Over the past 20 years, southeastern marshes have experienced several episodes of dieback, where the salt marsh cord grass, Spartina alterniflora, dies and the area converts to bare mud. The cause of these episodes is unclear, but they have been linked to drought and associated increases in soil salinity. The loss of marsh plants could have negative effects on fisheries resources, water quality, soil erosion, and the property values of adjacent upland areas.
Now, new research shows that ribbed mussels growing in clusters around the stems of the cordgrass enhance water storage around the plants’ roots and prevent increases in soil salinity. The study, published August 18 in Nature Communications, was performed in part at UGAMI by Dr. Christine Angelini from the University of Florida in association with colleagues from four universities in the Netherlands and Duke University.
They showed that cordgrass in dieback areas had only a one percent chance of surviving. However, when the plants were found in association with ribbed mussels their chance of survival increased to 64 percent. By being embedded in the soil, the two- to three-inch mussels seem to trap water as the tide recedes. Angelini and her fellow researchers also speculated that mussels attract burrowing crabs that create a network of tunnels in the soil that effectively store water. The presence of ribbed mussels also promoted the recolonization of dieback areas by cordgrass. Where there were no mussels, simulation models estimated the recovery times of 2,000 square-meter dieback areas to be over 100 years, whereas identically-sized areas in which mussels were present were estimated to recover in 9 to 22 years. Dr. Angelini, who is a UGAMI-affiliated faculty member at the University of Florida, received support for this research from the National Science Foundation. This research was featured on the NSF website on August 19, 2016.