Investigation of an Artemia-based diet for larvae of the mud crab Scylla serrata

摘要

Techniques for the mass propagation of the mud crab Scylla spp. in hatcheries are in demand to supply the requirements of an expanding growout industry. Culture of the crab larvae currently utilizes an Artemia-based diet through most of the hatcherycycle. A series of experiments was designed to test the performance of the nauplii of different commercially available Artemia cyst products, sourced from various geographic regions, and nauplii enriched with a commercial lipid emulsion. The influence of microalgae addition to the larval culture medium to allow continuous enrichment of Artemia was also tested. Each of the test diets was analyzed biochemically and the resulting profile, combined with larval performance data was used to determine the relationships between larval growth and mortality and nutritional components. Nauplii of eight Artemia cyst products were tested, but only two promoted growth and survival through the first metamorphosis from the zoea to the megalopa stage. Crab larval growth and survival were similar among the Artemia types fed up to the onset of metamorphosis, at around days 12 to 16. From this point onwards, the 'good' and the 'poor' Artemia types diverged. Larvae fed with nauplii of the 'poor' Artemia types failed to complete the metamorphic molt. To obtain maximum larval performance when using an Artemia nauplii diet, mud crab hatcheries need to be selective of cyst source. Enriching Artemia nauplii elevated total lipid levels and those of a number of fatty acids, including docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). However, it did not influence the ability of larvae to complete development. The nutritional component that best correlated with larval survival was phospholipid. It is suggested that further work is required to elucidate the role of phospholipid in the diet of mud crab larvae.