Acantharians (supergroup Rhizaria) can be important contributors to surface primary production and to carbon flux to the deep sea, but are often underestimated because their delicate structures are destroyed by plankton nets or dissolved by chemical fixatives. As they are also uncultured, relatively little is known about acantharian biology, especially regarding their life cycles. Here, we take a paired approach, bringing together high‐throughput, in situ imaging and metabarcode sequencing, to investigate acantharian abundance, vertical distribution, and life history in the western North Pacific. Concentrations of imaged acantharian cells correlated well with relative abundances of 18S rRNA gene sequences from acantharians with known, recognizable morphologies, but not to sequences corresponding to acantharians with unknown morphology. These results suggest that morphologically undescribed clades may lack the characteristic star‐shaped acantharian skeleton or are much smaller than described acantharians. The smaller size of acantharians imaged at depth supports current hypotheses regarding nonsymbiotic acantharian life cycles: cysts or vegetative cells release reproductive swarmer cells in deep water and juvenile cells grow as they ascend toward the surface. Moreover, sequencing data present the possibility that some photosymbiotic acantharians may also reproduce at depth, like their nonsymbiotic, encysting relatives, which is counter to previous hypotheses. Finally, in situ imaging captured a new acantharian behavior that may be a previously undescribed predation strategy.

中文翻译：

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配对的高通量，原位成像和高通量测序可阐明棘鱼的丰度和垂直分布

棘皮动物（根茎超群）可能是地表初级生产和深海碳通量的重要贡献者，但由于它们的脆弱结构被浮游生物网破坏或被化学固定剂溶解而常常被低估。由于它们也是未经养殖的，因此对棘皮动物生物学知之甚少，特别是关于它们的生命周期。在这里，我们采用了一种配对方法，将高通量，原位成像和元条形码测序结合在一起，以研究北太平洋西部棘皮动物的丰富度，垂直分布和生活史。成像的棘皮动物细胞的浓度与来自已知，可识别形态的棘皮动物的18S rRNA基因序列的相对丰度有很好的相关性，但与对应于形态未知的棘皮动物的序列却不相关。这些结果表明，形态上未描述的进化枝可能缺少特征性的星形棘皮动物骨骼或比描述的棘皮动物小得多。深度成像的较小棘皮动物支持当前关于非共生棘皮动物生命周期的假说：囊肿或营养细胞在深水中释放繁殖性繁殖细胞，而幼小细胞则随着向表面的上升而生长。此外，测序数据还显示出一些光共生棘壳动物也可能在深度繁殖的可能性，例如其非共生关系，即吞噬亲戚，这与先前的假设相反。最后，原位成像捕获了新的棘生动物行为，这可能是先前未描述的捕食策略。