著者

紀平 肇 近藤 高貴

出版者

日本貝類学会

雑誌

貝類学雑誌 (ISSN:00423580)

巻号頁・発行日

vol.58, no.3, pp.145-149, 1999

参考文献数

7

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The age composition of 101 individuals of Oguranodonta ogurae, which were collected in a small pond at Hirakata City, Osaka Prefecture in the late autumn of 1998, was determined by examination of the annual gorwth-interruption lines. Individuals with 5 growth-interruption lines (i. e. 6 years old) were most abundant, and there were only 5 individuals younger than 5 years old. The scarcity of young individuals may be due to the heavy drought occurred in the summer of 1994. Based on the assumption of the stable age distribution, a life table was estimated. The estimated generation time was 6.3 years.