Abstract
The influences of temperature and water on the ability of turtle embryos to tolerate hypoxia were investigated by measuring critical oxygen tension, P~c~, at different levels of temperature (22, 27, and 32Β°C) and hydric conditions (3 and 13% gravimetric water content). Eggs were halfβburied in sand with 3 or 13% gravimetric water content and incubated at a constant 30Β°C. Using a closed metabolic chamber, oxygen consumption, \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} $\end{document}, was measured at decreasing oxygen tensions. Embryonic \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} $\end{document} varied as a function of incubation day and temperature, whereas the P~c~ differed among temperatures but not among incubation days. At a given incubation day, the P~c~ increased in direct proportion to temperature. Eggs incubated in sand with 13% gravimetric water content achieved greater mass at days 30 and 39 than did those in sand with 3% gravimetric water content. However, \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} $\end{document}, P~c~, and masses of yolkβfree hatchlings were similar in the two hydric conditions, indicating that hypoxic tolerance of turtle eggs is not curtailed by excessive water absorption. The similarity in P~c~ is likely attributable to the small \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} $\end{document}/surface area ratio of turtle eggs. Within the range of parameters studied, temperature, but not water, can modify the P~c~ of turtle embryos. Β© 1994 WileyβLiss, Inc.