Freshwater Snails Of Niger-Cem, Nkalagu Eastern Nigeria: Observations On Some Demographic Aspects Of The Schistosome-Transmitting Bulinids

Abstract

The results of snail collections carried out in the freshwater habitats of Niger-Cem in Nkalagu from August to November 2002 are reported. Also repored are findings on abundance, diversity and age structure of the snails. A total of 3491 pulmonate snails were collected, belonging to 3 families: Planorbidae (3133); Lymnaeidae (199) and Ampullariidae (159). Bulinus globosus was most abundant, with mean abundance (MA = 627.66) followed by B. truncatus (MA = 294) and Biomphalaria pfeifferi, the least abundant (MA = 6.33). Analysis of the collected snails gave the following: Shannon\'s index of diversity, H = 1.2889; Simpson\'s index of dominance, D = 0.3642 and the number of snails per man-hour = 174.6. Age structure findings demonstrated a ‘lag\' phase in the period of peak abundance between B. globosus and B. truncatus. Fndingson the reproductive to pre-reproductive (R/P) ratios, suggest smilar demographic strategies for the two buliniid mollusc species.

Keywords: Abundance, Diversity, Demographic Strategy, Bulinus globosus, Bulinus truncatus

Animal Research International Vol. 1 (2) 2004 pp. 120-124