When someone mentions “ecosystem restoration,” what are the most common pictures that pop up in a typical mind?
The first one is probably reforestation. The iconic act of planting new forests might be followed by an image of aquatic habitat restoration – for example, restoring a natural riverbed or re-creating a wetland.
However, very few will think about seagrass bed restoration. The absence of these ecosystems from our mental maps is slightly unjust since they are highly valuable both as habitats and as climate buffers.
Luckily, things are about to change.
Why is seagrass important?
Seagrasses and the underwater meadows they create are essential marine habitats and global ecosystem service providers. The seagrass beds provide food, habitat and act as a reproductive sanctuary to numerous marine vertebrates and invertebrates.
Sea grasses also stabilize the seafloor and help maintain good water quality. Last but not least, seagrasses help sequester carbon and nitrogen from the seawater. Studies have shown that the presence of seagrass near reefs can even lessen the coral bleaching phenomenon (related: Coral Bleaching of the Great Barrier Reef)
Now, the world’s largest seagrass restoration project is here – and is already bringing us new knowledge on the real significance of these unique biological communities.
The Seagrass Restoration Project
Virginia Institute of Marine Science and The Nature Conservancy have been conducting the world’s most extensive seagrass meadow restoration for 20 years now, successfully creating 3,612 hectares of new seagrass beds on a formerly cleared slate.
To achieve that, the team of researchers and volunteers had to actively plant more than 70 million seeds of eelgrass (Zostera marina) on a 200-hectare plot just off the southern end of Virginia’s Eastern Shore.
To realize the order of magnitude, we have to make a comparison – for example, the largest Australian seagrass project aims to restore ten hectares of seagrass beds.
Seagrass ecosystems help to store carbon
The conclusions of long-term monitoring are finally in and have been published this October in Science Advances. The results reveal that seagrass ecosystems are highly resilient and very successful at trapping carbon and nitrogen, restoring coastal ecosystem services, and benefiting both the local biodiversity and the global climate.
The study shows that seagrass ecosystems sequester more carbon and nitrogen as they mature, managing to reach historical, original sequestration levels in 20 years.
The beds are now sequestering about 3,000 metric tons of carbon and more than 600 metric tons of nitrogen per year.
“(The study) offers a blueprint for restoring and maintaining healthy seagrass ecosystems that others can adapt elsewhere in the world,” says Karen McGlathery, a coastal ecologist at the University of Virginia. “It’s the first to put a number on how much carbon restored meadows take out of the atmosphere and store.”
Besides being beneficial for mitigating emissions and pollution, researchers hope that this project will be a beacon in the dark for other devastated marine ecosystems, which now suffer poor water quality, algal blooms, and fish kills as a consequence of seagrass disappearance. However, the lead author of the study, Robert J. Orth, reveals that “once the water is cleaned up, our work suggests that seagrasses can recover rapidly.”
The authors also hope that restoration will have a positive effect on coastal communities. After all, you can’t dispute that seahorses that thrive in the lush seagrass are an uplifting sign.
Orth, R. J., Lefcheck, J. S., McGlathery, K. S., Aoki, L., Luckenbach, M. W., Moore, K. A., … & Lusk, B. (2020). Restoration of seagrass habitat leads to rapid recovery of coastal ecosystem services. Science advances, 6(41), eabc6434. DOI: 10.1126/sciadv.abc6434
Unsworth, R. K., Collier, C. J., Henderson, G. M., & McKenzie, L. J. (2012). Tropical seagrass meadows modify seawater carbon chemistry: implications for coral reefs impacted by ocean acidification. Environmental Research Letters, 7(2), 024026. doi:10.1088/1748-9326/7/2/024026
Polidoro, J. (2020, October 14). How planting 70 million eelgrass seeds led to an ecosystem’s rapid recovery. Science News. https://www.sciencenews.org/article/seagrass-restoration-project-virginia-ecosystem-rapid-recovery
Importance of seagrass. (n.d.). Florida Fish and Wildlife Conservation Commission. https://myfwc.com/research/habitat/seagrasses/information/importance/