Mediterranean invasive factsheet www.iucn-medmis.org

Species report pacifica (Jewel box oyster)

AFFILIATION MOLLUSCS

SCIENTIFIC NAME AND COMMON NAME REPORTS Chama pacifica 3

Key Identifying Features often white.

A large ovoid-shaped oyster that can grow to about 8–10 cm in length. The shell is usually thick and irregularly rounded. The valves are different sizes, the lower one usually being larger and deeper than the upper, which is usually flat.

The external valve surface bears short spines that curve out from the surface and are larger and more prominent on the larger valve near the shell margin. The internal margin of the shells is encircled by a rim of close, fine ridges that look like a zip fastener. The external colour is highly variable, from white to pinkish-red with pale-rose blotches around the shell margin; the spines are

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Identification and Habitat Other species that look similar

Chama pacifica occurs on rocky shores and hard substrates, usually on exposed sites from the intertidal zone down to a few metres’ depth, occasionally to 40 m. It is able to thrive in harbour environments and is usually found together with other oysters ( sp.) on bare rocks where it attaches tightly to the substrate with one valve. Fouling organisms often attach to the shells. It has a low tolerance to salinity changes, particularly low salinity.

Reproduction

Sexes are separate and fertilization is external. The jewel box oyster has a single, annual, temperature-dependent spawning season, usually occurring during spring and summer when the water temperature is higher than 21 °C. This prolonged spawning period partly contributes to the success of the species in new environments. Eggs hatch as free-swimming planktonic larvae.

Similar Species

The native oyster can be distinguished by its smaller size (up to 2.5 cm), irregular radial ‘ribs’ arranged in concentric rows and the white colour of its shell.

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History and Route of densities. These bivalves are also strongly Introduction attached to the sea bottom and their eradication involves the removal of part of the local benthic Widespread in the Indo-West Pacific, C. pacifica communities and their substratum. This was recorded for the first time in the procedure clearly has a considerable impact and Mediterranean Sea from Alexandria (Egypt) in must be shown to be justifiable by means of an 1905. From here, it colonized many areas of the environmental impact assessment, as in the case south-eastern basin: Israel, Lebanon, Cyprus, of the other alien bivalve Spondylus spinosus. Turkey, Syria and Greece. Its presence in the Mediterranean is due to the opening of the Suez Further Reading Canal, while it has probably been spread further by ships and recreational boats as part of the Crocetta, F. & Russo, P., 2012. The alien hull fouling assemblage. spreading of Chama pacifica Broderip, 1835 (: : ) in the Ecological Impacts Mediterranean Sea. Turk J Zool 37:1-5.

Chama pacifica has become an important http://www.ciesm.org/atlas/Chamapacifica.html component of the eastern Mediterranean shallow benthos, and is occasionally found in association with Erythrean spiny oyster, Spondylus spinosus, another alien oyster. Both species singly or together can form dense aggregations, producing solid reefs at some sites and completely replacing native species such as the European thorny oyster, Spondylus gaederopus, or the smaller oyster, Chama gryphoides. Competition and reduced plankton availability caused by decreased water flow can also slow down the growth of other benthic organisms.

Economic Impacts

It is a valuable species for seashell collectors, with a small trading market. The impact of this invasive species is unknown.

Management Options

A suggested prevention action is to conduct public awareness campaigns combined with monitoring.

Control actions are feasible only in specific circumstances, such as when individuals are localized in a very confined area. Fouling communities on recreational boats and ships can be removed but larvae can re-establish previous

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Map of sightings of the species Chama pacifica (Jewel box oyster)

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

2013-2021 © IUCN Centre for Mediterranean Cooperation. More info: www.iucn-medmis.org Pag. 4/5 Mediterranean invasive species factsheet www.iucn-medmis.org

MPAs, Country Date Density Measure

Shiqmona, Israel Before 2013 -- --

Rosh Hanikra islands, Israel Before 2013 -- --

-- 10/04/2014 -- --

How to cite this tab: Chama pacifica - Invasive Alien Species Fact Sheet for Mediterranean Network of MPAs. From Online Database MedMIS (IUCN Center for Mediterranean Cooperation, Download date 02/10/2021.

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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