Long-term carbon storage and its recent loss in an estuarine Posidonia australis meadow (Albany, Western Australia)

Mohammad Rozaimi Jamaludin, Paul S. Lavery, Oscar Serrano, Danielle Kyrwood

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Oyster Harbour, on the south coast of Western Australia, supports 3.6-3.9 km2 of seagrass meadows, following the loss of approximately 2.8-3.1 km2 in the 1980s. This small area of prevailing meadows hold significant carbon stores accumulated over the past 3000 years. In this study, we sampled three sediment cores from a Posidonia australis meadow and analysed organic matter (OM), organic carbon (OC) and inorganic carbon (IC) contents in bulk sediments, and δ13C signatures of OM. The OM and OC contents (mean ± SE) in the cores were 9.07 ± 0.36% and 2.24 ± 0.05%, respectively. The mean IC content was 3.16 ± 0.17%. δ13C signatures of the sedimentary OM ranged from -10.01‰ to -13.28‰. Using a Bayesian isotopic mixing model, it is estimated that 57-67% of the OM in the seagrass sediments was derived from P. australis detrital matter. The total carbon (TC) stores in 150 cm-thick seagrass sediments averaged 27.92 kg TC m-2 (10.79 kg OC m-2 and 17.13 kg IC m-2). Based on radiocarbon dating, the mean sediment accumulation rate was 0.0494 cm yr-1, which led to a long-term TC accumulation rate of 8.92 g TC m-2 yr-1 (3.45 g OC m-2 yr-1 and 5.47 g IC m-2 yr-1). Based on historical seagrass cover (3.6-6.7 km2 during the 1960s to 1980s), the estimated TC stores in 150 cm-thick seagrass sediments at Oyster Harbour would have been 101-187 Gg TC. The eutrophication-driven loss of seagrasses during the 1980s resulted in the absence of OC accumulation capacity amounting to 280-310 Mg OC (over 29 years). The loss of seagrass area could also have resulted in the release of 37-41 Gg CO2, assuming that all of the OC in shallow sediment is remineralised after meadow disturbance. These results exemplify the importance of seagrasses meadows as important carbon sinks and the potential for losses of carbon stores due to ecosystem degradation.

Original languageEnglish
Pages (from-to)58-65
Number of pages8
JournalEstuarine, Coastal and Shelf Science
Volume171
DOIs
Publication statusPublished - 20 Mar 2016

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carbon sequestration
Western Australia
meadow
meadows
organic carbon
seagrass
carbon
inorganic carbon
organic matter
sediment
carbon sinks
sediments
accumulation rate
harbor
seagrass meadow
posidonia
loss
Posidonia
carbon sink
radiocarbon dating

Keywords

  • Blue carbon sink
  • Carbonate
  • Eutrophication
  • Global change
  • Organic matter
  • Seagrass

ASJC Scopus subject areas

  • Aquatic Science
  • Oceanography

Cite this

Long-term carbon storage and its recent loss in an estuarine Posidonia australis meadow (Albany, Western Australia). / Jamaludin, Mohammad Rozaimi; Lavery, Paul S.; Serrano, Oscar; Kyrwood, Danielle.

In: Estuarine, Coastal and Shelf Science, Vol. 171, 20.03.2016, p. 58-65.

Research output: Contribution to journalArticle

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