2.2 Survey of freshwater snails in relation to physico-chemical factors
Four sampling sites were purposely selected along the bank of the dam, site one was selected based on the observed frequency of human activities such as swimming, fishing, farming and washing of clothes, the second on vegetation cover, the third on lentic (flowing water) and the fourth was on lotic (standing water). The coordinates of the sampling sites were human activity N11.44’44.8” E009.13’00.4”, vegetation cover N11.44’42.9” E009.13’04.5”, lotic N11, 44’54.3” E009.12’44.9” and lentic N11. 44’51.1” E009.12’57.8”. Sampling at each station was done within ninety meters along the shoreline and 5 meters in shore.
Each of the four (4) sites was sampled once in a month from April to October, 2019 for the presence of freshwater snails. Sampling of snails were done using long handled steel scoop nets (0.2mm mesh) and those that were attached to objects were collected by hand picking using hand gloves. Fresh water snails collected were kept in labeled perforated/aerated plastic containers and transported to the Biology Laboratory, Federal University Dutse. They were sorted and then morphologically identified into their respective species as described by Brown, (1994). The snails were counted to determine the number of each snail species collected per site. The plants associated with the freshwater snails were collected, transported to the Herbarium of Department of Biological Sciences, Federal University Dutse where they were identified using standard key.
Surface water samples for determining physico-chemical factors were collected in 1L plastic containers. The physico-chemical factors of surface water measured on the field include temperature measured using ordinary mercury glass thermometer, pH using pH meter, current/velocity by means of conductivity meter, turbidity using Secchi disc and depth of water body at a distance of 5 meters in shore by means of a meter rule. Chemical properties such as colour, calcium, magnesium, nitrate and phosphate were determined at Challawa Central Laboratory Kano, Kano State using spectrophotometer DR 3900 model. Determination of Dissolved Oxygen and Total Dissolved Solid were done using multi-parallel equivalent machine, model HM 100.