Quagga mussel
Overview
 
The quagga mussel is a subspecies of freshwater mussel, an aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...

 bivalve mollusk.

It is one of seven Dreissena
Dreissena
Dreissena is a genus of small freshwater mussels in the family Dreissenidae.-Species:* Dreissena polymorpha, the zebra mussel** Dreissena polymorpha polymorpha** Dreissena polymorpha andrusovi* Dreissena bugensis, the quagga mussel...

 species and has an average life span of 3 to 5 years.

This subspecies is indigenous to the Dnieper River
Dnieper River
The Dnieper River is one of the major rivers of Europe that flows from Russia, through Belarus and Ukraine, to the Black Sea.The total length is and has a drainage basin of .The river is noted for its dams and hydroelectric stations...

 drainage of Ukraine
Ukraine
Ukraine is a country in Eastern Europe. It has an area of 603,628 km², making it the second largest contiguous country on the European continent, after Russia...

. The species is named after the quagga
Quagga
The quagga is an extinct subspecies of the plains zebra, which was once found in great numbers in South Africa's Cape Province and the southern part of the Orange Free State. It was distinguished from other zebras by having the usual vivid marks on the front part of the body only...

, an extinct subspecies of African zebra
Zebra
Zebras are several species of African equids united by their distinctive black and white stripes. Their stripes come in different patterns unique to each individual. They are generally social animals that live in small harems to large herds...

, possibly because, like the quagga, its stripes fade out towards the ventral side.

The quagga mussel is currently of major concern in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 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 quagga mussel shell is striped, as is that of the zebra mussel
Zebra mussel
The zebra mussel, Dreissena polymorpha, is a small freshwater mussel. This species was originally native to the lakes of southeast Russia being first described in 1769 by a German zoologist Peter Simon Pallas in the Ural, Volga and Dnieper rivers. They are still found nearby, as Pontic and Caspian...

, but the quagga shell is more pale toward the end of the hinge.
Encyclopedia
The quagga mussel is a subspecies of freshwater mussel, an aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...

 bivalve mollusk.

It is one of seven Dreissena
Dreissena
Dreissena is a genus of small freshwater mussels in the family Dreissenidae.-Species:* Dreissena polymorpha, the zebra mussel** Dreissena polymorpha polymorpha** Dreissena polymorpha andrusovi* Dreissena bugensis, the quagga mussel...

 species and has an average life span of 3 to 5 years.

This subspecies is indigenous to the Dnieper River
Dnieper River
The Dnieper River is one of the major rivers of Europe that flows from Russia, through Belarus and Ukraine, to the Black Sea.The total length is and has a drainage basin of .The river is noted for its dams and hydroelectric stations...

 drainage of Ukraine
Ukraine
Ukraine is a country in Eastern Europe. It has an area of 603,628 km², making it the second largest contiguous country on the European continent, after Russia...

. The species is named after the quagga
Quagga
The quagga is an extinct subspecies of the plains zebra, which was once found in great numbers in South Africa's Cape Province and the southern part of the Orange Free State. It was distinguished from other zebras by having the usual vivid marks on the front part of the body only...

, an extinct subspecies of African zebra
Zebra
Zebras are several species of African equids united by their distinctive black and white stripes. Their stripes come in different patterns unique to each individual. They are generally social animals that live in small harems to large herds...

, possibly because, like the quagga, its stripes fade out towards the ventral side.

The quagga mussel is currently of major concern in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 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....

.

Appearance

The quagga mussel shell is striped, as is that of the zebra mussel
Zebra mussel
The zebra mussel, Dreissena polymorpha, is a small freshwater mussel. This species was originally native to the lakes of southeast Russia being first described in 1769 by a German zoologist Peter Simon Pallas in the Ural, Volga and Dnieper rivers. They are still found nearby, as Pontic and Caspian...

, but the quagga shell is more pale toward the end of the hinge. There is a large range of shell morphologies
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....

, including a distinct morph in Lake Erie
Lake Erie
Lake Erie is the fourth largest lake of the five Great Lakes in North America, and the tenth largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time. It is bounded on the north by the...

 that is pale or completely white. The quagga is slightly larger than the zebra mussel, about 20 millimetre (0.78740157480315 in) wide, roughly about the size of an adult human's thumbnail. The quagga has a rounded carina and a convex ventral side.

Diet

The quagga 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,...

. They use their cilia to pull water into their shell cavity where it passes through an incurrent siphon and it is here that desirable particulate matter is removed. Each adult mussel is capable of filtering one or more liters of water each day, where they remove 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...

, 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"...

, algae
Algae
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 even their own veliger
Veliger
A veliger is the planktonic larva of many kinds of marine and freshwater gastropod molluscs, as well as most bivalve mollusks.- Description :...

s. Any undesirable particulate matter is bound with mucus
Mucus
In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...

, known as pseudofeces
Pseudofeces
Pseudofeces or pseudofaeces are a way that filter-feeding bivalve mollusks get rid of suspended particles which have been rejected as unsuitable for food. The rejected particles are wrapped in mucus, and are expelled without having passed through the digestive tract...

, and ejected out the incurrent siphon. The particle-free water is then discharged out the excurrent siphon.

