Lauderia annulata

General Close


(diatoms) Having radial symmetry, i.e., cell is shaped like a coin or a tuna can or a soup can.

Shape Cylindrical
Size Length 20 - 96 μm, diameter 15 - 75 μm
Colour Yellow-brown
Connection Close


In diatoms, the structurally distinct halves of the cell wall (Becker 1996).

directly touching, with Close


In some diatoms, "closed or solid structures projecting from the cell wall;" in dinoflagellates, solid projections that usually taper to a point.

on the Close


The outline or border that defines the shape of an organism or cell.

Covering Silica Close


In diatoms, the hard and porous silica cell wall (Horner 2002).



(plural: flagella) A tail-like projection that sticks out from the cell body and enables movement.



An organelle in the cell that contains the cell pigments (Horner 2002). This is where photosynthesis occurs. A chloroplast is a specialized chromatophore.

Numerous small lobes
Lifestyle Close


The chemical process by which light energy, water and carbon dioxide are combined to produce oxygen and organic compounds. Photoautotrophic organisms (plants and algae) use this reaction to produce their own food.

. Sexual/asexual. Close


In diatoms, the special cells that restore normal size following cell division. Auxospores are associated with sexual reproduction (Horner 2002).

present. Close

Resting spore

In diatoms, a cell that requires a dormancy period prior to germination and can survive for several years; usually developed to survive adverse conditions. They are commonly observed in centric but not pennate diatoms. The morphology of the spore may be similar or different from a vegetative cell; they usually have heavily silicified walls and are rich in storage products (Horner 2002).

Resting stage
may be present.


A rapid increase or accumulation of algal populations in an aquatic system. This will likely involve one or a few dominant phytoplankton species. This follows seasonal patterns (i.e., spring, summer or fall bloom) with dominant species being those that are best adapted to the environmental conditions of that time period. Discolouration of the water may be observed because of the algae's pigmentation. Blooms are often green but may be yellow-brown or red depending on the species present.

Information not available
Harmful effects None known
Habitat Close


Describing shallow, near-shore areas and the organisms that live there. Refers to shallow marine waters ranging from the low tide mark to the continental shelf. Varying amounts of sunlight penetrate the water, allowing photosynthesis by both phytoplankton and bottom-dwelling organisms. Close proximity to land favours high nutrient content and biological activity (Encyclopedia Britannica 2011).

Geographic Temperate to warm water regions
Seasonal Common in spring around the world
Growth Conditions


The dissolved ion content of a body of water. Can be measured in the following units: parts per thousand (PPT or ‰), practical salinity units (PSU), and absolute salinity (g/kg). PPT is measured by weight, denoting the number of parts salt per thousand total parts or a value of 10-3. PSU measures the conductivity of saltwater and compares it in a ratio to a standard KCl solution (because this is a ratio, salinity measured in this way can also be written without units). The newest unit of salinity is absolute salinity, which uses the mass fraction of salt in seawater (g salt per kg seawater) rather than its conductivity (TEOS-20 2010).

31 - 39
Temperature -2 - 29 °C


Lauderia borealis Gran 1900 Close


A difference in type. In naming species, a heterotypic synonym is one that comes into being when a taxon becomes part of a different taxon. Compare to homotypic.

(Guiry and Guiry 2011)


Empire Eukaryota
Kingdom Chromista
Subkingdom Harosa
Infrakingdom Heterokonta
Phylum Ochrophyta
Subphylum Khakista
Class Mediophyceae
Subclass Thalassiosirophycidae
Order Thalassiosirales
Family Lauderiaceae
Genus Lauderia
Species L. annulata Cleve 1873

(Guiry and Guiry 2011)


Photosynthetic. Reproduces sexually and asexually (Guiry 2011). Resting stage may be present (Ishii et al. 2009).
Only cells with diameter 24 - 40 μm have been shown to form Close


A reproductive cell (sperm or ovum) that can combine with another reproductive cell to create a new individual.

and auxospores. Sexualisation is positively correlated with light intensity. High light intensity and Close


The amount of time in a day that an organism is exposed to daylight. This varies between seasons, with photoperiods being longer in the summer and shorter in the winter.

of 16 h are optimal for sexualisation of cells. Sexualisation is inhibited by long and continuous illumination (Lin and Weng 1994).


