title: Cable Bacteria Control Iron-Phosphorus Dynamics in Sediments of a Coastal Hypoxic Basin.
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 iron-phosphorus 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 iron-phosphorus cycling in aquatic sediments worldwide.
authors.affiliation: Department of Earth Sciences, Geochemistry, Faculty of Geosciences, Utrecht University , Utrecht, The Netherlands.
authors.forename: Fatimah
authors.initials: F
authors.lastname: Sulu-Gambari
authors.affiliation: Department of Ecosystem Studies, Royal Netherlands Institute for Sea Research , Yerseke, The Netherlands.
authors.forename: Dorina
authors.initials: D
authors.lastname: Seitaj
authors.affiliation: Department of Ecosystem Studies, Royal Netherlands Institute for Sea Research , Yerseke, The Netherlands.
authors.forename: Filip J R
authors.initials: FJ
authors.lastname: Meysman
authors.affiliation: Center for Geomicrobiology and Section for Microbiology, Department of Bioscience, Aarhus University , Aarhus, Denmark.
authors.forename: Regina
authors.initials: R
authors.lastname: Schauer
authors.affiliation: Department of Earth Sciences, Geochemistry, Faculty of Geosciences, Utrecht University , Utrecht, The Netherlands.
authors.forename: Lubos
authors.initials: L
authors.lastname: Polerecky
authors.affiliation: Department of Earth Sciences, Geochemistry, Faculty of Geosciences, Utrecht University , Utrecht, The Netherlands.
authors.forename: Caroline P
authors.initials: CP
authors.lastname: Slomp
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D005068:Eutrophication; D005290:Ferric Compounds / Q000737:chemistry / Q000378:metabolism; D005296:Ferrous Compounds / Q000737:chemistry / Q000378:metabolism; D019015:Geologic Sediments / Q000737:chemistry* / Q000382:microbiology*; D007501:Iron / Q000032:analysis / Q000378:metabolism*; D009426:Netherlands; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010758:Phosphorus / Q000032:analysis / Q000378:metabolism*; D011157:Population Dynamics; D012621:Seasons; D014867:Water / Q000737:chemistry
chemical_list: D005290:Ferric Compounds; D005296:Ferrous Compounds; D014867:Water; C000499:ferric oxide; D010758:Phosphorus; D007501:Iron; D010100:Oxygen; C022597:ferrous sulfide