The Chrysophyceae, usually called chrysophytes, chrysomonads, golden-brown algae or golden algae are a large group of
algae
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular micr ...
, found mostly in freshwater.
Golden algae is also commonly used to refer to a single species, ''
Prymnesium parvum'', which causes
fish kill
The term fish kill, known also as fish die-off, refers to a localized die-off of fish populations which may also be associated with more generalized mortality of aquatic life.University of Florida. Gainesville, FL (2005) ''Plant Management in Fl ...
s.
The Chrysophyceae should not be confused with the
Chrysophyta
Chrysophyta or golden algae is a term used to refer to certain heterokonts.
It can be used to refer to:
* Chrysophyceae (golden algae), Bacillariophyceae (diatoms), and Xanthophyceae (yellow-green algae) together. E.g., Pascher (1914).
* Chrysoph ...
, which is a more ambiguous
taxon
In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...
. Although "chrysophytes" is the anglicization of "Chrysophyta", it generally refers to the Chrysophyceae.
Members
Originally they were taken to include all such forms of the
diatom
A diatom ( Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising se ...
s and multicellular
brown algae
Brown algae (singular: alga), comprising the class Phaeophyceae, are a large group of multicellular algae, including many seaweeds located in colder waters within the Northern Hemisphere. Brown algae are the major seaweeds of the temperate and p ...
, but since then they have been divided into several different groups (e.g.,
Haptophyceae
The haptophytes, classified either as the Haptophyta, Haptophytina or Prymnesiophyta (named for ''Prymnesium''), are a clade of algae.
The names Haptophyceae or Prymnesiophyceae are sometimes used instead. This ending implies classification at ...
,
Synurophyceae
The synurids (order Synurales) are a small group of heterokont algae, found mostly in freshwater environments, characterized by cells covered in silica scales.
Characteristics
They are covered in silicate scales and spines. In ''Synura'', th ...
) based on pigmentation and cell structure. Some heterotrophic flagellates as the
bicosoecids and
choanoflagellates were sometimes seen as related to golden algae too.
They are now usually restricted to a core group of closely related forms, distinguished primarily by the structure of the
flagella
A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates.
A microorganism may have fro ...
in motile cells, also treated as an order Chromulinales. It is possible membership will be revised further as more species are studied in detail.
The Chrysophyceae have been placed by some in the polyphyletic
Chromista
Chromista is a biological kingdom consisting of single-celled and multicellular eukaryotic species that share similar features in their photosynthetic organelles ( plastids). It includes all protists whose plastids contain chlorophyll ''c'', ...
. The broader monophyletic group to which the Chrysophyceae belong includes various non-algae including the bicosoecids, not the collar flagellates, opalines, oomycete fungi, proteromonads, actinophryid heliozoa, and other heterotrophic flagellates and is referred to as the
Stramenopiles
Stramenopile is a clade of organisms distinguished by the presence of stiff tripartite external hairs. In most species, the hairs are attached to flagella, in some they are attached to other areas of the cellular surface, and in some they have be ...
.
Description
The "primary" cell of chrysophytes contains two
specialized flagella. The active, "feathered" (with
mastigonemes) flagellum is oriented toward the moving direction. The smooth passive flagellum, oriented toward the opposite direction, may be present only in rudimentary form in some species.
An important characteristic used to identify members of the class Chrysophyceae is the presence of a siliceous cyst that is formed endogenously. Called statospore, stomatocyst or statocyst, this structure is usually globose and contains a single pore. The surface of mature cysts may be ornamented with different structural elements and are useful to distinguish species.
* Most members are unicellular
flagellate
A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word ''flagellate'' also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and thei ...
s, with either two visible flagella, as in ''
Ochromonas'', or sometimes one, as in ''
Chromulina''. The
Chromulinales as first defined by Pascher in 1910 included only the latter type, with the former treated as the order
Ochromonadales. However, structural studies have revealed that a short second flagellum, or at least a second basal body, is always present, so this is no longer considered a valid distinction. Most of these have no cell covering. Some have loricae or shells, such as ''
Dinobryon'', which is sessile and grows in branched colonies. Most forms with silicaceous scales are now considered a separate group, the
synurids, but a few belong among the Chromulinales proper, such as ''
Paraphysomonas''.
