Determining the upper thermal tolerance of Athabasca Rainbow Trout (Oncorhynchus mykiss) across naturally varying stream temperatures

Stream temperature is a key driver of physiological function in ectothermic fish, and fish have clear upper and lower limits to thermal habitat use. Stream temperature increases from climate change are a major threat to coldwater taxa like Athabasca Rainbow Trout (Oncorhynchus mykiss), listed as End...

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Main Authors: Sarah Hnytka, Jordan Rosenfeld, Eva C. Enders
Format: Article
Language:English
Published: Canadian Science Publishing 2025-01-01
Series:FACETS
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Online Access:https://facetsjournal.com/doi/10.1139/facets-2023-0241
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author Sarah Hnytka
Jordan Rosenfeld
Eva C. Enders
author_facet Sarah Hnytka
Jordan Rosenfeld
Eva C. Enders
author_sort Sarah Hnytka
collection DOAJ
description Stream temperature is a key driver of physiological function in ectothermic fish, and fish have clear upper and lower limits to thermal habitat use. Stream temperature increases from climate change are a major threat to coldwater taxa like Athabasca Rainbow Trout (Oncorhynchus mykiss), listed as Endangered under Canada's Species at Risk Act. To better understand their vulnerability to climate change and prioritize recovery locations, Athabasca Rainbow Trout were collected in August 2021 from three streams in the upper Athabasca River, Alberta, Canada, across a gradient of thermal regimes ranging from cold to warm. Individual thermal tolerance was measured using two physiological metrics: agitation temperature (Tag) and critical thermal maxima (CTmax) using a portable streamside laboratory. Tag is a behavioural indicator of a thermal avoidance threshold, whereas CTmax is a physiological response that can be interpreted as the upper thermal limit where long term survival is reduced. Results provide strong evidence that CTmax is a plastic metric in Athabasca Rainbow Trout; however, Tag is not. This suggests that Athabasca Rainbow Trout demonstrate some thermal plasticity in terms of CTmax, yet the lack of plasticity in Tag indicates potential limitations in their adaptability to warming stream temperatures.
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spelling doaj-art-b8d776abe7e446faa3e044a68fa35c492025-08-20T02:31:44ZengCanadian Science PublishingFACETS2371-16712025-01-011011110.1139/facets-2023-0241Determining the upper thermal tolerance of Athabasca Rainbow Trout (Oncorhynchus mykiss) across naturally varying stream temperaturesSarah Hnytka0Jordan Rosenfeld1Eva C. Enders2Freshwater Institute, Fisheries and Oceans Canada, Winnipeg, Manitoba R3T 2N6, CanadaMinistry of Environment, Vancouver, Vancouver, BC, CanadaInstitut national de la recherche scientifique, Quebec City, Quebec G1K 9A9, CanadaStream temperature is a key driver of physiological function in ectothermic fish, and fish have clear upper and lower limits to thermal habitat use. Stream temperature increases from climate change are a major threat to coldwater taxa like Athabasca Rainbow Trout (Oncorhynchus mykiss), listed as Endangered under Canada's Species at Risk Act. To better understand their vulnerability to climate change and prioritize recovery locations, Athabasca Rainbow Trout were collected in August 2021 from three streams in the upper Athabasca River, Alberta, Canada, across a gradient of thermal regimes ranging from cold to warm. Individual thermal tolerance was measured using two physiological metrics: agitation temperature (Tag) and critical thermal maxima (CTmax) using a portable streamside laboratory. Tag is a behavioural indicator of a thermal avoidance threshold, whereas CTmax is a physiological response that can be interpreted as the upper thermal limit where long term survival is reduced. Results provide strong evidence that CTmax is a plastic metric in Athabasca Rainbow Trout; however, Tag is not. This suggests that Athabasca Rainbow Trout demonstrate some thermal plasticity in terms of CTmax, yet the lack of plasticity in Tag indicates potential limitations in their adaptability to warming stream temperatures.https://facetsjournal.com/doi/10.1139/facets-2023-0241critical thermal maximaagitation temperaturethermal physiologyAthabasca Rainbow Troutstreamside laboratoryclimate change
spellingShingle Sarah Hnytka
Jordan Rosenfeld
Eva C. Enders
Determining the upper thermal tolerance of Athabasca Rainbow Trout (Oncorhynchus mykiss) across naturally varying stream temperatures
FACETS
critical thermal maxima
agitation temperature
thermal physiology
Athabasca Rainbow Trout
streamside laboratory
climate change
title Determining the upper thermal tolerance of Athabasca Rainbow Trout (Oncorhynchus mykiss) across naturally varying stream temperatures
title_full Determining the upper thermal tolerance of Athabasca Rainbow Trout (Oncorhynchus mykiss) across naturally varying stream temperatures
title_fullStr Determining the upper thermal tolerance of Athabasca Rainbow Trout (Oncorhynchus mykiss) across naturally varying stream temperatures
title_full_unstemmed Determining the upper thermal tolerance of Athabasca Rainbow Trout (Oncorhynchus mykiss) across naturally varying stream temperatures
title_short Determining the upper thermal tolerance of Athabasca Rainbow Trout (Oncorhynchus mykiss) across naturally varying stream temperatures
title_sort determining the upper thermal tolerance of athabasca rainbow trout oncorhynchus mykiss across naturally varying stream temperatures
topic critical thermal maxima
agitation temperature
thermal physiology
Athabasca Rainbow Trout
streamside laboratory
climate change
url https://facetsjournal.com/doi/10.1139/facets-2023-0241
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AT jordanrosenfeld determiningtheupperthermaltoleranceofathabascarainbowtroutoncorhynchusmykissacrossnaturallyvaryingstreamtemperatures
AT evacenders determiningtheupperthermaltoleranceofathabascarainbowtroutoncorhynchusmykissacrossnaturallyvaryingstreamtemperatures