Evaluation of recently isolated Australian tropical microalgae for the enrichment of the dietary value of brine shrimp, Artemia nauplii

Thirteen species of tropical Australian microalgae (both benthic and planktonic) were compared in terms of survival and growth of Artemia and enrichment of polyunsaturated fatty acids (PUFAs), including eicosapenaenoic acid (EPA; 20:5n−3) and docosahexaenoic acid (DHA; 22:6n−3) in Artemia. Artemia nauplii showed enhanced growth beyond the unfed control value after 24 h feeding with all species of microalgae except Isochrysis NT14. However, when the growth was compared against the commercial northern hemisphere species Isochrysis galbana TISO, only Artemia fed Cryptomonas CRFI01 showed better growth (significance at P<0.05). Artemia fed Chaetoceros sp. CS256, Nephroselmis GOC52, Tetraselmis sp. NT18 and Nitzschia palacea NT7 showed similar growth over 24 h to those fed TISO. Artemia consumed Isochrysis NT14 at a very low rate. In 7 day feeding trials, CRFI01, CS256 and GOC52 performed much better than TISO (P<0.05) as food sources for Artemia. The species Isochrysis sp. PS11, Tetraselmis spp. TEQL01 and NT18, and NT7 showed similar results to TISO. Survival of Artemia at the end of a 7 day feeding with seven species of microalgae (NT7, PS11, CRFI01, NT18, CS256, TEQL01, and GOC52) ranged from 65 to 97%, with NT18 showing a wide range of survival results, due to the crash of some of the cultures. The suitability of these tropical Australian microalgae as a food source for Artemia was related to the fatty acid composition of the microalgae, rather than the taxonomic group, size or proximate chemical composition. Artemia fed CRFI01 had significantly higher levels of EPA and DHA (P<0.05) than those fed TISO. Artemia fed CS256 and NT7 had highest levels of EPA, however, only Artemia fed CS260 had higher amounts of DHA than Artemia fed TISO. The results showed that one species of tropical Australian microalgae CRFI01 was superior to the commercial northern hemisphere TISO as a food source for Artemia. NT7, PS11, CS256 and GOC52 could be used as a replacement or supplementary feed to TISO