Losses and recovery of organic carbon from a seagrass ecosystem following disturbance.
Seagrasses are among the Earth's most efficient and long-term carbon sinks, but coastal development threatens this capacity. We report new evidence that disturbance to seagrass ecosystems causes release of ancient carbon. In a seagrass ecosystem that had been disturbed 50 years ago, we found that soil carbon stocks declined by 72%, which, according to radiocarbon dating, had taken hundreds to thousands of years to accumulate. Disturbed soils harboured different benthic bacterial communities (according to 16S rRNA sequence analysis), with higher proportions of aerobic heterotrophs compared with undisturbed. Fingerprinting of the carbon (via stable isotopes) suggested that the contribution of autochthonous carbon (carbon produced through plant primary production) to the soil carbon pool was less in disturbed areas compared with seagrass and recovered areas. Seagrass areas that had recovered from disturbance had slightly lower (35%) carbon levels than undisturbed, but more than twice as much as the disturbed areas, which is encouraging for restoration efforts. Slow rates of seagrass recovery imply the need to transplant seagrass, rather than waiting for recovery via natural processes. This study empirically demonstrates that disturbance to seagrass ecosystems can cause release of ancient carbon, with potentially major global warming consequences.
Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, PO Box 123, 2007, Broadway, Australia Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3216, Australia petermacreadie@gmail.com.
Peter I
PI
Macreadie
Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, PO Box 123, 2007, Broadway, Australia.
Stacey M
SM
Trevathan-Tackett
School of Life Science, University of Technology Sydney, PO Box 123, 2007, Broadway, Australia.
Charles G
CG
Skilbeck
CSIRO Sustainable Agriculture National Research Flagship, PMB 2, Glen Osmond, South Australia 5064, Australia Woods Hole Research Center, 149 Woods Hole Road, Falmouth MA 012540, USA.
Jonathan
J
Sanderman
Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, PO Box 123, 2007, Broadway, Australia.
Nathalie
N
Curlevski
Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights 2234, Australia.
Geraldine
G
Jacobsen
Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, PO Box 123, 2007, Broadway, Australia.
Justin R
JR
Seymour
D035961:Alismatales / Q000254:growth & development* / Q000378:metabolism*; D001419:Bacteria / Q000145:classification / Q000235:genetics; D002244:Carbon / Q000378:metabolism*; D057965:Carbon Sequestration; D003247:Conservation of Natural Resources; D017753:Ecosystem; D019015:Geologic Sediments / Q000737:chemistry; D009517:New South Wales; D009792:Oceans and Seas; D012336:RNA, Ribosomal, 16S
D012336:RNA, Ribosomal, 16S; D002244:Carbon
bacteria; blue carbon; carbon sink; disturbance; restoration; seagrass