Seagrass-Mediated Phosphorus and Iron Solubilization in Tropical Sediments

Kasper Elgetti Brodersen, Klaus Koren, Maria Moßhammer, Peter J. Ralph, Michael Kühl*, Jakob Santner

*Corresponding author

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Abstract

Tropical seagrasses are nutrient-limited owing to the strong phosphorus fixation capacity of carbonate-rich sediments, yet they form densely vegetated, multispecies meadows in oligotrophic tropical waters. Using a novel combination of high-resolution, two-dimensional chemical imaging of O2, pH, iron, sulfide, calcium, and phosphorus, we found that tropical seagrasses are able to mobilize the essential nutrients iron and phosphorus in their rhizosphere via multiple biogeochemical pathways. We show that tropical seagrasses mobilize phosphorus and iron within their rhizosphere via plant-induced local acidification, leading to dissolution of carbonates and release of phosphate, and via local stimulation of microbial sulfide production, causing reduction of insoluble Fe(III) oxyhydroxides to dissolved Fe(II) with concomitant phosphate release into the rhizosphere porewater. These nutrient mobilization mechanisms have a direct link to seagrass-derived radial O2 loss and secretion of dissolved organic carbon from the below-ground tissue into the rhizosphere. Our demonstration of seagrass-derived rhizospheric phosphorus and iron mobilization explains why seagrasses are widely distributed in oligotrophic tropical waters.

OriginalsprogEngelsk
TidsskriftEnvironmental Science and Technology
Vol/bind51
Udgave nummer24
Sider (fra-til)14155-14163
Antal sider9
ISSN0013-936X
DOI
StatusUdgivet - 19 dec. 2017
Udgivet eksterntJa

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