Reproduction

The quagga mussel is a prolific breeder, possibly contributing to its spread and abundance. Dreissena are dioecious
Dioecious
Dioecy is the property of a group of biological organisms that have males and females, but not members that have organs of both sexes at the same time. I.e., those whose individual members can usually produce only one type of gamete; each individual organism is thus distinctly female or male...

 (either male or female) with external fertilization. A fully mature female mussel is capable of producing up to one million eggs per year. After fertilization, pelagic microscopic larvae, or veligers, develop within a few days and these veligers soon acquire minute bivalve shells. Free-swimming veligers drift with the currents for three to four weeks feeding by their hair-like cilia while trying to locate suitable substrata to settle and secure byssal threads. Mortality in this transitional stage from planktonic veliger to settled juveniles may exceed 99%.

Invasive species

Zebra mussel
Zebra mussel
The zebra mussel, Dreissena polymorpha, is a small freshwater mussel. This species was originally native to the lakes of southeast Russia being first described in 1769 by a German zoologist Peter Simon Pallas in the Ural, Volga and Dnieper rivers. They are still found nearby, as Pontic and Caspian...

s, the first Dreissenid mussel introduced in North America, rapidly spread throughout many major river systems and the Great Lakes
Great Lakes
The Great Lakes are a collection of freshwater lakes located in northeastern North America, on the Canada – United States border. Consisting of Lakes Superior, Michigan, Huron, Erie, and Ontario, they form the largest group of freshwater lakes on Earth by total surface, coming in second by volume...

 causing substantial ecological and environmental impacts. The quagga mussel was first observed in North America in September 1989 when it was discovered in Lake Erie
Lake Erie
Lake Erie is the fourth largest lake of the five Great Lakes in North America, and the tenth largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time. It is bounded on the north by the...

 near Port Colborne, Ontario
Port Colborne, Ontario
Port Colborne is a city on Lake Erie, at the southern end of the Welland Canal, in the Niagara Region of southern Ontario, Canada...

. It was not identified as a distinct species until 1991.

The introduction of both Dreissenid species into the Great Lakes appears to be the result of ballast
Sailing ballast
Ballast is used in sailboats to provide moment to resist the lateral forces on the sail. Insufficiently ballasted boats will tend to tip, or heel, excessively in high winds. Too much heel may result in the boat capsizing. If a sailing vessel should need to voyage without cargo then ballast of...

 water discharge from transoceanic ships that were carrying veligers, juveniles, or adult mussels. The genus Dreissena is highly polymorphic and prolific with high potential for rapid adaptation attributing to its rapid expansion and colonization. Still, there are other factors that can aid in the spread of these species across North American waters, such as, larval drift in river systems or fishing and boating activities that allow for overland transport or movement between water basins. The success of overland transport of Dreissena species depends on their ability to tolerate periods of desiccation, and results suggest that, given temperate summer conditions, adult Dreissena may survive 3-5 days of aerial exposure.

Quaggas are prodigious water filterers, removing substantial amounts 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...

 and suspended particulate from the water. By removing the phytoplankton, quaggas in turn decrease the food source for 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"...

, therefore altering the food web. Impacts associated with the filtration of water include increases in water transparency, decreases in mean chlorophyll
Chlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...

 concentrations, and accumulation of pseudofeces. Water clarity increases light penetration causing a proliferation of aquatic plants that can change species dominance and alter the entire ecosystems. The pseudofeces that is produced from filtering the water accumulates and impacts the environment. As the waste particles decompose, oxygen is used up, water acidity increases (decreased pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

) and toxic byproducts are produced. In addition, quagga mussels accumulate organic pollutants within their tissues to levels more than 300,000 times greater than concentrations in the environment and these pollutants are found in their pseudofeces, which can be passed up the food chain, therefore increasing wildlife exposure to organic pollutants (Snyder et al., 1997). Another major threat involves the fouling of native freshwater mussels. Since quaggas were discovered in Lake Michigan
Lake Michigan
Lake Michigan is one of the five Great Lakes of North America and the only one located entirely within the United States. It is the second largest of the Great Lakes by volume and the third largest by surface area, after Lake Superior and Lake Huron...

 in 1998, plankton rings formed by the passage of storms have been eaten away by the quagga mussels, threatening the local ecosystem.
Dreissenas ability to rapidly colonize hard surfaces causes serious economic problems. These major biofouling
Biofouling
Biofouling or biological fouling is the undesirable accumulation of microorganisms, plants, algae, or animals on wetted structures.-Impact:...

 organisms can clog water intake structures, such as pipes and screens, therefore reducing pumping capabilities for power and water treatment
Water treatment
Water treatment describes those processes used to make water more acceptable for a desired end-use. These can include use as drinking water, industrial processes, medical and many other uses. The goal of all water treatment process is to remove existing contaminants in the water, or reduce the...

 plants, costing industries, companies, and communities. Recreation-based industries and activities have also been impacted; dock
Dock (maritime)
A dock is a human-made structure or group of structures involved in the handling of boats or ships, usually on or close to a shore.However, the exact meaning varies among different variants of the English language...

