Incubation temperature, energy expenditure and hatchling size in the green turtle ( Chelonia mydas ), a species with temperature-sensitive sex determination

Eggs from the Heron Island, Great Barrier Reef, nesting population of green turtles ( Chelonia mydas ) were incubated at all-male-determining (26°C) and all-female-determining (30°C) temperatures. Oxygen consumption and embryonic growth were monitored throughout incubation, and hatchling masses and body dimensions were measured from both temperatures. Eggs hatched after 79 and 53 days incubation at 26°C and 30°C respectively. Oxygen consumption at both temperatures increased to a peak several days before hatching, a pattern typical of turtle embryos, and the rate of oxygen was higher at 30°C than 26°C. The total amount of energy consumed during incubation, and hatchling dimensions, were similar at both temperatures, but hatchlings from 26°C had larger mass, larger yolk-free mass and smaller residual yolks than hatchlings from 30°C. Because of the difference in mass of hatchlings, hatchlings from 30°C had a higher production cost.