Marcelino Vanessa Rossetto, Morrow Kathleen M, van Oppen Madeleine J H, Bourne David G, Verbruggen Heroen
School of Biosciences, University of Melbourne, Melbourne, Vic., Australia.
Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, NH, USA.
Mol Ecol. 2017 Oct;26(19):5344-5357. doi: 10.1111/mec.14268. Epub 2017 Aug 24.
The health and functioning of reef-building corals is dependent on a balanced association with prokaryotic and eukaryotic microbes. The coral skeleton harbours numerous endolithic microbes, but their diversity, ecological roles and responses to environmental stress, including ocean acidification (OA), are not well characterized. This study tests whether pH affects the diversity and structure of prokaryotic and eukaryotic algal communities associated with skeletons of Porites spp. using targeted amplicon (16S rRNA gene, UPA and tufA) sequencing. We found that the composition of endolithic communities in the massive coral Porites spp. inhabiting a naturally high pCO reef (avg. pCO 811 μatm) is not significantly different from corals inhabiting reference sites (avg. pCO 357 μatm), suggesting that these microbiomes are less disturbed by OA than previously thought. Possible explanations may be that the endolithic microhabitat is highly homeostatic or that the endolithic micro-organisms are well adapted to a wide pH range. Some of the microbial taxa identified include nitrogen-fixing bacteria (Rhizobiales and cyanobacteria), algicidal bacteria in the phylum Bacteroidetes, symbiotic bacteria in the family Endozoicomoniaceae, and endolithic green algae, considered the major microbial agent of reef bioerosion. Additionally, we test whether host species has an effect on the endolithic community structure. We show that the endolithic community of massive Porites spp. is substantially different and more diverse than that found in skeletons of the branching species Seriatopora hystrix and Pocillopora damicornis. This study reveals highly diverse and structured microbial communities in Porites spp. skeletons that are possibly resilient to OA.
造礁珊瑚的健康与功能依赖于与原核和真核微生物的平衡共生关系。珊瑚骨骼中栖息着众多石内微生物，但其多样性、生态作用以及对包括海洋酸化（OA）在内的环境压力的响应，尚未得到充分表征。本研究利用靶向扩增子（16S rRNA基因、UPA和tufA）测序，测试了pH值是否会影响与多孔珊瑚属骨骼相关的原核和真核藻类群落的多样性和结构。我们发现，栖息在天然高pCO₂珊瑚礁（平均pCO₂ 811 μatm）的块状珊瑚多孔珊瑚属的石内群落组成，与栖息在参考地点（平均pCO₂ 357 μatm）的珊瑚没有显著差异，这表明这些微生物群落受海洋酸化的干扰比之前认为的要小。可能的解释是，石内微生境具有高度的稳态性，或者石内微生物对广泛的pH范围具有良好的适应性。鉴定出的一些微生物类群包括固氮细菌（根瘤菌目和蓝细菌）、拟杆菌门中的杀藻细菌、内共生菌科中的共生细菌以及石内绿藻，石内绿藻被认为是珊瑚礁生物侵蚀的主要微生物媒介。此外，我们测试了宿主物种是否对石内群落结构有影响。我们表明，块状多孔珊瑚属的石内群落与分支物种刺鹿角珊瑚和鹿角杯形珊瑚骨骼中的群落有很大不同，且更加多样。这项研究揭示了多孔珊瑚属骨骼中高度多样且结构复杂的微生物群落，这些群落可能对海洋酸化具有恢复力。
