Can heterotrophic uptake of dissolved organic carbon and zooplankton mitigate carbon budget deficits in annually bleached corals?
Can heterotrophic uptake of dissolved organic carbon and zooplankton mitigate carbon budget deficits in annually bleached corals?
复制标题
溶解有机碳和浮游动物的异养吸收能否减轻每年白化珊瑚的碳预算赤字？
DOI：
10.1007/s00338-015-1390-z
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发表时间：
2016
期刊：
影响因子：
3.5
通讯作者：
Warner, Mark E.
中科院分区：
文献类型：
--
作者：
Levas, Stephen;Grottoli, Andréa G.;Schoepf, Verena;Aschaffenburg, Matthew;Baumann, Justin;Bauer, James E.;Warner, Mark E.
由于海洋表面温度上升而导致的年度珊瑚漂白事件预计将在本世纪中叶在全球发生，最早将在2025年在加勒比发生，并严重影响珊瑚礁。我们推测，浮游动物形式的异养碳(C)和溶解有机碳(DOC)是漂白珊瑚碳的重要来源。因此，利用多个固定碳库和/或增加从一个或多个固定碳库获得的固定碳量(这里定义为异养可塑性)的能力可能是珊瑚在未来海洋变暖情景下适应和持续的基础。在这里，三种加勒比海珊瑚-Porites divaricata、P.astreoides和Orbecella Faveolata-连续两年被实验漂白2.5周，并允许在野外恢复。在单次漂白和重复漂白后评估浮游动物的摄食，而在单次漂白、在礁上11个月和重复漂白后确定DOC通量和DOC对总碳收支的贡献。浮游动物是磷的一大碳源。黄花蛇舌兰，但只能经过一次漂白。DOC是单次漂白珊瑚C的来源，占每日代谢需求(CHARDOC)的11-36%，但代表重复漂白珊瑚C的净损失。在重复漂白的珊瑚中，DOC的损失加剧了所有三个物种的负C收支。因此，珊瑚异养可塑性的能力在年度漂白下受到损害，DOC和浮游动物的异养吸收并不能缓解年度漂白珊瑚的碳预算赤字。总体而言，这些发现表明，由于缺乏异养可塑性，一些加勒比珊瑚可能比单一漂白更容易受到重复漂白的影响，珊瑚在不断增加的漂白频率下的持久性可能最终取决于其他因素，如能量储备和共生体洗牌。
Annual coral bleaching events due to increasing sea surface temperatures are predicted to occur globally by the mid-century and as early as 2025 in the Caribbean, and severely impact coral reefs. We hypothesize that heterotrophic carbon (C) in the form of zooplankton and dissolved organic carbon (DOC) is a significant source of C to bleached corals. Thus, the ability to utilize multiple pools of fixed carbon and/or increase the amount of fixed carbon acquired from one or more pools of fixed carbon (defined here as heterotrophic plasticity) could underlie coral acclimatization and persistence under future ocean-warming scenarios. Here, three species of Caribbean coral—Porites divaricata,P. astreoides, andOrbicella faveolata—were experimentally bleached for 2.5 weeks in two successive years and allowed to recover in the field. Zooplankton feeding was assessed after single and repeat bleaching, while DOC fluxes and the contribution of DOC to the total C budget were determined after single bleaching, 11 months on the reef, and repeat bleaching. Zooplankton was a large C source forP. astreoides,but only following single bleaching. DOC was a source of C for single-bleached corals and accounted for 11–36 % of daily metabolic demand (CHARDOC), but represented a net loss of C in repeat-bleached corals. In repeat-bleached corals, DOC loss exacerbated the negative C budgets in all three species. Thus, the capacity for heterotrophic plasticity in corals is compromised under annual bleaching, and heterotrophic uptake of DOC and zooplankton does not mitigate C budget deficits in annually bleached corals. Overall, these findings suggest that some Caribbean corals may be more susceptible to repeat bleaching than to single bleaching due to a lack of heterotrophic plasticity, and coral persistence under increasing bleaching frequency may ultimately depend on other factors such as energy reserves and symbiont shuffling.