Mytilus galloprovincialis
(Mediterranean mussel)

The Mediterranean mussel, Mytilus galloprovincialis, has been introduced to various regions around the world outside its native Mediterranean range, both unintentionally through shipping and through cultivation. It is considered highly invasive, at least in some parts of the world, due to its quick rate of spread and its ability to displace and outcompete native mussels.

Mytilus galloprovincialis lives on hard substrates from the intertidal zone to depths of 40 m. It is found along coasts and rocky shores, and in sheltered harbours and estuaries. The native range is in the Mediterranean (Barsotti and Meluzzi, 1968) and the eastern Atlantic, from Ireland and the United Kingdom (Gosling, 1992) to northern Africa (Comesana et al., 1998); presumably range expansion into the Atlantic has been natural. This species is also found on the Pacific coast of North America (McDonald and Koehn, 1988) and in Japan (Wilkins et al., 1983), Hong Kong (Lee and Morton, 1985), South Africa (Grant and Cherry, 1985), Chile (Hilbish et al., 2000; Gérard et al., 2008), and Australia (Hilbish et al., 2000; Gérard et al., 2008). Introduction to these regions has undoubtedly been due to human activities, unless the native Australian mussels are considered to be part of the same species as M. galloprovincialis (McDonald et al., 1991; Daguin and Borsa, 2000; Gérard et al., 2008; Hilbish et al., 2000). Historical introductions have probably been accidental, but this species is actively cultivated so aquaculture may also be the source of secondary introductions; it was introduced into Washington State through hatcheries because of its putative greater resistance to disseminated-hemic neoplasia than the native M. trossulus, and its subsequent spread in the region has probably been through shipping and boating (Wonham, 2004). Fly et al. (2015) provide a paper on the physiology and biogeography of European mussels (including M. galloprovincialis) in response to climate change.

Delineating the exact range of Mytilus galloprovincialis is complicated by the lack of reliable morphological differences between Mytilus species and by hybridization. For example, in France, Britain and Ireland, M. galloprovincialis is sympatric with M. edulis and the two interbreed (Gosling, 1992). Outside its native range, M. galloprovincialis is known to hybridize with M. trossulus in the Pacific (Rawson and Hilbish, 1995; Brannock et al., 2009). In Chile, Australia, and New Zealand there is evidence for two distinct types of mussels, one of which is M. galloprovincialis (Hilbish et al., 2000; Gérard et al., 2008), but whether or not they are hybridizing is unknown.

Mytilus galloprovincialis is cultivated in Albania, Bulgaria (where it is one of the most important commercial species -- Merdzhanova et al., 2016), China, Croatia, Egypt, France, Greece, Italy, Morocco, Portugal, the Russian Federation, Spain, South Africa, Turkey, Ukraine, the former Yugoslavia (Hickman, 1992; FIGIS, 2005), Canada (J Shields, University of Queensland, Australia, personal communication, 2010), and Scotland (UK) (Beaumont, 2008). Because of the difficulties of species identification, it is likely that some farms may be inadvertently rearing M. galloprovincialis in addition to native Mytilus species. Aquaculture facilities may use new techniques to produce triploid and tetraploid mussels, which are functionally sterile, thereby eliminating the risk of wild populations establishing (McEnnulty et al., 2001).

Reproductive Biology

Genetics

There have been numerous population genetic studies of M. galloprovincialis, motivated by the poor resolution of morphology for species identification and the propensity of this species to hybridize with other mussels – with M. edulis in the natural species range, and M. trossulus in its introduced range.

Genetic markers have been developed to differentiate these species, but each marker varies in its ability to distinguish between them:

• ITS – distinguishes between M. trossulus and M. galloprovincialis/M. edulis, but not between M. galloprovincialis and M. edulis (Heath et al., 1995).

• PLIIa – distinguishes between M. trossulus and M. galloprovincialis/M. edulis, but not between M. galloprovincialis and M. edulis (Heath et al., 1995).

• Glu5’ (same as Me15/16 (Inoue et al., 1995)) – a nuclear DNA locus that produces three alleles diagnostic for M. edulis, M. galloprovincialisand M. trossulus. Hybrid mussels are identified as heterozygous (Rawson et al., 1996).

Genomic research of M. galloprovincialis has recently been advanced by the latest next-generation pyrosequencing technology (Craft et al., 2010). This recent pyrosequencing has provided extensive genomic information for M. galloprovincialis and identified novel expression differences among various tissues, mitochondria and associated microorganisms (Craft et al., 2010). It will also facilitate the much needed production of an oligonucleotide microarray for M. galloprovincialis, further advancing genomic research of this organism.

Environmental

• Pollution indicator

General

• Research model

Human food and beverage

• Canned meat
• Fresh meat
• Frozen meat
• Meat/fat/offal/blood/bone (whole, cut, fresh, frozen, canned, cured, processed or smoked)

31/10/2017 Updated by:

Vicki Bonham, consultant, UK

30/03/2010 Updated by:

Jody Shields, The University of Queensland, Australia

Cynthia Riginos, The University of Queensland, Australia

29/05/2005: Original text by:

Vicki Bonham, consultant, UK