Short description of Arcuatula senhousia, Asian date mussel

A small (10-30 mm) plump, greenish mussel. The shell has radiating reddish lines at broader end; often with thicker purple-brown wavy/zigzag, concentric lines. The shell is thin and smooth, the anterior end is narrowly rounded with the beak separate. The shell interior is lustrous purplish-grey with the external concentric markings often showing through. When settling on soft sediment it creates a byssal cocoon/bag which can almost completely enclose it; where large aggregations form the cocoons intertwine to form a dense mat.

Impact summary: Arcuatula senhousia, Asian date mussel

Large aggregations of Arcuatula senhousia can dramatically alter the ecology of soft shores. The intertwined byssal mats stabilize the sediments creating firm substrate, altering the hydrodynamics, sediment structure, nutrient cycling, and animal behaviour. Seagrass beds can be negatively impacted possibly due to toxins in the sediment. Arcuatula senhousia may also compete for space and food with other bivalves, but can provide a new food source for a variety of predators such as shorebirds. There can also be a negative economic impact on bivalve shellfisheries e.g. clams.

Habitat summary: Arcuatula senhousia, Asian date mussel

Prefers enclosed lower intertidal and shallow subtidal flats (to 20 m), on soft or hard substrates; can attach to seaweeds, including seagrasses, and artificial structures. Can aggregate into dense, extensive mats in shallow coastal waters (Kikuchi, 1964; Crooks, 1996). Tolerant of low salinities (down to 17 psu), and low oxygen concentrations, but vulnerable to desiccation (Willan, 1987; Magni et al., 2006; Cohen, 2011).

Overview table

Environment	Marine
Species status	Non-Native
Native range	Northwestern Pacific
Functional type	Filter-feeder
Status in England	Non-Native
Status in Scotland	Non-Native
Status in Wales	Non-Native
Location of first record	Southampton Water
Date of first record	2011

Origin

Native range believed to be in the Western Pacific from Siberia to Singapore. Its status in the Indian Ocean, whether native or introduced, is unclear (Crookes, 1996, Bachelet et al., 2009).

First Record

Southampton Water, in 2011.

Pathway and Method

Given its arrival in Southampton Water the most likely pathway was via shipping, either as hull-fouling or in ballast water. Its presence in marinas in the area, indicate that recreational vessels are a potential vector. In the Bay of Biscay, the western Mediterranean and NW America it was probably imported with commercial shellfish such as Pacific oysters, whereas in the eastern Mediterranean shipping via the Suez Canal appears to have been a factor, shipping is also likely for its introduction to Australia and New Zealand (Hoenselaar & Hoenselaar, 1989; Crooks, 1996).

Species Status

<i>Arcuatula senhousia</i> is frequently referred to under its former name <i>Musculista senhousia</i>. In GB this is a relatively new non-native arrival; it is considered established in Southampton Water (Barfield et al., 2018; Holman et al., 2019; NBNAtlas, 2020; Taylor et al., 2020). It has also been recorded from Chichester Harbour and the Isle of Wight (Dr G. Watson, in litt., 2020). The first European record was from the eastern Mediterranean (Israel) in 1960 and it probably arrived in the western Mediterranean (France) in 1978 (Barash & Danin, 1971; Hoenselaar & Hoenselaar, 1989). However it was not found in the NE Atlantic (southern Bay of Biscay) until 2002 (Bachelet et al., 2009). It has more recently been reported from the Netherlands (Faase, 2018). It has also invaded many other parts of the world including the Pacific coast of N America (1924), where it has been recorded from Mexico to British Columbia; New Zealand (1980) and Australia (1983) in the southwest Pacific; Zanzibar and Madagascar in the western Indian Ocean; Venezuela in the western Atlantic (2002) and Guinea Bissau in the eastern Atlantic (Kincaid, 1947; Slack-Smith & Brearley, 1987; Willan, 1987; Hoenselaar & Hoenselaar, 1989; Martínez-Escarbassiere et al., 2003; Bachelet et al., 2009; Lourenco et al., 2018).

Dispersal Mechanisms

Although the adults are sessile, the long-lived larvae can disperse over quite long distances.

Reproduction

This species is gregarious and fast growing, reaching adult size in only 9 months, with a maximum life span of around 2 years. The sexes are separate, large numbers of eggs are produced (a single female can release as many as 137,000 at one time), with fertilization occurring externally. The eggs and larvae have a long planktonic dispersal phase (14-55 days). The reproductive season in GB is not known, however it is likely to be in the late summer and autumn as it prefers to spawn when water temperatures are 15-20 C (Kulikova 1978; Sgro et al., 2002).

Known Predators/Herbivores

Elsewhere in the world Arcuatula senhousia is preyed upon by a wide variety of species including gastropods, crustaceans such as shore crabs, echinoderms, fish, shore birds and diving ducks (Yamamuro; Oka, 1998; Crooks, 2002; Mistri, 2002). Barfield (2018) speculates that in GB predatory gastropods may be drilling their shells.

Resistant Stages

None known.

