Skeletonema costatum

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 2 - 61 μm, diameter 2 - 21 μm
Colour Yellow-brown
Connection Marginal ring of Close


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

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.

Two per cell
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

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


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.

Causes water Close


Change of water colour due to an algal bloom.

Harmful effects Close


Describing a condition where there is no available oxygen for primary production. Oxygen may be present in complexed forms that are not available for phytoplankton. A related term is hypoxia, where oxygen is present at very low concentrations.

waters during blooms
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 Close


Widely distributed; occurring in many parts in the world.

in coastal systems except in polar seas
Seasonal Blooms locally in spring and fall
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).

18 - 25 (optimal)
Temperature 25 °C (optimal)


Melosira costata Greville 1866 Close


The original name for an organism. In botany, the original published nomenclature from which a new binomial nomenclature is derived for a particular group of organisms (Tindall 1999).

) (Guiry 2011)


Empire Eukaryota
Kingdom Chromista
Subkingdom Chromobiota
Infrakingdom Heterokonta
Phylum Bacillariophyta
Class Coscinodiscophyceae
Subclass Thalassiosirophycidae
Order Thalassiosirales
Family Skeletonemaceae
Genus Skeletonema
Species S. costatum (Greville) Cleve 1873

(Guiry and Guiry 2011)


Photosynthetic. Reproduces sexually and asexually (Guiry 2011). Close


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

are sometimes present (Cupp 1943). Resting stage can survive up to 6 years (Lewis 1999).


Cells are short and cylindrical, usually connected in long, straight or slightly undulate chains by a Close


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

ring of spines 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
). The Close


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

face is convex to flat. Spines interlock midway between adjacent cells, visible as a dotted ring; spine lengths are variable (Horner 2002). There are two chloroplasts per cell and 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 located centrally (Cupp 1943).
Strutted processes are tubular but semicircular in cross section. One Close

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
is present near the center of the valve inside the ring of Close


A natural projection or appendage on an organism.

(Horner 2002).
*Molecular data has recently separated S. costatum into several species. These distinctions cannot be made without detailed examination of their morphology (Sarno et al. 2005, and Zingone et al. 2005, all cited in Kraberg et al. 2010).


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
): 2 - 61 μm
Diameter: 2 - 21 μm

Marginal process

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

Marginal processes
: 6 - 30 (total)
(Hasle and Syvertsen 1997)

Similar species

Other cylindrical diatoms. S. costatum can be identified by its cell connections, where the strutted processes join to form a "straight line."

Harmful effects

May cause water discolouration (Kraberg et al. 2010). Produces reactive aldehydes that negatively impact hatching copepods (Miralto et al. 1999). May produce arsenite and dimethylarsenic (Andreae and Klumpp 1979 and Sanders and Windom 1980, cited in Howard et al. 1995), which may block important biochemical pathways in algae, as arsenic is chemically similar to nitrogen and phosphorous (Howard et al. 1995).


Neritic (Cupp 1943).


Cosmopolitan in coastal except polar seas (Horner 2002).
Often forms extensive spring blooms (Horner 2002).
One of the most abundant species, especially from February to April (Cupp 1943). Also forms blooms in autumn.

Growth conditions

This species is more likely to bloom under high temperature and high illumination, with optimal conditions at 25 °C and 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).

of 1.6×1016 quanta/s⋅cm2 (Yan et al. 2002). It has an optimal salinity range of 18 - 25 (Yan et al. 2002), although it is capable of significant growth in salinities 5 - 40 (Brand 1984). It is often dominant in waters characterized by salinity fluctuations (Rijstenbil 1987, cited in Rijstenbil 1988).
S. costatum may be favoured under high (> 100) N:P ratios (Hori et al. 1998). It is dominant under non-limiting Close


Various chemical substances that an organism needs for metabolism (i.e., to live and grow). These are usually taken up from the environment. Some examples include nitrate, phosphate, silica (for diatoms), iron, copper, etc. Some nutrients, like copper, are required for growth, but can also be toxic at high levels.

(NO3-, PO43- and Close

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).

) conditions and often forms dense blooms, especially when silicate concentrations are higher than 2 μmol L-1 (Hu et al. 2011). It is also tolerant of Close


Water that is enriched in natural or artificial mineral and organic matter, which promotes an abundance of plant life (i.e., algae), and can result in reduced oxygen conditions.

conditions (Abdalla et al. 1995).

Environmental Ranges

Depth range (m): 0 - 292
Temperature range (°C): -1.541 - 29.468
Nitrate (μmol L-1): 0.053 - 28.280
Salinity: 19.590 - 37.775
Oxygen (mL L-1): 4.444 - 9.002
Phosphate (μmol L-1): 0.046 - 2.337
Silicate (μmol L-1): 0.648 - 59.039
(OBIS 2011, cited in EOL 2011)

Bloom characteristics

Shows three types of abundance patterns: a) bimodal (winter-spring and summer blooms) bloom pattern with the winter-spring bloom greater; b) unimodal pattern with reduced winter-spring and large summer bloom; c) autumn peak abundance (Borkman and Smayda 2009).


