Mesophotic foraminiferal-algal nodules play a role in the Red Sea carbonate budget

Valentina Alice Bracchi*, Sam J. Purkis, Fabio Marchese, Megan K.B. Nolan, Tullia Isotta Terraneo, Silvia Vimercati, Giovanni Chimienti, Mattie Rodrigue, Ameer Eweida, Francesca Benzoni

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


During two scientific expeditions between 2020 and 2022, direct surveys led to the discovery of free-living mesophotic foraminiferal-algal nodules along the coast of the NEOM region (northern Saudi Arabian Red Sea) where they form an unexpected benthic ecosystem in mesophotic water depths on the continental shelf. Being mostly spheroidal, the nodules are transported en masse down slope, into the deep water of the basin, where they stop accreting. Radiometric dating informs that these nodules can be more than two thousand years old and that they collectively contribute up to 66 g m−2 year−1 to the mesophotic benthic carbonate budget and account for at least 980 megatons of calcium carbonate, a substantial contribution considering the depauperate production of carbonate by other means in this light-limited environment. Our findings advance the knowledge of mesophotic biodiversity and carbonate production, and provide data that will inform conservation policies in the Saudi Arabian Red Sea.

Original languageEnglish (US)
Article number288
JournalCommunications Earth and Environment
Issue number1
StatePublished - Dec 2023

ASJC Scopus subject areas

  • General Environmental Science
  • General Earth and Planetary Sciences


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