Distribution, abundance and infection rate of water snails in Hadejia River Valley, Jigawa State, Nigeria

Abstract

This study was carried out to determine the distribution, abundance and infection rate of water snails in Hadejia river valley, Jigawa State, Nigeria. A total of 150 and 437 snails were collected during dry and rainy season respectively. Snail species collected in rainy season were higher than those collected in the dry season. Pila ovata was the only snail species collected during the dry season. The Highest abundance (56.7%) of Pila ovata was collected in the month of May and least (19.3%) snail collection was in March. Pila ovata and Lanistes varicus are the snail species collected during the rainy season. Higher snails collection was in July (37.9%) followed by August (36.1%) and least snails species collection was in September (26.0%). There was an association between the two snail species in monthly collection (p˂0.05). Pila ovata was the most abundant snail species during rainy season (370) and Lanistes varicus was the least abundance (57). Distribution of 150 Pila ovata collected among three sites of collection during dry season showed (42.0%) of snails species were collected in the farm, followed by river (30.7%) and least snails’ collection was in the dam (27.3%). There was no association between the two snails species collected from the sites (p˃0.05). Out of 150 snails collected in the dry season the overall infection rate of snails by cercariae was 7.33%. Highest infection rate was recorded in the farm 5.33%, followed by river with infection rate of 1.33% and least infection rate was 0.67% in the dam. During the rainy season, overall infection rate by cercariae was 12.2%. Highest infection rate of P. ovata was 7.9% in the river, followed by the farm with 1.87% and least infection rate was 0.23% in the dam. Higher infection rate by cercariae of Lanistes varicus in both farm and dam recorded 0.4% each and least infection rate of 0.23% was in the river. There was significant difference in seasonal infection rate of snails (p˃0.05) by cercariae based on sites of collection. Surface temperature of water during dry season ranges between 22 and 25oC and surface temperature of water during the rainy season ranged between 19 and 21oC. Seasonal abundance of snails increased with decreased in temperature in both dry and rainy seasons. The pH of water ranged between 10.0 and 11.5 and snail abundance increased with increased in the pH in both dry and rainy season. The mean rainfall ranged between 144 and 198.5 mm and snails abundance decreased with increased in rainfall. Mean relative humidity ranged between 1.599 and 2.420 in dry season, while in rainy season mean relative humidity ranged between 2.019 and 2.060 and snails abundance increased with increased in relative humidity during dry season, but in rainy season snail abundance decreased with increased in relative humidity. There was no significant difference between seasonal abundance snails (p˃0.05)in relation to physico-chemical parameters.