| The maintenance of a functional energy balance in ectothermic fauna could be challenging in a thermally disparate environment. Biochemical adaptations at the enzyme and membrane levels allows for a set compensatory mechanism that allow the individual to maintain an energetic surplus, thus allocating energy for growth and reproduction. The present work describes how the energetic machinery in the cell, particularly the mitochondrion, could be affected by temperature changes. More specifically, this work aimed to determine how environmental temperature affects the mitochondria energetic performance of fishes from disparate thermal regimes.;Mitochondrial ATP production efficiency was evaluated in fishes from polar, tropical and subtropical regions. In polar fishes, mitochondria remained functional at temperatures well beyond whole organismal critical temperatures. On the other hand, tropical and subtropical teleosts exhibited a decrease in mitochondrial efficiency at temperatures commonly found during summer seasons. This remarkable variability of mitochondrial thermal sensitivity may restrict the energy allocated for growth and reproduction during the summer months in tropical and subtropical regions. The observed variation in the thermal window of tolerance of mitochondrial function in fishes provides further insight into how the energetic machinery responds to thermal changes, like those associated with warming trends in marine ecosystems. In addition, the reduced efficiency in mitochondrial function among teleosts from latitudinal gradients suggest that warm-adapted species are close to their upper tolerance range, and further warming trends could severely impact the energy budget of fishes. |
