Asian mussel
Encyclopedia
The Asian mussel, Musculista senhousia, is a small saltwater mussel
, a marine
bivalve mollusk species in the family Mytilidae. Its common names include: the Asian date mussel, the Japanese mussel, Senhouse's mussel, the green mussel and the green bagmussel. It is differentiated from other mollusks by its relatively small size and inflated shape, as well as the greenish colour of its outer periostracal layer. The mussel also has radiating reddish lines on its posterior, small internal teeth on the dorsal edge posterior to the ligament
of the shell, and small ribs anterior to the umbones. It can grow up to 30 mm in length. It is also known for its relatively fast growth and has a maximum lifetime of about two years.
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Musculista senhousia is native to the Pacific Ocean, inhabiting coastal areas from Siberia
and the Kuril Islands
south to Singapore
. The mussel is an invasive species in California
, the Mediterranean, Australia, and New Zealand. It was introduced to the Western coast of the United States sometime in the early twentieth century with shipments of Japanese oysters. In 1983, large specimens of the species were collected in the Swan River
estuary
in Western Australia
. The mussel has been present in Auckland
harbour since 1980 and specimens have also been reported at Tamar estuary
in Tasmania
. Invasion of the aforementioned locales is thought to have been achieved in a variety of manners: the mussels were transported on the hulls of ships, in water-intake chambers and the ducts of ships, as plankton
ic larva
e carried in the ballast
water of bulk-cargo vessels, in association with intentionally introduced oysters, and by Lessepsian migration through the Suez Canal
.
mussel is found in intertidal zones with densities up to 2500 individuals per square metre. In Australia, the invasive species
is found from 0.5 to 4 metres below the surface of the water in slightly higher densities. Along the Western coast of North America, however, the species generally reaches densities of 5000 to 10,000 individuals per square metre and has been recorded at densities of up to 150,000 individuals per square metre in Mission Bay in San Diego, California
, USA. The mussel is most abundant in the summer and early autumn. In the Swan River
estuary
in Western Australia
, the mussel population has a high mortality rate in the late autumn and early winter. This may be the result of a decrease in water salinity from increased rainfall.
, and detritus
on its surface.
estuary
of Western Australia
, for example, predation
occurs mainly by boring carnivorous
gastropods such as Nassarius burchardi or Bedeva paivae, which drill through the mussel's thin shell. In Mission Bay in San Diego, however, the mussel's main predators include the yellowfin croaker
, spotfin croaker
, sargo
, willet
, and the marbled godwit
(three fish and two bird species respectively). Other less significant predators include carnivorous
gastropods (especially Pteropurpura festiva
), crustaceans, echinoderms, fish
, and diving ducks. Recent research has emphasized the importance of the predation
of Musculista senhousia by native fauna as a means of reducing the negative effects of the invasive species
on ecosystems. Asian mussels also face predation
by humans. The mussel is gathered as food in China, as food for domestic organisms in Japan, Thailand
, and India, as well as bait for fishing throughout Asia. There are currently no commercial or recreational uses for the mussel in the invaded areas. It has been suggested that harvesting the species might help control their invasion, however there are a number of detrimental effects associated with benthic harvesting.
estuary
in Western Australia
, for example, the presence of mats of Musculista senhousia has caused an increase in the biomass
of benthic macro-organisms in general.
In Mission Bay
in San Diego, California
, USA, the increasing abundance of Asian mussels has caused a decrease in species richness and abundance of the native Solen rostriformis as well as the complete disappearance of the native Chione fluctifraga. The Asian mussel has also become one hundred times more abundant than any native bivalves. Two other native species have appeared in the bay, however: Macoma nasuta and Chione undatella. Laboratory experiments using these species show that the growth and survival of the surface-dwelling and suspension-feeding species of the Chione genus decrease dramatically in areas where the Asian mussel is abundant. Populations of the deeper-dwelling and deposit-feeding Macoma nasuta are not significantly affected, however, by the invasion of the mussel.
Similar occurrences have been observed at Sacca di Goro, a brackish lagoon
in the Po River Delta of the Northern Adriatic Sea
in Italy, which the Asian mussel invaded in the early 1990s. Researchers there have found that growth and survival of suspension feeders
has significantly decreased following the arrival of the Asian mussel. There has also been a concomitant increase in the abundance of detritivores and herbivores.
