Onset of symbiosis and distribution patterns of symbiotic dinoflagellates in the larvae of scleractinian corals
Onset of symbiosis and distribution patterns of symbiotic dinoflagellates in the larvae of scleractinian corals
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DOI：
10.1007/s00227-009-1162-9
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发表时间：
2009-05-01
期刊：
影响因子：
2.4
通讯作者：
Hidaka, Michio
中科院分区：
文献类型：
--
作者：
Harii, Saki;Yasuda, Naoko;Hidaka, Michio
由于需要光合作用获得的营养，在早期发育阶段建立共生对于造礁珊瑚很重要。珊瑚产卵和精子，或孵化浮浪幼虫并将其排入水中。一些珊瑚卵或浮浪藻直接从父母那里继承了共生甲藻（Symbiodinium spp.），而另一些则在每一代中都获得了它们。在迄今为止检查的大多数物种中，没有甲藻的幼虫（无共生幼虫）可以在幼虫阶段获得共生体，但对于共生开始的时间和详细过程知之甚少。我们在实验室条件下研究了九种石珊瑚中幼虫对共生甲藻的摄取、早期幼虫阶段共生的开始，以及两种顶孔珊瑚在存活时和组织学上共生体在幼虫宿主内的分布模式。在所有检查的珊瑚中，幼虫在浮游阶段获得了共生甲藻，其中包括鹿角珊瑚、佛罗里达珊瑚、中间珊瑚、细珊瑚、Palifera、Favia pallida、F. lizardensis、Pseudosiderastrea tayamai 和 Ctenactis echinata。 A. digitalifera 和 A. tenuis 的幼虫分别在受精后 6 天和 5 天首次获得共生体。在A. digitalifera 幼虫中，这与口腔孔和腔肠的形成同时发生。在两个物种的实验期间，共生甲藻的数量都增加了。为了检验营养物质促进共生吸收的假设，比较了存在和不存在均质卤虫的情况下掺入的甲藻的数量。假设对数线性模型的似然比检验表明卤虫属。对共生体的获得具有显着的积极影响。这些结果表明，在幼虫阶段获得共生甲藻是许多珊瑚物种的共同点，并且口腔和腔肠的发育在共生体的获得中发挥着重要作用。
The establishment of symbiosis in early developmental stages is important for reef-building corals because of the need for photosynthetically derived nutrition. Corals spawn eggs and sperm, or brood planula larvae and shed them into the water. Some coral eggs or planulae directly inherit symbiotic dinoflagellates (Symbiodinium spp.) from their parents, while others acquire them at each generation. In most species examined to date, the larvae without dinoflagellates (aposymbiotic larvae) can acquire symbionts during the larval stage, but little is known regarding the timing and detailed process of the onset of symbiosis. We examined larval uptake of symbiotic dinoflagellates in nine species of scleractinian corals, the onset of symbiosis through the early larval stages, and the distribution pattern of symbionts within the larval host, while living and with histology, of two acroporid corals under laboratory conditions. The larvae acquired symbiotic dinoflagellates during the planktonic phase in all corals examined which included Acropora digitifera, A. florida, A. intermedia, A. tenuis, Isopora palifera, Favia pallida, F. lizardensis, Pseudosiderastrea tayamai, and Ctenactis echinata. The larvae of A. digitifera and A. tenuis first acquired symbionts 6 and 5 days after fertilization, respectively. In A. digitifera larvae, this coincided with the formation of an oral pore and coelenteron. The number of symbiotic dinoflagellates increased over the experimental periods in both species. To test the hypothesis that nutrients promotes symbiotic uptake, the number of incorporated dinoflagellates was compared in the presence and absence of homogenized Artemia sp. A likelihood ratio test assuming a log-linear model indicated that Artemia sp. had a significantly positive effect on symbiont acquisition. These results suggest that the acquisition of symbiotic dinoflagellates during larval stages is in common with many coral species, and that the development of both a mouth and coelenteron play important roles in symbiont acquisition.