Hatchling crocodiles maintain a plateau of thermal independence for activity, but at what cost?

Campbell, Hamish A., Sissa, Ornella, Dwyer, Ross G. and Franklin, Craig E. (2013) Hatchling crocodiles maintain a plateau of thermal independence for activity, but at what cost?. Journal of Herpetology, 47 1: 11-14. doi:10.1670/11-160


Author Campbell, Hamish A.
Sissa, Ornella
Dwyer, Ross G.
Franklin, Craig E.
Title Hatchling crocodiles maintain a plateau of thermal independence for activity, but at what cost?
Journal name Journal of Herpetology   Check publisher's open access policy
ISSN 0022-1511
1937-2418
Publication date 2013-01-01
Year available 2013
Sub-type Article (original research)
DOI 10.1670/11-160
Open Access Status Not yet assessed
Volume 47
Issue 1
Start page 11
End page 14
Total pages 4
Place of publication Salt Lake City, UT, United States
Publisher Society for the Study of Amphibians and Reptiles
Language eng
Subject 1103 Clinical Sciences
1105 Dentistry
Abstract Crocodilians show a broad plateau of thermal independence for sustained activity. It has been hypothesized that this reflects a performance breadth necessary for carrying out ecologically important behaviors across a range of ambient temperatures. Here, we swam Saltwater Crocodiles (Crocodylus porosus) in a thermally controlled flume at 23, 28, and 33 degrees C and recorded oxygen consumption (VO2) before and after swimming activity. Ambient temperature altered spontaneous VO2 in a positively linear manner, but there was no significant difference in the distance the crocodiles would swim voluntarily. Excess postexercise oxygen consumption (EPOC) increased 10-fold between swimming trials at 28 and 33 degrees C, and the anaerobic debt took 3 times longer to clear at the higher temperature. The results show that, although C. porosus demonstrated a broad thermal breadth for swimming performance, a higher degree of anaerobic metabolism was required to sustain activity at the upper limits of the thermal plateau. Why crocodiles should choose to sustain an anerobic debt rather than reduce their swimming activity when exposed to high experimental temperatures is perplexing, but the study findings provide a physiological rationale for some of the diel and seasonal activity patterns observed in wild crocodilians.
Formatted abstract
Crocodilians show a broad plateau of thermal independence for sustained activity. It has been hypothesized that this reflects a performance breadth necessary for carrying out ecologically important behaviors across a range of ambient temperatures. Here, we swam Saltwater Crocodiles (Crocodylus porosus) in a thermally controlled flume at 23, 28, and 33°C and recorded oxygen consumption (VO2) before and after swimming activity. Ambient temperature altered spontaneous VO2 in a positively linear manner, but there was no significant difference in the distance the crocodiles would swim voluntarily. Excess postexercise oxygen consumption (EPOC) increased 10-fold between swimming trials at 28 and 33°C, and the anaerobic debt took 3 times longer to clear at the higher temperature. The results show that, although C. porosus demonstrated a broad thermal breadth for swimming performance, a higher degree of anaerobic metabolism was required to sustain activity at the upper limits of the thermal plateau. Why crocodiles should choose to sustain an anerobic debt rather than reduce their swimming activity when exposed to high experimental temperatures is perplexing, but the study findings provide a physiological rationale for some of the diel and seasonal activity patterns observed in wild crocodilians.
Keyword Zoology
Zoology
ZOOLOGY
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Biological Sciences Publications
 
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