Biennial reproduction with embryonic diapause in Lopholithodes foraminatus (Anomura: Lithodidae) from British Columbia waters

Abstract

. A paucity of data on the reproductive cycle of crabs in the family Lithodidae inhibits both the development of management strategies and the formulation of hypotheses regarding the evolution of lithodid life histories. Life-history parameters of Lopholithodes foraminatus from British Columbia, Canada, were investigated based on 26 females maintained in the laboratory and supplementary observations on other living and preserved animals. The rate of embryonic development was determined by measuring the percentage area occupied by yolk in lateral views of eggs removed from brooding females throughout development. Females of L. foraminatus exhibited biennial reproduction including an 18-month brooding period. Females molted, mated, and extruded eggs in mid-summer, and did not release larvae until late winter or early spring of the second year after fertilization. Embryogenesis included a 12-month diapause at the gastrula stage. Females released larvae over a mean interval of 69 d, the longest reported for any lithodid. While the development stage of embryos was observed to be heterogeneous within a brood, no spatial gradient in development rate was observed, calling into question the oxygen limitation hypothesis of extended hatching. Biennial reproduction of individuals of L. foraminatus may be a consequence of a relatively low-quality habitat. Relative to annual reproduction, biennial reproduction halves the potential rate of increase of a population and increases vulnerability to overharvesting, suggesting that L. foraminatus is not a good candidate for commercial exploitation. The adaptive value of embryonic diapause is uncertain and warrants further research.