EGG-PRODUCTION, GROWTH AND DEVELOPMENT OF THE CYCLOPOID COPEPOD OITHONA-SIMILIS

Egg production, growth and development rates of Oithona similis were m easured in the laboratory as a function of food concentration and comp osition. On an optimum diet, development is isochronal and growth is n ear exponential. The maximum juvenile growth rate at 15 degrees C (0.2 day(-1)) is similar to juvenile growth in calanoid copepods. The maxi mum weight-specific egg production rate (0.1 day(-1)), on the other ha nd, is substantially less than in free-spawning calanoids, but similar to that in egg-carrying calanoids. In the Kattegat, Oithona spp. egg production is strongly limited by food during summer and controlled by temperature during winter. The seasonal signal in fecundity and popul ation biomass is much weaker than in the co-occurring free-spawning ca lanoid genera, where fecundity and population biomass undergo dramatic seasonal variation.