Thalassiosira weissflogii
Encyclopedia
Thalassiosira weissflogii is a species
of centric diatom
, a unicellular microalga. It is found in marine environments and also in inland waters in many parts of the world.
evidence suggests that Thalassiosira weissflogii is a species complex
and that several different genetic populations exist. There was found to be a divergence between one clade
from the east and west Atlantic Ocean and California and another from Hawaii
and Indonesia
. The latter was considered to consist of two different biological species, one from Hawaii and one from the Indonesian archipelago.
with two frustule
s or valves, a larger epivalve and a smaller hypovalve. The face of the valves vary in shape but are basically irregular rings with one labiate and two or more central processes
. Other features that may be present include an irregularly shaped areola or pore, further processes on the rim of the valves, marginal spines, striations and thick radial ribs.
and occurs in coastal waters in the Atlantic
and Pacific Ocean
s and in rivers and lakes in Europe, Asia, South and North America, including the Great Lakes
, where it was thought to have been introduced in ballast water
.
s or red tide
s.
It is very tolerant to poor water quality. It flourishes in environments with high carbon dioxide
levels, high chlorine
, high cadmium
and high pH
. Its growth may be limited by the availability of iron, nickel, zinc, nitrogen and silicon.
or sexual means. The asexual phase involves cell division with each of the new individuals receiving one of the valves. This means that the offspring are of unequal sizes and successive generations tend to decrease in size. Large individuals can also reproduce sexually. This event may be triggered by some external factor such as a variation in light intensity, temperature or day length.
, Thalassiosira weissflogii is used to feed to shrimp
and shellfish
larva
e in hatcheries. It is considered preferable for this purpose to the other commercially available microalgae, Chaetoceros
and Tetraselmis
, because of its larger size which means it can continue to be used at more advanced larval stages. It is available as a culture of "Instant Algae" which can be stored at 0-4 °C.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of centric diatom
Diatom
Diatoms are a major group of algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons , fans , zigzags , or stellate colonies . Diatoms are producers within the food chain...
, a unicellular microalga. It is found in marine environments and also in inland waters in many parts of the world.
Taxonomy
rDNARDNA
rDNA may stand for:*ribosomal DNA*recombinant DNARDNA is also an acronym for*Reformed Druids of North America...
evidence suggests that Thalassiosira weissflogii is a species complex
Species complex
A species complex is a group of closely related species, where the exact demarcation between species is often unclear or cryptic owing to their recent and usually still incomplete reproductive isolation. Ring species, superspecies and cryptic species complex are example of species complex...
and that several different genetic populations exist. There was found to be a divergence between one clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
from the east and west Atlantic Ocean and California and another from Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
and Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
. The latter was considered to consist of two different biological species, one from Hawaii and one from the Indonesian archipelago.
Description
Thalassiosira weissflogii is a short cylinder in shape and varies in size from 4 to 32 µm in diameter. It tends to be larger in winter, typically 15 µm in diameter, but smaller in summer (5 µm). It occurs both singly and in groups and may be embedded in a gelatinous matrix. There is a silicaceous cell wallCell wall
The cell wall is the tough, usually flexible but sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism. A major function of the cell wall is to...
with two frustule
Frustule
A frustule is the hard and porous cell wall or external layer of diatoms. The frustule is composed almost purely of silica, made from silicic acid, and is coated with a layer of organic substance, which was referred to in the early literature on diatoms as pectin, a fiber most commonly found in...
s or valves, a larger epivalve and a smaller hypovalve. The face of the valves vary in shape but are basically irregular rings with one labiate and two or more central processes
Process (anatomy)
In anatomy, a process is a projection or outgrowth of tissue from a larger body. The vertebra has several kinds of processes,such as: transverse process, prezygapophysis, postzygapophysis.-Examples:Examples of processes include:...
. Other features that may be present include an irregularly shaped areola or pore, further processes on the rim of the valves, marginal spines, striations and thick radial ribs.
Distribution and habitat
The native range of Thalassiosira weissflogii is unclear, but it is found in marine, brackish and freshwater environments. It seems to grow best at higher salinitiesSalinity
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...
and occurs in coastal waters in the Atlantic
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
and Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
s and in rivers and lakes in Europe, Asia, South and North America, including 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...
, where it was thought to have been introduced in ballast water
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...
.
Ecology
Thalassiosira weissflogii is non-toxic but it is sometimes associated with other microalgae that cause algal bloomAlgal bloom
An algal bloom is a rapid increase or accumulation in the population of algae in an aquatic system. Algal blooms may occur in freshwater as well as marine environments. Typically, only one or a small number of phytoplankton species are involved, and some blooms may be recognized by discoloration...
s or red tide
Red tide
Red tide is a common name for a phenomenon also known as an algal bloom , an event in which estuarine, marine, or fresh water algae accumulate rapidly in the water column and results in discoloration of the surface water. It is usually found in coastal areas...
s.
It is very tolerant to poor water quality. It flourishes in environments with high carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
levels, high chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
, high cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
and high 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...
. Its growth may be limited by the availability of iron, nickel, zinc, nitrogen and silicon.
Biology
Reproduction in Thalassiosira weissflogii can be by either asexualAsexual reproduction
Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without...
or sexual means. The asexual phase involves cell division with each of the new individuals receiving one of the valves. This means that the offspring are of unequal sizes and successive generations tend to decrease in size. Large individuals can also reproduce sexually. This event may be triggered by some external factor such as a variation in light intensity, temperature or day length.
Uses
In aquacultureAquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
, Thalassiosira weissflogii is used to feed to shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
and shellfish
Shellfish
Shellfish is a culinary and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater environments, some kinds are found only in freshwater...
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 in hatcheries. It is considered preferable for this purpose to the other commercially available microalgae, Chaetoceros
Chaetoceros
Chaetoceros is probably the largest genus of marine planktonic diatoms with approximately 400 species described. Although a large number of these descriptions are no longer valid. It is often very difficult to distinguish between different Chaetoceros species...
and Tetraselmis
Tetraselmis
Tetraselmis is a genus of phytoplankton. Tetraselmis has a very high lipid level; their amino acids stimulate feeding in marine organisms . Tetraselmis is green, motile, and usually grows 10 µm long x 14 µm wide.The species T...
, because of its larger size which means it can continue to be used at more advanced larval stages. It is available as a culture of "Instant Algae" which can be stored at 0-4 °C.