Fauna returned quickly in the planted eelgrass meadow

A study of eelgrass meadows planted by researchers from the University of Gothenburg showed that fauna returned quickly once eelgrass started growing. Already after the second summer, the biodiversity in the planted meadows was about the same as in the established eelgrass meadows.

Eelgrass meadows have declined drastically in the southern Bohus area in recent decades and in many places have disappeared completely. Researchers at the University of Gothenburg have been working on eelgrass restoration for twelve years. These grasslands are important for biodiversity, as eelgrass serves as a habitat or nursery for cod, crabs and young shrimp for example.

In a new study, researchers have evaluated how quickly replanted eelgrass is colonized by a variety of invertebrates. This research has been going on for over two years in a bay near the island of Gåsö to the west of Skaftö in the Bohus region, and the findings are very positive. The researchers counted the abundance of invertebrates living or hiding in the bottom sediments or on the surface of the bottom sediments.

Size is less important

“Recolonization is very fast. After the first three months of the growing season, up to 80 percent of the invertebrates have returned to newly planted eelgrass,” says Eduardo Infantes, a marine biologist at the University of Gothenburg.

During the summer of 2019, the researchers planted eelgrass shoots in four test plots of different sizes on the seafloor, and with different spacing between the shoots. According to the researchers’ observations in the fall of 2020, size plays little to the restoration of biodiversity in eelgrass meadows.

In fact, even if eelgrass did not have time to grow to the same density as in established eelgrass meadows, biodiversity was similar after only two growing seasons to that in reference areas of eelgrass cured in the same bays. Smaller patches embedded within larger restoration plots showed good results.

Their findings are reported in a scientific journal article published in Restoration Ecology.

Can save money

“This is good news for future restoration and new planting of eelgrass meadows. We can plant new smaller plots with fewer shoots and this saves money because it is an expensive method of restoring biodiversity on the seabed,” said Eduardo Infantes.

Eelgrass meadows have many functions that make it important to protect them. In addition to their important role in coastal ecosystems, eelgrass roots bind sediment and prevent erosion and limit sediment resuspension in the water.