Perna viridis
Encyclopedia
The Asian green mussel (Perna viridis), also known as the Philippine green mussel, is an economically important mussel
, a bivalve belonging to the family
Mytilidae
. It is harvested for food but is also known to harbor toxins and cause damage to submerged structures such as drainage pipes. It is native in the Asia-Pacific
region and was introduced in the waters of the Caribbean
, Japan
, North America
, and South America
.
Perna viridis ranges from 80 to 100 millimeters in length and may occasionally reach 165 mm. Its shell ends in a downward-pointing beak. The smooth periostracum
is dark green, becoming increasingly brownish towards its point of attachment (umbo
), where it is lighter. Younger mussels are bright green and that becomes darker as it ages. The shell’s interior has a pale-blue sheen.
The mussel has a large mobile foot which it uses to climb vertically should it be covered by sediments. It also produce byssus
to help it attach to its substrate.
Perna canaliculus and Perna perna
are two similar species, native to the waters of New Zealand
and Africa
respectively.
via boat hulls
and water ballasts.
The mussel inhabits estuarine
habitats and is found in densities as high as 35,000 individuals per square meter in any submerged marine object. Although vivid green in appearance, the mussels are shrouded with overgrowth and are often hard to find. The mussels live in waters that are 11-32ºC with a wide-ranging salinity
of about 18-33 ppt
. P. viridis grows fastest at 2 meters below the surface, in high salinity and high concentration of phytoplankton
although it can tolerate a range of salinity and turbid water.
The Asian green mussel has separate sexes and fertilizes externally. There are a very few functional hermaphrodite
s (<0.1%). The mussel's sexual development was shown to be affected by temperature. Spawning ordinarily occurs twice a year between early spring and late autumn; however, the mussels found in the Philippines
and Thailand
are known to spawn all year round.
The zygote transforms to a larva 7-8 hours after fertilization. The larvae stay in the water column for 10-12 days before undergoing metamorphosis
into a juvenile and settling onto a surface. The juveniles become sexually mature when they are 15-30 mm in length, a size reached within 2-3 months. Growth is influenced by the availability of food, temperature, water movement, mussel's age, and caging. Cage culturing can prevent entry of predators and barnacles increases marketability but slows down the mussel's growth rate. The adult can live to up 2-3 years. Due to its fast growth, it can outcompete other fouling organisms and cause changes in marine ecological relationships.
The mussel is a filter feeder
that feeds on phytoplankton, zooplankton
and suspended organic materials. They are eaten by fishes, crustaceans, seastars, octopuses and humans.
region as a food source due to its fast growth. However, it can harbor deadly Saxitoxin
produced by the dinoflagellate
s that it feeds upon. It can also be used as a biomonitor to indicate pollution caused by heavy metals, organochloride
s and petroleum products. Mussels that are in contaminated areas have labile lysosomal
membranes due to metal-induced stress.
The mussel is also notorious for clogging water pipes used by industrial complexes and fouling marine equipment. It has fouled the intake condenser tunnels of power plants in India and Florida
and the navigational buoys in China where their biomass has grown to up to72 kg/m2.Chlorination of pipes and using high velocity water was shown to decrease or remove P. viridis population. However, the mussel excretes ammonia which reacts with the chlorine to form chloramine
, a weaker disinfectant than chlorine. Ammonia can also accelerate the corrosion of copper-based alloys found in the water pipes. Heat treatment is also being considered as an alternative to chlorination due to the safety and environmental concerns raised by the latter method.
As an invasive species
, the mollusk is viewed as threat to the United States' oyster fishery. It might also displace native mussels by introducing harmful parasites and diseases.
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 bivalve belonging to the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Mytilidae
Mytilidae
Mytilidae is a family of small to large saltwater mussels, marine bivalve mollusks in the order Mytiloida. It is the only family in the order...
. It is harvested for food but is also known to harbor toxins and cause damage to submerged structures such as drainage pipes. It is native in the Asia-Pacific
Asia-Pacific
Asia-Pacific or Asia Pacific is the part of the world in or near the Western Pacific Ocean...
region and was introduced in the waters of the Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
.
Description
Periostracum
The periostracum is a thin organic coating or "skin" which is the outermost layer of the shell of many shelled animals, including mollusks and brachiopods. Among mollusks it is primarily seen in snails and clams, i.e. in bivalves and gastropods, but it is also found in cephalopods such as the...
is dark green, becoming increasingly brownish towards its point of attachment (umbo
Umbo
Umbo may refer to:*A shield boss* umbo , at the top of some mushrooms*The Umbo of tympanic membrane - a part of the human body*Umbo is the part of a Bivalve shell which was formed when the animal was a juvenile...
), where it is lighter. Younger mussels are bright green and that becomes darker as it ages. The shell’s interior has a pale-blue sheen.
The mussel has a large mobile foot which it uses to climb vertically should it be covered by sediments. It also produce byssus
Byssus
Byssus means both a silky filament by which certain molluscs attach themselves to hard surfaces, and a rare fabric, also called sea silk and its fibre source.-Word:...
to help it attach to its substrate.
