Elevated temperatures and nutrients are degrading coral reef ecosystems, but the understanding of how early life stages of reef corals respond to these stressors remains limited. Here, we test the impact of temperature (mean ~ 27 °C vs. ~ 29 °C) and nitrate and phosphate enrichment (ambient, + 5 µM nitrate, + 1 µM phosphate and combined + 5 µM nitrate with 1 µM phosphate) on coral larvae using three Hawaiian coral species with different modes of symbiont transmission and reproduction: Lobactis scutaria (horizontal, gonochoric broadcast spawner), Pocillopora acuta (vertical, hermaphroditic brooder) and Montipora capitata (vertical, hermaphroditic broadcast spawner). Temperature and nutrient effects were species specific and appear antagonistic for L. scutaria and M. capitata , but not for P. acuta . Larvae survivorship in all species was lowest under nitrate enrichment at 27 °C. M. capitata and L. scutaria survivorship increased at 29 °C. However, positive effects of warming on survivorship were lost under high nitrate, but phosphate attenuated nitrate effects when N/P ratios were balanced. P. acuta larvae exhibited high survivorship (> 91%) in all treatments and showed little change in larval size, but lower respiration rates at 29 °C. Elevated nutrients (+N+P) led to the greatest loss in larvae size for aposymbiotic L. scutaria , while positive growth in symbiotic M. capitata larvae was reduced under warming and highest in +N+P treatments. Overall, we report a greater sensitivity of broadcast spawners to warming and nutrient changes compared to a brooding coral species. These results suggest variability in biological responses to warming and nutrient enrichment is influenced by life-history traits, including the presence of symbionts (vertical transmission), in addition to nutrient type and nutrient stoichiometry.

中文翻译：

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共生体传播和繁殖方式影响三种夏威夷珊瑚幼虫对高温和养分的反应

升高的温度和营养物质正在退化珊瑚礁生态系统，但对珊瑚礁早期生命阶段如何应对这些压力因素的了解仍然有限。在这里，我们测试了温度（平均 ~ 27 °C vs. ~ 29 °C）和硝酸盐和磷酸盐富集（环境、+ 5 µM 硝酸盐、+ 1 µM 磷酸盐和 + 5 µM 硝酸盐与 1 µM 磷酸盐的组合）对珊瑚幼虫使用三种具有不同共生体传播和繁殖模式的夏威夷珊瑚物种：Lobactis scutaria（水平、淋病繁殖者）、Pocillopora acuta（垂直、雌雄同体育雏器）和 Montipora capitalata（垂直、雌雄同体广播繁殖者）。温度和养分效应是物种特异性的，似乎对 L. scutaria 和 M. capitalata 具有拮抗作用，但对 P. acuta 则不然。所有物种的幼虫存活率在 27 °C 时硝酸盐富集条件下最低，而 L. scutaria 存活率在 29 °C 时增加。然而，在高硝酸盐条件下，变暖对存活率的积极影响会消失，但当 N/P 比率平衡时，磷酸盐会减弱硝酸盐的影响。P. acuta 幼虫在所有处理中都表现出高存活率 (> 91%)，幼虫大小几乎没有变化，但在 29 °C 时呼吸速率较低。升高的养分 (+N+P) 导致无共生体 L. scutaria 幼虫大小的最大损失，而共生 M.capitata 幼虫的正生长在变暖下减少，并且在 +N+P 处理中最高。总体而言，我们报告说，与育雏珊瑚物种相比，广播产卵者对变暖和营养变化的敏感性更高。