Habitat Occupied in GB

Arcuatula senhousia has been recorded from sheltered estuarine sites both subtidally and on mud-flats. It has also been found in a marina attached to submerged surfaces.

In GB this species is currently restricted to the central part of the south coast, having only been reported from Southampton Water, Chichester Harbour and the Isle of Wight. It has been recorded from benthic samples, on intertidal mudflats, on submerged surfaces in one marina and recorded from e-DNA samples at another marina in the area (Barfield et al., 2018; Holman et al., 2019; NBNAtlas, 2020; Taylor et al., 2020; Dr G. Watson, in litt., 2020).

Environmental Impact

When occurring intertidally on soft sediments, aggregations can develop, with densities typically up to 15,000 per square metre (highest 170,000 per sqm). The deposition of faeces and pseudofaeces and the formation of extensive byssal mats which stabilize the surface mud may alter hydrodynamic, sedimentary, and microtopographic features on the bottom, as well as nutrient cycling and the behaviour of other species in the community. This can dramatically affect the ecology of the shore, in some instances this may be considered a positive impact as native species richness, and abundance of some species may increase. In California it was found to inhibit the growth of seagrass, possibly due to the deposition of toxic metabolites such as sulphides. Arcuatula senhousia can also compete for food and space with other sessile fauna and smother other bivalves (Morton, 1974; Willan, 1987; Crooks, 1996, 2001; Reusch & Williams, 1998; Crooks & Soule, 1999; Mistri, 2004; Munari, 2008).

Health and Social Impact

Economic Impact

The presence of extensive mussel mats creates social and economic impacts, since growth and survival of infaunal clams may be reduced. In the Sacca lagoon in the Adriatic, culture of the Manila clam was seriously affected; and within its native range, in Japan, a bivalve shellfishery was severely damaged by an outbreak of A. senhousia (Mistri, 2004; Willan, 1987).

Identification

Barfield, P., Holmes, A., Watson, G., & Rowe, G. (2018). First evidence of Arcuatula senhousia (Benson, 1842), the Asian Date Mussel, in UK waters. Journal of Conchology, 43(2), 217-222.

Morton, B. (1974). Some aspects of the biology, population dynamics, and functional morphology of Musculista senhausia Benson (Bivalvia, Mytilidae). Pacific Science, 28:19-33.

Biology, ecology, spread, vectors

Bachelet, G., Blanchet, H., Cottet, M., Dang, C., de Montaudouin, X., de Moura Queirós, A., ... & Lavesque, N. (2009). A round-the-world tour almost completed: first records of the invasive mussel Musculista senhousia in the north-east Atlantic (southern Bay of Biscay). Marine Biodiversity Records, 2.

Barash, A. L., & Danin, Z. (1971). Mollusca from the stomach of Sparus auratus fished in the lagoon of Bardawil. Argamon, 2(3-4), 79-104.

Barfield, P., Holmes, A., Watson, G., & Rowe, G. (2018). First evidence of Arcuatula senhousia (Benson, 1842), the Asian Date Mussel, in UK waters. Journal of Conchology, 43(2), 217-222.

Cohen, A. N. (2011). The Exotics Guide: Non-native Marine Species of the North American Pacific Coast. Center for Research on Aquatic Bioinvasions, Richmond, CA, and San Francisco Estuary Institute, Oakland, CA. Revised September 2011. http://www.exoticsguide.org

Faasse M. (2018) A record of the Asian mussel Arcuatula senhousia (Benson in Cantor, 1842) from NW Europe (the Netherlands). Spirula, 416, 14-15.

Hoenselaar, H. J., & Hoenselaar, J. (1989). Musculista senhousia (Benson in Cantor, 1842) in the western Mediterranean (Bivalvia, Mytilidae). Basteria, 53(4/6), 73-76.

Holman, L. E., de Bruyn, M., Creer, S., Carvalho, G., Robidart, J., & Rius, M. (2019). Detection of introduced and resident marine species using environmental DNA metabarcoding of sediment and water. Scientific reports, 9(1), 1-10.

Kikuchi, T. (1964). Ecology and biological production of Lake Naka-umi and adjacent region, 3. Macrobenthic communities of Lake Shinji-ko and Lake Naka-umi. Special Publ. Seto Mar. BioI. Lab. (B), pt. 3: 21-44.

Kincaid, T. (1947). The acclimatization of marine animals in Pacific northwest waters. Minutes Conchological Club of Southern California 72:1-3.

Kulikova, V. A. (1978). Morphology, seasonal population dynamics, and settlement of larvae of the bivalve mollusc Musculista senhousia in Busse Lagoon (South Sakhalin). Soviet Journal of Marine Biology 4:769-773.

Lourenço, P. M., Henriques, M., Catry, I., Granadeiro, J. P., & Catry, T. (2018). First record of the invasive Asian date mussel Arcuatula senhousia (Benson, 1842) (Mollusca: Bivalvia: Mytilidae) in West Africa. Journal of Natural History, 52(39-40), 2567-2571.

Magni, P., Como, S., Montani, S., & Tsutsumi, H. (2006). Interlinked temporal changes in environmental conditions, chemical characteristics of sediments and macrofaunal assemblages in an estuarine intertidal sandflat (Seto Inland Sea, Japan). Marine Biology, 149(5), 1185-1197.

