Relationships between the distribution of Galba truncatula (Gastropoda: Lymnaeidae) climatic conditions and the altitude of municipalities in Haute Vienne (France)

Abstract

A retrospective study on 7407 populations of Galba truncatula found in the department of Haute Vienne for 37 years (1970–2006) was carried out to determine if altitude and climate on acid soils had an effect on the distribution of populations and the characteristics of their habitats. Out of a total of 13 478 water points surveyed in 179 municipalities, the overall frequency of snail populations was 54.9% but varied with the habitat type and the municipality on which these water points are located. The frequency of snail populations significantly decreased when the mean altitude of municipalities or their mean annual rainfall increased. Conversely, this frequency significantly increased with increasing mean annual temperature. The characteristics of habitats were analysed for 6281 populations in relation to the mean altitude of municipalities. The area of G. truncatula habitats and the density of overwintering snails per m2 of habitat significantly decreased with increasing altitude. On the acid soils of Haute Vienne, the distribution of G. truncatula populations is closely related to the altitude and climatic conditions of municipalities.