Environmental Controls of iron-reducing microorganisms in Antarctic marine sediments (ECIMAS)

AROMOKEYE DAVID A.; WILLIS PORATTI GRACIANA; WUNDER LEA C.; OTERSEN CAROLIN; HENKEL SUSANN; FRIEDRICH MICHAEL

Workshop; Coordination Workshop SPP 1158; 2020

DFG

Rapid warming has affected the Western Antarctic Peninsula (WAP) strongly over the last 50 years resulting in glacier retreat at unprecedented rates. As a consequence, sediment accumulation rates have increased including large amounts of iron(III) oxides [1,2]. Microbial iron reduction of insoluble iron(III) oxides linked to organic matter oxidation can produce dissolved iron in pore water, contributing to benthic Fe(II) fluxes and potentially to the export of iron compounds to the Southern Ocean, known for being limited in primary productivity [3]. Depending on the availability of organic matter and electron donors, iron reduction can out-compete sulfate reduction in marine sediments [4]. However, little is known about geochemical cycling, organic matter degradation and metal/sulfate reduction in Antarctic sediments. The aim of our work is to elucidate the ecology of iron-reducing microbial communities, and their environmental controls in Antarctic marine sediments. We focus on hots spots of environmental change at King George Island (KGI, Isla 25 de Mayo, WAP) including sites that have been newly exposed due of receding glaciers, accumulating iron oxides and high dissolved iron concentrations compared to typical sulfidogenic sites as a reference, indicative of sulfate reduction. For that, factors that are potentially controlling iron and sulfate reducing microorganisms will be studied, such as electron donor type and availability, electron acceptor availability, terrigenic inputs and temperature variations.