Energetics and metabolism of yellowtail kingfish (Seriola lalandi Valenciennes 1833) during embryogenesis

A study was undertaken to measure changes in oxygen consumption and metabolite concentration (ammonia, free amino acids, glucose, glycogen, ninhydrin positive substances and protein) in embryos of yellowtail kingfish (Seriola lalandi) incubated at different temperatures (17, 19, 21 and 23 °C). The oxygen uptake at hatch and total oxygen consumed during embryogenesis was negatively correlated with temperature, and resulted in Q10 values less than 1. This was attributed to the fact that embryos and first hatch larvae have been reported to be smaller at warmer incubation temperatures and therefore consumed less oxygen. Free amino acids were present in high concentrations immediately after spawning (188 ± 15.3 nmol ind− 1) and were dominated by the neutral amino acids alanine, glycine, isoleucine, leucine, serine, and valine. The free amino acid pool was rapidly depleted until hatch (20–40 nmol ind− 1), after which the pool was dominated by glycine, serine, valine and arginine/taurine (unresolved). The loss of positive buoyancy around the time of hatch was likely to be correlated with the decrease in free amino acid content during embryogenesis. The sequence of metabolic fuel use during embryogenesis is likely to be similar to that observed in other marine fish species with pelagic eggs, namely that carbohydrates, lipid and protein are of relatively minor importance compared to the catabolism of free amino acids for energy. Eggs incubated at 17, 19 and 21 °C had similar profiles of metabolite concentration during embryogenesis, however, eggs incubated at 23 °C were found to have a considerably different pattern of substrate utilisation, possibly indicative of abnormal physiological development at a temperature above that which is routinely encountered in the wild.