Evaluation of centrifuged microalgae concentrates as diets for Penaeus monodon Fabricius larvae

Concentrates of nine microalgae widely used in marine hatcheries were prepared by centrifugation, stored chilled for either 9 or 14 weeks and then compared with their fresh counterpart as feeds for Penaeus monodon larvae. The nine species - Chaetoceros muelleri, C. calcitrans, Isochrysis sp. 'Tahitian' (T-ISO), Nannochloropsis oculata, Pavlova lutheri, Skeletonema costatum, Phaeodactylum tricornutum, Tetraselmis chuii and Thalassiosira pseudonana - in fresh and centrifuged forms were fed at high and low cell densities. The Larvatron, a computer-controlled apparatus for rearing planktonic animals, was used for the experiments. Fresh C. muelleri and T. pseudonana promoted the highest survival and fastest development of P. monodon to mysis 1. Although the survival rate of larvae fed concentrated C. muelleri, P. lutheri and T-ISO was comparable with those fed the fresh C. muelleri diet, the larvae fed these concentrates generally developed more slowly. The higher cell density, whether of fresh or concentrated algae, usually produced both higher survival and faster development of larvae. nannochloropsis oculata and P. tricornutum were poor diets, regardless of their form or feeding density. Concentrating C. calcitrans and S. costatum markedly reduced their efficacy as diets. The centrifuged concentrates were unsuitable as complete replacements for fresh algae in larval culture when stored for either 9 or 14 weeks. However, the concentrates may be more successful in combination with other concentrates, fresh algae and/or artificial diets, or when stored for a shorter time.