Oxygen levels in mound nests of Crocodylus porosus and Alligator mississippiensis are high, and gas exchange occurs primarily by diffusion, not convection.

Grigg, Gordon C., Thompson, Michael B., Beard, Lyn A. and Harlow, Peter (2010) Oxygen levels in mound nests of Crocodylus porosus and Alligator mississippiensis are high, and gas exchange occurs primarily by diffusion, not convection.. Australian Zoologist, 35 2: 235-244.


Author Grigg, Gordon C.
Thompson, Michael B.
Beard, Lyn A.
Harlow, Peter
Title Oxygen levels in mound nests of Crocodylus porosus and Alligator mississippiensis are high, and gas exchange occurs primarily by diffusion, not convection.
Journal name Australian Zoologist   Check publisher's open access policy
ISSN 0067-2238
Publication date 2010-04-01
Sub-type Article (original research)
Volume 35
Issue 2
Start page 235
End page 244
Total pages 10
Editor Dan Lunney
Place of publication Sydney, Australia
Publisher Royal Zoological Society of New South Wales
Collection year 2011
Language eng
Formatted abstract
We measured gas exchange of eggs and mound material as well as gas concentrations at different times during ncubatlon in the mound nests of the salt water crocodile, Crocodylus porosus and the American alligator, Alligator mississippiensis. Oxygen consumption increased gradually during development in both species, peaking well before hatching (at approximately 80% of the incubation period in A. mississippiensis). The RE of eggs at 30 °C and at peak O, was 0.74 in C. porosus and 0.70 in A mississippiensis. In a typical mound nest of C. porosus, the oxygen demand of the decomposing nest itself is likely to be 4-7 times that of the clutch at the end of incubation, with a respiratory exchange ratio (RE) of about 0.9. Despite the oxygen demand of nest material, the gaseous environment of the nest is favourable for embryonic development. The lowest pO2 we measured was 125 Torr in nests of C. porosus and 133 Torr in nests of A mississippiensis, with maximum pCO 2 of 22 Torr for C. porosus and 23 Torr for A mississippiensis. Although convective gas exchange might be expected through the nest mound, gas exchange between the clutch and the outside air occurs by diffusion. No unifying theory has yet emerged to provide a satisfactory explanation for the apparently random distribution of hole-nesting and mound-nesting within the Crocodylidae.
Keyword Carbon dioxide production
Crocodilian
Eggs
Incubation
Oxygen consumption
Respiratory exchange ratio
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2011 Collection
School of Biological Sciences Publications
 
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Created: Tue, 14 Dec 2010, 11:21:52 EST by Gail Walter on behalf of School of Biological Sciences