US scientists report the successful reforestation of large seagrass meadows, which are the foundation of a newly formed ecosystem and in addition store large quantities of carbon dioxide. The scientists inform about their approach to re-introduce seagrass in wiped out coastal areas and how the plants have improved water quality and the abundance of other species in an article from October 07, 2020 published in Science Advances.
The bottom of the sea was barren and empty when scientists started to sow seagrass seeds in the coastal area of Virginia (USA) in 1999. A pandemic slime mold disease had eradicated almost all seagrass on the American east coast and European west coast in the 1930th. With the marine plants, many other species were lost in the areas, as seagrass is important as food source and shelter for marine life. The plants did not find their way back to the shores naturally, therefore Virginian researchers started a large-scale attempt to restore an ecosystem.
Over a period of more than twenty years, scientists and volunteers have planted almost 75 million seeds per hand, in more than 500 plots that spanned over 213 ha of ocean floor. With the return of the green meadows on the sea floor, water clarity and quality improved and other species returned.
The scientists measured the effect of their actions by determining the biomass of animals: The number of invertebrates, such as shrimp and star fish, increased by more than a thousand percent, the mass of fish by more than six thousand percent. Both types of creatures were almost completely extinct in this region when the project started. In addition, the diversity of the different species is again very high and comparable to that of naturally occurring seagrass meadows.
Once the seagrass was re-established along the coasts of Virginia, the plants reproduced on their own, which lead to an increase of seabed cover to over 3600 ha. This is good news for the coastal residents as this gives them the opportunity to use of the ecosystem commercially. The bay scallop, a form of muscle, has returned to the region in large numbers and can be caught for the lucrative resale. The seagrass itself can be used as fertilizer, insulation, or packing material.
Moreover, the restored seagrass beds have the advantage of storing carbon and nitrogen. In this way, the meadows contribute to fighting climate crisis. The scientists found that young plants have a low storage capacity, but the uptake of carbon and nitrogen increases drastically, once they are mature.
All over the world, seagrass coverage of the ocean floor is declining. The US scientists hope to inspire many more nature conservationists to follow their leads. Because this could help to protect many ecosystems and the global climate.
All over the world the seagrass cover of the seabed is decreasing. The US scientists hope to inspire many conservationists to follow their example. Because this could help protect many ecosystems and the global climate.
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.