Abdalla, R. R., Zaghloul, F. A. and Hussein, N. R. 1995. A statistical modelling of phytoplankton eutrophication in the Eastern Harbour, Alexandria, Egypt. Bulletin of the National Institute of Oceanography and Fisheries (Egypt). 21(1): 125-146.

Andreae, M. O. and Klumpp, D. 1979. Biosynthesis and release of organoarsenic compounds by marine algae. Environmental Science and Technology, 13, 738741.

Brand, L. E. 1984. The salinity tolerance of forty-six marine phytoplankton isolates. Estuarine, Coastal and Shelf Science, 18(5): 543-556.

Borkman, D. G. and Smayda, T. 2009. Multidecadal (1959 - 1997) changes in Skeletonema abundance and seasonal bloom patterns in Narragansett Bay, Rhode Island, USA. Journal of Sea Research, 61: 84-94.

Cleve, P. T. 1873. Examination of diatoms found on the surface of the Sea of Java. Bihang till Kongliga Svenska Vetenskaps-Akademiens Handlingar,1(11): 1-13.

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

Encyclopedia of Life (EOL). Skeletonema costatum(Greville) Cleve. Accessed 10 Jun 2011.

Guiry, M. D. 2011. Skeletonema costatum(Greville) Cleve, 1873. Accessed 05 May 2011.

Guiry, M. D. and Guiry, G. M. 2011. Skeletonema costatum (Greville) Cleve. Accessed 05 May 2011.

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

Hori, Y., Miyahara, K., Nagai, S., Tsujino, K., Nakajima, M., Yamamoto, K., Yoshida, Y., Araki, N. and Sakai, Y. 1998. Relationships between the dominant phytoplankton and DIN:DIP ratios in Osaka Bay and Harima-Nada. Nippon Suisan Gakkaishi. 64(2): 243-248.

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

Howard, A. G., Comber, S. D. W., Kifle, D., Antai, E. E. and Purdie, D. A. 1995. Arsenic speciation and seasonal changes in nutrient availability and micro-plankton abundance in Southampton Water, U. K. Estuarine, Coastal and Shelf Science, 40(4): 435-450.

Hu, H., Zhang, J. and Chen, W. 2011. Competition of bloom-forming marine phytoplankton at low nutrient concentrations. Journal of Environmental Science, 23(40): 656-663.

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

Kuylenstierna, M. and Karlson, B. 2006. Swedish Meteorological and Hydrological Institute: Skeletonema costatum (Greville) Cleve 1873. Accessed 05 May 2011.

Lewis, J., Harris, A. S. D., Jones, K. J. and Edmonds, R. L. 1999. Long-term survival of marine planktonic diatoms and dinoflagellates in stored sediment samples. Journal of Plankton Research, 20(2): 343-354.

Miralto, A., Barone, G., Romano, G., Poulet, S. A., Ianora, A., Russo, G. L., Buttino, I., Mazzarella, G., Laabir, M., Cabrini, M. and Giacobbe, M. G. 1999. The insidious effect of diatoms on copepod reproduction. Nature. 402: 173-176.

Ocean Biogeographic Information System (OBIS). Skeletonema costatum. Accessed 10 Jun 2011.

Red-Tide. Skeletonema costatum. Accessed 05 May 2011.

Rijstenbil, J. W. 1987. Phytoplankton composition of stagnant and tidal ecosystems in relation to salinity, nutrients, light and turbulence. Netherlands Journal of Sea Research, 21: 113-123.

Rijstenbil, J. W. 1988. Selection of phytoplankton species in culture by gradual salinity changes. Netherlands Journal of Sea Research, 22:291-300.

Sanders, J. G. and Windom, H. L. 1980. The uptake and reduction of arsenic species by marine algae. Estuarine, Coastal and Marine Science, 10: 555-567.

Sarno, D., Kooistra, W. H. C. F., Medlin, L. K., Percopo, I. and Zingone, A. 2005. Diversity in the genus Skeletonema (Bacillariophyceae). II. An assessment of the taxonomy of S. costatum-like species with the description of four new species. Journal of Phycology, 41(1): 151-176.

Yan, T., Zhou, M. and Qian, P. 2002. Combined effects of temperature, irradiance and salinity on growth of diatom Skeletonema costatum. Chinese Journal of Oceanology and Limnology, 20(3): 237-243.

Zingone, A., Percopo, I., Sims, P. A. and Sarno, D. 2005. Diversity in the genus Skeletonema (Bacillariophyceae). I. A re-examination of the type material of S. costatum with the description of S. grevillei sp. nov. Journal of Phycology, 41(1): 140-150.

a place of mind, The Univeristy of British Columbia

UBC Department of Earth, Ocean and Atmospheric Sciences,
2020 - 2207 Main Mall, Vancouver, BC Canada V6T 1Z4.
 |  Legal |  Valid XHTML 1.0 Transitional

Emergency Procedures  | Accessibility  | Contact UBC  | © Copyright The University of British Columbia