Role of lipids in the diet of cultured and wild rock lobster larvae

Food web interactions and appropriate forms of feed to promote growth and survivorship of phyllosoma larvae of rock lobsters in culture were examined. In particular, the role of key lipid nutrients has been investigated. These important steps are critical for closing the life cycle of rock lobster in aquaculture. Several protocols for enrichment of brine shrimp, Artemia, with essential polyunsaturated fatty acids (PUPA) were trialed. For the first time, Artemia were simultaneously enriched with essential PUPA [arachidonic (AA), eicos~pentaenoic (EPA) and docosahexaenoic (DHA) acids] in ratios specific to, and based on analyses of, wild phyllosomata. Newly-hatched phyllosomata of southern rock lobster, Jasus edwardsii, were fed enriched Artemia and on-grown to stage V in flow-through aquaria. Larvae decreased in total lipid from stages 1-V. The major lipid class in all phyllosomata was polar lipid (PL), followed by sterol (ST), with no triacylglycerol (TAG) detected. Cultured phyllosomata had levels of AA and EPA similar to wild phyllosomata, although lowerDHA. To elucidate feeding capabilities, phyllosomata of packhorse lobster, Jasus verreauxi, were presented various food items and given chemical/tactile stimulation to induce feeding response. Phyllosomata are capable of processing hard prey items, and become entangled and fail to feed on soft tissue, such as jellyfish and mussel gonad. This represents the first documentation of the ability to process and ingest food by live phyllosomata. Results from feeding trials, and analyses of potential prey items and pueruli, indicate that phyllosomata may require PUPA in PL form, which is largely unavailable via Artemia. Therefore, J. edwardsii phyllosomata were on-grown from newlyhatched to stage V, in static culture with antibiotics. Feeding larvae utilizing a PLrich diet attached to mesh was compared to feeding with Artemia, enriched with a TAG-rich or an ethyl ester (EE)-rich nutrient source. For Artemia-fed phyllosomata, survival was high and total lipid remained generally constant to stage V. Both were notably higher than observed in previous feeding trials. The main fatty acids were oleic, linoleic, palmitic, EPA, stearic, cis-vaccenic, AA and DHA. Essential PUPA decreased from newly-hatched to stage V, although phyllosomata had absolute levels of essential PUP A greater than prior trials. The PL-rich diet displayed potential, as presence of faecal trails and molting confirmed that phyllosomata were consuming the diet. This thesis has furthered understanding of phyllosomata physiology in challenging traditional ideology that larvae require PUPA in TAG form (i.e. Artemia). It demonstrated that lipids and PUP A are important nutritional components in rock lobster larvae. Feeding lipid-enriched Artemia was proven successful in early stages. The development of diets suitable for later stage larvae, with emphasis on enhancing PL, is a new and promising approach. Advancement of these concepts will facilitate successful culture of rock lobsters.