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5th Euro-Global Summit on Aquaculture & Fisheries

Madrid, Spain

Federico G Witt

Federico G Witt

AlgaEnergy S A
Spain

Title: Nannochloropsis limnetica (Eustigmatophyceae): A new freshwater microalga for rotifer feed in marine hatcheries

Biography

Biography: Federico G Witt

Abstract

Inert feeds are available in the aquaculture market for mass production and enrichment of the rotifer Brachionus plicatilis. Nevertheless, microalgae are still the preferred feed. Although good rotifer growth rates can be achieved with the freshwater Chlorella, marine strains of Nannochloropsis are more suitable due to their higher content in omega-3 PUFAs, mainly EPA. In this work, the growth of the freshwater species Nannochloropsis limnetica at different temperatures in semi-continuous cultures was studied. N. limnetica could be cultured in the range between 15°C and 27°C with highest dry-weight productivities at 22°C. When compared with N. gaditana in semi-continuous cultures at laboratory scale, productivities of both species were similar, reaching 0.64 g l−1 day−1. Moreover, the nutritional values for B. plicatilis of N. limnetica and N. gaditana were compared. Regarding FA, both species showed similar profiles. In laboratory-scale cultures with high algal rations, B. plicatilis concentrations and egg ratios of the rotifer cultured with N. limnetica doubled those attained with identical doses of N. gaditana, while maintaining the same FA profile in the filter-feeder. These results proved the potential of this freshwater species for marine aquaculture. In hatchery-scale experiments in which B. plicatilis was fed with baker's yeast supplemented either with on-site produced fresh microalgal cultures or with concentrated algae, similar growth results were obtained for both microalgal species in 5-day batch cultures, although higher dry weights and slightly better egg ratios were observed with the freshwater strain. Our results demonstrate the potential of the freshwater N. limnetica as a substitute of Chlorella in live-feed production protocols due to its better FA profile. Moreover, N. limnetica promotes higher growth in the rotifer Brachionus plicatilis than its relative marine N. gaditana. Additionally, no potentially pathogenic marine bacteria would be present in cultures of the freshwater species in comparison to its marine counterparts.