Mediterranean invasive species factsheet www.iucn-medmis.org
Species report Venerupis (Ruditapes) philippinarum
(Japanese carpet shell, manila clam)AFFILIATION MOLLUSCS
SCIENTIFIC NAME AND COMMON NAME REPORTS Venerupis (Ruditapes) philippinarum 2
Key Identifying Features
The shell is formed of two valves of equal shape and size. Three teeth are present inside where the two valves are hinged. The shell is oval in outline, thick, and longer than high. The shell surface shows evident radial ribs that are more pronounced towards the margin, while the inside shell is smooth. The colour is extremely variable, usually cream, with irregular brown spots and/or stripes. The internal surface of the shells is often pinkish/purplish or pale yellow/brown. Adults can reach up to 5 cm in shell length.
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Other species that look similar
Identification and Habitat
The Japanese carpet shell or Manila clam is a filterfeeder, generally found in estuaries and lagoons, on sandy and muddy bottoms, from the surface to a few metres’ depth. It can reach high concentrations of individuals (over 2,000 per square metre) and live for several days out of the water, as it is tolerant of a wide range of salinities, oxygen concentrations and temperatures.
Reproduction
It requires temperatures above about 12 °C to spawn and reproduction usually occurs from June to September at water temperatures of 20–23 °C. Its larvae spend 3–4 weeks drifting in the plankton, then settle to the bottom and attach by threads to rocks or shells.
Similar Species
In the Mediterranean, the Japanese carpet shell Venerupis philippinarum is most likely to be confused with the cross-cut carpet shell clam, History and Route of Ruditapes decussatus, whose shell surface has Introduction radiating and concentric ridges that are more widely spaced. In Ruditapes decussatus the Venerupis philippinarum is native to the outline of the shell is more elongated than oval, Indo-Pacific region. Broodstock was introduced it lacks teeth inside the valves near the hinge, for farming along the Atlantic coast of France to and the inside of the shell is generally replace the native clam Ruditapes decussatus in completely white. 1972. Since then, culture has spread to the Mediterranean Sea in Italy, France and Turkey, the first seedlings having been introduced in the Venice lagoon in 1983. Wild populations now thrive in all the lagoons along the northern Adriatic coast and in other coastal areas.
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Ecological Impacts Management Options
Its high potential for dispersal, fast growth and Suggested prevention actions are to avoid the great ability to adapt to new environments as an establishment of further wild populations by invasive species can have a major impact on the means of education and public macrobenthic fauna and flora, since it competes awareness-raising, together with a monitoring for food and space with other filter-feeding programme to monitor parasites that can infect invertebrates. It can supplant the indigenous native bivalves. Monitoring in MPAs also grooved carpet shell, Venerupis decussata, and facilitates early detection of populations so that lead to the extinction of other local mollusc they can be eradicated or contained before they populations, as has been observed in the Venice can spread further. Aquaculture farms near lagoon. MPAs should be encouraged to cultivate other, native species. An abundance of bivalves can significantly increase sediment erosion and re-suspension Control: eradication of this species from the rates and overenrich sediments with biodeposits, environment is unfeasible at the moment due to leading to sediment anoxia which inhibits the large numbers of individuals forming new nitrification and kills benthic fauna. This species populations. Only in particular conditions, as can destabilize the sediment, and it may also where a new population is localized in a very compete for resources with other species and restricted area, can targeted trawling to inhibit their population recruitment by ingesting eradicate the species be attempted. pelagic larvae, which may lead to changes in benthic communities. Further Reading
Economic Impacts Sladonja et al, 2011. Manila Clam (Tapes philippinarum Adams & Reeve, 1852) in the The Japanese carpet shell is one of the most Lagoon of Marano and Grado (Northern Adriatic important species in shellfish farming. World Sea, Italy): Socio-Economic and Environmental production of this one species accounts for 20% Pathway of a Shell Farm. Aquaculture and the of the global shellfish market. Italy is the largest Environment - A Shared Destiny, Dr. Barbara European producer of Venerupis philippinarum Sladonja (Ed.). with 90% of the market, worth over 100 million euros. The negative economic impact of the http://www.ciesm.org/atlas/Ruditapesphilippinarum.html species has not yet been quantified. http://www.nobanis.org/MarineIdkey/Bivalvia/RuditapesPhilippinarum.htm
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Legend
Algae Angiosperm Cnidarians Centre for Mediterranean Molluscs Crustaceans Ascidians Cooperation Combjellies / Fishes Ctenophores
More Information: Guide and reports platform for Marine Protected Areas (MPAs) in the Mediterranean. www.iucn-medmis.org
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MPAs, Country Date Density Measure
Miramare, Italy Before 2013 -- --
-- 22/02/2017 -- --
How to cite this tab: Venerupis (Ruditapes) philippinarum - Invasive Alien Species Fact Sheet for Mediterranean Network of MPAs. From Online Database MedMIS (IUCN Center for Mediterranean Cooperation, Download date 11/10/2021.
More information about this species from: Otero, M., Cebrian, E., Francour, P., Galil, B., Savini, D. 2013. Monitoring Marine Invasive Species in Mediterranean Marine Protected Areas (MPAs): A strategy and practical guide for managers. Malaga, Spain: IUCN. 136 pages www.iucn.org/dbtw-wpd/edocs/2013-008-Es.pdf .
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