Symbiotic stony and soft corals: Is their host-algae relationship really mutualistic at lower mesophotic reefs?
Symbiotic stony and soft corals: Is their host-algae relationship really mutualistic at lower mesophotic reefs?
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DOI：
10.1002/lno.11990
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发表时间：
2021-11-24
影响因子：
4.5
通讯作者：
Fine, Maoz
中科院分区：
文献类型：
--
作者：
Ferrier-Pages, Christine;Bednarz, Vanessa;Fine, Maoz
中光珊瑚生态系统（30-150米深）具有高度的海洋生物多样性，但仍然是研究最少的珊瑚礁生境之一，特别是在60米深以下。在这里，我们已经评估了光合作用和溶解无机碳（DIC）和氮（DIN）同化共生藻科与四个软珊瑚种属Sinularia和两个石珊瑚种属Leptoseris分别收集在65和80-90米的深度在埃拉特湾。我们的研究表明，Leptoseris和Sinularia物种有有限的自养能力在中低中光深度。DIC和DIN同化率总体上类似于10倍，低于浅珊瑚从10米深，在同一个珊瑚礁。虽然Leptoseris共生体转移至少50%的收购氮到他们的主机后，8小时的孵育，大部分的氮被保留在共生体的Sinularia。此外，Sinularia物种的宿主组织呈现出非常高的结构碳氮比（C：N）相比，Leptoseris或浅珊瑚物种，这表明氮限制在这些中光软珊瑚。软珊瑚共生体获取DIN和转移到珊瑚动物的能力有限，以及高C：N比，可能解释共生软珊瑚在中低中光深度的稀缺性相比，他们的患病率在较浅的珊瑚礁。总的来说，这项研究突出了DIN的意义，在中光深度的刺胞动物-共生藻科协会的分布。
Mesophotic coral ecosystems (30-150 m depth) present a high oceanic biodiversity, but remain one of the most understudied reef habitats, especially below 60 m depth. Here, we have assessed the rates of photosynthesis and dissolved inorganic carbon (DIC) and nitrogen (DIN) assimilation by Symbiodiniaceae associated with four soft coral species of the genus Sinularia and two stony coral species of the genus Leptoseris collected respectively at 65 and 80-90 m depth in the Gulf of Eilat. Our study demonstrates that both Leptoseris and Sinularia species have limited autotrophic capacities at mid-lower mesophotic depths. DIC and DIN assimilation rates were overall similar to 10 times lower compared to shallow corals from 10 m depth in the same reef. While Leptoseris symbionts transferred at least 50% of the acquired nitrogen to their host after 8-h incubation, most of the nitrogen was retained in the symbionts of Sinularia. In addition, the host tissue of Sinularia species presented a very high structural carbon to nitrogen ratio (C : N) compared to Leptoseris or to the shallow coral species, suggesting nitrogen limitation in these mesophotic soft corals. The limited capacity of soft coral symbionts to acquire DIN and transfer it to the coral animal, as well as the high C : N ratios, might explain the scarcity of symbiotic soft corals at mid-lower mesophotic depths compared to their prevalence in the shallower reef. Overall, this study highlights the significance of DIN for the distribution of the Cnidarian- Symbiodiniaceae association at mesophotic depth.