Objective 5: Measuring Blue Carbon in Mauritius’ Seagrass Meadows

Seagrass meadows are not just underwater gardens – they are powerful allies in the fight against climate change. Through the process known as blue carbon, they capture carbon dioxide and store it long-term in sediments and roots. In this objective, we investigate how efficiently our five native seagrass species in Mauritius sequester carbon and contribute to climate mitigation.

What is blue carbon, and why seagrasses matter

Seagrasses are among the most efficient natural carbon sinks. Although they occupy a tiny fraction of the ocean floor, they account for a disproportionately large share of carbon burial in marine sediments.

Most of the carbon they absorb is stored belowground – in their roots, rhizomes, and the sediment that builds up around them – where it can remain for centuries to millennia if undisturbed.

Because of this, protecting, restoring, and mapping seagrass meadows is not only an ecological priority but a climate strategy.

What we aim to do in Mauritius

Quantify carbon stocks in seagrass meadows dominated by the five species found in Mauritius (Syringodium isoetifolium, Halodule sp., Halophila ovalis, Halophila stipulacea, and Thalassodendron ciliatum).
Compare species performance: which species (or combinations) are most effective at accumulating carbon under our local conditions.
Map carbon storage across lagoons to identify priority zones for conservation and restoration.
Assess risks of carbon loss in degraded or disturbed meadows, for example through storms, and other disturbances.
Examine sequestration rates across time in restored meadows.

What we already know in Mauritius

A first local study under the WIO-SAP programme (2022) measured organic carbon (Cₒᵣ₉) sequestration in Mauritian seagrass meadows, providing baseline estimates for future work. (for Martin to check)

Additionally, national policy efforts are underway to expand the inventory of blue carbon ecosystems – including seagrasses – across Mauritius’ entire maritime zone, in order to feed into climate commitments.

Why this objective matters

Bridging ecology and climate policy: Quantified carbon data gives weight to seagrass conservation in national climate strategies and helps attract climate finance mechanisms.
Selecting restoration targets: Knowing which species or habitats store more carbon helps us prioritise where to restore or protect first.
Safeguarding against carbon release: Disturbing seagrass meadows can reverse their benefit, releasing stored carbon back into the water and atmosphere. Quantifying carbon loss risk strengthens the case for protection.
Long-term monitoring: Tracking changes over time shows whether restored or conserved areas are gaining carbon, holding steady, or losing it.

By embedding blue carbon science into our project, we aim to show that seagrass conservation is not only good for biodiversity and coasts, but also a climate-smart solution that benefits all Mauritians.