Viliame P Waqalevu
Post Doctorate Fellow at Ecole Pratique des Hautes Etudes (CRIOBE - Centre de Recherche Insulaire et Observatoire de l’Environnement). PhD graduate of the United Graduate School of Agricultural Sciences (combined Saga University, Ryukyus University, Kagoshima University). Specializes in marine fish aquaculture, post-larval reef fish capture, identification and culture and coastal ecology. PhD dissertation on 'Development of enrichment of Brachionus plicatilis species complex for initial feeding to marine fish larvae'.
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[Methods] Three commercial rotifer enrichment formulations were tested: DHA-enriched Super Chlorella vulgaris (E1), frozen and concentrated Nannochloropsis oculata (E2), and Salmon roe emulsion oil (E3) which were batch cultured in 5L polycarbonate tanks for 24 hours. The rotifers were fed a control diet of C. vulgaris (C1), directly harvested from the continuous culture system. Lipids were extracted from samples and fatty acid analysis was conducted. Growth ratio (%) was calculated by population density (rotifers/mL) measurements immediately before enrichment and after 24 hours of enrichment.
[Results] E3 was observed to be the optimal enrichment treatment for SS-type rotifers, with significant difference in levels of DHA proportion (8.4 ± 1.93% (neutral lipid), 8.55 ± 2.20% (phospholipid)). Significant differences were found in EPA proportions in E2 treatment (5.51 ± 1.60% (phospholipid)) and in E3 (1.54 ± 2.83% (phospholipid)). For L-type rotifers, E1 contained significant differences in DHA levels in content per rotifer (1.91 ± 0.17mg/g (neutral lipid)) and in proportion (0.54 ± 0.14% (phospholipid)). ARA levels were observed to be highest in E2 for SS-type rotifers (8.76 ± 1.67% (neutral lipid)). EPA levels were observed to be low in E2 treatment in both SS-type and L-type, which may be an indication of insufficient N. oculata dosage for effective enrichment. Despite the high nutritional value of the emulsion oil treatment, it was found that it had the lowest survival rate and growth ratio in both SS and L-type.
[Methods] Three commercial rotifer enrichment formulations were tested: DHA-enriched Super Chlorella vulgaris (E1), frozen and concentrated Nannochloropsis oculata (E2), and Salmon roe emulsion oil (E3) which were batch cultured in 5L polycarbonate tanks for 24 hours. The rotifers were fed a control diet of C. vulgaris (C1), directly harvested from the continuous culture system. Lipids were extracted from samples and fatty acid analysis was conducted. Growth ratio (%) was calculated by population density (rotifers/mL) measurements immediately before enrichment and after 24 hours of enrichment.
[Results] E3 was observed to be the optimal enrichment treatment for SS-type rotifers, with significant difference in levels of DHA proportion (8.4 ± 1.93% (neutral lipid), 8.55 ± 2.20% (phospholipid)). Significant differences were found in EPA proportions in E2 treatment (5.51 ± 1.60% (phospholipid)) and in E3 (1.54 ± 2.83% (phospholipid)). For L-type rotifers, E1 contained significant differences in DHA levels in content per rotifer (1.91 ± 0.17mg/g (neutral lipid)) and in proportion (0.54 ± 0.14% (phospholipid)). ARA levels were observed to be highest in E2 for SS-type rotifers (8.76 ± 1.67% (neutral lipid)). EPA levels were observed to be low in E2 treatment in both SS-type and L-type, which may be an indication of insufficient N. oculata dosage for effective enrichment. Despite the high nutritional value of the emulsion oil treatment, it was found that it had the lowest survival rate and growth ratio in both SS and L-type.