Loss of 'Blue Carbon' from Coastal Salt Marshes Following Habitat Disturbance

Macreadie, PI; Hughes, AR; Kimbro, DL

Loss of 'Blue Carbon' from Coastal Salt Marshes Following Habitat Disturbance

Macreadie, PI

Hughes, AR Kimbro, DL

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Publication Type:: Journal Article
Citation:: PLoS ONE, 2013, 8 (7)
Issue Date:: 2013-07-08

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Field	Value	Language
dc.contributor.author	Macreadie, PI https://orcid.org/0000-0001-7362-0882	en_US
dc.contributor.author	Hughes, AR	en_US
dc.contributor.author	Kimbro, DL	en_US
dc.date.available	2013-06-12	en_US
dc.date.issued	2013-07-08	en_US
dc.identifier.citation	PLoS ONE, 2013, 8 (7)	en_US
dc.identifier.uri	http://hdl.handle.net/10453/35867
dc.description.abstract	Increased recognition of the global importance of salt marshes as 'blue carbon' (C) sinks has led to concern that salt marshes could release large amounts of stored C into the atmosphere (as CO2) if they continue undergoing disturbance, thereby accelerating climate change. Empirical evidence of C release following salt marsh habitat loss due to disturbance is rare, yet such information is essential for inclusion of salt marshes in greenhouse gas emission reduction and offset schemes. Here we investigated the stability of salt marsh (Spartina alterniflora) sediment C levels following seagrass (Thallasia testudinum) wrack accumulation; a form of disturbance common throughout the world that removes large areas of plant biomass in salt marshes. At our study site (St Joseph Bay, Florida, USA), we recorded 296 patches (7.5 ± 2.3 m2 mean area ± SE) of vegetation loss (aged 3-12 months) in a salt marsh meadow the size of a soccer field (7 275 m2). Within these disturbed patches, levels of organic C in the subsurface zone (1-5 cm depth) were ~30% lower than the surrounding undisturbed meadow. Subsequent analyses showed that the decline in subsurface C levels in disturbed patches was due to loss of below-ground plant (salt marsh) biomass, which otherwise forms the main component of the long-term 'refractory' C stock. We conclude that disturbance to salt marsh habitat due to wrack accumulation can cause significant release of below-ground C; which could shift salt marshes from C sinks to C sources, depending on the intensity and scale of disturbance. This mechanism of C release is likely to increase in the future due to sea level rise; which could increase wrack production due to increasing storminess, and will facilitate delivery of wrack into salt marsh zones due to higher and more frequent inundation. © 2013 Macreadie et al.	en_US
dc.relation	http://purl.org/au-research/grants/arc/DE130101084
dc.relation.ispartof	PLoS ONE	en_US
dc.relation.isbasedon	10.1371/journal.pone.0069244	en_US
dc.subject.classification	General Science & Technology	en_US
dc.subject.mesh	Sodium Chloride	en_US
dc.subject.mesh	Carbon	en_US
dc.subject.mesh	Organic Chemicals	en_US
dc.subject.mesh	Linear Models	en_US
dc.subject.mesh	Geologic Sediments	en_US
dc.subject.mesh	Wetlands	en_US
dc.title	Loss of 'Blue Carbon' from Coastal Salt Marshes Following Habitat Disturbance	en_US
dc.type	Journal Article
utslib.citation.volume	7	en_US
utslib.citation.volume	8	en_US
utslib.for	0602 Ecology	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
utslib.copyright.status	open_access
pubs.issue	7	en_US
pubs.publication-status	Published	en_US
pubs.volume	8	en_US

Abstract:

Increased recognition of the global importance of salt marshes as 'blue carbon' (C) sinks has led to concern that salt marshes could release large amounts of stored C into the atmosphere (as CO2) if they continue undergoing disturbance, thereby accelerating climate change. Empirical evidence of C release following salt marsh habitat loss due to disturbance is rare, yet such information is essential for inclusion of salt marshes in greenhouse gas emission reduction and offset schemes. Here we investigated the stability of salt marsh (Spartina alterniflora) sediment C levels following seagrass (Thallasia testudinum) wrack accumulation; a form of disturbance common throughout the world that removes large areas of plant biomass in salt marshes. At our study site (St Joseph Bay, Florida, USA), we recorded 296 patches (7.5 ± 2.3 m2 mean area ± SE) of vegetation loss (aged 3-12 months) in a salt marsh meadow the size of a soccer field (7 275 m2). Within these disturbed patches, levels of organic C in the subsurface zone (1-5 cm depth) were ~30% lower than the surrounding undisturbed meadow. Subsequent analyses showed that the decline in subsurface C levels in disturbed patches was due to loss of below-ground plant (salt marsh) biomass, which otherwise forms the main component of the long-term 'refractory' C stock. We conclude that disturbance to salt marsh habitat due to wrack accumulation can cause significant release of below-ground C; which could shift salt marshes from C sinks to C sources, depending on the intensity and scale of disturbance. This mechanism of C release is likely to increase in the future due to sea level rise; which could increase wrack production due to increasing storminess, and will facilitate delivery of wrack into salt marsh zones due to higher and more frequent inundation. © 2013 Macreadie et al.

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