Triggers for hatching of Paracartia grani (Copepoda: Calanoida) resting eggs: An experimental approach

Abstract

Dormancy represents the main strategy in copepod ecology, together with migration, for maintaining a viable population during adverse environmental conditions. Different types of dormancy have been described in the literature: diapause, quiescence and delayed-hatching eggs. Paracartia grani is known to produce resting eggs; however, the type of resting eggs has not yet been determined. The aims of this study were to determine the type of P. grani resting eggs produced in the Thau lagoon, southern France, and the triggers (temperature and/or photoperiod regimes) of the exit from dormancy. Three types of eggs were identified based on morphological criteria and hatching success. An experimental approach using resting eggs exposed to different temperature and photoperiod conditions indicates the production of diapause eggs by P. grani. There is a statistically significant positive effect of temperature on the hatching success of diapause eggs and a combined influence of temperature and photoperiod acted as synergic effects as higher hatching rates occurred under light conditions. © 2013 The Author.