Blue carbon: past, present and future, with emphasis on macroalgae

John Raven (Lead / Corresponding author)

    Research output: Contribution to journalReview articlepeer-review

    41 Citations (Scopus)


    Blue carbon did not originally include macroalgal ecosystems; however evidence is mounting that macroalgal ecosystems function in marine carbon sequestration. The great majority of present day marine macroalgal net primary productivity (NPP) involves haptophytic algae on eroding shores. For these organisms the long-term storage of particulate organic carbon involves export from the site of production of biomass that has evaded parasites and grazers, and that some of the exported biomass is sedimented and stored rather than being mineralized en route by detritivores (microbes and fauna). Export from eroding shores, and subsequent storage, of haptophytic marine macroalgal particulate organic carbon could have started by 1.6 Ga. Storage on depositing shores close to the site of NPP by rhizophytic macroalgae and then by rhizophytic coastal seagrasses, tidal marshes and mangroves began not less than 209 Ma ago. Future increases in surface ocean temperatures may bring tropical marine macroalgae to their upper temperature limit, while temperate marine macroalgae will migrate poleward, in both cases assuming that temperature increases faster than genetic adaptation to higher temperature. Increased CO2 in the surface ocean will generally favour uncalcified over calcified marine macroalgae. This results in decreased CO2 release from decreased calcification, as well as decreased ballasting by CaCO3 of exported particulate organic carbon resulting in decreasing sedimentation. While much more work is needed, the available information suggests that macroalgae play a significant role in marine organic carbon storage.

    Original languageEnglish
    Article number20180336
    Pages (from-to)1-5
    Number of pages5
    JournalBiology Letters
    Issue number10
    Early online date3 Oct 2018
    Publication statusPublished - Oct 2018


    • Blue carbon
    • Carbon export
    • Carbon sequestration
    • Marine macroalgae
    • Palaeobiology

    ASJC Scopus subject areas

    • Agricultural and Biological Sciences (miscellaneous)
    • General Agricultural and Biological Sciences


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