ケフサイソガニの個体群構造の季節的変化について
1987 年 37 巻 2 号 p. 81-89
詳細
1987 年 37 巻 2 号 p. 81-89
The life cycle of a grapsid crab Hemigrapsus penicillatus inhabiting the intertidal boulder shore was investigated in the Gamo Estuary over a two-year period using stone-filled basket traps. Ovigerous females occurred from June to September, with the maximum ratio to the total number of adults being present from August to September. Megalopae larvae settled intensively in September. It was estimated that only 0.17% of the eggs produced in the population developed as far as juveniles of 0.3 cm carapace width. By early December these had reached 0.6 cm width. Little further growth was evident until March, but by the following December individuals had reached 2.0 cm. Mature size was reached 10-11 months after settiement. Life table analysis of this population suggested a 2-year life span with two overlapping cohorts.
