Food availability as a potential source of bias in the egg production method for copepods

The measurement of copepod adult female fecundity as an estimate of adult growth (production) rates has been an approach widely used in both laboratory and field studies. Here we demonstrate that the basic assumption of this approach, i.e. that estimated egg production during the incubation reflects the 'in situ' conditions, is not always legitimate and that it is temperature dependent. The enhancement of metabolic rates induced by high temperatures induces a more accented bias of the method. We also provide guidelines on how to conduct the incubations in order to obtain more reliable estimates.