Martínez-Escarbassiere, R., Capelo, J. C., García, J. V., Lasso, C. A., Pereira, G., & Lasso-Alcalá, O. M. (2003). Primer registro del mejillón dátil asiático, Musculista senhousia (Benson 1842)(Bivalvia: Mytilidae) especie introducida en Venezuela. Mem. Fund. La Salle CienciasNaturales159, 160, 309-312.

Mistri, M. (2002). Ecological characteristics of the invasive Asian date mussel, Musculista senhousia, in the Sacca di Goro (Adriatic Sea, Italy). Estuaries, 25(3), 431-440.

NBNAtlas. (2020). NBN Atlas occurrence download at http://nbnatlas.org. Accessed 17 July 2020.

Sgro, L., Turolla, E., Rossi, R., & Mistri, M. (2002). Sexual maturation and larval development of the immigrant Asian date mussel, Musculista senhousia, in a Po River deltaic lagoon. Italian Journal of Zoology, 69(3), 223-228.

Slack-Smith, S. M., & Brearley, A. (1987). Musculista senhousia (Benson, 1842); a mussel recently introduced into the Swan River estuary, Western Australia (Mollusca: Mytilidae). Records of the Western Australian Museum, 13(2), 225-230.

Taylor, J., Bishop, J. D. D., Wood, C. A. (2020). Mapping Invasive Alien Species in intertidal habitats within Natura 2000 sites in the Solent. Report to EMFF on grant no. ENG_2578. 64 pp.

Yamamuro, M., & Oka, N. (1998). Predation by diving ducks on the biofouling mussel Musculista senhousia in a eutrophic estuarine lagoon. Marine Ecology Progress Series, 174, 101-106.

Management and impact

Crooks, J. A. (1996). The population ecology of an exotic mussel, Musculista senhousia, in a southern California bay. Estuaries, 19(1), 42-50.

Crooks, J. A. (2001). Assessing invader roles within changing ecosystems: historical and experimental perspectives on an exotic mussel in an urbanized lagoon. Biological Invasions, 3(1), 23-36.

Crooks, J. A. (2002). Predators of the invasive mussel Musculista senhousia (Mollusca: Mytilidae). Pacific Science, 56(1), 49-56.

Crooks, J. A., Soulé, M. E., & Sandlund, O. T. (1999). Lag times in population explosions of invasive species: causes and implications. Invasive species and biodiversity management, 103, 125.

McEnnulty, F. R., Bax, N. J., Schaffelke, B., & Campbell, M. L. (2001). A review of rapid response options for the control of ABWMAC listed introduced marine pest species and related taxa in Australian waters. Centre for Research on Introduced Marine Pests Technical Report, 23, 1-99.

Mistri, M., Rossi, R., & Fano, E. A. (2004). The spread of an alien bivalve (Musculista senhousia) in the Sacca di Goro Lagoon (Adriatic Sea, Italy). Journal of Molluscan Studies, 70(3), 257-261.

Morton, B. (1974). Some aspects of the biology, population dynamics, and functional morphology of Musculista senhausia Benson (Bivalvia, Mytilidae). Pacific Science, 28:19-33.

Munari, C. (2008). Effects of the exotic invader Musculista senhousia on benthic communities of two Mediterranean lagoons. Hydrobiologia, 611(1), 29-43.

Reusch, T. B., & Williams, S. L. (1998). Variable responses of native eelgrass Zostera marina to a non-indigenous bivalve Musculista senhousia. Oecologia, 113(3), 428-441.

Willan, R. C. (1987). The mussel Musculista senhousia in Australasia; another aggressive alien highlights the need for quarantine at ports. Bulletin of Marine Science, 41(2), 475-489.

General

Narscius, A. (2019). Arcuatula senhousia. In: AquaNIS. Editorial Board, 2015. Information system on Aquatic Non-Indigenous and Cryptogenic Species. World Wide Web electronic publication. www.corpi.ku.lt/databases/aquanis. www.corpi.ku.lt/databases/aquanis. Version 2.36+. Accessed 2020-07-17.

Cohen, A. N. (2011). The Exotics Guide: Non-native Marine Species of the North American Pacific Coast. Center for Research on Aquatic Bioinvasions, Richmond, CA, and San Francisco Estuary Institute, Oakland, CA. Revised September 2011. http://www.exoticsguide.org

Fofonoff, P. W., Ruiz, G. M., Steves, B., Simkanin, C., & Carlton, J. T. (2018). National Exotic Marine and Estuarine Species Information System. http://invasions.si.edu/nemesis/. Access Date: 17-July -2020

Global Invasive Species Database (GISD) 2015. Species profile Musculista senhousia. Available from: http://www.iucngisd.org/gisd/species.php?sc=1031 [Accessed 17 July 2020]

MolluscaBase eds. (2020). MolluscaBase. Arcuatula senhousia (Benson, 1842). Accessed through: World Register of Marine Species at: http://marinespecies.org/aphia.php?p=taxdetails&id=505946 on 2020-07-17