Recovery of Eelgrass (Zostera marina L.) in Casco Bay, Maine, Following Destruction by European Green Crabs

Science Center Objects

Eelgrass provides essential functions to the ecology and economy of Maine’s coastal zone. When over half the eelgrass in Casco Bay, Maine, disappeared between 2012 and 2013, USGS experimental evidence identified disturbance from invasive European green crabs as the leading cause. Natural revegetation is occurring, but there is interest in learning whether restoration may hasten recover.

The Challenge: Eelgrass provides essential functions to the ecology and economy of Maine’s coastal zone. When over half the eelgrass in Casco Bay, Maine, disappeared between 2012 and 2013, USGS experimental evidence identified disturbance from invasive European green crabs as the leading cause. Loss of vegetation is expected to precipitate a range of impacts, including reduced fish and wildlife populations, degraded water quality, increased shoreline erosion, and reduced capacity to remove anthropogenic carbon dioxide emissions and mitigate coastal acidification. Therefore, reversing eelgrass loss in Casco Bay is of critical ecological and economic importance.  

The Science: A large partnership has formed to determine approaches for eelgrass restoration that yield the highest success rates in the fine sediments of upper Casco Bay and to build local capacity for eelgrass restoration. Specific project objectives are to identify sites that are suitable for large-scale restoration, determine eelgrass transplant methods that yield the highest success rate, determine whether green crab control is required to restore eelgrass in Casco Bay, and identify environmental factors contributing to measured rates of eelgrass restoration success.

The Future: This project will generate information on the best methods to restore eelgrass beds in upper Casco Bay to hasten ecosystem recovery. Importantly, by involving a large cadre of professionals from federal, state, local government, and nongovernmental organizations with interest in and responsibility for eelgrass conservation and management in Casco Bay, this project will also build state-wide capacity for eelgrass restoration.