Thompson Anne W, Ward Anna C, Sweeney Carey P, Sutherland Kelly R
Department of Biology, Portland State University, Portland, OR, USA.
Oregon Institute of Marine Biology, University of Oregon, Eugene, OR, USA.
ISME Commun. 2021 Apr 14;1(1):11. doi: 10.1038/s43705-021-00007-1.
Pyrosomes are widely distributed pelagic tunicates that have the potential to reshape marine food webs when they bloom. However, their grazing preferences and interactions with the background microbial community are poorly understood. This is the first study of the marine microorganisms associated with pyrosomes undertaken to improve the understanding of pyrosome biology, the impact of pyrosome blooms on marine microbial systems, and microbial symbioses with marine animals. The diversity, relative abundance, and taxonomy of pyrosome-associated microorganisms were compared to seawater during a Pyrosoma atlanticum bloom in the Northern California Current System using high-throughput sequencing of the 16S rRNA gene, microscopy, and flow cytometry. We found that pyrosomes harbor a microbiome distinct from the surrounding seawater, which was dominated by a few novel taxa. In addition to the dominant taxa, numerous more rare pyrosome-specific microbial taxa were recovered. Multiple bioluminescent taxa were present in pyrosomes, which may be a source of the iconic pyrosome luminescence. We also discovered free-living marine microorganisms in association with pyrosomes, suggesting that pyrosome feeding impacts all microbial size classes but preferentially removes larger eukaryotic taxa. This study demonstrates that microbial symbionts and microbial prey are central to pyrosome biology. In addition to pyrosome impacts on higher trophic level marine food webs, the work suggests that pyrosomes also alter marine food webs at the microbial level through feeding and seeding of the marine microbial communities with their symbionts. Future efforts to predict pyrosome blooms, and account for their ecosystem impacts, should consider pyrosome interactions with marine microbial communities.
火体虫是广泛分布的浮游被囊动物，当其大量繁殖时有可能重塑海洋食物网。然而，它们的摄食偏好以及与背景微生物群落的相互作用却鲜为人知。这是首次对与火体虫相关的海洋微生物进行研究，旨在增进对火体虫生物学、火体虫大量繁殖对海洋微生物系统的影响以及与海洋动物的微生物共生关系的理解。利用16S rRNA基因的高通量测序、显微镜检查和流式细胞术，将北加利福尼亚洋流系统中大西洋火体虫大量繁殖期间与火体虫相关的微生物的多样性、相对丰度和分类学与海水进行了比较。我们发现火体虫拥有一个与周围海水不同的微生物群落，该群落由少数新分类群主导。除了优势分类群外，还发现了许多更为罕见的火体虫特异性微生物分类群。火体虫中存在多种生物发光分类群，这可能是标志性火体虫发光的来源。我们还发现了与火体虫相关的自由生活海洋微生物，这表明火体虫的摄食会影响所有微生物大小类别，但优先去除较大的真核生物分类群。这项研究表明，微生物共生体和微生物猎物是火体虫生物学的核心。除了火体虫对较高营养级海洋食物网的影响外，这项工作还表明，火体虫还通过摄食以及用其共生体播种海洋微生物群落，在微生物水平上改变海洋食物网。未来预测火体虫大量繁殖并评估其对生态系统影响的工作应考虑火体虫与海洋微生物群落的相互作用。
