Effect of temperature on yolk and oil droplet consumption by spotted rose snapper larvae Lutjanus guttatus(Perciformes: Lutjanidae)

The yolk is the main energy source for eggs and marine fish larvae. Temperature is a key factor in determining the efficiency of yolk conversion into body tissues, which can affect the size larvae at first feeding. In this work, the effect of different temperatures on the yolk sac consumption and oil droplet by the spotted rose snapper, Lutjanus guttatus was evaluated, in order to determine the adequate culture temperature during the first days after hatch. The fertilized eggs were placed in 20 L plastic tanks at different temperatures (22, 25, 28 and 31°C) with three replicates per treatment. The time and percentage of hatching, larvae total length, yolk consumption (TCV) and oil droplet (TCGA) rates at 0, 24, 48 and 72 h after hatching (HDE) were determined. Eggs incubated at 22°C did not hatch, while hatching time in eggs incubated at 31°C decreased significantly. No differences were observed in hatching percentage between treatments of temperature. Larvae reared at 31°C obtained the higher length value than those reared at 25°C at 0 and 24 HDE. The yolk and oil droplet were consumed faster by larvae reared at 31°C at 0 and 24 HDE. Total mortality was registered for larvae reared at 25 and 31°C at 48 and 72 HDE, respectively. The optimal temperature for egg incubation and newly-hatched L. guttatus larvae was 28°C, which would favorably impel the consumption of energy reserves for its growth and survival.