Carbon dioxide influences environmental sex determination in two species of turtles

Published source details Etchberger C.R., Ewert M.A., Phillips J.B. & Nelson C.E. (2002) Carbon dioxide influences environmental sex determination in two species of turtles. Amphibia-Reptilia, 23, 169-175.
Share Tweet Email

Actions

This study is summarised as evidence for the following.

	Action	Category
	Relocate nests/eggs for artificial incubation: Tortoises, terrapins, side-necked & softshell turtles Action Link

Relocate nests/eggs for artificial incubation: Tortoises, terrapins, side-necked & softshell turtles

A replicated study in 1992 in Pennsylvania, USA (Ewert et al. 2002) found that most artificially incubated pond slider Trachemys scripta and Mississippi map turtle Graptemys pseudogeographica kohni eggs hatched successfully, but higher CO₂ concentrations during incubation led to lower hatching success for pond sliders in two of three comparisons and a higher proportion of female hatchlings for both species. Compared to 0% CO_2,hatching success was lower at the highest concentration of CO₂ for pond sliders (24 of 25 eggs at 0% CO₂ vs 4 of 25 at 15% CO₂; all with 21% oxygen), but remained similar at medium CO₂ concentrations for both species (pond sliders: 21 of 25 at 10% CO₂; map turtles: 12 of 14 at 0% CO₂ vs 7 of 14 at 10% CO₂; all with 21% oxygen). The proportion of males to females was lower at higher concentrations of CO₂ for pond sliders (0%: 22:2; 10%: 11:12; 15%: 4:6) and map turtles (0%: 10:2; 10%: 3:6). A separate trial for pond slider eggs at high CO₂ (15%) and 10% oxygen resulted in 0 of 24 eggs hatching successfully and a sex ratio of one male to six female embryos. In 1992, gravid, wild female turtles were injected with oxytocin to obtain their eggs. Groups of 25 pond slider eggs were incubated at 0, 10 or 15% CO₂, and groups of 14 map turtle eggs were incubated at 0 or 10% CO₂, all with 21% oxygen. A further 24 pond slider eggs were assigned to a treatment involving high CO₂ (15%) and reduced oxygen levels (10%).

(Summarised by: William Morgan)