Digestive enzyme profiles reveal digestive capacity and potential energy sources in fed and starved spiny lobster (Jasus edwardsii) phyllosoma larvae

The impact of starvation on the digestive enzyme (protease, trypsin, lipase and amylase) activities of Stage I and IV Jasus edwardsii phyllosoma larvae was used to identify the nutrients metabolised or conserved during food deprivation, highlighting the most critical energy reserves. Protease activities increased significantly in both Stages I and IV phyllosoma, suggesting that protein catabolism provided energy during food deprivation. Lipase activity decreased significantly in starved Stages I and IV larvae indicating that lipid may be spared for fuelling later developmental moults. The use of protein, while sparing lipid, may provide immediate energy but not at the expense of long-term lipid energy stores which are known to be important during their lengthy larval phase. The preferential use of protein during short-term periods of starvation suggests that particular attention must be given to providing sufficient protein in artificial diets at all times. Amylase activity in starved Stage I larvae was lower than in fed animals, suggesting that the starved animals are not gaining sufficient carbohydrate. However, amylase activity was similar in fed and starved Stage IV larvae, possibly due to the catabolism of accumulated glycogen stores that were not sufficiently developed in Stage I animals.