Laboratory research has also shown that deeper-dwelling species are less affected by the invasion of the Asian mussel. Mussel mats have no significant effect on the mortality of deeper-dwelling clam
species such as Tapes decussatus and Ruditapes philippinarum.
Competition with native species is the primary cause of concern in areas of New Zealand where the Asian mussel has invaded. There are significantly fewer macrofaunal invertebrates and there has been an eightfold decrease in the abundance of infaunal bivalves. Scientists suggest, however, that the adverse environmental effects of the mussel in New Zealand will be localized and short-lived.
Musculista senhousia shares its habitat with eelgrass
(Zostera marina) in many of the areas in which it has invaded. The presence of the mussel has been shown to affect rhizome
growth in the eelgrass. This decreases the ability of established patches to spread. The Asian mussel had the most detrimental affect on rhizome growth in areas where the eelgrass was sparse and patchy. This is a cause of concern for conservationists because beds of eelgrass are already degraded and sparse as a result of anthropogenic forces. The presence of Musculista senhousia can only worsen the situation.
Mussel
The common name mussel is used for members of several families of clams or bivalvia mollusca, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.The...
, a marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
bivalve mollusk species in the family Mytilidae. Its common names include: the Asian date mussel, the Japanese mussel, Senhouse's mussel, the green mussel and the green bagmussel. It is differentiated from other mollusks by its relatively small size and inflated shape, as well as the greenish colour of its outer periostracal layer. The mussel also has radiating reddish lines on its posterior, small internal teeth on the dorsal edge posterior to the ligament
Ligament
In anatomy, the term ligament is used to denote any of three types of structures. Most commonly, it refers to fibrous tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.Ligament can also refer to:* Peritoneal...
of the shell, and small ribs anterior to the umbones. It can grow up to 30 mm in length. It is also known for its relatively fast growth and has a maximum lifetime of about two years.
Distribution
Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...
and the Kuril Islands
Kuril Islands
The Kuril Islands , in Russia's Sakhalin Oblast region, form a volcanic archipelago that stretches approximately northeast from Hokkaidō, Japan, to Kamchatka, Russia, separating the Sea of Okhotsk from the North Pacific Ocean. There are 56 islands and many more minor rocks. It consists of Greater...
south to Singapore
Singapore
Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...
. The mussel is an invasive species in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, the Mediterranean, Australia, and New Zealand. It was introduced to the Western coast of the United States sometime in the early twentieth century with shipments of Japanese oysters. In 1983, large specimens of the species were collected in the Swan River
Swan River (Western Australia)
The Swan River estuary flows through the city of Perth, in the south west of Western Australia. Its lower reaches are relatively wide and deep, with few constrictions, while the upper reaches are usually quite narrow and shallow....
estuary
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
in Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
. The mussel has been present in Auckland
Auckland
The Auckland metropolitan area , in the North Island of New Zealand, is the largest and most populous urban area in the country with residents, percent of the country's population. Auckland also has the largest Polynesian population of any city in the world...
harbour since 1980 and specimens have also been reported at Tamar estuary
Tamar River Conservation Area
The Tamar Conservation Area covers approximately 4,633 ha on the Tamar River estuary in Tasmania. It includes the Tamar Island Wetlands Reserve and a stretches through the upper part of the Tamar Estuary from St Leonards to the Batman Bridge...
in Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
. Invasion of the aforementioned locales is thought to have been achieved in a variety of manners: the mussels were transported on the hulls of ships, in water-intake chambers and the ducts of ships, as plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
ic larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e carried in the ballast
Ballast tank
A ballast tank is a compartment within a boat, ship or other floating structure that holds water.-History:The basic concept behind the ballast tank can be seen in many forms of aquatic life, such as the blowfish or argonaut octopus, and the concept has been invented and reinvented many times by...
water of bulk-cargo vessels, in association with intentionally introduced oysters, and by Lessepsian migration through the Suez Canal
Suez Canal
The Suez Canal , also known by the nickname "The Highway to India", is an artificial sea-level waterway in Egypt, connecting the Mediterranean Sea and the Red Sea. Opened in November 1869 after 10 years of construction work, it allows water transportation between Europe and Asia without navigation...
