Newly planted eelgrass in the study. 15 months later, the biodiversity in the plot was almost the same as in an old established eelgrass meadow. Credit: Eduardo Infantes
Key points:
- Researchers have planted eelgrass meadows to replace the ones that are rapidly disappearing.
- A new study shows biodiversity can be restored to the planted meadows within just two growing seasons.
- Additionally, the lot size of the meadows does not matter, saving time and resources.
A study of eelgrass meadows planted by researchers at the University of Gothenburg shows that fauna return rapidly once the eelgrass has started to grow. After only 15 months—two summers— the biodiversity in the newly planted meadow was almost the same as in the previous eelgrass meadows.
Eelgrass meadows have declined rapidly in Sweden in recent decades, and in some places have disappeared altogether. Researchers at the University of Gothenburg have been working on the restoration of eelgrass meadows for 12 years as the marine environment serves as an important habitat for young cod, shrimp and crab.
In summer 2019, in a bay near Gåsö island, researchers planted the eelgrass shoots in four test plots of different sizes on the seabed, and with different spacing between the shoots. To their surprise, recolonization occurred rapidly. After the first three-month growing season, up to 80 percent of the invertebrates had returned to the newly planted eelgrass.
The researchers were surprised to find that the plot size of the meadow did not play a large role in recovery. According to the study results, published in Restoration Ecology, even if the eelgrass did not have time to grow to the same density as in an established meadow, the biodiversity was similar. After only two growing seasons, biodiversity in the new meadow was the same as the “old” preserved meadow. Even smaller patches embedded within larger restoration plots showed good results, the researchers said.
“This is good news for future restorations and new plantings of eelgrass meadows. We can plant new smaller plots with fewer shoots and this saves money because this is an expensive method for restoring biodiversity on the seabed,” said lead researcher Eduardo Infantes.
Beyond protecting young marine species, eelgrass meadows are responsible for a variety of functions that make them extremely important to the area. They also serve an important role in the coastal ecosystem, since eelgrass roots bind the sediment and prevent erosion and limit resuspension of sediment in the water.