By Jane Disney, Ph.D, and Anna Farrell
Scientists, AmeriCorps Environmental Stewards, and college interns at the MDIBL Community Environmental Health Laboratory (CEHL) worked with the Maine Coast Heritage Trust and numerous community volunteers to restore eelgrass in upper Frenchman Bay throughout the summer of 2014. In total, 8,060 eelgrass plants were collected from the subtidal area of Stave Island, which hosts an expansive eelgrass bed, to five different sites in upper Frenchman Bay. In all, 130 volunteers spent 745 hours making grids, collecting eelgrass plants, weaving eelgrass onto grids, developing other restoration methods, and carrying out restoration projects.
This massive restoration effort followed a two year disappearance of eelgrass in upper Frenchman Bay: its complete dieback in 2012 and its failure to re-emerge during the 2013 growing season. CEHL researchers and interns spent a lot of the summer attempting to determine what caused the disappearance in the upper bay and why eelgrass does well at outer island sites, despite warming trends in the Gulf of Maine and high green crab populations at all sites. They collected data about water quality, plant strength, plant abundance, density, biomass, and composition, and green crab type and abundance in hopes of discovering a relationship between these variables that might explain the eelgrass loss. Two students participating in the National Science Foundation's Research Experience for Undergraduates (REU) at MDIBL designed experiments around these variables.
Mary Badger,a student at Smith College, studied the genetics of green crabs from around MDI. She determined that both northern and southern varieties of the invasive green crab could be found at all study locations, and that there was no correlation between the proportion of crabs with northern haplotypes (purported to be more destructive to marine habitats) and eelgrass abundance.
Alden Dirks, a student at Swarthmore College, studied eelgrass from seven sites around MDI in an effort to explain differences in eelgrass abundance between the upper bay and the outer bay. Dirks looked at the correlation between a variety of eelgrass attributes and water quality variables, and found only one significant correlation: plant biomass is correlated with nitrate levels in the water column. The relationship between this correlation and eelgrass loss is still under investigation.
Read more about the research and findings of our REU students here
, and the new restorations methods developed by volunteers here