Feasibility of incubation experiments to estimate moulting rates in marine copepods

Moulting rate estimates of Temora longicornis and Pseudocalanus elongatus in short incubation experiments in the laboratory were compared with shipboard experiments in the North Sea. Absence of food, rotation of bottles and (an extremely small) container size did not affect the moulting rate in well-fed copepods. A minor bias was found due to gentle handling. High variance was due to the use of different samples, one before and one after incubation, which is part of the so-called 'Kimmerer method'. This error can be reduced by monitoring the new production of exuviae in a single sample, which makes sorting of individuals unnecessary, while conserving the estimate of moulting rate in individual stages.