LC-PUFAS AND GUT MICROBIAL COMMUNITY OF WILD AND HATCHERY RABBIT FISH Siganus guttatus LARVAE

Duy V.B. Le*,**, Phuoc N. Nguyen, Kristof Dierckens, Dung V. Nguyen, Nico Boon, Tim Lacoere Frederiek-Maarten Kerckhof, Jo De Vrieze, Peter Bossier
 
*Laboratory of Aquaculture & Artemia Reference Center, Ghent University
Ghent B-9000, Belgium
**Faculty of Fisheries, Hue University of Agriculture and Forestry, Hue 53000, Vietnam
VanBaoDuy.Le@UGent.be
 

In this study, the PUFA composition of body tissue and the gut MC of hatchery and wild larvae of rabbit fish at 3 different locations in Vietnam (ThuanAn, QuangNam and BinhDinh) over a period of 3 years were investigated. Results from this study showed that rabbit fish larvae contained high proportion of ARA. The ARA proportion of wild larvae was stable between sampling locations over the three-year period, and no significant differences were detected in the ARA level between wild and hatchery samples. The DHA/EPA ratios in fish larvae were very high and varied between locations. The PUFA composition is within the normal range in the wild. The difference between temperatures at the 3 locations are negatively correlated with the DHA content and the DHA/EPA ratio, but not the EPA content.

The results of Illumina analysis of 16S libraries of wild samples showed that the location affected the gut MC composition. The bacteria that were identified in the rabbit fish gut content were mainly belonging in the Proteobacteria, Bacteroidetes, Fusobacteria,Actinobacteria and Firmicutes phyla. In addition, the gut MC diversity and composition of hatchery larvae, which were fed probiotic-enriched rotifers, was completely different than those in the gut of wild larvae. The probiotic strains (Lactobacillus plantarum, L. fermentum, L. brevis, Pediococcus acidilactici, P. pentosaceus and B. subtilis) were predominant in the hatchery larvae. Next, relative genetic distances between ThuanAn and BinhDinh/QuangNam were bigger than those between BinhDinh-QuangNam. More importantly, sampling location had significant impacts on the MC. The diversity of gut MC increased significantly from the north to the south.  In conclusion, the current larval rearing protocol is reliable in terms of PUFA profile and probiotics. The hatchery larvae should not be treated differently in the future.