Evidence of long-term macroalgal carbon sequestration in deep-sea sediments from ancient eDNA samples

Ms Ellyn Erlania¹, Prof Peter  Macreadie¹, Dr Adam Miller¹, Dr Alecia  Bellgrove¹

¹Deakin University, Warrnambool, Australia

Macroalgae (seaweeds) have been proposed as globally significant contributors to ocean carbon drawdown (blue carbon), exporting carbon-rich plant biomass from their coastal origins to the deep sea. However, no studies have verified the long-term sequestration of macroalgal carbon within deep-sea sediments. Here, we provide evidence of macroalgal DNA products from ancient marine sediments collected from ~20 km off the southern Australian coast in water depths ranging from 68-104 m.  Using Shotgun metagenomic DNA sequencing of genetic material sediments age-dated (210PB and 14C) up to ~9,000 cal. yr. BP, we successfully identified 227 macroalgal species including members of the Chlorophyta (green), Rhodophyta (red), and Phaeophyceae (brown). This finding, for the first time, provides empirical evidence of long-term sequestration of macroalgal carbon within deep sea sediments.

Biography:

“Ellyn” Erlania is a PhD Candidate at Deakin University as well as a researcher at the National Research and Innovation Agency – Indonesia. My current project is investigating seaweed contribution to marine carbon sequestration using eDNA and fatty acid-specific isotope biomarkers.