Diving in a warming world : the thermal sensitivity and plasticity of diving performance in juvenile estuarine crocodiles (**Crocodylus porosus**)

Rodgers, Essie M.; Schwartz, Jonathon J.; Franklin, Craig E.

doi:10.1093/CONPHYS/COV054

Title

Diving in a warming world : the thermal sensitivity and plasticity of diving performance in juvenile estuarine crocodiles (**Crocodylus porosus**)

Author

Rodgers, Essie M.

Schwartz, Jonathon J.

Franklin, Craig E.

Abstract

Air-breathing, diving ectotherms are a crucial component of the biodiversity and functioning of aquatic ecosystems, but these organisms may be particularly vulnerable to the effects of climate change on submergence times. Ectothermic dive capacity is thermally sensitive, with dive durations significantly reduced by acute increases in water temperature; it is unclear whether diving performance can acclimate/acclimatize in response to long-term exposure to elevated water temperatures. We assessed the thermal sensitivity and plasticity of fright-dive capacity in juvenile estuarine crocodiles ( Crocodylus porosus ; n = 11). Crocodiles were exposed to one of three long-term thermal treatments, designed to emulate water temperatures under differing climate change scenarios (i.e. current summer, 28°C; moderate climate warming, 31.5°C; high climate warming, 35°C). Dive trials were conducted in a temperature-controlled tank across a range of water temperatures. Dive durations were independent of thermal acclimation treatment, indicating a lack of thermal acclimation response. Acute increases in water temperature resulted in significantly shorter dive durations, with mean submergence times effectively halving with every 3.5°C increase in water temperature ( Q10 0.17, P < 0.001). Maximal dive performances, however, were found to be thermally insensitive across the temperature range of 2835°C. These results suggest that C. porosus have a limited or non-existent capacity to thermally acclimate sustained fright-dive performance. If the findings here are applicable to other air-breathing, diving ectotherms, the functional capacity of these organisms will probably be compromised under climate warming.

Language

English

Source (journal)

Conservation physiology

Publication

2015

ISSN

2051-1434

DOI

10.1093/CONPHYS/COV054

Volume/pages

3 :1 (2015) , 9 p.