Taxonomy

Mytilicola orientalis

Distribution

Status

Conservation status

Not Assessed

First reported in the wild

1993

Invasiveness

Invasive species - risk of Medium Impact

Irish status

Occasionally present, casual, vagrant, migratory

Introduction pathways - 1

Transport Contaminant

Introduction pathways subclass - 1

Parasites on animals

Invasive score

15

NAPRA Ireland risk assessed

No

Species Biology

Identification

Parasitic copepod of oysters, females are up to 9mm in length, pink or orange in colour and found in the gut of Pacific oysters, C. gigas. (Holmes & Minchin, 1995).

Ecology

Oysters infected with this species showed no differences in condition or growth (Steele & Mulcahy, 2001), however high infection rates in the native mussel Mytilus edulis were found in the Wadden Sea (Elsner et al., 2011), suggesting this species could facilitate displacement of native mussels by C. gigas and impact on mussel aquaculture. May have a greater impact on 'naive' hosts, such as Mytilus edulis, than traditional host species.

Habitat

Marine

Reproduction

No information is available on the life cycle at this time, though appears to infect larger oysters more readily than smaller (Dare, 1985).

Pathway and vector description

Imported with stocks of Crasstorea gigas sprat, unknown at present can it survive and spread naturally in Irish waters. Likely to be reintroduced to Ireland with oyster stocks based on the concentrations in introduced oysters (Holmes & Minchin, 1995; Steele & Mulcahy, 2001).

Mechanism of impact

Parasitism

Broad environment

Marine

Habitat description

Endoparasite of the Pacific oyster, Crasstorea gigas.

Species group

Invertebrate

Native region

Temperate Asia

Distribution

World distribution(GBIF)

Irish distribution

Present in the wild - Localised. Records from Dungarvan and Carlingford Lough (Holmes & Minchin, 1995; Steel & Mulcahy, 2001), may not be established but merely continually reintroduced with stocks of Crasstorea gigas. Infection rates of C. gigas stocks have been measured at 7.3% (Holmes & Minchin, 1995) to 12.3% (Steele & Mulcahy, 2001) suggesting it is a common but not abundant endoparasite of introduced oysters.

Native distribution

Native to Japan.

Temporal change

Date of first record category

1991-2000

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

References

Publications

Holmes, J. M. C., & Minchin, D. (1995). Two exotic copepods imported into Ireland with the Pacific oyster Crassostrea gigas (Thunberg). The Irish Naturalists' Journal, 17-20. Steel, S., & Mulcahy, M. F. (2001). Impact of the copepod Mytilicola orientalis on the Pacific oyster Crassostrea gigas in Ireland. Diseases of aquatic organisms, 47(2), 145-149. Dare, P. J. (1982). The susceptibility of seed oysters of Ostrea edulis L. and Crassostrea gigas Thunberg to natural infestation by the copepod Mytilicola intestinalis Steuer. Aquaculture, 26(3), 201-211. Elsner, N. O., Jacobsen, S., Thieltges, D. W., & Reise, K. (2011). Alien parasitic copepods in mussels and oysters of the Wadden Sea. Helgoland Marine Research, 65(3), 299-307.

CABI Datasheet