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

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.

Diet changes thermal acclimation capacity, but not acclimation rate in a marine ectotherm (Girella nigricans) during warming

“…Christen et al . [59] found significant negative linear relationships between thermal limits (time to CT max ) and omega-3 fatty acid composition in Salvelinus alpinus, Salvelinus fontinalis , and their hybrids. Here, there were some significant correlations between specific fatty acids and cardiac thermal limits, although there was no significant linear regression found between overall DBI and cardiac thermal limits.…”

“…Given the high degree to which cells can regulate membrane performance and the many other functions for lipids in the body, it is not surprising that only ~20-30% of the variation in fHmax could be explained by fatty acid composition. Christen et al [59] found significant negative linear relationships between thermal limits (time to CTmax) and omega-3 fatty acid composition in Salvelinus alpinus, Salvelinus fontinalis, and their hybrids. Here, there were some significant correlations between specific fatty acids and cardiac thermal limits, although there was no significant linear regression found between overall DBI and cardiac thermal limits.…”

“…Given the high degree to which cells can regulate membrane performance and the many other functions for lipids in the body, it is not surprising that only ~20-30% of the variation in fHmax could be explained by fatty acid composition. Christen et al [59] found significant negative linear relationships between thermal limits (time to CTmax) and omega-3 fatty acid composition (which was not certified by peer review) is the author/funder. All rights reserved.…”

Diet changes thermal acclimation capacity, but not acclimation rate, in a marine ectotherm (Girella nigricans) during warming

“…Given the high degree to which cells can regulate membrane performance and the many other functions for lipids in the body, it is not surprising that only approximately 20-30% of the variation in f Hmax could be explained by fatty acid composition. Christen et al [59] found significant negative linear relationships between thermal limits (time to CT max ) and omega-3 fatty acid composition in Salvelinus alpinus, S. fontinalis, and their hybrids. Here, there were some significant correlations between specific fatty acids and cardiac thermal limits, although there was no significant linear regression found between overall DBI and cardiac thermal limits.…”

Summer Is Coming! Tackling Ocean Warming in Atlantic Salmon Cage Farming

“…Still, there is no consensus about the OCLTT hypothesis (e.g., [ 65 , 66 ]) including in salmon, as other studies have shown that the aerobic scope of Atlantic salmon (~450 g fish) remains the same across different temperatures (13, 18, 23 °C) [ 61 ]. Thus, thermal tolerance limits of fish could be oxygen-independent [ 67 ] and be related to other mechanisms, namely loss of macromolecular integrity (e.g., [ 68 ]), dysregulation of sarcolemmal ion regulation (altering ventricular excitation, e.g., [ 69 ]) and disruption of biological membranes and antioxidant capacity (e.g., [ 70 ], and see [ 71 ] for a brief discussion). Other authors have also shown that thermal tolerance limits are modulated by heat-induced neural dysfunction associated with limited oxygen availability [ 72 ].…”