Salt marshes and other coastal habitats have been degraded worldwide by development, altered river flows, and other human impacts. Many land managers have sought to mitigate these effects through large-scale restoration—planting marsh grasses, seagrasses, oysters, and other ecologically important species. But restoration can be prohibitively expensive, and it has at times required repeated replanting. Recently, small-scale field experiments have suggested that restoration could be improved by taking advantage of natural partnerships between organisms. For example, marsh grasses planted in clumps can grow twice as fast as dispersed plantings, and sea otters can help marsh grasses by removing grass-eating crabs.
To test whether these partnerships can increase yields and decrease costs of large-scale restoration under a variety of conditions, the Lenfest Ocean Program is supporting Dr. Brian Silliman of Duke University and colleagues to conduct experiments at four active restoration sites around the world. The sites are in North Carolina, California, The Netherlands, and China. The team will compare clumped plantings with plantings that are dispersed, in keeping with current restoration practice. It will also compare grass plantings in the presence of potential cross-species partners, such as oysters and otters, with plantings in the absence of such species. The project is set to last from 2018 through 2021, with monitoring to continue at least through 2028.