will be considered. Pathogens and parasites (see Chapter 11) also influence the ecology of bivalve populations. Finally, the potential and observed impacts of climate change on marine ecosystems will be discussed.
Before describing the major factors that influence mussel distribution patterns, information on global and local ranges of representative marine mussel species is presented in the following section.
Global and Local Distribution Patterns
The World Register of Marine Species (WoRMS; www.marinespecies.org) is a database that provides an authoritative and comprehensive list of names of marine organisms. The content of the registry is edited and maintained on an ongoing basis by scientific specialists on each group of organisms. It provides information on the marine global distribution of individual species in specific geographical units, such as North Sea, Baltic Sea, Gulf of Mexico and Mediterranean Sea. Published sources occurrence records are also included. The registry is linked to numerous websites, including the Encyclopedia of Life (www.eol.org), a free online collaborative encyclopedia intended to document all of the 1.3 million species that have been identified and described on Earth to date. It is compiled from existing databases and from contributions by experts and non‐experts throughout the world. It also provides distribution maps and records for individual species.
Global Distribution
Mussels in the genus Mytilus are a dominant component of rocky shore communities in cooler waters of the Northern and Southern Hemispheres. As described in Chapters 5 and 9, Mytilus edulis has a wide distribution in the Northern Hemisphere, occurring in European waters from Spitsbergen (74–81 °N; Berge et al. 2005) to western France, and on the Atlantic coast of North America from the Canadian Maritimes (New Brunswick, Nova Scotia and Prince Edward Island), along the coast of Maine (Hayhurst & Rawson 2009), to Cape Hatteras in North Carolina. In the subarctic and Arctic, M. edulis is the most abundant Mytilus species, being recorded in Arctic regions of Russia, along the Norwegian coast, in Iceland and on the west Greenland coast (Mathiesen et al. 2017 and references therein). Like M. edulis, Mytilus trossulus inhabits cool water regions of the Northern Hemisphere such as the coasts of the North Pacific, eastern Canada, the Baltic Sea, Scotland, Iceland, the Barents Sea, the White Sea and Norwegian fjords (Zbawicka et al. 2012; Brooks & Farmen 2013). It is also found from Alaska south to Monterey Bay, California (~38 °N). Mytilus galloprovincialis occurs in the Mediterranean Sea, the British Isles, continental Europe and on Moroccan and Mediterranean Tunisian shores (Lourenço et al. 2015), and it has been introduced, intentionally, for aquaculture into parts of the NE Pacific (e.g. Washington, USA and British Columbia, Canada; Wonham 2004). It is also found from Mexico north to Humboldt Bay, California (~38 °N). What seems like a stable hybrid zone between indigenous M. trossulus and invasive M. galloprovincialis extends between San Diego (∼32 °N) and Humboldt Bay (Wonham 2004 and references therein). The species has also been reported in SW Greenland, Svalbard Island to the east of Greenland and in the Pechora Sea, NW Russia (Mathiesen et al. 2017). Some of the present distribution of M. galloprovincialis is due to accidental introductions into Hawaii (Apte et al. 2000), Japan (Wilkins et al. 1983), Hong Kong (Lee & Morton 1985), South Korea (Daguin & Borsa 2000), SE China (McDonald et al. 1990), southern California (Geller 1999), southern Chile (Toro et al. 2005; Larraín et al. 2018), the south and west coastlines of South Africa (McQuaid et al. 2015 and references therein) and Australia and New Zealand (Westfall & Gardner 2010; Ab Rahim et al. 2016 and references therein). In Australia, M. galloprovincialis is distributed throughout Tasmania, in Perth in Western Australia and along the mainland coast of Victoria, extending as far north as Port Stephens in New South Wales. In New Zealand, its distribution includes the South and North Islands and all offshore islands, spanning approximately 35–52 °S latitude (1800 km). Other Mytilus species have a more restricted range. For example, the Californian mussel, M. californianus, is confined to the Pacific coast of North America, occurring from northern Mexico to the Aleutian Islands of Alaska (Addison et al. 2008), a distance of ~6000 km, while the Chilean mussel (Mytilus chilensis) is distributed along approximately 1900 km of the Chilean coast from the Arauco Gulf (35 °S) in the north to Cape Horn (55 °S) in the south (Araneda et al. 2016 and references therein).
