Department of Biology, Hopkins Marine Station of Stanford University, Pacific Grove, California, United States of America.
Palau International Coral Reef Center, Koror, Palau.
PLoS One. 2022 Sep 9;17(9):e0269206. doi: 10.1371/journal.pone.0269206. eCollection 2022.
Widespread mapping of coral thermal resilience is essential for developing effective management strategies and requires replicable and rapid multi-location assays of heat resistance and recovery. One- or two-day short-term heat stress experiments have been previously employed to assess heat resistance, followed by single assays of bleaching condition. We tested the reliability of short-term heat stress resistance, and linked resistance and recovery assays, by monitoring the phenotypic response of fragments from 101 Acropora hyacinthus colonies located in Palau (Micronesia) to short-term heat stress. Following short-term heat stress, bleaching and mortality were recorded after 16 hours, daily for seven days, and after one and two months of recovery. To follow corals over time, we utilized a qualitative, non-destructive visual bleaching score metric that correlated with standard symbiont retention assays. The bleaching state of coral fragments 16 hours post-heat stress was highly indicative of their state over the next 7 days, suggesting that symbiont population sizes within corals may quickly stabilize post-heat stress. Bleaching 16 hours post-heat stress predicted likelihood of mortality over the subsequent 3-5 days, after which there was little additional mortality. Together, bleaching and mortality suggested that rapid assays of the phenotypic response following short-term heat stress were good metrics of the total heat treatment effect. Additionally, our data confirm geographic patterns of intraspecific variation in Palau and show that bleaching severity among colonies was highly correlated with mortality over the first week post-stress. We found high survival (98%) and visible recovery (100%) two months after heat stress among coral fragments that survived the first week post-stress. These findings help simplify rapid, widespread surveys of heat sensitivity in Acropora hyacinthus by showing that standardized short-term experiments can be confidently assayed after 16 hours, and that bleaching sensitivity may be linked to subsequent survival using experimental assessments.
广泛绘制珊瑚热弹性图谱对于制定有效的管理策略至关重要，需要可重复且快速的多地点耐热和恢复能力分析。先前曾采用 1 或 2 天的短期热应激实验来评估耐热性，然后对漂白状况进行单次测定。我们通过监测位于密克罗尼西亚帕劳的 101 株 Acropora hyacinthus 珊瑚的碎片对短期热应激的表型反应，测试了短期热应激抗性的可靠性，并将抗性和恢复性测定联系起来。短期热应激后，在 16 小时、每天 7 天以及恢复 1 个月和 2 个月后记录漂白和死亡率。为了跟踪珊瑚随时间的变化，我们利用了一种定性的、非破坏性的视觉漂白评分指标，该指标与标准共生体保留测定法相关。珊瑚碎片在热应激后 16 小时的漂白状态高度指示了它们在接下来 7 天内的状态，这表明珊瑚内共生体种群数量可能在热应激后迅速稳定下来。16 小时后热应激的漂白状态预测了随后 3-5 天内死亡的可能性，之后死亡的可能性很小。总的来说，短期热应激后表型反应的快速测定是总热处理效果的良好指标。此外，我们的数据证实了帕劳种内变异的地理模式，并表明在应激后第一周内，珊瑚之间的漂白严重程度与死亡率高度相关。我们发现，在应激后第一周幸存下来的珊瑚碎片中，在应激后两个月有 98%的高存活率和 100%的可见恢复率。这些发现有助于通过显示标准化的短期实验在 16 小时后可以有信心地进行测定，并且漂白敏感性可以通过实验评估与随后的存活相关联，从而简化对 Acropora hyacinthus 热敏感性的快速、广泛调查。
