The Critical Importance of Rhodoliths in the Life Cycle Completion of Both Macro- and Microalgae, and as Holobionts for the Establishment and Maintenance of Marine Biodiversity
The Critical Importance of Rhodoliths in the Life Cycle Completion of Both Macro- and Microalgae, and as Holobionts for the Establishment and Maintenance of Marine Biodiversity
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DOI：
10.3389/fmars.2018.00502
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发表时间：
2019-01-08
影响因子：
3.7
通讯作者：
Schmidt, William E.
中科院分区：
文献类型：
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作者：
Fredericq, Suzanne;Krayesky-Self, Sherry;Schmidt, William E.
红柱藻是在墨西哥湾西北部的碎石生境中附着底栖大型藻类的主要坚硬基质，该生境与盐丘有关，这是路易斯安那州和德克萨斯州近海大陆架上类似50-90米深的独特的深滩生境。随着更多测序技术的出现，生物多样性评估的方法现在正迅速转向DNA元编码，即环境DNA与标准化分子标记(如16S V4)混合的高通量测序(HTS)，以实现快速、经济有效的生物多样性测量。我们新测试了16S V4变种编码，编码在中生性红柱石的石器内部分，表现出低光生细菌定殖率，揭示了以孢子、繁殖体和意外的生活史阶段为目标的隐藏的、隐秘的藻类多样性。我们探索了冷冻-扫描电子显微镜作为一种潜在的比常规扫描电子显微镜更具信息量的方法，以减少在研究石器内细胞包裹体时的样品制备伪影，这揭示了一系列微藻阶段。我们能够区分弗洛里德淀粉和细胞内含物。我们将解剖生长模式对生物来源红柱石中细胞内含物的存在或不存在的影响联系起来。对两个红藻目Halymeniales和Bonnemaisoniales的16S V4元代码和16S Sanger序列的分析，增加了该地区已有的多样性记录。我们认为红藻是海洋生物多样性的热点，可以作为种子库、具有重要生态意义的真核微藻生活史阶段的临时储存库，以及大型藻类，或者作为环境胁迫后生态系统弹性的避难所。
Rhodoliths are the main hard substrata for the attachment of benthic macroalgae in the NW Gulf of Mexico rubble habitats that are associated with salt domes, unique deep bank habitats at similar to 50-90m depth on the continental shelf offshore Louisiana and Texas. With the advent of additional sequencing technologies, methodologies for biodiversity assessments are now rapidly shifting to DNA metabarcoding, i.e., High Throughput Sequencing (HTS) of environmental DNA mixtures with standardized molecular markers, such as 16S V4, for rapid, cost-effective biodiversity measurement. We newly tested 16S V4 metabarcoding on endolithic portions of mesophtic rhodoliths exhibiting low phototroph colonization that revealed a hidden, cryptic algal diversity targeting spores, propagules, and unsuspected life history stages. We explored cryo-SEM as a potentially more informative method than regular SEM to minimize artifacts of sample preparation in the study of endolithic cell inclusions which brought to light a suite of microalgal stages. We were able to differentiate floridean starch from cellular inclusions. We associated the effect of anatomical growth pattern on presence or absence of cellular inclusions in biogenic rhodoliths. Analyses of combined 16S V4 metabarcodes and 16S Sanger sequences of two red algal orders, the Halymeniales and Bonnemaisoniales, increased the established record of diversity in the region. We view rhodoliths as marine biodiversity hotspots that may function as seedbanks, temporary reservoirs for life history stages of ecologically important eukaryotic microalgae, and macroalgae or as refugia for ecosystem resilience following environmental stress.