.
Habitat
The Asian mussel is generally found in sheltered mud or other soft substrates up to twenty metres below the surface of the water. In China and Japan, the nativeIndigenous (ecology)
In biogeography, a species is defined as native to a given region or ecosystem if its presence in that region is the result of only natural processes, with no human intervention. Every natural organism has its own natural range of distribution in which it is regarded as native...
mussel is found in intertidal zones with densities up to 2500 individuals per square metre. In Australia, the invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
is found from 0.5 to 4 metres below the surface of the water in slightly higher densities. Along the Western coast of North America, however, the species generally reaches densities of 5000 to 10,000 individuals per square metre and has been recorded at densities of up to 150,000 individuals per square metre in Mission Bay in San Diego, California
San Diego, California
San Diego is the eighth-largest city in the United States and second-largest city in California. The city is located on the coast of the Pacific Ocean in Southern California, immediately adjacent to the Mexican border. The birthplace of California, San Diego is known for its mild year-round...
, USA. The mussel is most abundant in the summer and early autumn. In the Swan River
Swan River (Western Australia)
The Swan River estuary flows through the city of Perth, in the south west of Western Australia. Its lower reaches are relatively wide and deep, with few constrictions, while the upper reaches are usually quite narrow and shallow....
estuary
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
in Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
, the mussel population has a high mortality rate in the late autumn and early winter. This may be the result of a decrease in water salinity from increased rainfall.
Behavior
Musculista senhousia uses byssal threads to form a sort of cocoon around itself. The cocoon may be necessary for protection due to the relatively thin shells of the species as well as to assist in the stabilization of the species in the sediment. The cocoons of each individual can intertwine to form a mat that tends to collect shells, sediment, algaeAlgae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
, and detritus
Detritus
Detritus is a biological term used to describe dead or waste organic material.Detritus may also refer to:* Detritus , a geological term used to describe the particles of rock produced by weathering...
on its surface.
Predators
Predators of the Asian mussel vary depending on the native fauna of the area. In the Swan RiverSwan River (Western Australia)
The Swan River estuary flows through the city of Perth, in the south west of Western Australia. Its lower reaches are relatively wide and deep, with few constrictions, while the upper reaches are usually quite narrow and shallow....
estuary
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
of Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
, for example, predation
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
occurs mainly by boring carnivorous
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
gastropods such as Nassarius burchardi or Bedeva paivae, which drill through the mussel's thin shell. In Mission Bay in San Diego, however, the mussel's main predators include the yellowfin croaker
Yellowfin croaker
Yellowfin croaker is a species of croaker occurring from the Gulf of California, Mexico, to Point Conception, California. They frequent bays, channels, harbors and other nearshore waters over sandy bottoms...
, spotfin croaker
Spotfin croaker
Spotfin croaker is a species of croaker occurring from Mazatlán, Mexico, to Point Conception, California, including the Gulf of California. It is the only species in the genus Roncador. In California, they are most commonly found south of Los Angeles Harbor...
, sargo
Sargo
Sargo is a town in the Kongoussi Department of Bam Province in northern Burkina Faso. It has a population of 1,628.-External links:*...
, willet
Willet
The Willet, Tringa semipalmata , is a large shorebird in the sandpiper family. It is a good-sized and stout scolopacid, the largest of the shanks...
, and the marbled godwit
Marbled Godwit
The Marbled Godwit, Limosa fedoa, is a large shorebird. On average, it is the largest of the 4 species of godwit. The total length is , including a large bill of , and wingspan is . Body mass can vary from ....
(three fish and two bird species respectively). Other less significant predators include carnivorous
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
gastropods (especially Pteropurpura festiva
Pteropurpura festiva
The Festive Murex, Pteropurpura festiva, is a species of predatory snail in the family Muricidae. Native to the Eastern Pacific, they grow to 34-67 mm in length....
