Investigating the feasibility and conditions for outdoor microalgae cultivation in Seychelles

Abstract

Microalgae play a critical role in aquaculture hatcheries as a primary food source, supplying lipids, proteins, and vitamins to nearly all aquaculture species. Their cultivation is mostly indoors under controlled conditions, making production resource-intensive. The potential for outdoor microalgae farming in equatorial regions like Seychelles was investigated, relying on abundant sunlight and stable high temperatures for a more cost-effective approach accessible to a broader range of aquaculture practitioners. The optimal light and temperature conditions for growing Tetraselmis spp. and Chaetoceros muelleri, chosen for their hardiness and importance to various aquaculture species, were explored in a factorial experimental design with four treatments: shaded, unshaded, cooling system, non-cooling system, alongside an indoor control. C. muelleri cell density peaked at 887,000 cells/ml in the unshaded-cooled treatment (24.4 - 34.4 °C). Tetraselmis spp. cell density peaked at 159,000 cells/ml indoors at 28.9 °C, though their growth in unshaded-cooled outdoor treatments requires further investigation.