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Vulnerability of seagrass blue carbon to microbial attack following exposure to warming and oxygen.
Macreadie, P I; Atwood, T B; Seymour, J R; Fontes, M L Schmitz; Sanderman, J; Nielsen, D A; Connolly, R M.
Affiliation
  • Macreadie PI; School of Life and Environmental Sciences, Centre for Integrative Ecology, Deakin University, Victoria 3216, Australia; Climate Change Cluster, University of Technology Sydney, NSW 2007, Australia. Electronic address: p.macreadie@deakin.edu.au.
  • Atwood TB; Department of Watershed Sciences and The Ecology Center, Utah State University, Logan, UT 84322, USA.
  • Seymour JR; Climate Change Cluster, University of Technology Sydney, NSW 2007, Australia.
  • Fontes MLS; Climate Change Cluster, University of Technology Sydney, NSW 2007, Australia.
  • Sanderman J; Woods Hole Research Center, 149 Woods Hole Road, Falmouth, MA 02540, USA; CSIRO Agriculture, Waite Campus, Waite Rd, Urrbrae, SA 5064, Australia.
  • Nielsen DA; School of Life Sciences, University of Technology Sydney, NSW 2007, Australia.
  • Connolly RM; Australian Rivers Institute - Coast & Estuaries, School of Environment and Science, Gold Coast campus, Griffith University, Queensland 4222, Australia.
Sci Total Environ ; 686: 264-275, 2019 Oct 10.
Article in En | MEDLINE | ID: mdl-31181514
ABSTRACT
Seagrass meadows store globally-significant quantities of organic 'blue' carbon. These blue carbon stocks are potentially vulnerable to anthropogenic stressors (e.g. coastal development, climate change). Here, we tested the impact of oxygen exposure and warming (major consequences of human disturbance) on rates of microbial carbon break-down in seagrass sediments. Active microbes occurred throughout seagrass sediment profiles, but deep, ancient sediments (~5000 yrs. old) contained only 3% of the abundance of active microbes as young, surface sediments (<2 yrs. old). Metagenomic analysis revealed that microbial community structure and function changed with depth, with a shift from proteobacteria and high levels of genes involved in sulfur cycling in the near surface samples, to a higher proportion of firmicutes and euraracheota and genes involved in methanogenesis at depth. Ancient carbon consisted almost entirely (97%) of carbon considered 'thermally recalcitrant', and therefore presumably inaccessible to microbial attack. Experimental warming had little impact on carbon; however, exposure of ancient sediments to oxygen increased microbial abundance, carbon uptake and sediment carbon turnover (34-38 fold). Overall, this study provides detailed characterization of seagrass blue carbon (chemical stability, age, associated microbes) and suggests that environmental disturbances that expose coastal sediments to oxygen (e.g. dredging) have the capacity to diminish seagrass sediment carbon stocks by facilitating microbial remineralisation.
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Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Climate Change / Poaceae Language: En Journal: Sci Total Environ Year: 2019 Document type: Article

Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Climate Change / Poaceae Language: En Journal: Sci Total Environ Year: 2019 Document type: Article