Seagrass protects coastal areas from erosion

Seagrass fortifies coastal areas and could be key to buffering the sea level rises predicted by climate change scenarios, according to new research. The plant significantly reduces water current and wave energy.  

Seagrasses, mangroves and marsh ecosystems in coastal areas provide benefits for human beings by capturing carbon from the atmosphere and storing it in coastal sediment.

They also stabilize the sediment against erosion caused by water movement and can trap floating sediment to help build up the coastline.

These are the findings of new research conducted by King Abdullah University of Science and Technology (KAUST) in Saudi Arabia.

KAUST microbial biologist Daniele Daffonchio and postdoc Marco Fust, together with an international team of researchers, measured how seagrass impacts the elevation of the sediment it is rooted in across four sites in Scotland, Kenya, Tanzania and Saudi Arabia.

These measurements, which were taken over two years, were then compared to elevation changes in adjacent patches of coastal sediment that were not covered in vegetation.

The investigations revealed that in areas of coastal sediment without vegetation, the sediment levels were generally falling. However, in areas covered with seagrass, the levels were rising. The difference between the two sites averaged 31 milimeters per year.

Also measured were the strength of waves and tidal movements in each location by hanging readily erodible plaster blocks in the seagrass meadows and non-vegetated patches.

After a period of 48 hours, the plaster blocks lost 32 per cent weight when hung in seagrass meadows, compared to 42 per cent in non-vegetated coastal patches. This demonstrates how seagrass can significantly reduce water current and wave energy, according to the scientists.

“The study confirms the role of seagrass in buffering sea level rises predicted by climate change scenarios,” commented Daffonchio in a statement about the research. “Seagrass and mangrove protection is becoming pivotal for the future sustainability of coastal management.”

Photo credit: Donna Smith/ CC BY-NC 2.0

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