* Some members are generally
amoeboid
An amoeba (; less commonly spelled ameba or amœba; plural ''am(o)ebas'' or ''am(o)ebae'' ), often called an amoeboid, is a type of cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudopo ...
, with long branching cell extensions, though they pass through flagellate stages as well. ''
Chrysamoeba'' and ''
Rhizochrysis'' are typical of these. There is also one species, ''
Myxochrysis paradoxa'', which has a complex life cycle involving a
multinucleate
Multinucleate cells (also known as multinucleated or polynuclear cells) are eukaryotic cells that have more than one nucleus per cell, i.e., multiple nuclei share one common cytoplasm. Mitosis in multinucleate cells can occur either in a coordina ...
plasmodial stage, similar to those found in
slime mold
Slime mold or slime mould is an informal name given to several kinds of unrelated eukaryotic organisms with a life cycle that includes a free-living single-celled stage and the formation of spores. Spores are often produced in macroscopic mul ...
s. These were originally treated as the order
Chrysamoebales. The superficially similar ''
Rhizochromulina
''Rhizochromulina'' is an unusual genus of marine heterokont algae, with one species, ''Rhizocromulina marina''. They are colored amoeboids with a single flagellum, and produce distinctive spindle-shaped zoospores. These have a cell structure ty ...
'' was once included here, but is now given its own order based on differences in the structure of the flagellate stage.
* Other members are non-motile. Cells may be naked and embedded in
mucilage
Mucilage is a thick, gluey substance produced by nearly all plants and some microorganisms. These microorganisms include protists which use it for their locomotion. The direction of their movement is always opposite to that of the secretion of m ...
, such as ''
Chrysosaccus'', or coccoid and surrounded by a cell wall, as in ''
Chrysosphaera''. A few are filamentous or even
parenchyma
Parenchyma () is the bulk of functional substance in an animal organ or structure such as a tumour. In zoology it is the name for the tissue that fills the interior of flatworms.
Etymology
The term ''parenchyma'' is New Latin from the word � ...
tous in organization, such as ''
Phaeoplaca''. These were included in various older orders, most of the members of which are now included in separate groups. ''
Hydrurus'' and its allies, freshwater genera which form branched gelatinous filaments, are often placed in the separate order
Hydrurales, but may belong here.
Classifications
Pascher (1914)
Classification of the class Chrysophyceae according to Pascher (1914):
* Division
Chrysophyta
Chrysophyta or golden algae is a term used to refer to certain heterokonts.
It can be used to refer to:
* Chrysophyceae (golden algae), Bacillariophyceae (diatoms), and Xanthophyceae (yellow-green algae) together. E.g., Pascher (1914).
* Chrysoph ...
** Class Chrysophyceae
*** Order
Chrysomonadales
*** Order
Chrysocapsales
*** Order
Chrysosphaerales
Chrysosphaerales is an order of Chrysophyceae
The Chrysophyceae, usually called chrysophytes, chrysomonads, golden-brown algae or golden algae are a large group of algae, found mostly in freshwater. Golden algae is also commonly used to refer ...
*** Order
Chrysotrichales
** Class
Heterokontae
** Class
Diatom
A diatom ( Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising se ...
eae
Smith (1938)
According to
Smith (1938):
* Class Chrysophyceae
** Order
Chrysomonadales
*** Suborder
Cromulinae (e.g., ''
Mallomonas'')
*** Suborder
Isochrysidineae (e.g., ''
Synura'')
*** Suborder
Ochromonadineae (e.g., ''
Dinobryon'')
** Order
Rhizochrysidales (e.g., ''
Chrysamoeba'')
** Order
Chrysocapsales (e.g., ''
Hydrurus'')
** Order
Chrysotrichales (e.g., ''
Phaeothamnion'')
** Order
Chrysosphaerales
Chrysosphaerales is an order of Chrysophyceae
The Chrysophyceae, usually called chrysophytes, chrysomonads, golden-brown algae or golden algae are a large group of algae, found mostly in freshwater. Golden algae is also commonly used to refer ...
