ヒバリガイモドキとムラサキインコガイの殻長組成, 生殖腺重量の季節的変化と分布変動

概要

論文の詳細を見る
The seasonal changes in size structure and gonad weight, and the yearly fluctuation in spatial distribution of the two mytilids, Hormomya mutabilis and Septifer virgatus were investigated on a rocky shore at Mezu Cape, middle Japan (33°46′N, 135°18′E). In H. mutabilis, the gonads developped mainly on the mantles and were matured from April to August. The sex ratio was ca. 1.0. The juveniles were common in the small-mussel colony from May to August, but scarce in the large-mussel colony. The first-year individuals grew from June to November and from March to May when they merged in size with the older-year ones. The spatial distribution and the percent coverage for rock surfaces by the colonies fluctuated markedly between the successive two years. In S. virgatus, the gonads developped mainly on the mantles and their weight was larger from March to September than in other seasons. The sex ratio was ca. 1.0. The juveniles were common in the colony of adult mussels from April to December, and some of the first-year individuals seemed to grow from April to July. The spatial distribution and the percent coverage for rock surfaces by the colonies were temporally constant compared to H. mutabilis. It was suggested that the avoidance of the large-adult colonies by the recruits of H. mutabilis, and the constant larval settlement in the adult colonies in S. virgatus cause the observed difference in the population dynamics between the two species.
1996-12-31