Evaluation of microalgae diets for Litopenaeus vannamei larvae using a simple protocol

M. Nuñez, C. Lodeiros, M. de Donato, C. Graziani-2002

Aquaculture International, 10(3) : 177-187

Abstract :

We evaluated native marine microalgae isolated from Northeastern Venezuela, as food for Litopenaeus vannamei larvae, compared to six microalgae commonly used in aquaculture. We evaluated the microalgal ingestability calculating the biomass consumed by larvae, later we evaluated three monoalgal diets on protozoea stages of L. vannamei over 72 hr based on the larval biomass, RNA/DNA index and the proportion of stage retarded larvae. The presence of every microalgae species in the protozoea's digestive tract indicated their consumption. Chaetoceros spp. showed high ingestability and Tetraselmis spp. and Skeletonema sp. Ch1 showed low ingestability. The native microalgae Chaetoceros sp. A1 and Chaetoceros sp. G1 were evaluated as monoalgal diets compared to Chaetoceros gracilis. Ch. gracilis demonstrated the best results when the evaluation was performed with the RNA/DNA index. However, the survival rate, larval biomass and percentage of stage retarded larvae fed with Chaetoceros sp. G1 were not statistically different from those fed with Ch. gracilis. Taking into account that native microalgae produced higher biomass in shorter times when they were cultured in field conditions, the results suggest that native microalgae are adequate for large-scale culture conditions, thus reducing costs. The determination of microalgal size and the larval consumption, dry and organic larvae biomass and specially the RNA/DNA index, were valuable features of this evaluation. The protocol developed in this study could be used to evaluate microalgae quality under different environmental conditions and production regimes.

(Universidad de Oriente, Núcleo de Sucre, Instituto Oceanográfico de Venezuela, Cumaná, 6101, Venezuela, e-mail of C. Lodeiros : clodeiro@sucre.udo.edu.ve)

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