Critical thermal maxima of early life stages of three tropical fishes: effects of rearing temperature and experimental heating rate

Marine ectotherms are often sensitive to thermal stress, and certain life stages can be particularly vulnerable (e.g., larvae or spawners). In this study, we investigated the critical thermal maxima (CTmax) of larval and early juvenile life stages of three tropical marine fishes (Acanthochromis polyacanthus, Amphiprion melanopus, and Lates calcarifer). We tested for potential effects of developmental acclimation, life stage, and experimental heating rates, and we measured metabolic enzyme activities from aerobic (citrate synthase, CS) and anaerobic pathways (lactate dehydrogenase, LDH). A slightly elevated rearing temperature neither influenced CTmax nor CS activity, which otherwise could have indicated thermal acclimation. However, we found CTmax to either remain stable (Acanthrochromis polyacanthus) or increase with body mass during early ontogeny (Amphiprion melanopus and Lates calcarifer). In all three species, faster heating rates lead to higher CTmax. Acute temperature stress did ...

海洋外温动物（marine ectotherms）通常对热胁迫较为敏感，特定生命阶段尤为脆弱（如幼体或产卵个体）。本研究针对3种热带海洋鱼类——多棘刺雀鲷（Acanthochromis polyacanthus）、眼斑双锯鱼（Amphiprion melanopus）、尖吻鲈（Lates calcarifer）的幼体与早期稚鱼阶段，开展了临界热极限（critical thermal maxima，CTmax）的相关研究。我们检测了发育驯化（developmental acclimation）、生命阶段以及实验升温速率的潜在影响，并测定了有氧代谢途径相关的柠檬酸合酶（citrate synthase，CS）与无氧代谢途径相关的乳酸脱氢酶（lactate dehydrogenase，LDH）的代谢酶活性。略高于常规水平的饲养温度既未对CTmax产生影响，也未改变CS活性——这一结果本可提示存在热驯化（thermal acclimation）现象。然而，我们发现CTmax要么保持稳定（多棘刺雀鲷），要么随早期个体发育过程中的体质量增加而升高（眼斑双锯鱼与尖吻鲈）。在所有3个物种中，更快的升温速率均会导致更高的CTmax。急性温度胁迫未……