(e.g., ''
Epichrysis'')
Bourrely (1957)
According to Bourrely (1957):
* Class Chrysophyceae
** Order
Phaeoplacales
** Order
Stichogloeales
** Order
Phaeothamniales
Phaeothamniales is an order of alga in the Ochrophyta
The ochrophytes, subphylum Ochrophytina, is a group of mostly photosynthetic heterokonts. Their plastid is of red algal origin.
The classification of the group is still being worked out. ...
** Order
Chrysapionales
** Order
Thallochrysidales
** Order
Chrysosphaerales
Chrysosphaerales is an order of Chrysophyceae
The Chrysophyceae, usually called chrysophytes, chrysomonads, golden-brown algae or golden algae are a large group of algae, found mostly in freshwater. Golden algae is also commonly used to refer ...
** Order
Chrysosaccales
** Order
Rhizochrysidales
** Order
Ochromonadales
** Order
Isochrysidales
** Order
Silicoflagellales
** Order
Craspedomonadales
** Order
Chromulinales
Starmach (1985)
According to Starmach (1985):
* Class Chrysophyceae
** Subclass
Heterochrysophycidae
*** Order
Chromulinales
*** Order
Ochromonadales
** Subclass
Acontochrysophycidae
*** Order
Chrysarachniales
*** Order
Stylococcales
*** Order
Chrysosaccales
*** Order
Phaeoplacales
** Subclass
Craspedomonadophycidae
*** Order
Monosigales
Kristiansen (1986)
Classification of the class Chrysophyceae and splinter groups according to Kristiansen (1986):
* Class Chrysophyceae
:* Order
Ochromonadales
:* Order
Mallomonadales
:* Order
Chrysamoebales
:* Order
Chrysocapsales
:* Order
Hydrurales
:* Order
Chrysosphaerales
Chrysosphaerales is an order of Chrysophyceae
The Chrysophyceae, usually called chrysophytes, chrysomonads, golden-brown algae or golden algae are a large group of algae, found mostly in freshwater. Golden algae is also commonly used to refer ...
:* Order
Phaeothamniales
Phaeothamniales is an order of alga in the Ochrophyta
The ochrophytes, subphylum Ochrophytina, is a group of mostly photosynthetic heterokonts. Their plastid is of red algal origin.
The classification of the group is still being worked out. ...
:* Order
Sarcinochrysidales
* Class
Pedinellophyceae
:* Order
Pedinellales
Pedinellales is a group of single-celled algae found in both marine environments and freshwater.
These are found in both freshwater and marine environments, and most genera are sessile, attached by posterior stalks. The flagellum is at the ante ...
* Class
Dictyochophyceae
Dictyochophyceae sensu lato is a photosynthetic lineage of heterokont algae.
Taxonomy
* Class Dictyochophyceae Silva 1980 s.l.
** Subclass Sulcophycidae Cavalier-Smith 2013
*** Order Olisthodiscales Cavalier-Smith 2013
**** Family Olisthodisca ...
:* Order
Dictyochales
Margulis et al. (1990)
Classification of the phylum Chrysophyta according to Margulis et al. (1990):
* Phylum
Chrysophyta
Chrysophyta or golden algae is a term used to refer to certain heterokonts.
It can be used to refer to:
* Chrysophyceae (golden algae), Bacillariophyceae (diatoms), and Xanthophyceae (yellow-green algae) together. E.g., Pascher (1914).
* Chrysoph ...
** Class
Chrysophyceae
The Chrysophyceae, usually called chrysophytes, chrysomonads, golden-brown algae or golden algae are a large group of algae, found mostly in freshwater. Golden algae is also commonly used to refer to a single species, '' Prymnesium parvum'', whic ...
