NOBANIS - Marine invasive species in Nordic waters - Fact Sheet

Petricola pholadiformis

Author of this species fact sheet: Kathe R. Jensen, Zoological Museum, Natural History Museum of Denmark, Universitetsparken 15, 2100 København Ø, Denmark. Phone: +45 353-21083, E-mail: [email protected]

Bibliographical reference – how to cite this fact sheet: Jensen, Kathe R. (2010): NOBANIS – Invasive Alien Species Fact Sheet – Petricola pholadiformis – From: Identification key to marine invasive species in Nordic waters – NOBANIS www.nobanis.org, Date of access x/x/201x.

Species description

Species name Petricola pholadiformis, Lamarck, 1818

Synonyms Petricolaria pholadiformis.

Common names American piddock, American rock-borer (U.K.), False angel wing (USA), Amerikansk boremusling (DK), Amerikansk boreskjell (NO), Amerikansk borrmussla (SE), Amerikanische Bohrmuschel, Engelsflügel (DE), Amerikaanse boormossel (NL).

Identification Although the shell is externally similar to the native true piddocks Barnea candida (Linnaeus, 1758), Pholas dactylus Linnaeus, 1758, and Zirfaea crispata (Linnaeus, 1767), this species belongs to a different superfamily, the Veneroidea. It is usually referred to a separate family, the Petricolidae, but recent phylogenetic analysis has shown that it may be included in the family Veneridae (Mikkelsen et al., 2006). The true piddocks belong to the family Pholadidae, which have a distinct tooth-like attachment, apophysis, internally at the hinge-line. In P. pholadiformis the hinge have regular cardinal teeth, two in the right valve and three in the left. Also, Pholadidae often have accessory shell plates, which are not found in P. pholadiformis.

Petricola pholadiformis preserved specimens Petricola pholadiformis shell external

Petricola pholadiformis interior shell with cardinal teeth

Barnea candida – white piddock, see:

• Conchological Society of Great Britain & Ireland • Marine Life Information Network

Distribution: DK: North Sea, Wadden Sea, Skagerrak, Limfjord, Kattegat, northern Belt Sea. NO: sections 1-13 (Brattegard & Holthe, 2001).

The native Barnea candida for comparison, interior Barnea candida shell exterior

Pholas dactylus – common piddock, see:

• Marine Life Information Network

Distribution: DK: North Sea, Skagerrak, northern Kattegat (one record, empty shell) (Jensen & Knudsen, 1995). NO: only recorded in section 13 (Brattegard & Holthe, 2001); no records from Swedish waters (Hansson, 2003a).

Zirfaea crispata – oval piddock, see:

• The Marine Species Identification Portal

Distribution: DK: North Sea and Limfjord NO: whole coast. SE: Bohuslän-Öresund. DE: Kieler Bucht, North Sea?

Petricola pholadiformis – American rock-borer, see:

• Conchological Society of Great Britain & Ireland

Size: Shell length up to 80mm.

Distribution

Native area From Prince Edward Island in the north to Uruguay in the south, including the West Indies and Texas (Abbott, 1974; Zenetos et al., 2009).

Introduced area The American piddock was introduced to the UK with American oysters around 1890; the first record is from 1893. It was then recorded in Belgium in 1899 (Loppens, 1902). The first Danish record is from 1905 in the Wadden Sea (Jensen & Knudsen, 2005), from where it has now almost completely disappeared (Jensen, 1992). This has led to placing the species on the Red List as vulnerable for the Wadden Sea (Petersen et al., 1996). There is a dubious record from the western Baltic Sea (Schlesch, 1931), but see also Nehring (2000). There are very few records from southern Norway (Vestfold to Vest-Agder county) (Brattegard & Holthe, 2001), where it was first recorded in 1955. In Sweden it occurs only at the Skagerrak and northern Kattegat coast (Främmande arter, 2006). P. pholadiformis has also been introduced to the Pacific coast of the USA, occurring only in three bays from San Fancisco to Washington (Carlton, 1992). The most recent introduction is to the eastern Mediterranean (southeastern Greece) (Zenetos et al., 2009).

Ecology

The boring mechanism has been studied by Ansell & Nair (1969) and by Ansell (1970). It is not well adapted for boring. The bore-holes are oblique and the siphons extend from the opening. It is only able to bore in relatively soft types of rock, i.e. compacted clay, peat or chalk. They probably need at least a shallow concavity or a crack to start the boring activity. It is also able to burrow into sand, like other veneroid bivalves. P. pholadiformis has a high retention efficiency for particles of a wide size range (Jørgensen et al., 1984).

