Symbiotic dinoflagellates divert energy away from mutualism during coral bleaching recovery
Symbiotic dinoflagellates divert energy away from mutualism during coral bleaching recovery
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DOI：
10.1007/s13199-023-00901-3
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发表时间：
2023-01-28
期刊：
影响因子：
2.5
通讯作者：
Barott, Katie L.
中科院分区：
文献类型：
--
作者：
Allen-Waller, Luella;Barott, Katie L.
在一个变暖的世界里，珊瑚礁的未来取决于珊瑚从白化中恢复的能力，在海洋热浪中，它们的共生鞭毛藻（共生藻科）的消失。耐热共生体在热胁迫下仍能维持共生关系，但在环境条件下向寄主提供的光合作用往往少于热敏共生体。了解热胁迫如何改变这种在胁迫耐受性和互惠贡献之间权衡的动态，对于预测气候变化下珊瑚的成功至关重要。为了测试共生资源分配如何影响珊瑚从热胁迫中恢复，我们将承载热敏Cladocopium C31 (C)或耐热Durusdinium glynnii (D)的Montipora capitata珊瑚暴露于热胁迫下。热处理后D的共生体密度和光化学效率的恢复比C快，但共生体的恢复并没有使珊瑚生物量和钙化率恢复到漂白前的水平。即使在热胁迫下，D种群对宿主的光合作用也比C种群少。此外，这两个物种的高密度共生种群比低密度种群保留了更多的光合作用，而接受较少光合作用的珊瑚表现出更低的钙化率和更低的细胞内ph。这是第一个证明共生密度和碳转运呈负相关的证据，也是第一个建立共生科碳转运与珊瑚细胞稳态之间联系的证据。综上所述，这些结果表明，白化后共生体再生的能量需求降低了它们的共生贡献，从而延迟了宿主的恢复。当全息生物克服压力时，重新建立有益的内共生关系会增加额外的成本，这可能解释了在野外减轻热应激后珊瑚种群的潜在死亡率。
The future of coral reefs in a warming world depends on corals' ability to recover from bleaching, the loss of their symbiotic dinoflagellate algae (Symbiodiniaceae) during marine heatwaves. Heat-tolerant symbiont species can remain in symbiosis during heat stress, but often provide less photosynthate to the host than heat-sensitive species under ambient conditions. Understanding how heat stress changes the dynamics of this tradeoff between stress tolerance and mutualism contribution is crucial for predicting coral success under climate change. To test how symbiont resource allocation affects coral recovery from heat stress, we exposed the coral Montipora capitata hosting either heat-sensitive Cladocopium C31 (C) or heat-tolerant Durusdinium glynnii (D) to heat stress. D regained symbiont density and photochemical efficiency faster after heat treatment than C, but symbiont recovery did not restore coral biomass or calcification rates to pre-bleaching levels in the initial recovery period. D populations also contributed less photosynthate to the host relative to C, even during heat stress. Further, higher-density symbiont populations of both species retained more photosynthate than lower-density populations, and corals receiving less photosynthate exhibited reduced calcification rates and lower intracellular pH. This is the first evidence that symbiont density and carbon translocation are negatively related, and the first to establish a link between Symbiodiniaceae carbon translocation and coral cellular homeostasis. Together, these results suggest the energy demand of symbiont regrowth after bleaching reduces their mutualism contribution and can thus delay host recovery. Reestablishing a beneficial endosymbiosis imposes additional costs as holobionts overcome stress, and may explain latent mortality among coral populations after alleviation of heat stress in the field.