Species in the genus Perna have a subtropical to tropical distribution in the Southern Hemisphere. The brown mussel, Perna perna, is found throughout South Africa and on the Atlantic coasts of Namibia and Andsteina; in the Cape Verde Islands and from Mauritania northward; on the Indian Ocean coast of Mozambique and the west coast of Madagascar; extending through the Gulf of Aden into the Red Sea; along the Atlantic coast of South America from Rio de la Plata, Argentina to Recife, Brazil; and on to the Caribbean shores of Venezuela (Wood et al. 2007). The mussel has invaded the western Gulf of Mexico, including Texas and northern Mexico (Hicks & McMahon 2002). The green mussel, Perna viridis, has an extensive Indo‐Pacific distribution from the Persian Gulf through India and South East Asia as far north as Japan, Korea and southern China and as far east as Papua New Guinea (Wood et al. 2007; McDonald 2012). The species is a recent invader in the Caribbean Sea, including the subtropical southeastern United States (SE‐US) region (Baker et al. 2007). The green‐lipped or New Zealand mussel, Perna canaliculus, is endemic to New Zealand – with one exception, when very small numbers were reported at Port Adelaide in Southern Australia in 1996. There is no evidence that the species has since become established in the area (Wiltshire et al. 2010).
Modiolus modiolus, the horse mussel, is found on the European coasts of the Atlantic Ocean. It has been recorded from the White Sea and Norway, off the Faroes and Iceland, south to the Bay of Biscay, in the Mediterranean Sea, occasionally in North Africa and from Labrador to North Carolina in the Atlantic and from the Bering Sea south to Japan and to California in the Pacific (Tyler‐Walters 2007). The bearded horse mussel, Modiolus barbatus, occurs from the British Isles south to Mauritania, West Africa and is also found in the Mediterranean Sea and along the Croatian coastline of the Adriatic Sea (Peharda et al. 2007). The eared horse mussel, Modiolus auriculatus, inhabits the western Indian Ocean, the Red Sea, the eastern Mediterranean, the North Atlantic Ocean, New Zealand, Mozambique and South Africa (www.marinespecies.org). The ribbed mussel, Geukensia demissa, occurs along the Atlantic coast of North America from Cape Cod, Massachusetts to the Gulf of Maine, Florida and the Gulf of Mexico (Franz 2001). In the late 1880s, it was introduced into San Francisco Bay on the Pacific West Coast of California, and since then has extended its range as far as Texas (GISD 2015) and Venezuela (Honig 2013 and references therein).
The charru mussel, Mytella charruana, is native to Central and South America, with a distribution on the Pacific coast from Mexico to Ecuador and on the South Atlantic coast from Columbia to Argentina (Yuan et al. 2016b). Since 2004, it has been found along the SE‐US from South Carolina to Florida. The introduced SE‐US population originated from multiple source populations, with the Panama region the primary one (Calazans et al. 2018). The mangrove mussel, Mytella bicolor, previously known as Mytella guyanensis, is found in intertidal zones of mangrove and estuarine regions from western Mexico to Peru and from Venezuela to Brazil (Introíni et al. 2010). The pharaonic mussel, Brachidontes pharaonis, is native to the Indian Ocean but has colonised the eastern part of the Mediterranean Sea via the Suez Canal, becoming abundant on the coasts of Israel, Egypt, Syria, Lebanon, southern Turkey, Greece, Croatia and Sicily (CABI 2020). The scorched mussel, Brachidontes exustus, is a complex of five species in the Gulf of Mexico and the Caribbean Sea, plus two
