Invasion
Invasion Description
1st Records: SW England/Dart, Teign and Exe Rivers (Utting and Spencer 1992); SW Ireland/Atlantic Ocean (1989, Minchin 2007)
Geographic Extent
SW England/Dart, Teign and Exe Rivers (1989, Utting and Spencer 1992); SW Ireland/Atlantic Ocean (1989, Minchin 2007); Ireland/Tralee Bay, Shannon Estuary, Galway Bay, Lough Swilly, Lough Foyle (Kochman et al., 2013, occasional to common, feral populations); Donegal/Ireland/Lough Swilly (Vye et al. 2017); Plymouth (marinas), Devon/England/English Channel (2010, 2013, Bishop et al. 2015b)
Vectors
| Level | Vector |
|---|---|
| Probable | Oyster Intentional |
Regional Impacts
| Economic Impact | Fisheries | |
| Magallana gigas is extensively cultured on the coast of southwestern England and Ireland (Utting and Spencer 1992; Minchin 2007) | ||
| Ecological Impact | Habitat Change | |
| Magallana gigas, settling on an intertidal boulder field in Lough Swilly, Ireland, had complex effects on the epibenthic community. Some organisms, such as early settling stages of the polychaete Sabellaria alveolata, the gastropods Gibbula umbilicalis and Nucella lapillus, and the seaweed Fucus vesiculosus were favored on rocks with live oysters. Both living and dead oysters increased habitat complexity, but the filtration and biodepostion of oysters may have favored Fucus, adversely affecting a tunicate Ascidia conchilega through competition. While settlement of the reef-building polychaete Sabellaria was favored by oysters, long-term survival and colony formation did not occur on boulders with live or dead oysters. Habitat effects on several species appeared to be complex and unpredictable (Green and Crowe 2013a; Green and Crowe 2013b). Oysters on fouling plates reduced the settlement of the introduced barnacle Austrominius modestus, but not the native barnacle Semibalanus balanoides (Vye et al. 2017). In natural and artificial habitats, Pacific Oysters received more settlement of the inva.sive barnacle Austrominus modestus, comparted to the native limpet Patella vulgata (Firth et al. 2020). When Pacific Oysters were planted on mudflats, biodiversity increased, but when oysters were added to mussel beds, biodiversity decreased. Ammonium fluxes and benthic respiration increased with addition of oysters to both habitats, but silicate fluxes showed opposing reponses, increasing in mudflats, but decreasing in mudflats (Green and Crowe 2013a; Green and Crowe 2013b; Herbert et al. 2016). While invasion of mudflat and mussel bed habitats altered the density and diversity of epifauna, benthic assemlages were similar between M. gigas and native Ostrea edulis communities in southwest England (Zwerschke et al. 2016; Zwerschke et al. 2018). | ||