Cable bacteria control iron-phosphorus dynamics in sediments of a coastal hypoxic basin

Sulu-Gambari, Fatimah; Seitaj, Dorina; Meysman, Filip J.R.; Schauer, Regina; Polerecky, Lubos; Slomp, Caroline P.

doi:10.1021/ACS.EST.5B04369

Title

Cable bacteria control iron-phosphorus dynamics in sediments of a coastal hypoxic basin

Author

Sulu-Gambari, Fatimah

Seitaj, Dorina

Meysman, Filip J.R.

Schauer, Regina

Polerecky, Lubos

Slomp, Caroline P.

Abstract

Phosphorus is an essential nutrient for life. The release of phosphorus from sediments is critical in sustaining phytoplankton growth in many aquatic systems and is pivotal to eutrophication and the development of bottom water hypoxia. Conventionally, sediment phosphorus release is thought to be controlled by changes in iron oxide reduction driven by variations in external environmental factors, such as organic matter input and bottom water oxygen. Here, we show that internal shifts in microbial communities, and specifically the population dynamics of cable bacteria, can also induce strong seasonality in sedimentary ironphosphorus dynamics. Field observations in a seasonally hypoxic coastal basin demonstrate that the long-range electrogenic metabolism of cable bacteria leads to a dissolution of iron sulfides in winter and spring. Subsequent oxidation of the mobilized ferrous iron with manganese oxides results in a large stock of iron-oxide-bound phosphorus below the oxic zone. In summer, when bottom water hypoxia develops and cable bacteria are undetectable, the phosphorus associated with these iron oxides is released, strongly increasing phosphorus availability in the water column. Future research should elucidate whether formation of iron-oxide-bound phosphorus driven by cable bacteria, as observed in this study, contributes to the seasonality in ironphosphorus cycling in aquatic sediments worldwide.

Language

English

Source (journal)

Environmental science and technology / American Chemical Society. - Easton, Pa

Publication

Easton, Pa : 2016

ISSN

0013-936X [print]

1520-5851 [online]

DOI

10.1021/ACS.EST.5B04369

Volume/pages