EFFECTS OF INCUBATION-TEMPERATURE ON THE ENERGETICS OF EMBRYONIC-DEVELOPMENT AND HATCHLING MORPHOLOGY IN THE BRISBANE RIVER TURTLE EMYDURA-SIGNATA

Incubation temperature and the amount of water taken up by eggs from t he substrate during incubation affects hatchling size and morphology i n many oviparous reptiles. The Brisbane river turtle Emydura signata l ays hard-shelled eggs and hatchling mass was unaffected by the amount of water gained or lost during incubation. Constant temperature incuba tion of eggs at 24 degrees C, 26 degrees C, 28 degrees C and 31 degree s C had no effect on hatchling mass, yolk-free hatchling mass, residua l yolk mass, carapace length, carapace width, plastron length or plast ron width. However, hatchlings incubated at 26 degrees C and 28 degree s C had wider heads than hatchlings incubated at 24 degrees C and 31 d egrees C. Incubation period varied inversely with incubation temperatu re, while the rate of increase in oxygen consumption during the first part of incubation and the peak rate of oxygen consumption varied dire ctly with incubation temperature. The total amount of oxygen consumed during development and hatchling production cost was significantly gre ater at 24 degrees C than at 26 degrees C, 28 degrees C and 31 degrees C. Hatchling mass and dimensions and total embryonic energy expenditu re was directly proportional to initial egg mass.