Microbial associates of an endemic Mediterranean seagrass enhance the access of the host and the surrounding seawater to inorganic nitrogen under ocean acidification

Abstract

Seagrasses are important primary producers in oceans worldwide. They live in shallow coastal waters that are experiencing carbon dioxide enrichment and ocean acidification. Posidonia oceanica, an endemic seagrass species that dominates the Mediterranean Sea, achieves high abundances in seawater with relatively low concentrations of dissolved inorganic nitrogen. Here we tested whether microbial metabolisms associated with P. oceanica and surrounding seawater enhance seagrass access to nitrogen. Using stable isotope enrichments of intact seagrass with amino acids, we showed that ammonification by free-living and seagrass-associated microbes produce ammonium that is likely used by seagrass and surrounding particulate organic matter. Metagenomic analysis of the epiphytic biofilm on the blades and rhizomes support the ubiquity of microbial ammonification genes in this system. Further, we leveraged the presence of natural carbon dioxide vents and show that the presence of P. oceanica enhanced the uptake of nitrogen by water column particulate organic matter, increasing carbon fixation by a factor of 8.6–17.4 with the greatest effect at \(\mathrm{CO_2}\) vent sites. However, microbial ammonification was reduced at lower pH, suggesting that future ocean climate change will compromise this microbial process. Thus, the seagrass holobiont enhances water column productivity, even in the context of ocean acidification.

Related items
Environmental Data
Metagenomic Data

Citation

BibTeX citation:

@online{a._pfister2023,
  author = {A. Pfister, Catherine and Cardini, Ulisse and Mirasola,
    Alice and M. Montilla, Luis and Veseli, Iva and Gattuso, Jean-Pierre
    and Teixido, Nuria},
  title = {Microbial Associates of an Endemic {Mediterranean} Seagrass
    Enhance the Access of the Host and the Surrounding Seawater to
    Inorganic Nitrogen Under Ocean Acidification},
  date = {2023-11-15},
  url = {https://www.luismmontilla.com/papers/pfister2023/},
  doi = {https://doi.org/10.1038/s41598-023-47126-4},
  langid = {en},
  abstract = {Seagrasses are important primary producers in oceans
    worldwide. They live in shallow coastal waters that are experiencing
    carbon dioxide enrichment and ocean acidification. \_Posidonia
    oceanica\_, an endemic seagrass species that dominates the
    Mediterranean Sea, achieves high abundances in seawater with
    relatively low concentrations of dissolved inorganic nitrogen. Here
    we tested whether microbial metabolisms associated with \_P.
    oceanica\_ and surrounding seawater enhance seagrass access to
    nitrogen. Using stable isotope enrichments of intact seagrass with
    amino acids, we showed that ammonification by free-living and
    seagrass-associated microbes produce ammonium that is likely used by
    seagrass and surrounding particulate organic matter. Metagenomic
    analysis of the epiphytic biofilm on the blades and rhizomes support
    the ubiquity of microbial ammonification genes in this system.
    Further, we leveraged the presence of natural carbon dioxide vents
    and show that the presence of \_P. oceanica\_ enhanced the uptake of
    nitrogen by water column particulate organic matter, increasing
    carbon fixation by a factor of 8.6–17.4 with the greatest effect at
    \$\textbackslash mathrm\{CO\_2\}\$ vent sites. However, microbial
    ammonification was reduced at lower pH, suggesting that future ocean
    climate change will compromise this microbial process. Thus, the
    seagrass holobiont enhances water column productivity, even in the
    context of ocean acidification.}
}

For attribution, please cite this work as:

A. Pfister, Catherine, Ulisse Cardini, Alice Mirasola, et al. 2023. “Microbial Associates of an Endemic Mediterranean Seagrass Enhance the Access of the Host and the Surrounding Seawater to Inorganic Nitrogen Under Ocean Acidification.” Scientific Reports, November 15. https://doi.org/https://doi.org/10.1038/s41598-023-47126-4.