Environmental regulation of the annual reproductive season of Strongylocentrotus purpuratus (Stimpson).

Abstract

1. The annual reproductive cycle of the Palos Verdes (Southern California) subtidal population of S. purpuratus correlates with seasonal changes in ocean temperature: a rise of temperature above 17° C (June) coincides with cessation of gamete production and storage.2. Sea urchins maintained at low temperature (13° C) retained gametes nearly two months (as long as they were observed) beyond the date when the field population had apawned out.3. At a time when the field population was reproductively active, the spawning capability of a laboratory population was terminated by three weeks of warm water temperature(19° C).4. The spawning capability of animals kept at 13° C was not terminated by long-day photoperiod (14L:10D).5. The onset of reproductive activity in animals started during the summer months could not be accelerated experimentally by 10 weeks of low temperature (13° C).6. In laboratory animals maintained at 13° C, the onset of reproductive activity was neither enhanced by short-day (10L:14D), no...