ENVIRONMENTAL REGULATION OF THE ANNUAL REPRODUCTIVE SEASON OF <i>STRONGYLOCENTROTUS PURPURATUS</i> (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), nor retarded by long-day (14L:10D) photoperiod.