Invasion
Invasion Description
1st Record: New South Wales/Pamboola River (1967, Nell 2001)
Geographic Extent
New South Wales/Pamboola River (1967, Nell 2001); New South Wales/Clyde River, Nelson Lake, Shoalhaven River, Wapengo Lake (Nell 2001); Narooma, Bermagui/New South Wales/Tasman Strait (Nell 2001); Port Stephens/New South Wales/Karuah River estuary, Tasman Sea (1984, Krassoi et al. 2008); Wanda Wanda Head, Port Stephens/New South Wales/Pacific Ocean (Wilkie et al. 2012. 32°43'S, 151°59'E); Sydney/New South Wales/Chowder Bay, Sydney Harbour (Hedge and Johnston 2014; Scanes et al. 2016, 16% of oysters overall. 85% of oysters at upper sites, favored by artificial substrates)
Vectors
| Level | Vector |
|---|---|
| Alternate | Natural Dispersal |
| Alternate | Oyster Intentional |
Regional Impacts
| Economic Impact | Fisheries | |
| Magallana gigas has ben cultured in New South Wales since 1967 (Nell 2001), although it has been regarded as a pest for competition with the native Sydney Rock Oyster (Saccostrea glomerata) (Nell et al. 2001; Krassoi et al. 2008). In the Port Jackson estuary, M. gigas outnumbered S. glomerata in the upper reaches fo the estuary (Scanes et al. 2016). | ||
| Ecological Impact | Competition | |
| Magallana gigas overgrows and smothers the native Sydney Rock Oyster (Saccostrea glomerata) in subtidal to mid-intertidal zones, but has 80% mortality in the high intertidal zone, where S. glomerata dominates. Magallana gigas has superior growth rates to S. glomerata, but is less tolerant of abiotic stress (Krassoi et al. 2008). The larger recruits of M. gigas have greater survival than S. glomerata under various condtions of density and predation reduction (Hedge and Johnston 2014). | ||
| Ecological Impact | Habitat Change | |
| Magallana gigas on experimental plates in oysterbeds at Wanda Wanda Head, Port Stephens, grew larger than the native Saccostrea glomerata, and supported higher abundances of epibiotic organisms, but the identity of the biota on the two oyster species did not differ (Wilkie et al. 2012). | ||