Adaptation and Resilience of Coral Reefs to Climate Change, Australian Institute of Marine Science, PMB 3 Townsville MC, Townsville, Queensland 4810, Australia; ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland 4811, Australia.
Adaptation and Resilience of Coral Reefs to Climate Change , Australian Institute of Marine Science , PMB 3 Townsville MC, Townsville, Queensland 4810 , Australia.
R Soc Open Sci. 2016 Jun 29;3(6):160322. doi: 10.1098/rsos.160322. eCollection 2016 Jun.
Sensitive molecular analyses show that most corals host a complement of Symbiodinium genotypes that includes thermo-tolerant types in low abundance. While tolerant symbiont types are hypothesized to facilitate tolerance to temperature and recovery from bleaching, empirical data on their distribution and relative abundance in corals under ambient and stress conditions are still rare. We quantified visual bleaching and mortality of coral hosts, along with relative abundance of C- and D-type Symbiodinium cells in 82 Acropora millepora colonies from three locations on the Great Barrier Reef transplanted to a central inshore site over a 13 month period. Our analyses reveal dynamic change in symbiont associations within colonies and among populations over time. Coral bleaching and declines in C- but not D-type symbionts were observed in transplanted corals. Survival and recovery of 25% of corals from one population was associated with either initial D-dominance or an increase in D-type symbionts that could be predicted by a minimum pre-stress D : C ratio of 0.003. One-third of corals from this population became D dominated at the bleached stage despite no initial detection of this symbiont type, but failed to recover and died in mid to late summer. These results provide a predictive threshold minimum density of background D-type symbionts in A. millepora, above which survival following extreme thermal stress is increased.
敏感的分子分析表明，大多数珊瑚宿主都拥有共生藻 Symbiodinium 的多种基因型，其中包括低丰度的耐热型。虽然耐受共生体类型被假设为有助于耐受温度和从漂白中恢复，但在环境和胁迫条件下珊瑚中它们的分布和相对丰度的经验数据仍然很少。我们在 13 个月的时间内，量化了大堡礁三个地点的 82 株移植物 Acropora millepora 珊瑚宿主的视觉漂白和死亡率，以及 C-和 D-型共生藻细胞的相对丰度。我们的分析揭示了随着时间的推移，珊瑚体内和种群之间共生体关系的动态变化。在移植的珊瑚中观察到珊瑚漂白和 C-型但不是 D-型共生体的减少。一个种群的 25%的珊瑚的存活率和恢复与初始的 D 型优势或 D 型共生体的增加有关，这可以通过最小应激前 D: C 比 0.003 来预测。尽管最初没有检测到这种共生体类型，但该种群三分之一的珊瑚在漂白阶段变为 D 型优势，但未能恢复并在夏末死亡。这些结果提供了一个预测性的阈值，即在极端热应激后，A. millepora 珊瑚中背景 D 型共生体的最小密度增加，存活率提高。
