ON THE POPULATION BIOLOGY AND NATURE OF DIAPAUSE OFLABIDOCERA AESTIVA(COPEPODA: CALANOIDA)

Abstract

The calanoid copepod, L. aestiva, was collected from Vineyard Sound, Massachusetts [USA] between July and Dec. 1978. Adult size (cephalothorax and total body length) was inversely proportional to surface water temperature at the time of collection. The major switch from subitaneous to resting egg production occurred during late Aug. to early Sept., but a small percent of subitaneous eggs continued to be produced throughout the fall. Resting eggs were cold-resistant and when chilled at 5.degree. C hatched synchronously when warmed to 21-23.degree. C. Individual resting eggs kept continuously at 19.degree. C took longer to hatch and emergence was asynchronous. The resting eggs of L. aestiva appear to be in a stage of diapause similar to many insects, and photoperiod may be the primary cue inducing the production of resting eggs.