State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Institute of Marine Microbes and Ecospheres, Xiamen University, Xiamen, China.
Fujian Key Laboratory of Marine Carbon Sequestration, Xiamen University, Xiamen, China.
Microbiol Spectr. 2024 Apr 2;12(4):e0242423. doi: 10.1128/spectrum.02424-23. Epub 2024 Mar 15.
Microeukaryotic plankton (0.2-200 µm), which are morphologically and genetically highly diverse, play a crucial role in ocean productivity and carbon consumption. The Pacific Ocean (PO), one of the world's largest oligotrophic regions, remains largely unexplored in terms of the biogeography and biodiversity of microeukaryotes based on large-scale sampling. We investigated the horizontal distribution of microeukaryotes along a 16,000 km transect from the west to the east of the PO. The alpha diversity indices showed a distinct decreasing trend from west to east, which was highly correlated with water temperature. The microeukaryotic community, which was clustered into the western, central, and eastern PO groups, displayed a significant distance-decay relationship. Syndiniales, a lineage of parasitic dinoflagellates, was ubiquitously distributed along the transect and dominated the community in terms of both sequence and zero-radius operational taxonomic unit (ZOTU) proportions. The prevailing dominance of Syndiniales-affiliated ZOTUs and their close associations with dinoflagellates, diatoms, and radiolarians, as revealed by SparCC correlation analysis, suggested that parasitism may be an important trophic strategy in the surface waters of the PO. Geographical distance and temperature were the most important environmental factors that significantly correlated with community structure. Overall, our study sheds more light on the distribution pattern of both alpha and beta diversities of microeukaryotic communities and highlighted the importance of parasitisms by Syndiniales across the tropical PO.IMPORTANCEUnderstanding the biogeographical and biodiversity patterns of microeukaryotic communities is essential to comprehending their roles in biogeochemical cycling. In this study, planktonic microeukaryotes were collected along a west-to-east Pacific Ocean transect (ca. 16,000 km). Our study revealed that the alpha diversity indices were highly correlated with water temperature, and the microeukaryotic communities displayed a distinct geographical distance-driven pattern. The predominance of the parasitic dinoflagellate lineage Syndiniales and their close relationship with other microeukaryotic groups suggest that parasitism may be a crucial survival strategy for microeukaryotes in the surface waters of the Pacific Ocean. Our findings expand our understanding of the biodiversity and biogeographical pattern of microeukaryotes and highlight the significance of parasitic Syndiniales in the surface ocean.
微型真核浮游生物（0.2-200 µm）形态和遗传上高度多样化，在海洋生产力和碳消耗中起着至关重要的作用。太平洋（PO）是世界上最大的贫营养区之一，根据大规模采样，其微型真核生物的生物地理学和生物多样性在很大程度上仍未得到探索。我们调查了从 PO 的西部到东部的 16000 公里横断线上微型真核生物的水平分布。α多样性指数显示出从西到东明显减少的趋势，这与水温高度相关。微型真核生物群落聚类为西、中、东 PO 群，显示出显著的距离衰减关系。Syndiniales 是寄生甲藻的一个谱系，沿横断带广泛分布，在序列和零半径操作分类单元（ZOTU）比例方面均占主导地位。通过 SparCC 相关分析显示，Syndiniales 相关 ZOTUs 的盛行优势及其与甲藻、硅藻和放射虫的密切关联表明，寄生可能是 PO 表层水域的一种重要营养策略。地理距离和温度是与群落结构显著相关的最重要环境因素。总的来说，我们的研究更深入地了解了微型真核生物群落的α和β多样性分布模式，并强调了 Syndiniales 在热带 PO 中的寄生作用的重要性。
