Thermal tolerance and fish heart integrity: fatty acids profiles as predictors of species resilience

• Published in: Conservation physiology 2020, Vol.8 (1), p.coaa108-coaa108
• Main Authors: Christen, Felix, Dufresne, France, Leduc, Gabriel, Dupont-Cyr, Bernard A, Vandenberg, Grant W, Le François, Nathalie R, Tardif, Jean-Claude, Lamarre, Simon G, Blier, Pierre U
• Format: Article
• Language: English
• Subjects: Environmental aspects; Fatty acids; Fishes; Heart; Heat tolerance (Biology); Physiological aspects
• ISSN: 2051-1434; 2051-1434
• DOI: 10.1093/conphys/coaa108

The capacity of ectotherms to adapt to new thermal habitat depends on the physiological impact of changes in temperature. We observed here that heart tolerance to oxidative stress, dictated by membrane fatty acid profile, might be a significant driver in setting upper thermal limits in Arctic charr. Abstract The cardiovascular system is a major limiting system in thermal adaptation, but the exact physiological mechanisms underlying responses to thermal stress are still not completely understood. Recent studies have uncovered the possible role of reactive oxygen species production rates of heart mitochondria in determining species’ upper thermal limits. The present study examines the relationship between individual response to a thermal challenge test (CTmax), susceptibility to peroxidation of membrane lipids, heart fatty acid profiles and cardiac antioxidant enzyme activities in two salmonid species from different thermal habitats (Salvelinus alpinus, Salvelinus fontinalis) and their hybrids. The susceptibility to peroxidation of membranes in the heart was negatively correlated with individual thermal tolerance. The same relationship was found for arachidonic and eicosapentaenoic acid. Total H2O2 buffering activity of the heart muscle was higher for the group with high thermal resistance. These findings underline a potential general causative relationship between sensitivity to oxidative stress, specific fatty acids, antioxidant activity in the cardiac muscle and thermal tolerance in fish and likely other ectotherms. Heart fatty acid profile could be indicative of species resilience to global change, and more importantly the plasticity of this trait could predict the adaptability of fish species or populations to changes in environmental temperature.