), crustaceans, echinoderms, fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, and diving ducks. Recent research has emphasized the importance of the predation
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
of Musculista senhousia by native fauna as a means of reducing the negative effects of the invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
on ecosystems. Asian mussels also face predation
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
by humans. The mussel is gathered as food in China, as food for domestic organisms in Japan, Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
, and India, as well as bait for fishing throughout Asia. There are currently no commercial or recreational uses for the mussel in the invaded areas. It has been suggested that harvesting the species might help control their invasion, however there are a number of detrimental effects associated with benthic harvesting.
Impact on invaded ecosystems
Research has shown that the Asian mussel can have a variety of effects on various ecosystems. In the Swan RiverSwan River (Western Australia)
The Swan River estuary flows through the city of Perth, in the south west of Western Australia. Its lower reaches are relatively wide and deep, with few constrictions, while the upper reaches are usually quite narrow and shallow....
estuary
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
in Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
, for example, the presence of mats of Musculista senhousia has caused an increase in the biomass
Biomass
Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....
of benthic macro-organisms in general.
In Mission Bay
Mission Bay
Mission Bay may refer to:Australia*the former name of Minjilang, Northern TerritoryNew Zealand*Mission Bay, New Zealand, a suburb of Auckland...
in San Diego, California
San Diego, California
San Diego is the eighth-largest city in the United States and second-largest city in California. The city is located on the coast of the Pacific Ocean in Southern California, immediately adjacent to the Mexican border. The birthplace of California, San Diego is known for its mild year-round...
, USA, the increasing abundance of Asian mussels has caused a decrease in species richness and abundance of the native Solen rostriformis as well as the complete disappearance of the native Chione fluctifraga. The Asian mussel has also become one hundred times more abundant than any native bivalves. Two other native species have appeared in the bay, however: Macoma nasuta and Chione undatella. Laboratory experiments using these species show that the growth and survival of the surface-dwelling and suspension-feeding species of the Chione genus decrease dramatically in areas where the Asian mussel is abundant. Populations of the deeper-dwelling and deposit-feeding Macoma nasuta are not significantly affected, however, by the invasion of the mussel.
Similar occurrences have been observed at Sacca di Goro, a brackish lagoon
Lagoon
A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...
in the Po River Delta of the Northern Adriatic Sea
Adriatic Sea
The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan peninsula, and the system of the Apennine Mountains from that of the Dinaric Alps and adjacent ranges...
in Italy, which the Asian mussel invaded in the early 1990s. Researchers there have found that growth and survival of suspension feeders
Filter feeder
Filter feeders are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feeding are clams, krill, sponges, baleen whales, and many fish and some sharks. Some birds,...
has significantly decreased following the arrival of the Asian mussel. There has also been a concomitant increase in the abundance of detritivores and herbivores.
Laboratory research has also shown that deeper-dwelling species are less affected by the invasion of the Asian mussel. Mussel mats have no significant effect on the mortality of deeper-dwelling clam
Clam
The word "clam" can be applied to freshwater mussels, and other freshwater bivalves, as well as marine bivalves.In the United States, "clam" can be used in several different ways: one, as a general term covering all bivalve molluscs...
species such as Tapes decussatus and Ruditapes philippinarum.
Competition with native species is the primary cause of concern in areas of New Zealand where the Asian mussel has invaded. There are significantly fewer macrofaunal invertebrates and there has been an eightfold decrease in the abundance of infaunal bivalves. Scientists suggest, however, that the adverse environmental effects of the mussel in New Zealand will be localized and short-lived.
Musculista senhousia shares its habitat with eelgrass
Zostera
Zostera is a small genus of widely distributed seagrass, commonly called marine eelgrass or simply eelgrass . The genus Zostera contains sixteen species.-Ecology:Zostera is found on sandy substrates or in estuaries submerged or partially floating...
(Zostera marina) in many of the areas in which it has invaded. The presence of the mussel has been shown to affect rhizome
Rhizome
In botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...
growth in the eelgrass. This decreases the ability of established patches to spread. The Asian mussel had the most detrimental affect on rhizome growth in areas where the eelgrass was sparse and patchy. This is a cause of concern for conservationists because beds of eelgrass are already degraded and sparse as a result of anthropogenic forces. The presence of Musculista senhousia can only worsen the situation.