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Sub-lethal temperature thresholds indicate acclimation and physiological limits in brook trout Salvelinus fontinalis |
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| Authors: | Scott M Morrison Theresa E Mackey Travis Durhack Jennifer D Jeffrey Lilian M Wiens Neil J Mochnacz Caleb T Hasler Eva C Enders Jason R Treberg Ken M Jeffries |
| Institution: | 1. Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada;2. Biology Department, University of Winnipeg, Winnipeg, Manitoba, Canada;3. Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
Fisheries and Oceans Canada, Freshwater Institute, Winnipeg, Manitoba, Canada;4. Fisheries and Oceans Canada, Freshwater Institute, Winnipeg, Manitoba, Canada |
| Abstract: | The upper thermal tolerance of brook trout Salvelinus fontinalis was estimated using critical thermal maxima (CTmax) experiments on fish acclimated to temperatures that span the species' thermal range (5–25°C). The CTmax increased with acclimation temperature but plateaued in fish acclimated to 20, 23 and 25°C. Plasma lactate was highest, and the hepato-somatic index (IH) was lowest at 23 and 25°C, which suggests additional metabolic costs at those acclimation temperatures. The results suggest that there is a sub-lethal threshold between 20 and 23°C, beyond which the fish experience reduced physiological performance. |
| Keywords: | body condition critical thermal maxima fish hepato-somatic index lactate osmolality |