Influence of food organisms on the development and culture of pelagic copepods

Abstract

1. Growth rates of populations started with adult Euterpina acutifrons fed on 16 different unicellular algae, and 2 mixtures of these algae, were compared. Only algae of medium size can support growth rates as high as those obtained in the mixture. Smaller algae (6-7 μ) or wider ones (> 16 μ) give lower rates or do not support adult survival. 2. Of 5 algae tested, only those of medium size support all developmental stages from egg to adult of Euterpina acutifrons. These results show that the size of food is one of the factors limiting the production of copepods under laboratory conditions. 3. By feeding adult females of Euterpina acutifrons on Platymonas suecica at various concentrations, it was demonstrated that, when the food concentration increases, the rate of ingestion and the egg production of the copepod increases thereby reaching a plateau, while the rate of filtration decreases. 4. The same relation is found for the 5 algae tested in regard to ingestion and filtration activities. However, for the 5 algal species, the concentration at which the plateau is reached, and the value of ingestion at this plateau, are quite different. 5. When feeding female Euterpina acutifrons in excess unicellular solutions of the 5 algae or a mixture of all the algae used, egg production and adult life span differs according to the type of the food algae. Algal species which result in low egg production and short adult life span are most intensively ingested in terms of biomass. 6. By increasing the number of algal species and their concentration in the culture solution, we were able to cultivate some additional pelagic copepods through several generations. © 1970 Biologischen Anstalt Helgoland.