Invasion
Invasion Description
1st record: Northeast coast/Tasmania (1993, 1998, Thresher et al. 2003)
Geographic Extent
Cape Portland/Tasmania/Tasman Sea (1998, Thresher et al. 2003); St. Helens/Tasmania/Tasman Sea (1998, Thresher et al. 2003); St. Marys/Tasmania/Tasman Sea (1998, Thresher et al. 2003); Freycinet National Park/Tasmania/Tasman Sea (1998, Thresher et al. 2003); Triabunna/Tasmania/Tasman Sea (1998, Thresher et al. 2003); Tasmania/Blackman Bay (1998, Thresher et al. 2003)
Vectors
| Level | Vector |
|---|---|
| Alternate | Oyster Accidental |
| Alternate | Hull Fouling |
| Alternate | Ballast Water |
Regional Impacts
| Ecological Impact | Predation | |
| Abundance of Carcinus maenas was negatively correlated with that of the native venerid clam Katelysia scalarina. In caging experiments, predation rates of C. maenas greatly exceeded those of native crabs or other predators. Predation was concentrated on the smallest size-class of K. scalaris (Walton et al. 2002). Subtidal caging experiments in King Georges Sound, Tasmania, also showed that C. maenas had a major predatory impact on the bivalves Fulvia tenuicostata and Katelysia rhytiphora (Ross et al. 2004). | ||
| Ecological Impact | Competition | |
| The invasion of Carcinus maenas apparently resulted in the displacement of the native crab Pachygrapsus gaimardi (Ruiz et al. unpublished). Caging experiments in King Georges Sound, Tasmania, showed apparent competition between C. maenas and the introduced starfish Asterias amurensis. The two species overlapped in depth range, and prey choice, but showed partitioning, with C. maenas preferring shallower water and smaller clams (Ross et al. 2004). | ||
| Economic Impact | Fisheries | |
| Predation by Carcinus maenas is expected to adversely affect the fishery for the clam Katelysia scalarina in Tasmania (Walton et al. 2002). | ||