Green Crab - Maquoit Bay

Maquoit Bay is a shallow estuary that forms the northwestern arm of Casco Bay, ME. In 2001, the ME Department of Marine Resources eelgrass maps showed 570 ha of eelgrass in the bay. In 2012-2013, however, eelgrass area in Maquoit Bay declined dramatically; as of July 2013 there was almost no eelgrass remaining in the intertidal portion of the bay. The loss of eelgrass from Maquoit Bay is coincident with a documented population explosion of the European green crab in upper Casco Bay. Green crabs are known to clip and uproot eelgrass while foraging and are the leading cause of eelgrass loss in bays throughout Nova Scotia. USGS Scientist Hilary Neckles has transplanted eelgrass within and outside experimental crab exclosures in Maquoit Bay to test whether existing environmental conditions are favorable for eelgrass growth in the absence of crabs. If eelgrass grows successfully with crabs excluded and is disturbed in adjacent open control areas, then green crabs are a more likely cause of eelgrass loss than other environmental controls.