涸沼水系におけるカワザンショウガイの分布と各地域集団の個体群構造

概要

論文の詳細を見る
Assiminea japonica Martens, 1877 is commonly distributed in brackish waters in the Japanese main islands. Some local populations of the snail, however, have been reduced due to recent coastal developments. Distribution of the snail was surveyed along the Hinuma brackish water system and the size distributions of two local populations were monitored between May 1995 and January 1996. The snail was mainly distributed in reedy marshes and gravelly shores, but not on sandy shores or concrete banks. The snails inhabited brackish water where salinity was less than 8‰ and did not inhabit seawater or fresh water. Four shell color patterns were recognized. The ratio of the four shell color patterns within the population was different at every observation site. The snail widely occurred from intertidal to very shallow subtidal bottoms, but most snails did not migrate between these two bottoms during the tidal cycle. Seasonal changes in size composition in two snail populations were very different. A population in a reedy marsh was composed of adult snails throughout the year without recruitment, but a population on a gravelly shore was mainly composed of small juveniles.
日本貝類学会の論文
2001-06-30