author(s)
Augustin Siama, Pierre Saotoing and Alexandre Michel Njan Nloga

abstract
Malacological study was carried out by monthly manual harvests between April 2015 and March 2016 in the artificial reservoir of Douvar. The aim of this study was to identify mollusc’s species and to determine the population dynamics of Lymnaea natalensis. At the end of investigation, 4005 molluscs were hardvested. These molluscs were belonging to seven species among which Menaloides tuberculata (39.05%) and L. natalensis (22.8%), while Bullinus africanus (7%) and Bullinus truncatus (9%) are less abundant. The population of L. natalensis presents a single annual generation which varies between October and July with an abundance of juveniles (<10 mm) and young (11-15 mm) (F = 7.72; df= 47; p =0.0003). It begins its appearance on September and their number evolves differently until July with a peak between the end of the dry season and the middle of the rainy season (March and June). In addition, the variation in relative abundance of this population is significantly influenced by rainfall (r = -0.699; n = 24; p<0.05) and ambient temperature (r = 0.484; df = 24; p<0.05). This study had also shown significant and positive correlations with pH (r = 0.622; df = 11; p = 0.031), very significant and positive with Salinity (r = 0.751; df = 11; P = 0.005) and very negative significant with conductivity (r = -0.918; df = 11; p＜0.0001) and with TDS (r=-0.894; df=11; p＜0.0001). The population of L. natalensis has significantly influenced fasciolosis in the butcher's shop of Douvar (r = 0.484; df = 24; p<0.05). The Douvar dam therefore constitutes a favorite reservoir for the sustainability of fasciolosis intermediate host and molluscs of medical interest in the Far North Cameroon Region.