References
[1] Wirsing, A. J., Heithaus, M. R., & Dill, L. M. (2007). Fear factor: do dugongs (Dugong dugon) trade food for safety from tiger sharks (Galeocerdo cuvier)? Oecologia, 153, 1031–1040. https://doi.org/10.1007/s00442-007-0802-3
[2] Preen, A. R. (1995). Impacts of dugong foraging on seagrass habitats: observational and experimental evidence for cultivation grazing. Marine Ecology Progress Series, 124, 201–213. https://doi.org/10.3354/meps124201
[3] Schmitz, O. J. and Al Mealla, R. K. (2026) Integrating megafauna into blue carbon strategies: dugongs could enhance seagrass carbon storage. Frontiers in Marine Science. 13:1816090. https://10.3389/fmars.2026.1816090
[4] Fourqurean, J. W., Duarte, C. M., Kennedy, H., et al. (2012). Seagrass ecosystems as a globally significant carbon stock. Nature Geoscience, 5, 505–509. https://doi.org/10.1038/ngeo1477
[5] Unsworth, R. K. F., McKenzie, L. J., Collier, C. J., et al. (2022). The planetary role of seagrass conservation. Science, 377, 609–613. https://doi.org/10.1126/science.abq6923
[6] Atwood, T. B., Connolly, R. M., Ritchie, E. G., et al. (2015). Predators help protect carbon stocks in blue carbon ecosystems. Nature Climate Change, 5, 1038–1045. https://doi.org/10.1038/nclimate2763
[7] Tol, S. J., Jarvis, J. C., York, P. H., et al. (2017). Long distance biotic dispersal of tropical seagrass seeds by marine mega-herbivores. Scientific Reports, 7, 4458. https://doi.org/10.1038/s41598-017-04421-1
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Dugong
By grazing, recycling nutrients and dispersing seeds in seagrass meadows, dugongs can influence the productivity, recovery, connectivity and carbon storage of important coastal blue carbon habitats.
Dugongs are often described as sea cows because they feed almost exclusively on seagrass, but their role in seagrass ecosystems is not just one of consumption. Through grazing, movement, nutrient recycling and seed dispersal in their droppings, dugongs can shape the structure, productivity and recovery of the meadows they depend on. [1] [2] [3]
Seagrass meadows are among the world’s most important coastal blue carbon habitats, storing carbon in their plants and especially in their associated sediments. Globally, seagrass ecosystems hold significant organic carbon stocks, though these stocks depend on meadow condition, sediment stability and local ecological processes, including the functional roles of animals. [3] [4] [5]
Dugong grazing can have different effects depending on its intensity and ecological context. Intensive grazing can reduce seagrass shoot density and biomass in the short term, whilst also shifting meadows towards faster-growing, early successional stage species. [2] A recent model of seagrass beds in Bahrain estimated that a dugong aggregation of around 700 individuals could increase seagrass net primary production and net ecosystem carbon balance by 2.4 times, and sediment carbon stocks by 2.63 times, compared with a dugong-absent scenario. [3] Across the 145 km² focal conservation area, the same model estimated potential additional uptake of about 79,700 tonnes of carbon per year and increased sediment carbon storage of about 638,000 tonnes where dugongs are present.[3]
In Shark Bay, Australia, studies also suggest that tiger shark presence can alter dugong foraging behaviour, with dugongs using less destructive grazing tactics in riskier areas. In these areas of both dugong and shark presence, the seagrass ecosystem had a denser structure and higher carbon stocks than areas with just dugongs.[6] Therefore, it is important that the ecosystem is managed as a whole, maintaining ecological balance between predators, herbivores and seagrass structure.
Dugongs also support seagrass recovery by dispersing seeds. A study from the Great Barrier Reef in Australia found viable seagrass seeds in more than half of the sampled dugong faeces following digestion. The study estimates that dugongs in this area could disperse up to 2,500 viable seagrass seeds per day during the most productive periods, and can transport these seeds up to 25 km from where they were consumed. [7]
In fragmented or recovering seagrass systems, this movement of viable seeds can help maintain connectivity, support recolonisation and increase habitat resilience. [7]
Protecting dugongs, as well as their predators like tiger sharks, is therefore inseparable from protecting seagrass ecosystems. The evidence suggests that dugongs are not simply beneficiaries of seagrass conservation, but active contributors to seagrass ecosystem functioning, recovery and, potentially, blue carbon value. [3] [6]
Dugong
By grazing, recycling nutrients and dispersing seeds in seagrass meadows, dugongs can influence the productivity, recovery, connectivity and carbon storage of important coastal blue carbon habitats.
Dugongs are often described as sea cows because they feed almost exclusively on seagrass, but their role in seagrass ecosystems is not just one of consumption. Through grazing, movement, nutrient recycling and seed dispersal in their droppings, dugongs can shape the structure, productivity and recovery of the meadows they depend on. [1] [2] [3]
Seagrass meadows are among the world’s most important coastal blue carbon habitats, storing carbon in their plants and especially in their associated sediments. Globally, seagrass ecosystems hold significant organic carbon stocks, though these stocks depend on meadow condition, sediment stability and local ecological processes, including the functional roles of animals. [3] [4] [5]
Dugong grazing can have different effects depending on its intensity and ecological context. Intensive grazing can reduce seagrass shoot density and biomass in the short term, whilst also shifting meadows towards faster-growing, early successional stage species. [2] A recent model of seagrass beds in Bahrain estimated that a dugong aggregation of around 700 individuals could increase seagrass net primary production and net ecosystem carbon balance by 2.4 times, and sediment carbon stocks by 2.63 times, compared with a dugong-absent scenario. [3] Across the 145 km² focal conservation area, the same model estimated potential additional uptake of about 79,700 tonnes of carbon per year and increased sediment carbon storage of about 638,000 tonnes where dugongs are present.[3]
In Shark Bay, Australia, studies also suggest that tiger shark presence can alter dugong foraging behaviour, with dugongs using less destructive grazing tactics in riskier areas. In these areas of both dugong and shark presence, the seagrass ecosystem had a denser structure and higher carbon stocks than areas with just dugongs.[6] Therefore, it is important that the ecosystem is managed as a whole, maintaining ecological balance between predators, herbivores and seagrass structure.
Dugongs also support seagrass recovery by dispersing seeds. A study from the Great Barrier Reef in Australia found viable seagrass seeds in more than half of the sampled dugong faeces following digestion. The study estimates that dugongs in this area could disperse up to 2,500 viable seagrass seeds per day during the most productive periods, and can transport these seeds up to 25 km from where they were consumed. [7]
In fragmented or recovering seagrass systems, this movement of viable seeds can help maintain connectivity, support recolonisation and increase habitat resilience. [7]
Protecting dugongs, as well as their predators like tiger sharks, is therefore inseparable from protecting seagrass ecosystems. The evidence suggests that dugongs are not simply beneficiaries of seagrass conservation, but active contributors to seagrass ecosystem functioning, recovery and, potentially, blue carbon value. [3] [6]