials: J
authors.lastname: Jiang
authors.forename: Qing-wu
authors.initials: QW
authors.lastname: Jiang
mesh_terms: D000818:Animals; D004197:Disease Reservoirs; D017753:Ecosystem; D004777:Environment; D060106:Lakes; D012908:Snails