Addition of bacteria bioencapsulated in Artemia metanauplii to a rearing system for halibut larvae

• Published in: Aquaculture international Vol. 9; no. 3; pp. 225 - 235
• Main Authors: Makridis, P, Bergh, Oe, Skjermo, J, Vadstein, O
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.01.2001
• Subjects: Aquaculture; Artemia; Artemia franciscana; Bacteria; Experiments; Fish; Hippoglossus hippoglossus; Larvae; Marine; Species composition; Vibrio; Water analysis; Water sampling
• ISSN: 0967-6120; 1573-143X
• DOI: 10.1023/A:1016815929846

The aim of this study was to determine whether it is possible to influence the species composition of the gut microflora in 70-days old halibut larvae (Hippoglossus hippoglossus L.) by addition of bacteria bioencapsulated in Artemia franciscana in two short pulses. Two Vibrio strains, PB 1-11 and PB 6-1 were used. Two treatments received each strain alone, a third treatment received the two bacterial strains in mixture, whereas in a control treatment no bacteria were added. Five fish tanks were included in each treatment. The bacteria were bioencapsulated in Artemia franciscana metanauplii during a short-term incubation in bacterial suspensions of the specific strains, and were added in two pulses, on day 1 and day 10 of the experiment. Addition of bacteria did not increase the total number of colony-forming units (CFU) in the larval gut. The total CFU in the water was lower in tanks added bioencapsulated bacteria than in the control treatment (p < 0.05). An immunocolony blot assay was used to measure the numbers of the specific bacteria added in samples of water, A. franciscana, and fish larvae. At the end of the experiment on day 13, the strain PB 1-11 reached on average 10% of the total CFU when added alone and 25% when added in mixture with PB 6-1. Strain PB 6-1 reached at the end of the experiment 26.8% of the total CFU when added alone and 24.2% when added in mixture with PB 1-11, whereas the percentages of PB 1-11 and PB 6-1 in the control fish were 12.7% and 10.8% of the total CFU, respectively. However, the differences between the experimental treatments compared with the control group were not significant (p > 0.05). The addition of bioencapsulated bacteria in two pulses within a ten days period was therefore not sufficient to influence the species composition of the microflora of the halibut larvae.