INCUBATION OF TURTLE EGGS AT DIFFERENT TEMPERATURES - DO EMBRYOS COMPENSATE FOR TEMPERATURE DURING DEVELOPMENT

Freshwater turtle eggs are normally subjected to fluctuations in incub ation temperature during natural incubation. Because of this, developi ng embryos may make physiological adjustments to growth and metabolism in response to incubation at different temperatures. I tested this hy pothesis by incubating eggs of the Brisbane river turtle Emydura signa ta under four different temperature regimes, constant temperatures of 24 degrees C and 31 degrees C throughout incubation, and two swapped-t emperature treatments where incubation temperature was changed approxi mately halfway through incubation. Incubation at 31 degrees C took 42 d, and incubation at 24 degrees C look 78 d, with intermediate incubat ion periods for the swapped-temperature treatments. Hatchling mass, ha tchling size, and total oxygen consumed during development were simila r for all incubation regimes. The pattern of oxygen consumption during the last phase of incubation as reflected by rate of increase of oxyg en consumption, peak oxygen consumption, and fall in oxygen consumptio n before hatching was determined solely by the incubation temperature during the last phase of incubation; that is, incubation temperature d uring the first phase of incubation had no influence on these factors. Thus there is no evidence of temperature compensation in growth or de velopment during embryonic development of E. signata eggs.