Atlantic salmon show capability for cardiac acclimation to warm temperatures

Area of Science:

• Environmental physiology
• Ecology
• Climate change biology

Background:

• Global warming causes rising environmental temperatures, impacting ectotherm performance.
• Cardiac function is a known limiting factor for ectotherm tolerance to high temperatures.

Purpose of the Study:

• To investigate cardiac responses to acute warming in Atlantic salmon from different European populations.
• To assess the role of cardiac plasticity in Atlantic salmon's adaptation to rising temperatures.

Main Methods:

• Comparing cardiac responses of northern and southern Atlantic salmon populations to acute warming.
• Acclimating fish to common temperatures (12°C and 20°C) to assess thermal tolerance.
• Measuring maximum heart rate and temperature of cardiac collapse.

Main Results:

• Atlantic salmon populations showed similar cardiac responses to warming when acclimated to common temperatures.
• Cardiac collapse occurred around 21-23°C for fish acclimated to 12°C, with a max heart rate of ~150 bpm.
• Acclimation to 20°C raised the cardiac collapse temperature to 27.5°C and max heart rate to ~200 bpm.
• Minor population differences in cardiac response were observed, correlating with habitat temperature.

Conclusions:

• Atlantic salmon possess significant cardiac plasticity that is largely independent of natural habitat.
• This cardiac plasticity is a crucial mechanism for Atlantic salmon to potentially cope with the effects of global warming.