Taxonomy
Crepidula fornicata | American Slipper Limpet
Distribution
Status
Conservation status
Not Assessed
Legal status
Third Schedule listed species under Regulations 49 & 50 in the European Communities (Birds and Natural Habitats) Regulations 2011. (Note: Regulation 50 not yet enacted). Listed as a schedule 9 species under Articles 15 & 15A of the Wildlife Order (Northern Ireland) 1985 (Article 15A not yet enacted).
First reported in the wild
1902
Invasiveness
Invasive species - risk of High Impact
Irish status
Established
Introduction pathways - 1
Transport Contaminant
Introduction pathways subclass - 1
Contaminant on animals
Invasive score
21
NAPRA Ireland risk assessed
Yes. This species underwent a Non-native species APplication based Risk Analysis in 2014.
Overall risk of this species to Ireland is categorised as: MAJOR with a MEDIUM level of confidence.
Excerpt from overall conclusion summary: Once established, natural dispersal of the pelagic planktonic larval stage is likely to result in a moderately fast spread. Fishery practices may also aid in spread. Suitable inshore, offshore and open coastline habitat is vulnerable to colonisation. The potential economic impact of C.fornicata establishment should populations develop as they have along the French coast is likely to be major, with a losses of revenue to some fisheries and bivalve aquaculture. Environmental harm within its existing range is major at a local level and it is predicted that similar impacts may take place in Ireland.
View the full risk assessment: http://nonnativespecies.ie/wp-content/uploads/2014/03/Crepidula-fornicata-Slipper-Limpet.pdfSpecies Biology
Identification
Marine gastropod with a brown shell, up to 5cm in length.
Ecology
A filter feeder it is considered a pest of oysters due to its dietary overlap with the cultured Pacific oyster Crassostrea gigas (which is itself invasive) (Decottignies et al., 2007), though Thieltges et al., (2006) found no effects of competition between the two species. Similarly while it was found to inhibit and compete with native mussels Mytilus edulis, this was mitigated by a 4 fold decrease in starfish predation of mussels (Thieltges et al., 2006). Slipper limpets act as ecosystem engineers in invaded areas, altering the phytoplankton community away from toxic flagellates to diatoms (Thieltges et al., 2006), while decreasing the abundance of suprabenthic (organisms that live on the sea bed) biodiversity by converting soft sediments to hard substrates (Vallet et al., 2001). This can result in a decrease in the abundance of flatfish in nurseries where the slipper limpet is present (Le Pape et al., 2004).
Habitat
Marine
Reproduction
Slipper limpets are protandrous hermaphrodites (changing sex from male to female) and reproduce by forming large semi permanent stacks with the larger females on the bottom and males on top (Collin, 1995). In Europe egg laying period starts in mid-February and ends in late September with breeding peaking May - June, with females producing from 4,000 - 14,000 eggs each (Richard et al., 2006).
Pathway and vector description
Likely introduced with mussels from Britain, the exact mechanism of their arrival is unknown (McNeill et al., 2010). However now that it is present in Ireland it may spread by a number of means including attaching to hulls, in the transport of shellfish and natural dispersal.
Mechanism of impact
Competition, Bio-fouling, Other
Broad environment
Terrestrial
Habitat description
Found in shallow estuaries, bays and channels from low water to 30m depth, on muddy/sandy sediments or rocky substrates (Minchin, 2009).
Species group
Invertebrate
Native region
North America
Distribution
World distribution(GBIF)
Irish distribution
Established - Localised. Belfast Lough is the only known established population though there have previously been records of individual organisms (McNeill et al., 2010; Minchin, 2007).
Native distribution
Native to the Atlantic coast of North America
Temporal change
Date of first record category
1901-1910
Fifty year date category
1901-1950
Records submitted to Data Centre in 2024
The following map is interactive. If you would prefer to view it full screen then click here.
How can you help
Report any sightings to the National Biodiversity Data Centre.
Further information
Delivering Alien Invasive Species In Europe (DAISIE) project the slipper limpet this as one of the 100 Worst Invaders in Europe.
References
Publications
Collin, R. (1995). Sex, size, and position: a test of models predicting size at sex change in the protandrous gastropod Crepidula fornicata. American Naturalist, 815-831.
Decottignies, P., Beninger, P. G., Rincé, Y., Robins, R. J., & Riera, P. (2007). Exploitation of natural food sources by two sympatric, invasive suspension-feeders: Crassostrea gigas and Crepidula fornicata. Marine Ecology Progress Series, 334, 179-192.
Le Pape, O., Guerault, D., & Desaunay, Y. (2004). Effect of an invasive mollusc, American slipper limpet Crepidula fornicata, on habitat suitability for juvenile common sole Solea solea in the Bay of Biscay. Marine Ecology Progress Series, 277, 107-115.
McNeill, G., Nunn, J., & Minchin, D. (2010). The slipper limpet Crepidula fornicata Linnaeus, 1758 becomes established in Ireland. Aquatic Invasions, 5(1), 21-S25.
Richard, J., Huet, M., Thouzeau, G., & Paulet, Y. M. (2006). Reproduction of the invasive slipper limpet, Crepidula fornicata, in the Bay of Brest, France. Marine Biology, 149(4), 789-801.
Thieltges, D. W., Strasser, M., & Reise, K. (2006). How bad are invaders in coastal waters? The case of the American slipper limpet Crepidula fornicata in western Europe. Biological Invasions, 8(8), 1673-1680.
Vallet, C., Dauvin, J. C., Hamon, D., & Dupuy, C. (2001). Effect of the Introduced Common Slipper Shell on the Suprabenthic Biodiversity of the Subtidal Communities in the Bay of Saint-Brieuc. Conservation bBology, 15(6), 1686-1690.