PHOTOPERIODIC CONTROL OF DIAPAUSE IN THE MARINE CALANOID COPEPOD<i>LABIDOCERA AESTIVA</i>

Abstract

The calanoid copepod Labidocera aestiva was reared in the laboratory at 15°C. Individuals that developed under a photoperiod regime of 18L:6D produced subitaneous eggs, whereas copepods exposed to a short-day regime of 8L:16D produced mostly diapause eggs. The results indicate that photoperiod is an important factor controlling the life cycle of L. aestiva. It is suggested that in Vineyard Sound, MA, this species produces subitaneous eggs during the summer in response to long daylengths, and in the fall produces mostly diapause eggs in response to short daylengths.