Life history of an exotic sabellid polychaete, Terebrasabella heterouncinata: Fertilization strategy and influence of temperature on reproduction

The California abalone aquaculture industry has been struggling to rid itself of an exotic sabellid, Terebrasabella heterouncinata following its inadvertent introduction from South Africa in the late 1980s. The development of an effective management strategy is dependent upon understanding the life history of this sabellid, including its fertilization strategy (e.g. self-fertilization) and its generation time. In the present study, red abalone, Haliotis rufescens Swainson 1822, with single sabellid infestations were isolated in containers at 18 degree C (single host and sabellid per container). This first, parental generation (P), was held in isolation until individuals produced F sub(1) larvae. The F sub(1) larvae were subsequently isolated until individuals produced a second, F sub(2), generation. In a separate study, uninfested red abalone were exposed to sabellid infested abalone at 11.2 degree C, 15.6 degree C, and 20.9 degree C, temperatures typically encountered in California. The larvae were subsequently observed as they developed to specific life stages: the initiation of feeding, the development of all 11 setigers (which closely relates to sexual maturation) and the completion of their life cycle as recognized by the production of motile, infesting, larvae. Approximately 50% of the sabellids examined at 11.2 degree C, 15.6 degree C, and 20.9 degree C had developed the ability to feed by day 6, 5 and 4 (P < 0.001), had developed all 11 setigers by day 83, 68 and 48 (P < 0.001) and had produced larvae by day 298, 165 and 111 (P < 0.001), respectively. This research demonstrates that isolated individuals do pose the threat of producing fully functional offspring and that the generation time of T. heterouncinata is significantly temperature dependent.