** Class
Pedinellophyceae
** Class
Dictyochophyceae
Dictyochophyceae sensu lato is a photosynthetic lineage of heterokont algae.
Taxonomy
* Class Dictyochophyceae Silva 1980 s.l.
** Subclass Sulcophycidae Cavalier-Smith 2013
*** Order Olisthodiscales Cavalier-Smith 2013
**** Family Olisthodisca ...
(=
Silicoflagellata)
van den Hoek ''et al.'' (1995)
According to
van den Hoek, Mann and Jahns (1995):
* Class Chrysophyceae
** Order
Ochromonadales (e.g., ''
Ochromonas,
Pseudokephyrion,
Dinobryon'')
** Order
Mallomonadales (= Class
Synurophyceae
The synurids (order Synurales) are a small group of heterokont algae, found mostly in freshwater environments, characterized by cells covered in silica scales.
Characteristics
They are covered in silicate scales and spines. In ''Synura'', th ...
, e.g., ''
Mallomonas,
Synura'')
** Order
Pedinellales
Pedinellales is a group of single-celled algae found in both marine environments and freshwater.
These are found in both freshwater and marine environments, and most genera are sessile, attached by posterior stalks. The flagellum is at the ante ...
(= Class
Pedinellophyceae, e.g., ''
Pedinella'')
** Order
Chrysamoebidales (e.g., ''
Rhizochrysis,
Chrysarachnion'')
** Order
Chrysocapsales (e.g., ''
Chrysocapsa,
Hydrurus'')
** Order
Chrysosphaerales
Chrysosphaerales is an order of Chrysophyceae
The Chrysophyceae, usually called chrysophytes, chrysomonads, golden-brown algae or golden algae are a large group of algae, found mostly in freshwater. Golden algae is also commonly used to refer ...
(e.g., ''
Chrysosphaera'')
** Order
Phaeothamniales
Phaeothamniales is an order of alga in the Ochrophyta
The ochrophytes, subphylum Ochrophytina, is a group of mostly photosynthetic heterokonts. Their plastid is of red algal origin.
The classification of the group is still being worked out. ...
(e.g., ''
Phaeothamnion,
Thallochrysis'')
Preisig (1995)
Classification of the class Chrysophyceae and splinter groups according to Preisig (1995):
* Class Chrysophyceae
:* Order
Bicosoecales
:* Order
Chromulinales
:* Order
Hibberdiales
:* Order
Hydrurales
:* Order
Sancinochrysidales
:* Order
Chrysomioridales
* Class
Dictyochophyceae
Dictyochophyceae sensu lato is a photosynthetic lineage of heterokont algae.
Taxonomy
* Class Dictyochophyceae Silva 1980 s.l.
** Subclass Sulcophycidae Cavalier-Smith 2013
*** Order Olisthodiscales Cavalier-Smith 2013
**** Family Olisthodisca ...
:* Order
Pedinellales
Pedinellales is a group of single-celled algae found in both marine environments and freshwater.
These are found in both freshwater and marine environments, and most genera are sessile, attached by posterior stalks. The flagellum is at the ante ...
:* Order
Rhizochromulinales
Rhizochromulinales is an order of Dictyochophyceae. The order includes the genus, ''Rhizochromulina
''Rhizochromulina'' is an unusual genus of marine heterokont algae, with one species, ''Rhizocromulina marina''. They are colored amoeboids wit ...
:* Order
Dictyochales
* Class
Synurophyceae
The synurids (order Synurales) are a small group of heterokont algae, found mostly in freshwater environments, characterized by cells covered in silica scales.
Characteristics
They are covered in silicate scales and spines. In ''Synura'', th ...
:* Order
Synurales
Guiry and Guiry (2019)
According to Guiry and Guiry (2019):
* Class Chrysophyceae
** Order
Chromulinales
** Order
Hibberdiales
** Order
Hydrurales
** Order
Rhizochrysidales
** Order
Thallochrysidales
** Chrysophyceae ordo
incertae sedis
' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertain ...