Perna canaliculus and Perna perna
Perna perna
The brown mussel, Perna perna, is an economically important mussel, a bivalve mollusc belonging to the family Mytilidae. It is harvested as a food source but is also known to harbor toxins and cause damage to marine structures...
are two similar species, native to the waters of New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
and Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
respectively.
Habitat and distribution
The Asian green mussel is found in the coastal waters of the Indo-Pacific region. However the mussels are introduced to other areas as invasive speciesInvasive 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....
via boat hulls
Biofouling
Biofouling or biological fouling is the undesirable accumulation of microorganisms, plants, algae, or animals on wetted structures.-Impact:...
and water ballasts.
The mussel inhabits estuarine
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....
habitats and is found in densities as high as 35,000 individuals per square meter in any submerged marine object. Although vivid green in appearance, the mussels are shrouded with overgrowth and are often hard to find. The mussels live in waters that are 11-32ºC with a wide-ranging salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
of about 18-33 ppt
Parts-per notation
In science and engineering, the parts-per notation is a set of pseudo units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement...
. P. viridis grows fastest at 2 meters below the surface, in high salinity and high concentration of phytoplankton
Phytoplankton
Phytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...
although it can tolerate a range of salinity and turbid water.
Ecology and life history
Hermaphrodite
In biology, a hermaphrodite is an organism that has reproductive organs normally associated with both male and female sexes.Many taxonomic groups of animals do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both...
s (<0.1%). The mussel's sexual development was shown to be affected by temperature. Spawning ordinarily occurs twice a year between early spring and late autumn; however, the mussels found in the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
and 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...
are known to spawn all year round.
The zygote transforms to a larva 7-8 hours after fertilization. The larvae stay in the water column for 10-12 days before undergoing metamorphosis
Metamorphosis
Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation...
into a juvenile and settling onto a surface. The juveniles become sexually mature when they are 15-30 mm in length, a size reached within 2-3 months. Growth is influenced by the availability of food, temperature, water movement, mussel's age, and caging. Cage culturing can prevent entry of predators and barnacles increases marketability but slows down the mussel's growth rate. The adult can live to up 2-3 years. Due to its fast growth, it can outcompete other fouling organisms and cause changes in marine ecological relationships.
The mussel is a filter feeder
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,...
that feeds on phytoplankton, zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
and suspended organic materials. They are eaten by fishes, crustaceans, seastars, octopuses and humans.
Importance to humans
P. viridis is harvested in the Indo-PacificIndo-Pacific
The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...
region as a food source due to its fast growth. However, it can harbor deadly Saxitoxin
Saxitoxin
Saxitoxin is a neurotoxin naturally produced by certain species of marine dinoflagellates and cyanobacteria Saxitoxin (STX) is a neurotoxin naturally produced by certain species of marine dinoflagellates (Alexandrium sp., Gymnodinium sp., Pyrodinium sp.) and cyanobacteria Saxitoxin (STX) is a...
produced by the dinoflagellate
Dinoflagellate
The dinoflagellates are a large group of flagellate protists. Most are marine plankton, but they are common in fresh water habitats as well. Their populations are distributed depending on temperature, salinity, or depth...
s that it feeds upon. It can also be used as a biomonitor to indicate pollution caused by heavy metals, organochloride
Organochloride
An organochloride, organochlorine, chlorocarbon, chlorinated hydrocarbon, or chlorinated solvent is an organic compound containing at least one covalently bonded chlorine atom. Their wide structural variety and divergent chemical properties lead to a broad range of applications...
s and petroleum products. Mussels that are in contaminated areas have labile lysosomal
Lysosome
thumb|350px|Schematic of typical animal cell, showing subcellular components. [[Organelle]]s: [[nucleoli]] [[cell nucleus|nucleus]] [[ribosomes]] [[vesicle |vesicle]] rough [[endoplasmic reticulum]]...
membranes due to metal-induced stress.
The mussel is also notorious for clogging water pipes used by industrial complexes and fouling marine equipment. It has fouled the intake condenser tunnels of power plants in India and Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
and the navigational buoys in China where their biomass has grown to up to72 kg/m2.Chlorination of pipes and using high velocity water was shown to decrease or remove P. viridis population. However, the mussel excretes ammonia which reacts with the chlorine to form chloramine
Chloramine
Chloramines are derivatives of ammonia by substitution of one, two or three hydrogen atoms with chlorine atoms. Monochloramine is an inorganic compound with the formula NH2Cl. It is an unstable colourless liquid at its melting point of -66° temperature, but it is usually handled as a dilute...
, a weaker disinfectant than chlorine. Ammonia can also accelerate the corrosion of copper-based alloys found in the water pipes. Heat treatment is also being considered as an alternative to chlorination due to the safety and environmental concerns raised by the latter method.
As an 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....
, the mollusk is viewed as threat to the United States' oyster fishery. It might also displace native mussels by introducing harmful parasites and diseases.