Identification and Determination of the Geographical Distribution of Freshwater Snails in Lorestan, Iran

Snails are creatures present in various ecosystems that, in addition to being present in human surroundings, some of them are also important in veterinary medicine and medicine as the intermediate hosts of Digenean trematodes. The present study was conducted to identify and determine the geographical distribution of freshwater snails and investigate the relationship of variables, such as season and geographical region, with snail species and dispersion in Lorestan in the west of Iran. A total of 4400 samples of freshwater snails were collected using the multistage sampling method (i.e., stratified, cluster, and randomized) from 110 points in five geographical regions in four seasons and then identified based on their morphological characteristics by diagnostic keys. The ArcGIS software (version 10.3) was used to evaluate the spatial distribution of the freshwater snails. In this study, seven species of freshwater snails were identified in six families belonging to six genera, namely <em>Melanopsis doriae</em> (6.30% of the variation in species), <em>Theodoxus doriae</em> (5.55%), <em>Bithynia tentaculata</em> (43.22%, the dominant species), <em>Physa acuta</em> (24.98%), <em>Lymnaea truncatula</em> (9.75%), <em>Gyraulus euphraticus</em> (8.18%), and <em>Lymnaea gedrosiana</em> (2.02%). The geographic distribution of freshwater snails was recorded across five regions in 22 points per region for every season. The spatial distribution maps showed that the distribution of freshwater snails varies according to region and season (P<0.001). The obtained results revealed the effects of season and geographical region on the distribution and population density of snails in the province. These data can be used for the implementation of control programs against parasitic diseases in the region, including trematodes.