Invasion
Invasion Description
1st Record: Portland/ME/Casco Bay (Introduced, Established, 1902, Bryant 1906)
Geographic Extent
Cape Elizabeth/ME/Dyers Cove, Casco Bay (2010, Massachusetts Office of Coastal Zone Management 2013); Portland/ME/Casco Bay (1902, Introduced, Established, Bryant 1906); Harpswell/ME/Casco Bay (1905, Introduced, Established, Bryant 1906; Rathbun 1930); Brewer South Freeport Maine/ME/Casco Bay (2003, MIT Sea Grant 2003; 2010, Massachusetts Coastal Zone Management 2013)
Vectors
| Level | Vector |
|---|---|
| Alternate | Dry Ballast |
| Alternate | Hull Fouling |
| Alternate | Natural Dispersal |
| Alternate | Ballast Water |
Regional Impacts
| Ecological Impact | Habitat Change | |
| High densities of Green Crabs were reported by shellfishers in Casco Bay, coinciding with higher water temperatures in 2013. The population explosion was associated with a sharp reduction of Eelgrass (Zostera marina) in upper Casco Bay, due to damage to the plants during foraging. Exclosure experiments found that survival of eelgrass shoots was 82% inside the exclosures, but 24% outside (Neckles 2015). | ||
| Ecological Impact | Predation | |
| High densities of Green Crabs were reported by shellfishers in Casco Bay, coinciding with higher water temperatures in 2013. This population growth was associated with an absence of young Softshell Clams (Mya arenaria) (Neckles 2015). | ||