Phenology in Calanus finmarchicus; hypotheses about control mechanisms

Abstract

Calanus finmarchicus (Gunnerus) stratify nariowly near 500 m depth dunng their fifth copepodite resting phase in North Atlantic Slope Water off southern New England USA They probably a c h ~e v e this by migration to a specific, daytime isolume Photoperiod information provided by light intensity at depth could serve as a cue for termination of the resting phase Population data on tooth formation and gonad growth show that the reshng stock prepares foi termination in late winter and matures in February-March Photopel~ods are lengthening throughout that seasonal interval, and might cue arousal An endogenous, long-range timer that cues arousal after an interval of rest is another possible mechamsm '