(11 genera)
Ecology
Chrysophytes live mostly in
freshwater
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does incl ...
, and are important for studies of
food web
A food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community. Another name for food web is consumer-resource system. Ecologists can broadly lump all life forms into one o ...
dynamics in
oligotrophic
An oligotroph is an organism that can live in an environment that offers very low levels of nutrients. They may be contrasted with copiotrophs, which prefer nutritionally rich environments. Oligotrophs are characterized by slow growth, low rates o ...
freshwater ecosystems, and for
assessment
Assessment may refer to:
Healthcare
*Health assessment, identifies needs of the patient and how those needs will be addressed
*Nursing assessment, gathering information about a patient's physiological, psychological, sociological, and spiritual s ...
of
environmental degradation
Environmental degradation is the deterioration of the environment through depletion of resources such as quality of air, water and soil; the destruction of ecosystems; habitat destruction; the extinction of wildlife; and pollution. It is defin ...
resulting from
eutrophication
Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phyt ...
and
acid rain
Acid rain is rain or any other form of precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). Most water, including drinking water, has a neutral pH that exists between 6.5 and 8.5, but ac ...
.
[Sandgren et al. (1995).]
Evolution
Chrysophytes contain the pigment
fucoxanthin.
Because of this, they were once considered to be a specialized form of
cyanobacteria
Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, bl ...
. Because many of these organisms had a silica capsule, they have a relatively complete fossil record, allowing modern biologists to confirm that they are, in fact, not derived from cyanobacteria, but rather an ancestor that did not possess the capability to photosynthesize. Many of the chrysophyta precursor fossils entirely lacked any type of photosynthesis-capable pigment. The most primitive stramenopiles are regarded as heterotrophic, such as the ancestors of the Chrysophyceae were likely heterotrophic flagellates that obtained their ability to photosynthesize from an endosymbiotic relationship with fucoxanthin-containing cyanobacteria.
References
Bibliography
* Andersen, R. A. 2004
Biology and systematics of heterokont and haptophyte algae.''American Journal of Botany'' 91(10): 1508–1522. 2004.
* Duff, K.E., B.A. Zeeb & J.P. Smol. 1995. ''Atlas of Chrysophycean Cysts'', Vol. 1.
2001, Vol. 2
Kluwer Academic Publishers, Dordrecht.
* Jørgen Kristiansen. 2005. ''Golden algae: a biology of chrysophytes.'' A.R.G. Gantner Verlag, distributed by Koeltz Scientific Books, Königstein, Germany, vii + 167 pp. .
* Kristiansen, J. and R.A. Andersen
ds. 1986. ''Chrysophytes: Aspects and Problems.'' Cambridge University Press, Cambridge, xiv + 337 pp.
* Kristiansen, J. and Preisig, H.
ds. 2001. ''Encyclopedia of chrysophyte genera''. Bibliotheca Phycologica, Vol. 110, J. Cramer, Berlin.
* Medlin, L. K., W. H. C. F. Kooistra, D. Potter, G. W. Saunders, and R. A. Anderson. 1997
Phylogenetic relationships of the “golden algae” (haptophytes, heterokont chromophytes) and their plastids.''Plant Systematics and Evolution'' (Supplement) 11: 187–219.
* Sandgren, C.D., J.P. Smol, and J. Kristiansen
ds. 1995. ''Chrysophyte algae: ecology, phylogeny and development.'' Cambridge University Press, New York. .
* Škaloud, P., Škaloudová, M., Pichrtová, M., Němcová, Y., Kreidlová, J. & Pusztai, M. 2013. www.chrysophytes.eu – a database on distribution and ecology of silica-scaled chrysophytes in Europe. ''Nova Hedwigia'', Beiheft 142: 141-146
link
{{Taxonbar, from=Q1763065
Algae classes