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 th...

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Bibliographic Details
Published in:	Proceedings of the Royal Society. B, Biological sciences Biological sciences, 2015-10, Vol.282 (1817), p.20151537-20151537
Main Authors:	Macreadie, Peter I., Trevathan-Tackett, Stacey M., Skilbeck, Charles G., Sanderman, Jonathan, Curlevski, Nathalie, Jacobsen, Geraldine, Seymour, Justin R.
Format:	Article
Language:	eng
Subjects:	Alismatales - growth & development Alismatales - metabolism Bacteria Bacteria - classification Bacteria - genetics Blue Carbon Carbon - metabolism Carbon Sequestration Carbon Sink Conservation of Natural Resources Disturbance Ecosystem Geologic Sediments - chemistry New South Wales Oceans and Seas Restoration RNA, Ribosomal, 16S Seagrass
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Summary:	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.
ISSN:	0962-8452 1471-2954