Status
Conservation status
Not Assessed
Native status
Non-native
First reported in the wild
1973
Invasiveness
Invasive species - risk of High Impact
Irish status
Present in the wild
Introduction pathways - 1
Release in Nature
Introduction pathways subclass - 1
Aquaculture/Mariculture
Invasive score
19
NAPRA Ireland risk assessed
No
Species Biology
Identification
Filter feeding, marine bivalve, similar in apperance to the European oyster (Ostrea edulis), it has two elongated valves of varying shapes and sizes, 8-31cm in length, attached to the substrate by one of valve (Gollasch & Minchin, 2009).
Ecology
As filter feeders oysters remove particles of organic matter from the water column and producing pseudofaceaes that then settles on the surrounding substrate (Forrest et al., 2009). This can lead to an increase in organic and silt content of the underlying sediment, while also reducing the depth of the oxygenated layer, though these effects are thought to be small scale and isolated to the area immediately surrounding the oyster cultivation (Nugues et al., 1996). Generally filter feeding organisms are thought to impact negatively on macroalga through habitat alteration and competition and phyto- and zoo-plankton through predation, while benefitting mobile species (Thomsen et al., 2014).
Habitat
Marine
Reproduction
Broadcast spawners with planktonic larvae.
Pathway and vector description
Pacific oyster farming began in Ireland in 1973 and has since expanded (Minchin, 2007). 'Feral' populations of oysters have begun to spread from farm locations but exact extent of the spread and whether it is localised to areas with aquaculture is unknown (Kochmann et al., 2013).
Mechanism of impact
Competition, Bio-fouling, Other
Broad environment
Marine
Habitat description
Marine benthic organism that attaches to any hard surface, found from the lower intertidal down to 40m (Gollasch & Minchin, 2009).
Species group
Invertebrate
Native region
Temperate Asia
Similar species
European oyster (Ostrea edulis)
Distribution
World distribution(GBIF)
Irish distribution
Established - Widespread. Widely cultivated in Ireland (Minchin, 2007) but it is unclear how widespread recruitment to the 'feral' population of Pacific oysters, is other than in Lough Foyle where the cultivated oysters have been demonstrated to be genetically distinct from the wild oysters (Kochmann et al., 2012).
Native distribution
Native to the Pacific North west (Gollasch & Minchin, 2009).
Temporal change
Date of first record category
1971-1980
Fifty year date category
1951-2000
Records submitted to Data Centre in 2024
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How can you help
Report any sightings to the National Biodiversity Data Centre.
Further information
Delivering Alien Invasive Species In Europe (DAISIE) project list this as one of the 100 Worst Invaders in Europe.
References
Publications
Forrest, B. M., Keeley, N. B., Hopkins, G. A., Webb, S. C., & Clement, D. M. (2009). Bivalve aquaculture in estuaries: review and synthesis of oyster cultivation effects. Aquaculture, 298(1), 1-15.
Gollasch, S. & Minchin, D. (2009). Crassostrea gigas (Thunberg), Pacific (giant) oyster (Ostreidae, Mollusca). In: Handbook of Alien Species in Europe DAISIE, Drake, J.A. (ed) . Springer Series in Invasion Ecology, Springer.
Kochmann, J., Carlsson, J., Crowe, T. P., & Mariani, S. (2012). Genetic evidence for the uncoupling of local aquaculture activities and a population of an invasive species—a case study of Pacific oysters (Crassostrea gigas). Journal of Heredity, 103(5), 661-671.
Minchin, D. (2007) A checklist of alien and cryptogenic aquatic species in Ireland. Aquatic Invasions, 2(4), 341-366.
Nugues, M. M., Kaiser, M. J., Spencer, B. E., & Edwards, D. B. (1996). Benthic community changes associated with intertidal oyster cultivation. Aquaculture Research, 27(12), 913-924.
Thomsen, M.S., Byers, J.E., Schiel, D.R., Bruno, J.F., Olden, J.D., Wernber, T., & Silliman, B.R. (2014) Impacts of Marine invaders on bioidversity depends on trophic position and functional similarity. Marine Ecology Progress Series, 495:39-47.