Relative density and size (height) Distribution of Bithynia siamensis goniomphalos Morelet (Mesogastropoda: Bithyniidae)
1987
Sanit Tongsanga (Kasetsart Univ., Bangkok (Thailand). Faculty of Science. Department of Zoology)
Although, snail, Bithynia siamensis goniomphalos had been reported as the 1st intermediate host of human liver fluke (Opisthorchis viverrini) in the Northeast of Thailand since 1966, studies concerning about changes of population density of this snail species which might be served as the guideline for their controlling is not available. The objectives of these studies were to assess the fluctuation of the relative density related with time and the size (height) distribution of B. s. goniomphalos which sampled from Nong Prachug and Nong Sim, Udonthani Province. A five squared feet wooden quadrat was used as the sampling tool. Snails were sampled once a month at three different sampling spots along the inundated edge of each studied swamps. For each sampling spot, one quadrat was placed at the level of 5-15, 15-25, 25-35 and 35-45 cm, below the surface of water at a time, The bottom mud within each quadrat was scooped up and poured into a fine aluminium mesh sieve for sorting out of snails. They were preserved separately in bottles containing 75 % alcohol. Snails latter were counted and measured in mm. The results of the studies indicated that the relative density (No/5 ft. quadrat) of snails varied with the months they were sampling, the depth of water and the locations of swamps themselves. The average density was not significantly different between swamps (P0.05). There were hightly significant differences (P0.01) between sampling months, and significant differences among depths (P0.05). The height distribution graph indicated that the spawning period of this snail occurred during July to August
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