Impacts

The few existing records of impacts seem to be at best anecdotal. One particular event has been repeated over and over again, namely that P. pholadiformis almost completely replaced Barnea candida at the Dutch and Belgian coasts (Eno et al., 1997; Främmande Arter, 2006). However, this has not been observed elsewhere, and later studies have found that B. candida is now more common than P. pholadiformis in Belgium (Wouters, 1993). For Danish waters Collin (1883) wrote that Pholas dactylus was common in certain places in the Limfjord where calcareous rock was present. Petricola pholadiformis was first found in the Limfjord in 1926, and there are no recent records of P. dactylus in the Limfjord. However, suitable substrate in the Limfjord is very restricted and therefore competition may be tougher. Probably because there are so few recorded impacts, there have been few recent studies on this species.

References

Ansell, A.D. 1970. Boring and burrowing mechanisms in Petricola pholadiformis Lamarck. Journal of Experimental Marine Biology and Ecology 4: 211-220.

Ansell, A.D. and Nair, N.B. 1969. A comparative study of bivalves which bore mainly by mechanical means. American Zoologist 9: 857-868.

Ballerstedt, S. 2006. Barnea candida. White piddock. Marine Life Information Network (MarLIN)

Budd, G.C. 2005. Petricola pholadiformis. American piddock. Marine Life Information Network (MarLIN)

Duval, D.M. 1963. The biology of Petricola pholadiformis Lamark [sic] (Lamellibranchiata Petricolidae). Proceedings of the Malacological Society of London 35: 89-100. Duval, D.M. 1963. Observations on the annual cycle of Barnea candida. Proceedings of the Malacological Society of London 35: 101-102.

Eno, N.C., Clark, R.A. and Sanderson, W.G. 1997. Non-native marine species in British waters: a review and directory. Joint Nature Conservation Committee, Peterborough, UK, 136pp.

Främmande Arter 2006. American piddock (Petricola pholadiformis). Fact Sheet available here (pdf) (accessed 2 October 2007).

Hansson, H.G. 2003a. Faktablad Barnea candida. ArtDatabanken 2003-03-04, Sweden. Available here (pdf) (accessed 16 January 2008).

Hansson, H.G. 2003b. Faktablad Zirfaea crispata. ArtDatabanken 2003-02-27, Sweden. Available here (pdf) (accessed 16 January 2008).

Jensen, K.T. 1992. Macrozoobenthos on an intertidal mudflat in the Danish Wadden Sea: comparisons of surveys made in the 1930s, 1940s and 1980s. Helgoländer Meeresuntersuchungen 46(4): 363-376.

Jørgensen, C.B., Kiørboe, T., Møhlenberg, F. and Riisgård, H.U. 1984. Ciliary and mucus-net filter feeding, with special reference to fluid mechanical characteristics.. Marine Ecology Progress Series 15: 283-292.

Korringa, P. 1942. Crepidula fornicata’s invasion in Europe. Basteria 7(1-2): 12-23.

Loppens, K. 1902. Petricola pholadiformis L. Annales de la Société Royale Zoologique et Malacologique de Belgique 37: XLI-XLII.

Mikkelsen, P.M., Bieler, R., Kappner, I. and Rawlings, T.A. 2006. Phylogeny of Veneroidea (Mollusca: Bivalvia) based on morphology and molecules. Zoological Journal of the Linnean Society 148: 439-521.

Nehring, S. 2000. Neozoen im Makrozoobenthos der deutschen Ostsee-küste. Lauterbornia 39: 117-126.

Pinn, E.H., Richardson, C.A., Thompson and Hawkins, S.J. 2005. Burrow morphology, biometry, age and growth of piddocks (Mollusca: Bivalvia: Pholadidae) on the south coast of England. Marine Biology 147: 943-953.

Pinn, E.H., Thompson, R.C. and Hawkins, S.J. 2008. Piddocks (Mollusca: Bivalvia: Pholadidae) increase topographical complexity and species diversity in the intertidal. Marine Ecology Progress Series 355: 173-182.

Purchon, R.D. 1955. The functional morphology of the rock-boring lamellibranch Petricola pholadiformis Lamarck. Journal of the Marine Biological Association of the United Kingdom 34: 257-278.

Schlesch, H. 1932. Über die Einwanderung nordamerikanischer Meeresmollusken in Europa unter Berücksichtigung von Petricola pholadiformis Lam. und ihrer Verbreitung im dänischen Gebiet. Archiv für Molluskenkunde 64: 146-154, Plate 11.

Wouters, D. 1993. 100 jaar na de invasie van de Amerikaanse boormossel: de relatie Petricola pholadiformis Lamarck, 1818 / Barnea candida Linnaeus, 1758. De Strandvlo 13(1): 3-39 (In Dutch with English abstract?) [100 years after the invasion of the American piddock: the relation Petricola pholadiformis Lamarck, 1818 / Barnea candida Linnaeus, 1758.]

Zenetos, A., Ovalis, P. and Vardala-Theodorou, E. 2009. The American piddock Petricola pholadiformis Lamarck, 1818 spreading in the Mediterranean Sea. Aquatic Invasions 4(2): 385-387.