Risk of predation and hatching of resting eggs in the ostracod Heterocypris incongruens

Most crustaceans inhabiting temporary pools have resting stages that can remain dormant for many years. Only a fraction of the resting stages hatch each time the pool floods, as a safeguard against unpredictable events resulting in complete reproductive failure, There is likely to be a selective advantage in the ability of resting stages to respond to signals indicating likely environmental conditions and to adjust their hatching fraction in response. We examine whether such an ability exists in the resting stages (diapausing eggs) of the ostracod Heterocypris incongruens, which inhabits temporary freshwater pools in northern Israel. The active stages are subject in some seasons to predation by larvae of the fire salamander (Salamandra salamandra L.). We predicted that a lower fraction of H. incongruens eggs would hatch in water in which S. salamandra larvae had been kept than in water that had not contained S. salamandra larvae. We found no such effect. We discuss possible reasons for the absence of the expected response. A lower proportion of H, incongruens eggs hatched in water with higher conductivity. This may reduce the risk of active stages being killed by desiccation before being able to complete their life cycle.