Guinardia delicatula

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 - 70 μm, diameter 8 - 40 μm
Colour Yellow-brown
Connection Short Close


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

fitting into depression of adjacent 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.

Large, irregularly lobed
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.


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.

Usually follows spring species succession.
Harmful effects May clog gills of Close


The ecological zone at the bottom of a body of water.

shellfish. May be a source of arsenic.
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
Seasonal Late spring and summer
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).

28 - 39
Temperature -2 - 29 °C


Rhizosolenia delicatula Cleve 1900 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).

, Close


Expressing the same fundamental type or structure; may or may not be symmetrical (e.g., the two valves of a diatom, where they are the same shape and appearance, but one is bigger than the other). In naming species, a homotypic synonym is one that comes into being when a taxon gets a new name (without being added to an already existing taxon).

(Guiry and Guiry 2011)


Empire Eukaryota
Kingdom Chromista
Subkingdom Chromobiota
Infrakingdom Heterokonta
Phylum Bacillariophyta
Subphylum Coscinodiscophytina
Class Coscinodiscophyceae
Subclass Rhizosoleniophycidae
Order Rhizosoleniales
Family Rhizosoleniaceae
Genus Guinardia
Species G. delicatula (Cleve) Hasle 1997

(Guiry 2011)


Photosynthetic. Reproduces sexually and asexually (Guiry 2011).


Cells are cylindrical, with flat Close


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

, rounded only slightly on the Close


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

. Cells are in close, straight chains. The valves have a short, slightly slanted, marginal spine that fits into a dent on the adjacent cell (Cupp 1943). Cells have large, irregularly lobed and strongly pigmented chloroplasts. Each chloroplast has a Close


Any of various protein granules that can be found in the chloroplast of some algae species. It is associated with the production of starch.

(Kraberg et al. 2010). Cells are yellow-brown in colour (Guiry 2011).

Intercalary bands

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

Intercalary bands
are ring-shaped and difficult to see (Cupp 1943). "External depression with claspers " (EM; Sundstrom 1986, cited in Hasle and Syvertsen 1997).


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 - 70 μm (3 - 5 times the diameter)
Diameter: 8 - 40 μm
(Kraberg et al. 2010)

Similar species

Other cylindrical diatoms (e.g., Dactyliosolen fragilissimus, Cerataulina pelagica). G. delicatula can be recognized by the short, slightly slanted, marginal spines on the ends of its valves, which are usually seen on the ends of chains (Cupp 1943).

Harmful effects

Blooms, after Close


(settling out) The tendency for particles to settle out of the water column and come to rest at the bottom due to gravitational forces. Factors that influence the rate of sedimentation are particle size, water density and currents.

, can inhibit growth of benthic shellfish by clogging the gills (Chauvaud et al. 1998, Lorrain et al. 2000). May be a source of arsenic (III) and methylated arsenic, which may block important biochemical pathways in algae, as arsenic is chemically similar to nitrogen and phosphorous (Howard et al. 1995).


Neritic (Cupp 1943).


Warm to temperate regions (Hasle and Syvertsen 1997).
Blooms in late spring or summer (Gayoso 1999). Most abundant in summer in Northern European seas (Kraberg et al. 2010).
"Fairly common off California, abundant at times in the Gulf of California" (Cupp 1943).

Growth conditions

Increases in G. delicatula have been observed following Close


A great rise or overflow of a river from heavy rains or spring thaw. In the Strait of Georgia, this usually occurs from March to June. (pers. comm. D. Cassis).

in the fall (Malej 1995).

Environmental Ranges

Depth range (m): 0 - 470
Temperature range (°C): -1.838 - 29.468
Nitrate (μmol L-1): 0.056 - 34.037
Salinity: 27.525 - 39.226
Oxygen (mL L-1): 1.767 - 8.586
Phosphate (μmol L-1): 0.046 - 2.358

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 - 92.735
(OBIS 2011, cited in EOL 2011)

Bloom characteristics



Related to a single phytoplankton cell. For example, a unialgal culture is one derived from a single cell.

blooms of this species are known to follow the spring species succession (Grail and Jacques 1964, Grail 1972, Martin-Jézéquel 1983, all cited in Martin-Jézéquel et al. 1992).


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

Chauvaud, L., Thouzeau, G. and Paulet, Y. M. 1998. Effects of environmental factors on the daily growth rate. Journal of Experimental Marine Biology and Ecology. 227: 83.

Encyclopedia of Life (EOL). Guinardia delicatula (Cleve) G. R. Hasle. Accessed 16 Jul 2011.

Gayoso, A. M. 1999. Seasonal Succession Patterns of Phytoplankton in the Bahía Blanca Estuary (Argentina). Botanica Marina. 42: 367-375.

Grall, J. R. 1972. Developpement 'printanier'; de la diatomde Rhizosolenia delicatula pres de Roscoff. Mar. Biol. 16: 41-48.

Grall, J. R. and Jacques, G. 1964. Etude dynamique et variations saisonnieres du plancton de la region de Roscoff. Cahiers de Biologie Marine. 5: 423-455.

Guiry, M. D. 2011. Guinardia delicatula (Cleve) Hasle, 1997. Accessed 16 Jul 2011.

Guiry, M. D., Guiry, G. M. 2011. Guinardia delicatula (Cleve) Hasle. Accessed 16 Jul 2011.

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

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.

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

Lorrain, A., Paulet, Y. M., Chauvaud, L., Savoye, N., Nezan, E. and Guerin, L. 2000. Growth anomalies in Pecten maximus from coastal waters (Bay of Brest, France): relationship with diatom blooms. Journal of Marine Biological Association of the United Kingdom. 80(4): 667-673.

Malej, A., Mozetic, P., Malacic, V., Terzic, S. and Ahel, M. 1995. Phytoplankton responses to freshwater inputs in a small semi-enclosed gulf (Gulf of Trieste, Adriatic Sea). Marine Ecology Progress Series. 120(1-3): 111-121.

Martin-Jézéquel, V. 1983. Facteurs hydrologiques et phytoplancton en Baie de Morlaix (Manche Occidentale). Hydrobiologia. 102: 131-143.

Martin-Jézéquel, V., Sournia, A. and Birrien, J. L. 1992. A daily study of the diatom spring bloom at Roscoff (France) in 1985. III. Free amino acids composition studied by HPLC analysis. Journal of Plankton Research. 14(3): 409-421.

Ocean Biogeographic Information System (OBIS). Guinardia delicatula. Accessed 16 Jul 2011.

Sundstrom, B. G. 1986. The marine diatom genus Rhizosolenia. Doctoral Dissertation. Lund University, Lund, Sweden. 117.

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