Cells are cylindrical and joined as straight chains. Adjacent valve surfaces are touching. The centre of the valve is convex, with a rounded margin. Cells have one large unpaired spine and numerous small gelatinous threads on the valve face and margin, some reaching adjacent cells (see below for details on spines and threads). Chloroplasts are numerous small lobes, clustering around opposite ends of cell under high light intensity. The Close


(plural: nuclei) In eukaryotic cells, a membrane-bound organelle that contains the cell's genetic information; the nucleus controls the activities of the cell by controlling gene expression.

is roughly central, in a Close


In a eukaryotic cell, a gel-like substance within the cell membrane that contains all the organelles except for the nucleus.

cord, connecting centres of valves (Cupp 1943), or sometimes described as elongated and bi-lobed, with each lobe pressing against the valve ends (Holmes 1977). Cell colour is yellow-brown (Guiry 2011).
"A large Close

Marginal process

In some diatoms, a long, coarse external tube through the frustule (Tomas 1997).


Labiate process

In diatoms, a simple slit in the valve wall with two internal lips, one on each side of the slit. They can be useful in identification because they are positioned differently in different species (Horner 2002).

labiate process
. Numerous Close

Strutted process

(how is this different than marginal process?) In some diatoms, a narrow tube through the frustule that is usually associated with the secretion of chitin. It may appear as a marginal process or as a simple pore in the valve wall (Spaulding et al. 2010).

strutted processes
on valve face and margin. Long Close





A natural projection or appendage on an organism.

in marginal zone (types of processes not differentiated with Close


(light microscopy) "Using a microscope in which a beam of light passes through optical lenses to view an image of the specimen" (MCM LTER 2010).

)" (Hasle and Syvertsen 1997). The valve face is Close


(symmetry) Describing a shape that many axes of symmetry. That is, it does not have a left and right like humans do (bilateral symmetry), but can be divided into equal halves no matter where you place the axis. Some examples of radially symmetrical organisms include sea stars and centric diatoms like Thalassiosira.



(referring to pores in diatoms) In diatoms, a striation or row of pores on the valve face. "In centric diatoms, striae may be radial, running from the centre of the valve to the margin ... In pennate diatoms, striae may be parallel to the median line of the valve or raphe" (Horner 2002).

. Close

Intercalary bands

Girdle bands that are furthest away from the valve (Smithsonian 2011).

Intercalary bands
are collar-shaped, relatively delicate and indistinct except in older cells. Close


In diatoms, "the part of a valve that extends from the valve face, forming the valve edge." It is visible when the frustule is viewed in girdle view (Spaulding 2010).

surface delicately Close


Synonym: perforated. Describing a surface that has many holes. Often used to describe the valve surface of diatom frustules.

- Close


Marked with tiny coloured spots or depressions.

, Close


(plural: puncta) A sharp tip or small point on any part of an organism's anatomy.

in irregular rows." Puncta on intercalary bands are irregularly arranged (Cupp 1943).


Length Close

Pervalvar axis

The axis through the centre point of the two valves of a frustule. This axis is perpendicular to the valve face.

(pervalvar axis
): 20 - 96 μm
Diameter: 15 - 75 μm
Radial Close


Features that provide support to other structures in the cell.

on valve face: >30 in 10 μm
Puncta on intercalary bands: ∼16 in 10 μm
(Cupp 1943, Hasle and Syvertsen 1997, Kraberg et al. 2010)

Similar species

Other cylindrical diatoms, such as Detonula pumila. Valves of adjacent D. pumila cells do not touch, and thus have a gap between cells. Valves of adjacent L. annulata cells do touch.

Harmful effects

None known.


Neritic (Cupp 1943).


Temperate to warm water regions (Hasle and Syvertsen 1997).
Occurs mainly in spring but also in the summer in Northern European seas (Kraberg et al. 2010). Has bloomed in late winter around the Northern Adriatic Sea (Umani and Beran 2003). Common in spring and autumn around northwest Spain (Casas et al. 1999). One of the most abundant species during winter and spring in the Subtropical Convergence region near New Zealand (Chang and Gall 1998).
"Temperate species. Common but not abundant off California. Reported in Gulf of California and north to Scotch Cap, Alaska." (Cupp 1943).

