In species with complex life cycles, early developmental stages are often less thermally tolerant than adults, suggesting that they are key to predicting organismal response to environmental warming. Here we document the optimal and lethal temperatures of larval sea urchins, and we use those to calculate the warming tolerance and the thermal safety margin of early larval stages of seven tropical species. Larvae of Echinometra viridis, Echinometra lucunter, Lytechinus williamsi, Eucidaris tribuloides, Tripneustes ventricosus, Clypeaster rosaceus, and Clypeaster subdepressus were reared at 26, 28, 30, 32, and 34 °C for 6 days. The temperatures at which statistically significant reductions in larval performance are evident are generally the same temperatures at which statistically significant reductions in larval survival were detected, showing that the optimal temperature is very close to the lethal temperature. The two Echinometra species had significantly higher thermal tolerance than the other species, with some surviving culture temperatures of 34 °C and showing minimal impacts on growth and survival at 32 °C. In the other species, larval growth and survival were depressed at and above 30 or 32 °C. Overall, these larvae have lower warming tolerances (1 to 5 °C) and smaller thermal safety margins (−3 to 3 °C) than adults. Survival differences among treatments were evident by the first sampling on day 2, and survival at the highest temperatures increased when embryos were exposed to warming after spending the first 24 hours at ambient temperature. This suggests that the first days of development are more sensitive to thermal stress than are later larval stages.

中文翻译：

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加勒比海海胆的幼虫对巴拿马的慢性压力有很小的升温耐受性

在生命周期复杂的物种中，早期发育阶段的耐热性通常低于成虫，这表明它们是预测生物体对环境变暖的反应的关键。在这里，我们记录了海胆幼虫的最佳和致死温度，并使用这些温度来计算七种热带物种早期幼虫阶段的变暖耐受性和热安全边际。Echinometra viridis、Echinometra lucunter、Lytechinus williamsi、Eucidaris tribuloides、Tripneustes ventricosus、Clypeaster rosaceus 和 Clypeaster subdepressus 的幼虫在 26、28、30、32 和 34 °C 下饲养 6 天。幼虫性能显着降低的统计显着降低的温度通常与检测到幼虫存活率显着降低的温度相同，表明最佳温度非常接近致死温度。两种棘龙属物种的耐热性显着高于其他物种，一些存活的培养温度为 34°C，并且在 32°C 下对生长和存活的影响最小。在其他物种中，幼虫的生长和存活在 30 或 32 °C 及以上时受到抑制。总体而言，这些幼虫比成虫具有更低的升温耐受性（1 至 5°C）和更小的热安全裕度（-3 至 3°C）。在第 2 天的第一次取样时，处理之间的存活率差异很明显，并且当胚胎在环境温度下度过前 24 小时后暴露在加温下时，最高温度下的存活率会增加。这表明发育的第一天比后期的幼虫阶段对热应激更敏感。