Reproductive biology of the commercial sea cucumber Parastichopus californicus (Stimpson) (Echinodermata:Holothuroidea). II. Observations on the ecology of development, recruitment, and the juvenile life stage

Abstract

Evidence from in vitro culture of embryos and larvae of Parastichopus californicus (Stimpson) suggests that asynchronization of development through metamorphosis and settlement results in a variable pelagic period for larvae within a particular cohort. Additionally, considerable variation in size of 0 + yr recruits observed in situ may indicate that settlement had occurred continuously for some months within the population studied. Recruitment of at least seven species of echinoderms (including P. californicus) was observed at distinct sites that were notably free of the predatory sea stars Solaster dawsoni (Verrill), S. stimpsoni (Verrill), and S. endeca (L.). The swimming response characteristic of adult P. californicus when touched by the sunflower star Pycnopodia helianthoides (Brandt) did not occur with the same regularity or intensity in juveniles. S. dawsoni preyed upon small ( ≤ 2 yr of age) P. californicus in aquaria; sea cucumbers >2 yr avoided predation by swimming. Periodic collections of P. californicus recruits revealed a pattern of somatic weight loss in the fall and winter that is coincident with a similar pattern reported for the adults of this species. Visceral atrophy was observed in juvenile animals collected in the late fall. The polynoid worm Arctonoe pulchra (Johnson) and the endoparasitic gastropod Comenteroxenous parastichopoli Tikasingh, common symbionts of adult P. californicus, were also noted on or within juvenile animals.