Eelgrass (Zostera marina) beds are an ecologically and economically valuable resource and have become the focus of management initiatives in Massachusetts. The Great Marsh Area of Critical Environmental Concern (ACEC), a state-designated area that includes the water bodies of Plum Island Sound and Essex Bay, once contained acres of lush, thriving eelgrass beds that were wiped out by the mid-1900s. With funding from the MassBays Research and Planning Grant Program in 2012 and 2013 , the University of New Hampshire developed and tested a model that identified areas with good potential for the re-establishment and growth of eelgrass and began test-transplanting eelgrass at the most suitable sites in Plum Island Sound . The team also became aware of the existence of a hyper-abundant European green crab (Carcinus maenas) population in the system and began to investigate methods to address threats to restoration initiatives. 
MassBays 2014 Research and Planning Grant Eelgrass Restoration, Essex

In 2014, the team worked with the Town of Essex to expand upon the previous two years of work with ongoing assistance from local, state, and federal collaborators. In this next phase, the team conducted test-transplanting efforts at selected sites in Plum Island Sound and expanded to areas in Essex Bay where a new self-established bed, the first in the ACEC in over 75 years, had just been observed. In addition, the team collected data on the population structure of the European green crab in Great Marsh. Observed in hyper-abundant numbers throughout the Great Marsh system, the team collected data to determine its potential impacts on eelgrass beds. This work is a critical next step in bringing a thriving eelgrass population back to the waters of the Great Marsh ACEC, which is essential to a healthy, resilient coastal ecosystem.

Based on results, the team recommend conducting  large-scale restoration at select sites in Essex Bay using multiple donor sources while continuing test-transplanting efforts in Plum Island Sound. All transplant sites should be monitored and managed for green crabs through trapping. Findings indicated the need for more robust baseline information on the population structure of the European green crab and that data collection efforts in both Plum Island Sound and Essex Bay should continue. 

A more comprehensive description of the study and conclusions as well as detailed management recommendations are in the report .