Tag: Acartia

Reports

Experimental production of natural zooplankton and the quality of stored eggs

Published:

01/01/2011

Authors:

Jónína Þ. Jóhannsdóttir, Friðbjörn Möller (student), María Pétursdóttir, Rannveig Björnsdóttir

Supported by:

Fisheries Project Fund, University of Akureyri Research Fund, Student Innovation Fund

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.  

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Reports

Experimental production of natural zooplankton and the quality of stored eggs

Published:

01/03/2010

Authors:

Jónína Þ. Jóhannsdóttir, Hugrún Lísa Heimisdóttir (student of the University of Akureyri), Friðbjörn Möller, Rannveig Björnsdóttir

Supported by:

Fisheries Project Fund, Student Innovation Fund, University of Akureyri Research Fund

Experimental production of natural zooplankton and the quality of stored eggs

Plankton is the most important food for our juveniles' main fish stocks and redfish is the most common species of plankton in Iceland, but Acartia species can also be found in plankton almost all year round. The aim of the project was to cultivate selected species of natural zooplankton that are common in Iceland (redfish and Acartia) and produce hibernation eggs to ensure its supply all year round. In connection with the project, facilities have been set up for the cultivation of zooplankton and live algae that were used as feed for the plankton. Wild zooplankton has been collected using various methods and breeding experiments performed under different environmental conditions. Experiments have also been performed with the hatching eggs of Acartia tonsa in two separate experiments. The main results indicate that the animals are very sensitive to any kind of treatment as well as temperature changes during collection. There were large losses in the first days after collection and it proved difficult to keep the animals alive for more than a few weeks. Nutrition has a far-reaching effect on animal reproduction, performance and productivity, and the results indicate that the algae concentrate used was not suitable for the cultivation of zooplankton, but much better results were obtained with the use of live algae. The hatching of the laying eggs went well and they managed to get the animals to produce eggs. Subsequently, it is planned to investigate the effects of various factors such as the nutritional content of food, food supply and density on the development, sex ratio and egg production of the animals.

Zooplankton is the food source of our fish stocks, with Calanus finmarchicus being the most abundant species in the marine ecosystem around Iceland in addition to Acartia that may be found in the zooplankton throughout the year. The overall goal of this project was to culture natural zooplankton species (Calanus finmarchicus and Acartia) for production of eggs that is the basis for commercial production of copepods. Facilities for culturing zooplanktonic species and live algae have been set up as part of the project. Natural zooplankton has been collected using various approach and attempts have been made to culture copepods under various conditions. Eggs of Acartia tonsa have furthermore been hatched and cultured in two separate experiments. The main results indicate that zooplankton species are extremely sensitive to handling and temperature changes during collection and transport. Significant losses were observed during the first days following collection and the copepod cultures only survived through a few weeks. Previous studies show that nutrition profoundly affects reproduction, survival and productivity of zooplankton species. The present results indicate that the algae paste used did not fulfill the nutritional requirements of the copepods but improved results were achieved using live algae cultures. Hatching of dormant eggs proved successful and eggs have been collected from the experimental units. Further experiments are planned with the aim to study the effects of nutrition, food supply and copepod densities on the development, sex ratio and productivity of the cultures.

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