s, breakwalls, buoy
Buoy
A buoy is a floating device that can have many different purposes. It can be anchored or allowed to drift. The word, of Old French or Middle Dutch origin, is now most commonly in UK English, although some orthoepists have traditionally prescribed the pronunciation...

s, boat
Boat
A boat is a watercraft of any size designed to float or plane, to provide passage across water. Usually this water will be inland or in protected coastal areas. However, boats such as the whaleboat were designed to be operated from a ship in an offshore environment. In naval terms, a boat is a...

s, and beach
Beach
A beach is a geological landform along the shoreline of an ocean, sea, lake or river. It usually consists of loose particles which are often composed of rock, such as sand, gravel, shingle, pebbles or cobblestones...

es have all been heavily colonized. Many of the potential impacts of Dreissena are unclear due to the limited time scale of North American colonization. Nonetheless, it is clear that the genus Dreissena is highly polymorphic and has a high potential for rapid adaptation to extreme environmental conditions, possibly leading to significant long-term impacts on North American waters. Also, the colonization of deeper water by D. r. bugensis, exposes the quagga to a new range of environmental conditions and new habitats.

It causes many of the same problems (damaging boats, power plants, and harbors and destroying the native mussel population) as the equally invasive zebra mussel of Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

. It is also displacing native burrowing amphipod (Diporeia hoyi) from the deep waters of Lake Erie.

In January 2007, quagga mussels were discovered at a marina in the Nevada portion of Lake Mead
Lake Mead
Lake Mead is the largest reservoir in the United States. It is located on the Colorado River about southeast of Las Vegas, Nevada, in the states of Nevada and Arizona. Formed by water impounded by the Hoover Dam, it extends behind the dam, holding approximately of water.-History:The lake was...

, and two other lakes on the Colorado River
Colorado River
The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...

, Lake Mohave
Lake Mohave
Lake Mohave is a reservoir formed by Davis Dam on the Colorado River, which defines the border between Nevada and Arizona in the United States. The lake lies at an elevation of near Laughlin, Nevada, Searchlight, Nevada, Cottonwood Cove, Nevada, and Bullhead City, Arizona, about downstream from...

 and Lake Havasu
Lake Havasu
Lake Havasu is a large reservoir behind Parker Dam on the Colorado River, on the border between California and Arizona. Lake Havasu City sits on the lake's eastern shore. The lake has a capacity of . The concrete arch dam was built by the United States Bureau of Reclamation between 1934 and 1938...

.

In 2008 the threat of quagga mussels being introduced at Lake Casitas
Lake Casitas
Lake Casitas is an artificial lake in the Los Padres National Forest of Ventura County, California, created by the construction of Casitas Dam on Coyote Creek, two miles before it joins the Ventura River. Santa Ana Creek and North Fork Coyote Creek also flow into the lake. The dam was constructed...

 and Westlake Lake in California from recreational boating resulted in the lakes banning the use of outside boats. As of March 2008, other lakes such as Castaic and Lake Cachuma are considering similar bans. In June 2008, the mussels were confirmed in Lake Granby
Lake Granby
Lake Granby is the second largest body of water in Colorado. It was created as part of the Colorado-Big Thompson Project and forms a continuous body of water with Shadow Mountain Reservoir and Grand Lake. On its own, Lake Granby contains approximately 40 miles of shoreline. The lake is popular...

, Colorado. The larva form of quagga mussels were found in the water.

Quagga mussels as prey

In 1994, invasive species biologist Anthony Ricciardi determined that yellow perch
Yellow perch
The yellow perch is a species of perch found in the United States and Canada, where it is often referred to by the shortform perch. Yellow perch look similar to the European perch, but are paler and more yellowish, with less red in the fins. They have six to eight dark, vertical bars on their sides...

 did not find the invasive dreissenid species palatable. In 2004, he determined that yellow perch, over the intervening 10 years, had developed an appetite for the Quagga mussel. While sounding like good news, it is tempered with the knowledge that it introduces contaminants into the food chain
Food chain
A food web depicts feeding connections in an ecological community. Ecologists can broadly lump all life forms into one of two categories called trophic levels: 1) the autotrophs, and 2) the heterotrophs...

, notably Clostridium botulinum
Clostridium botulinum
Clostridium botulinum is a Gram-positive, rod-shaped bacterium that produces several toxins. The best known are its neurotoxins, subdivided in types A-G, that cause the flaccid muscular paralysis seen in botulism. It is also the main paralytic agent in botox. C. botulinum is an anaerobic...

.

Redear sunfish
Redear sunfish
The redear sunfish , also known as the shellcracker, Georgia bream, cherry gill, chinquapin, improved bream, rouge ear sunfish and sun perch, is native to the southeastern United States, but since it is a popular sport fish it has been introduced to bodies of water all over North America...

, a specialized mollusc-eating fish, are now being stocked in the Colorado River drainage as a defense against the quaggas. As with the yellow perch, this predator-prey relationship could cause toxins and microorganisms to move up the food chain.

Although quaggas are edible for humans, eating them is not recommended due to the accumulation of toxins, pollutants, and microorganisms within the mussels' bodies.

External links

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