Publication
Title
Physiological mechanisms constraining ectotherm fright-dive performance at elevated temperatures
Author
Abstract
Survival of air-breathing, diving ectotherms is dependent on their capacity to optimise the time available for obligate underwater activities, such as predator avoidance. Submergence times are thermally sensitive, with dive durations significantly reduced by increases in water temperature, deeming these animals particularly vulnerable to the effects of climate change. The physiological mechanisms underlying this compromised performance are unclear but are hypothesised to be linked to increased oxygen demand and a reduced capacity for metabolic depression at elevated temperatures. Here, we investigated how water temperature (both acute and chronic exposures) affected the physiology of juvenile estuarine crocodiles (Crocodylus porosus) performing predator avoidance dives (i.e. fright-dives). Diving oxygen consumption, fright bradycardia, haematocrit and haemoglobin (indicators of blood oxygen carrying capacity) were assessed at two test temperatures, reflective of different climate change scenarios (i.e. current summer water temperatures, 28°C, and high climate warming, 34°C). Diving oxygen consumption rate increased threefold between 28 and 34°C (Q10=7.4). The capacity to depress oxygen demand was reduced at elevated temperatures, with animals lowering oxygen demand from surface levels by 52.9±27.8% and 27.8±16.5% (means±s.e.m.) at 28°C and 34°C, respectively. Resting and post-fright-dive haematocrit and haemoglobin were thermally insensitive. Together these findings suggest decrements in fright-dive performance at elevated temperatures stem from increased oxygen demand coupled with a reduced capacity for metabolic depression.
Language
English
Source (journal)
The journal of experimental biology. - London
The journal of experimental biology. - London
Publication
London : 2017
ISSN
0022-0949
Volume/pages
220 :19 (2017) , p. 3556-3564
ISI
000412240500025
Full text (Publisher's DOI)
Full text (open access)
UAntwerpen
Publication type
Subject
External links
Web of Science
Record
Identification
Creation 15.10.2018
Last edited 19.09.2021