Hatching rate and diapause duration in eggs of Paracartia latisetosa (Copepoda: Calanoida)

Paracartia latisetosa is a seasonally dominant copepod species in Mediterranean coastal waters. This species is well known for the production of diapause eggs which allow it to over-winter. From September 2003 to December 2004, the eggs produced by a total of 329 adult females were maintained under constant conditions until hatching. Subitaneous eggs were produced on all the sampling dates and hatched during the first week after laying. Diapause eggs were produced in autumn times and they hatched after a period of obligatory rest (from 54 to 202 days). Regression analysis showed that the diapause duration was positively correlated with photoperiod lengthat the time of collection of the adults. As a result of this range in resting time, the majority of diapausing eggs hatched in February-March. This fact, as they are not influenced by external stimuli, suggests that the timer of diapause duration of the eggs is under parental control.