Outdoor rearing facilities of free spawning calanoid copepods for turbot larva can host a bank of resting eggs in the sediment

It is well established in Denmark to rear calanoid copepods in outdoor tanks for
use as live feed during turbot (Scophthalmus maximus) larval production. However, the copepod assemblages, composed of a mixture of all development stages and therefore body sizes, vary over time and do not always match the larval needs. When turbot larvae reach metamorphosis and are transferred indoor for weaning, the outdoor tank sediments may reveal vast amounts of copepod eggs undergoing dormancy. Here, we report a copepod
species succession firstly among Centropages hamatus and then Acartia spp. both with resting eggs as part of their life cycles as a result of two different nutrients treatments and a control. We found a tendency to a higher egg production and indeed more eggs in the sediment of nutrient amended tanks. In fact close to 5 million eggs per square meter, making up to 400 million eggs per tank was found in the sediment after one production.