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Biogeochemical niches and trophic plasticity of shallow and mesophotic corals recovering from mass bleaching
Limnology and Oceanography ( IF 4.5 ) Pub Date : 2022-06-01 , DOI: 10.1002/lno.12157
Veronica Z. Radice 1, 2 , Brian Fry 3 , Kristen T. Brown 1, 2, 4 , Sophie Dove 1, 2 , Ove Hoegh‐Guldberg 1, 2
Affiliation  

The differential survival of corals and their recovery from oceanic thermal stress is related not only to coral bleaching susceptibility but also physiological plasticity including trophic strategy. We investigated post-bleaching event recovery of three morphologically diverse, reef-building coral species from shallow (10 m) and mesophotic (30 m) reefs across the Maldives archipelago. Trophic plasticity was evaluated by carbon and nitrogen contents and stable isotopes of coral hosts and their algal symbionts including isotopic niche position and size. Seawater temperatures recorded before, during, and after the mass coral bleaching event revealed significant thermal stress in both shallow and mesophotic reefs although cumulative warming appeared lower in mesophotic reefs (9.0 vs. 5.9 degree heating weeks, respectively). Ten months following thermal stress, increased nitrogen stable isotope (δ15N) values in all three coral host species without concurrent changes in water column δ15N indicated enhanced heterotrophic feeding during thermal stress and/or recovery. Host C:N decreased in all species post-bleaching event while host carbon content (%C) decreased in shallow, more autotrophic populations of two species, suggesting prolonged stress. Host carbon stable isotope (δ13C) values were lower in mesophotic, more heterotrophic populations of two species compared to shallow counterparts. Biogeochemical and isotopic niches both showed different niche specialization among the three species. Consistent shifts in host isotopic niche positions support a conserved host response mechanism (heterotrophy) to oceanic thermal stress, but shallow and mesophotic corals still had not fully recovered almost one year after the bleaching event.

中文翻译:

从大规模漂白中恢复的浅层和中光珊瑚的生物地球化学生态位和营养可塑性

珊瑚的差异生存及其从海洋热应力中的恢复不仅与珊瑚白化易感性有关,还与包括营养策略在内的生理可塑性有关。我们研究了马尔代夫群岛浅水(10 m)和中光(30 m)珊瑚礁中三种形态多样的造礁珊瑚物种的漂白后事件恢复。通过珊瑚宿主及其藻类共生体的碳和氮含量以及稳定同位素(包括同位素位置和大小)来评估营养可塑性。在大规模珊瑚白化事件之前、期间和之后记录的海水温度显示,浅礁和中光礁存在显着的热应力,尽管中光礁的累积变暖似乎较低(分别为 9.0 和 5.9 度的加热周)。15 N) 所有三种珊瑚宿主物种的值,水柱 δ 15 N 没有同时变化,表明在热应激和/或恢复期间异养摄食增强。漂白事件后所有物种的宿主 C:N 均下降,而两个物种的较浅、更自养的种群中宿主碳含量 (%C) 下降,表明压力延长。宿主碳稳定同位素 (δ 13C)与浅层对应物相比,两个物种的中光、异养种群的值较低。生物地球化学和同位素生态位在三个物种之间都表现出不同的生态位专业化。宿主同位素生态位位置的一致变化支持对海洋热应力的保守宿主响应机制(异养),但在漂白事件发生近一年后,浅层和中生珊瑚仍未完全恢复。
更新日期:2022-06-01
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