Experimental production of natural zooplankton and the quality of stored eggs
The marine gliding community of the sea is very diverse and species-rich, and the glide contains a high proportion of n-3 fatty acids as well as proteins, pigments, wax esters and chitin. In addition to being the natural food of sea fish larvae, plankton contain a high percentage of fatty acids that are suitable for human consumption. For this reason, it is interesting to utilize this source of nutrients by cultivating under controlled conditions on land and accessing all year round. The main goal of the project was to develop methods to maintain the cultivation of Acartia tonsa that was hatched from resident eggs and to cultivate Acartia longiremis from plankton in the sea from Eyjafjörður, as well as to study the hatching rate of eggs after storage. A. longiremis is much more sensitive in all treatments compared to A. tonsa and requires a lower culture temperature. Facilities for the breeding of plankton and algae have been set up at the Matís, HA and Hafró laboratories in Akureyri. Conditions in the laboratory proved to satisfy the needs of both species for growth and maintenance, but the results indicate that better conditions need to be developed for the storage of A. longiremis eggs in order to increase their hatching rate. Results of experiments in which halibut juveniles were fed with Acartia spp. also give evidence of faster growth of halibut larvae and although there was evidence that metamorphosis was somewhat delayed, it seemed to be more successful.
The community of zooplankton includes many species and contains high proportion of n ‐ 3 fatty acids in addition to proteins, wax esters and chitin. Apart from being the natural food for marine larvae, zooplankton includes large quantities of high quality oil suitable for human consumption. It is therefore of importance to utilize this nutritional source by culturing zooplankton at controlled conditions throughout the year. The main goal of the project was to develop methods for maintaining cultures of Acartia tonsa that were hatched from dormant eggs, and to maintain cultures of Acartia longiremis collected from the marine environment in Eyjafjördur. The hatching rate of eggs following storage was furthermore investigated. Facilities for culturing of both zooplankton species and algae at controlled conditions have been set up in the laboratory and A. longiremis proved to be more sensitive to handling and require lower culturing temperatures compared with A. tonsa. Culturing conditions proved to fulfill the needs of the Acartia species for normal development and egg production. The results, however, indicate that conditions during egg storage need to be further developed for improved hatching rate of A. longiremis eggs. Offering Acartia spp. to halibut larvae may have resulted in improved growth and metamorphosis of larvae, however with delayed metamorphosis.