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How repeatable is CTmax within individual brook trout over short- and long-time intervals?

February 26, 2020

As stream temperatures increase due to factors such as heated runoff from impervious surfaces, deforestation, and climate change, fish species adapted to cold water streams are forced to move to more suitable habitat, acclimate or adapt to increased thermal regimes, or die. To estimate the potential for adaptation, a (within individual) repeatable metric of thermal tolerance is imperative. Critical thermal maximum (CTmax) is a dynamic test that is widely used to measure thermal tolerance across many taxa and has been used in fishes for decades, but its repeatability in most species is unknown. CTmax tests increase water temperature steadily over time until loss of equilibrium (LOE) is achieved. To determine if CTmax is a consistent metric within individual fish, we measured CTmax on the same lab-held individually-marked adult brook trout Salvelinus fontinalis at three different times (August & September 2016, September 2017). We found that CTmax is a repeatable trait (Repeatability ± S.E.: 0.48 ± 0.14). CTmax of individuals males was consistent over time, but the CTmax of females increased slightly over time. This result indicates that CTmax is a robust, repeatable estimate of thermal tolerance in a cold-water adapted fish.

Publication Year 2020
Title How repeatable is CTmax within individual brook trout over short- and long-time intervals?
DOI 10.1016/j.jtherbio.2020.102559
Authors Matthew J. O'Donnell, Amy M. Regish, Stephen D. McCormick, Benjamin H. Letcher
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Thermal Biology
Index ID 70209900
Record Source USGS Publications Warehouse
USGS Organization Leetown Science Center