Document Type

Article

Publisher

PLOS

Faculty

Faculty of Health, Engineering and Science

School

School of Natural Sciences

RAS ID

16423

Comments

This article was originally published as: Lavery, P., Mateo, M-A., Serrano, O., & Rozaimi, M. (2013). Variability in the carbon storage of seagrass habitats and its implications for global estimates of blue carbon ecosystem service. PLoS One, 8(9), e73748. Original article available here

Abstract

The recent focus on carbon trading has intensified interest in ‘Blue Carbon’–carbon sequestered by coastal vegetated ecosystems, particularly seagrasses. Most information on seagrass carbon storage is derived from studies of a single species, Posidonia oceanica, from the Mediterranean Sea. We surveyed 17 Australian seagrass habitats to assess the variability in their sedimentary organic carbon (Corg) stocks. The habitats encompassed 10 species, in mono-specific or mixed meadows, depositional to exposed habitats and temperate to tropical habitats. There was an 18-fold difference in the Corg stock (1.09– 20.14 mg Corg cm23 for a temperate Posidonia sinuosa and a temperate, estuarine P. australis meadow, respectively). Integrated over the top 25 cm of sediment, this equated to an areal stock of 262–4833 g Corg m22. For some species, there was an effect of water depth on the Corg stocks, with greater stocks in deeper sites; no differences were found among subtidal and inter-tidal habitats. The estimated carbon storage in Australian seagrass ecosystems, taking into account interhabitat variability, was 155 Mt. At a 2014–15 fixed carbon price of A$25.40 t21 and an estimated market price of $35 t21 in 2020, the Corg stock in the top 25 cm of seagrass habitats has a potential value of $AUD 3.9–5.4 bill. The estimates of annual Corg accumulation by Australian seagrasses ranged from 0.093 to 6.15 Mt, with a most probable estimate of 0.93 Mt y21 (10.1 t. km22 y21). These estimates, while large, were one-third of those that would be calculated if inter-habitat variability in carbon stocks were not taken into account. We conclude that there is an urgent need for more information on the variability in seagrass carbon stock and accumulation rates, and the factors driving this variability, in order to improve global estimates of seagrass Blue Carbon storage.

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