Journal
CONSERVATION PHYSIOLOGY
Volume 4, Issue -, Pages -Publisher
OXFORD UNIV PRESS
DOI: 10.1093/conphys/cow062
Keywords
Aerobic scope; body size; critical thermal maximum; freshwater fish; hypoxia tolerance; metabolic rate
Funding
- Natural Sciences and Engineering Research Council of Canada (NSERC) [443206-2013, 312201-2010]
- Fonds Quebecois de la Recherche sur la Nature et les Technologies [176498-2013]
- McGill University [00286]
- Canada Research Chair research funds [950-228 344]
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Key to predicting the response of fishes to climate change is quantifying how close fish are to their critical thermal limits in nature and their ability to adjust their thermal sensitivity to maintain performance. Here, we evaluated the effects of body size and habitat on aerobic scope (AS) and thermal tolerance of Nile perch Lates niloticus (L.), a fish of great economic and food security importance in East Africa, using respirometry and critical thermal maximum (CTmax) trials. Juvenile Nile perch from distinct habitats (high or low dissolved oxygen concentrations) of Lake Nabugabo, Uganda were exposed for 4.6 +/- 0.55 days to a temperature treatment (25.5, 27.5, 29.5 or 31.5 degrees C) prior to experimentation, with the lowest temperature corresponding to the mean annual daytime temperature in Lake Nabugabo and the highest temperature being 3 degrees C higher than the maximal monthly average. As expected, metabolic rates increased with body mass. Although resting metabolic rate increased with temperature, maximal metabolic rate showed no change. Likewise, AS did not vary across treatments. The CTmax increased with acclimation temperature. There was no effect of habitat on maximal metabolic rate, AS or CTmax; however, there was a trend towards a lower resting metabolic rate for Nile perch captured in the low-dissolved oxygen habitat than in well-oxygenated waters. This study shows that juvenile Nile perch maintain a large AS at temperatures near the upper limit of their natural thermal range and provides evidence that Nile perch have physiological mechanisms to deal with acute exposure to thermal stress.
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