Differential recycling of coral and algal dissolved organic matter via the sponge loop
Differential recycling of coral and algal dissolved organic matter via the sponge loop
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DOI：
10.1111/1365-2435.12758
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发表时间：
2017-03
影响因子：
5.2
通讯作者：
L. Rix;J. M. Goeij;D. Oevelen;U. Struck;F. Al-Horani;C. Wild;M. Naumann
中科院分区：
文献类型：
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作者：
L. Rix;J. M. Goeij;D. Oevelen;U. Struck;F. Al-Horani;C. Wild;M. Naumann
珊瑚和大型藻类释放大量溶解有机物 (DOM)，这是珊瑚礁产生的有机物的最大来源之一。通过快速吸收 DOM 并将其转化为颗粒碎屑，珊瑚礁海绵被认为在通过最近发现的海绵环将 DOM 中的能量和营养物质转移到更高营养水平方面发挥着关键作用。珊瑚和藻类释放的 DOM 在质量和成分上有所不同，但这些不同的 DOM 来源对海绵环回收的影响尚未得到研究。在这里，我们使用稳定同位素脉冲追踪实验来比较三种红海珊瑚礁海绵物种（Chondrilla sacciformis、Hemimycale arabica 和 Mycale fistulifera）对天然来源的珊瑚和藻类衍生的 DOM 的处理。进行孵化实验以在海绵组织和碎屑中追踪富含 13C 和 15N 的珊瑚和藻类衍生的 DOM。将 13C 掺入特定的磷脂衍生脂肪酸 (PLFA) 中，用于区分海绵全生物内的 DOM 同化（即海绵宿主与其相关细菌）。所有海绵都吸收了珊瑚和藻类来源的 DOM，但藻类来源的 DOM 的吸收率明显更高。海绵全生物对这两种 DOM 来源的处理也不同。藻类来源的 DOM 以更高的速率融入细菌特异性 PLFA，而珊瑚来源的 DOM 更容易融入海绵特异性 PLFA。海绵吸收的大部分溶解有机碳 (C) 和氮 (N) 随后转化为颗粒碎屑并释放（15-24% C 和 27-49% N）。然而，藻类来源的 DOM 以碎屑形式以更高的速率释放。与珊瑚来源的 DOM 相比，藻类的 DOM 吸收和转化率更高，这表明珊瑚礁群落从珊瑚到藻类优势的相变可能会刺激 DOM 通过海绵循环循环，从而对珊瑚礁生物地球化学循环和食物网产生潜在影响。
Corals and macroalgae release large quantities of dissolved organic matter (DOM), one of the largest sources of organic matter produced on coral reefs. By rapidly taking up DOM and transforming it into particulate detritus, coral reef sponges are proposed to play a key role in transferring the energy and nutrients in DOM to higher trophic levels via the recently discovered sponge loop. DOM released by corals and algae differs in quality and composition, but the influence of these different DOM sources on recycling by the sponge loop has not been investigated. Here, we used stable isotope pulse-chase experiments to compare the processing of naturally sourced coral- and algal-derived DOM by three Red Sea coral reef sponge species: Chondrilla sacciformis, Hemimycale arabica and Mycale fistulifera. Incubation experiments were conducted to trace 13C- and 15N-enriched coral- and algal-derived DOM into the sponge tissue and detritus. Incorporation of 13C into specific phospholipid-derived fatty acids (PLFAs) was used to differentiate DOM assimilation within the sponge holobiont (i.e. the sponge host vs. its associated bacteria). All sponges assimilated both coral- and algal-derived DOM, but incorporation rates were significantly higher for algal-derived DOM. The two DOM sources were also processed differently by the sponge holobiont. Algal-derived DOM was incorporated into bacteria-specific PLFAs at a higher rate while coral-derived DOM was more readily incorporated into sponge-specific PLFAs. A substantial fraction of the dissolved organic carbon (C) and nitrogen (N) assimilated by the sponges was subsequently converted into and released as particulate detritus (15–24% C and 27–49% N). However, algal-derived DOM was released as detritus at a higher rate. The higher uptake and transformation rates of algal- compared with coral-derived DOM suggest that reef community phase shifts from coral to algal dominance may stimulate DOM cycling through the sponge loop with potential consequences for coral reef biogeochemical cycles and food webs.