Assessing the CO₂ capture potential of seagrass restoration projects

Summary Seagrass meadows are important carbon sinks, and they are experiencing a global decline. Restoration of seagrass meadows provides a strategy to mitigate climate change while conserving these important ecosystems. We examined the long‐term carbon sequestration expected for seagrass restoration programmes by developing a model that combined models of patch growth, patch survival in seagrass planting projects and estimates of seagrass CO 2 sequestration per unit area for the five seagrass species commonly used in restoration programmes. The model results indicated that the cumulative C sequestered increased rapidly over time and with planting density to reach an asymptote at a planting density of 100 units ha −1 (or 6 m spacing between units). At this planting density, the modelled cumulative C sequestered ranges from 177 to over 1337 tons CO 2 ha −1 after 50 years. The value corresponding to this carbon sequestration suggests that the costs of seagrass restoration programmes may be fully recovered by the total CO 2 captured in societies with a carbon tax in place, providing additional ecosystem services derived from the role of seagrasses in providing ecosystem services, such as enhanced biodiversity. Synthesis and applications . Seagrass restoration programmes are economically viable strategies to mitigate climate change through carbon sequestration, particularly in subtropical and tropical island states where land‐based options have a limited scope.