Digestive enzyme profiles of spiny lobster Jasus edwardsii phyllosoma larvae

Digestive enzyme activities of cultured (Stage I to VI) and wild (Stage V to XI) phyllosoma larvae of the spiny lobster Jasus edwardsii were investigated over progressive stages of development to provide an indication of their digestive capabilities and nutritional requirements and to help identify the characteristics of their natural prey. Protease, trypsin, amylase, α-glucosidase, chitinase and lipase were detected in all cultured and wild specimens, suggesting phyllosoma can readily digest dietary protein, lipid and carbohydrate, including chitin at all stages of development. Protease and lipase activities were considerably higher than amylase and α-glucosidase, indicating that dietary protein and lipid is more important than carbohydrate and thus suggests a carnivorous diet. Total digestive enzyme activities (Units larva-1, units defined as the amount of enzyme that catalysed the release of 1 μmole of product per minute) increased significantly with larval development, reflecting the considerable increase in digestive capacity that is required to meet the metabolic requirements of increasing larval body mass. Relatively constant specific enzyme activity (Units mg-1) in cultured larvae fed the same diet suggests that specific activity variations evident in wild larvae may reflect changes in natural diet or feeding abilities. A large increase in protease, trypsin and amylase specific activity between wild phyllosoma Stages VI and VII may be driven by an increase in food availability or processing efficiency that precedes a large increase in phyllosoma size. Enzyme profiles for both cultured and wild J. edwardsii phyllosoma suggest that spiny lobster phyllosoma are capable of digesting a wide range of zooplankton prey, but they make best use of dietary items that are high in protein and lipid.