Co-existence of distinct Ostreococcus ecotypes at an oceanic front
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Clayton_et_al-2017-Limnology_and_Oceanography.pdf
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Author(s)
Lin, Yun-Chi
Worden, Alexandra Z.
Clayton, Sophie A
Follows, Michael J
Date Issued
September 2016
Journal
Limnology and Oceanography
Publisher
Wiley
Citation
Clayton, Sophie, et al. “Co-Existence of Distinct Ostreococcus Ecotypes at an Oceanic Front: Ocean Fronts Promote Biodiversity.” Limnology and Oceanography, vol. 62, no. 1, Jan. 2017, pp. 75–88. © 2016 The Authors
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Final published version
Abstract
Western boundary currents support high primary production and carbon export. Here, we performed a survey of photosynthetic picoeukaryotes in the North Pacific Ocean in four transects crossing the Kuroshio Front. Prasinophyte algae comprised 85% of 18S rRNA gene sequences for photosynthetic taxa in the <5 μm size fraction. The picoplanktonic (<2 μm) genera Micromonas and Ostreococcus comprised 30% and 51% of the total photosynthetic 18S rDNA sequences from five stations. Phylogenetic analysis showed that two Ostreococcus ecotypes, until now rarely found to co-occur, were both present in the majority of samples. Ostreococcus ecotype OI reached 6,830 ± 343 gene copies mL[superscript −1], while Ostreococcus ecotype OII reached 50,190 ± 971 gene copies mL−1based on qPCR analysis of the 18S rRNA gene. These values are higher than in studies of other oceanographic regions by a factor of 10 for OII. The data suggest that meso- and finer-scale physical dynamics had a significant impact on the populations at the front, either by mingling ecotypes from different source regions at fine scales (∼10s km) or by stimulating their growth through vertical nutrient injections. We investigate this hypothesis with an idealized diffusion-reaction model, and find that only a combination of mixing and positive net growth can explain the observed distributions and overlap of the two Ostreococcus ecotypes. Our field observations support larger-scale numerical ocean simulations that predict enhanced biodiversity at western boundary current fronts, and suggest a strategy for systematically testing that hypothesis.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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Creative Commons Attribution 4.0 International License
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DOI of Published Version
https://doi.org/10.1002/LNO.10373