Growth conditions

Favoured by high Si:N ratios under medium to low light (Sommer 1994). Grows fast under light-limiting conditions, which may help it form blooms in spring (Riegman et al. 1996).
More resistant to UV-B stress (compared to Synedra planctonica), but still received irreversible damage under high UV-B Close


Amount of solar energy per unit area on a surface (units: μE m-2 sec-1, where E is an Einstein, a mole of photons).

due to reduction in 15N-nitrate uptake (Döhler and Biermann 1987). Low UV-B irradiance (∼440 J m-2 d-1) slightly increased the biomass, as compared to cells with no exposure to UV-B; while higher irradiance (∼720 J m-2 d-1) decreased the protein and pigment content (Döhler 1984).

Environmental Ranges

Depth range (m): 0 - 170
Temperature range (°C): -1.948 - 29.468
Nitrate (μmol L-1): 0.053 - 13.830
Salinity (PSU): 31.191 - 39.226
Oxygen (mL L-1): 4.344 - 8.713
Phosphate (μmol L-1): 0.046 - 1.446

Silicic acid

A general term to describe chemical compounds containing silicon, oxygen and hydrogen with a general formula of [SiOx(OH)4-2x]n. Diatoms polymerize silicic acid into biogenic silica to form their frustules (Azam and Chisholm 1976).

(μmol L-1): 0.648 - 28.931
(OBIS 2011, cited in EOL 2011)

Bloom characteristics

Information not available.


Casas, B., Varela, M. and Bode, A. 1999. Seasonal succession of phytoplankton species on the coast of A Coruña (Galicia, northwest Spain). Boletin del Instituto Español de Oceanografia. 15(1-4): 413-429.

Chang, F. H., Gall and M. 1998. Phytoplankton assemblages and photosynthetic pigments during winter and spring in the Subtropical Convergence region near New Zealand. New Zealand Journal of Marine and Freshwater Research. 32(4): 515-530.

Cupp, E. E. 1943. Marine Plankton Diatoms of the West Coast of North America. University of California Press. Berkeley, California. 238.

Döhler, G. 1984. Effect of UV-B radiation on the marine diatoms Lauderia annulata and Thalassiosira rotula grown in different salinities. Marine Biology. 83(3): 247-253.

Döhler, G. and Biermann, I. 1987. Effect of UV-B irradiance on the response of 15N-nitrate uptake of Lauderia annulata and Synedra planctonica. Journal of Plankton Research. 9(5): 881-890.

Encyclopedia of Life (EOL). 2011. Lauderia annulata Cleve. Accessed 27 Aug 2011.

Guiry, M. D. 2011. Lauderia annulata Cleve, 1873. Accessed 27 Aug 2011.

Guiry, M. D. and Guiry, G. M. 2011. Lauderia annulata Cleve. Accessed 27 Aug 2011.

Hasle, G. R., Syvertsen, E. E. 1997. Marine diatoms. In: Tomas, C. R. (ed.) Identifying marine Phytoplankton. Academic Press, Inc., San Diego. 5-385.

Holmes, R. W. 1977. Lauderia annulata - a marine centric diatom with an elongate bilobed nucleus. Journal of Phycology. 13(2): 180-183.

Horner, R. A. 2002. A Taxonomic Guide To Some Common Phytoplankton. Biopress Limited, Dorset Press, Dorchester, UK. 200.

Ishii, K., Ishikawa, A. and Imai, I. 2009. Marine diatoms emerged from in situ surface sediment in a temperate embayment. Phycologia. 48(4, suppl.): 48.

Kraberg, A., Baumann, M. and Durselen, C. D. 2010. Coastal Phytoplankton: Photo Guide for Northern European Seas. Verlag Dr. Friedrich Pfeil, Munchen, Germany. 204.

Lin, J. and Weng, S. 1994. Production of gametes and auxopores in the centric diatom Lauderia borealis Gran. Oceanologia et limnologia sinica/Haiyang Yu Huzhao. 25(6): 601-605.

Ocean Biogeographic Information System (OBIS). 2011. Lauderia annulata. Accessed 27 Aug 2011.

Reigman, R., de Boer, M., de Senerpont Domis, L. 1996. Growth of harmful marine algae in multispecies cultures. Journal of Plankton Research. 18(10): 1851-1866.

Sommer, U. 1994. Are marine diatoms favoured by high Si:N ratios? Marine Ecology Progress Series. 115(3): 309-315.

Umani, S. F. and Beran, A. Seasonal variations in the dynamics of microbial plankton communities: First estimates from experiments in the Gulf of Trieste, Northern Adriatic Sea. Marine Ecology Progress Series. 247: 1-16.

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