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Vertical community patterns of Labyrinthulomycetes protists reveal their potential importance in the oceanic biological pump |
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| Authors: | Mohan Bai Ningdong Xie Yaodong He Jiaqian Li Jackie L. Collier Dana E. Hunt Zackary I. Johnson Nianzhi Jiao Guangyi Wang |
| Affiliation: | 1. Center for Marine Environmental Ecology, School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072 China These authors contributed equally to this work.;2. Center for Marine Environmental Ecology, School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072 China;3. School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York, 11794-5000 USA;4. Marine Laboratory, Duke University, Beaufort, NC, 28516 USA;5. Marine Laboratory, Duke University, Beaufort, NC, 28516 USA Biology Department, Duke University, Durham, NC, 27708 USA;6. Center for Marine Environmental Ecology, School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072 China State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, 361005 China |
| Abstract: | The biological pump plays a vital role in exporting organic particles into the deep ocean for long-term carbon sequestration. However, much remains unknown about some of its key microbial players. In this study, Labyrinthulomycetes protists (LP) were used to understand the significance of heterotrophic microeukaryotes in the transport of particulate organic matter from the surface to the dark ocean. Unlike the sharp vertical decrease of prokaryotic biomass, the LP biomass only slightly decreased with depth and eventually exceeded prokaryotic biomass in the bathypelagic layer. Sequencing identified high diversity of the LP communities with a dominance of Aplanochytrium at all depths. Notably, ASVs that were observed in the surface layer comprised ~20% of ASVs and ~60% of sequences in each of the deeper (including bathypelagic) layers, suggesting potential vertical export of the LP populations to the deep ocean. Further analyses of the vertical patterns of the 50 most abundant ASVs revealed niche partitioning of LP phylotypes in the pelagic ocean, including those that could decompose organic detritus and/or facilitate the formation of fast-sinking particles. Overall, this study presents several lines of evidence that the LP can be an important component of the biological pump through their multiple ecotypes in the pelagic ocean. |
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