title: Migration of Oncomelania quadrasi observed by the mark and release method in a wet bank of a stream in Leyte, Philippines.
abstract: The migration and population size of Oncomelania quandrasi were studied at two sites in a submerged bank of a stream in Leyte Philippines. The snails collected by filter paper in an experimental area were marked with manicure and released in the same area. Collection was repeated every 4 days in the same area for 5 more times and snails without mark were marked with manicure of different colors at each time. The immigration and emigration rates and population were calculated from the collection data. One experimental site with an area of 5.86 m2 was established at the edge of the water pathway, 3 sides of which were surrounded by wooden planks except that side facing the water pathway to determine the migration between the bank and water pathway. The other experimental site was 7.54 m2 in area, located in a submerged place close to high land and was left open in all sides. The ranges of the population, immigration and emigration rates during a 4 day period were 3845 to 7638, 0 to 0.4448 and 0.2263 to 0.8911, respectively in the former site. The results in the latter area were 1336 to 2468, 0.1261 to 0.6725 and 0.1349 to 1.2340, respectively. It was observed that the replacement of individual snails in a habitat was largely due to migration which in turn was influenced much by the change of water level in the bank. The emigration increased with the elevation of water level. On the other hand, the immigration increased with the lowering of water.
mesh_terms: D000818:Animals; D005618:Fresh Water; D010679:Philippines; D011159:Population Surveillance; D012908:Snails