Mediterranean factsheet www.iucn-medmis.org

Species report (Musculista) senhousia (Asian date ) AFFILIATION MOLLUSCS

SCIENTIFIC NAME AND COMMON NAME REPORTS Arcuatula (Musculista) senhousia 2

Key Identifying Features

The two valves are oval, elongated and similar in shape and size. The surface of the shell is marked with red lines that look like rays extending toward the edge. The longest side of the shells is slightly concave. The shell is shiny and pale olive-green with purple concentric stripes that sometimes are also visible inside. Adults can reach up to 3 cm in length and 1 cm in width.

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Other species that look similar

Identification and Habitat

Arcuatula senhousia occurs on soft, muddy bottoms of bays and , preferably in sheltered areas from the down to a depth of 20 m. The construct a nest of trapped sediment where many individuals live together. A. senhousia forms dense mats of individuals on the bottom (up to 8,000 individuals per square metre). Males and females are not different to the naked eye.

Reproduction

In the Mediterranean Sea, sperm and eggs are released in the water from September to November. It is a species with high fecundity, rapid growth and good dispersal ability, making it a successful invader. Larvae live in the for up to 55 days until they settle on the bottom. The Asian date mussel can reach adult size in only nine months and live for a maximum of two years. Adults can live for several days out of the water; they are tolerant of low salinities, oxygen concentrations and temperatures.

Similar Species

Mytilus galloprovincialis (young individuals). Arcuatula senhousia often lives in M. galloprovincialis beds, therefore young Mediterranean mussels can be confused with the alien species. Major differences are that in M. galloprovincialis: 1) the colour of the shell is shiny blue-violet or black; 2) the interior of the shell is mother-of-pearl; 3) it lacks red lines on the outer surface of the shell.

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History and Route of Further Reading Introduction http://www.europe-aliens.org/pdf/Musculista_senhousia.pdf Originally from the south-western Pacific, it was first recorded in the Mediterranean at Tel Aviv http://www.ciesm.org/atlas/Musculistasenhousia.html (Israel) in 1960. Thereafter, it has been reported in Egypt (1969), France (1984), the (1992), Slovenia (1997), Italy (Gulf of Taranto) (2001), Italy (Leghorn) (2001), Sardinia (Gulf of Olbia) (2002), and Sicily (Siracusa) (2006). The main pathway of introduction is through transfer with bivalve seed stock for aquaculture purposes; this species can also be spread by ship’s ballast waters (water pumped into and out of ships as ballast to maintain the correct buoyancy) or fouling (the communities encrusting a ship’s hull).

Ecological Impacts

Arcuatula senhousia forms dense aggregations that can change the physical structure of the bottom, dominating benthic communities and outcompeting other filter-feeding bivalves for food. It also develops on the roots of sea grasses slowing down their growth.

Economic Impacts

The species’ economic impact has not been quantified yet; however, it is highly possible that bivalve culture and harvesting might suffer due to strong competition. The Asian date mussel can damage marine engines by clogging cooling water intakes or industrial water intake pipes.

Management Options

A suggested prevention measure is to build up local public awareness combined with monitoring to help prevent its introduction into MPAs. Control actions are impossible as the large bivalve mats, if removed either manually or mechanically (e.g. by dredges), are easily fragmented and the detached individuals can spread to form new populations.

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Legend

Algae Angiosperm Cnidarians Centre for Mediterranean Molluscs Ascidians Cooperation Combjellies / 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

Isole Pelagie, Italy Before 2013 -- --

-- 12/07/2015 -- --

How to cite this tab: Arcuatula (Musculista) senhousia - Invasive Alien Species Fact Sheet for Mediterranean Network of MPAs. From Online Database MedMIS (IUCN Center for Mediterranean Cooperation, Download date 27/09/2021.

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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