Alexandrium catenella

General Dinoflagellate
Shape Spherical
Size Length 20 - 48 μm, width 18 - 34 μm
Colour Yellow-green to orange-brown
Connection Forms chains of 2, 4 or 8 cells
Covering Cellulose Close


(plural: thecae) Cell wall. In dinoflagellates, it is composed of cellulose plates within vesicles (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.

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.

. Asexual and sexual.


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.

When temperature increases above 12C
Harmful effects Paralytic shellfish poisoning Close

Paralytic Shellfish Poison

(PSP) Results from human consumption of filter-feeding shellfish that have fed on toxic saxitoxin-producing dinoflagellates. During certain phytoplankton blooms, shellfish can accumulate and bio-concentrate the toxins. The main species associated with PSP in Canada are dinoflagellates in the genus Alexandrium. "Symptoms of PSP begin with a tingling sensation or numbness around the lips within 5 - 30 minutes of ingestion, gradually spreading to the face and neck. With moderate to severe intoxication, symptoms include incoherent speech, stiffness and non-coordination of limbs and slight respiratory difficulty. Gastrointestinal symptoms of nausea, vomiting, diarrhea and abdominal pain are less common. Following high intake, paralysis of respiratory muscles may progress to respiratory arrest and death within 2 - 12 hours after consumption" (DFO 2010).

Habitat Coastal and Close


Of or relating to estuaries.

Geographic Cold temperate waters
Seasonal Late May and early June
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).

26 - 32
Temperature 17 - 23 °C


Gonyaulax catenella Whedon and Kafoid 1936
Protogonyaulax catenella (Whedon and Kafoid) Taylor 1979
Gessnerium catenellum (Loeblich III et Loeblich) Taylor 1979
(Horner 2002, Smithsonian 2012)


Empire Eukaryota
Kingdom Protozoa
Subkingdom Biciliata
Infrakingdom Alveolata
Phylum Dinoflagellata
Class Dinophyceae
Subclass Peridniphycidae
Order Gonyaulacales
Family Gonyaulacaceae
Genus Alexandrium
Species A. catenella (Whedon and Kafoid)

(Guiry and Guiry 2012)


Alexandrium catenella is a marine photosynthetic dinoflagellate (Olenina and Olenin 2006). This species has both sexual and asexual cycles of reproduction. It reproduces sexually with opposite mating types Close


(hetero- different; thallos green shoot or twig) Describing an organism that has male and female reproductive parts on different parts of the organism.

) and asexually by Close

Binary fission

A form of asexual reproduction where one cell divides into two identical cells. All prokaryotes and some eukaryotes reproduce in this manner. Compare with mitosis, where the nucleus must also divide, adding an extra step to the process.

binary fission
(Olenina and Olenin 2006). It has a life cycle with various stages: motile vegetative cells, Close


Containing one set of chromosomes (1n, where n is the number of unique chromosomes). For example, human gametes (sperm and eggs) are haploid and have 23 unique chromosomes (1n = 23). See also Diploid and Ploidy.



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

, Close


Containing two identical sets of chromosomes (2n, where n is the number of unique chromosomes). For example, humans are diploid and have 23 unique chromosomes (n = 23), so most cells in your body each have 46 chromosomes (2n = 46). Gametes (sperm and eggs) are haploid (1n = 23). See also Haploid and Ploidy.

zygotes, resting Close


"A thick-walled dormant cell" (Horner 2002).

and temporary cysts (Olenina and Olenin 2006). Its resting cysts are colourless ellipsoid cells with round ends covered by a smooth wall (Smithsonian 2012). The resting cysts are 38 - 56 μm long and 23 - 32 μm wide (Smithsonian 2012).


Alexandrium catenella forms chains of 2, 4 or 8 cells that swim together like a snake. Individual cells are almost round, slightly longer than wide (Olenina and Olenin 2006). It has a large U-shaped 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.

(MSIP 2012). The Close


(axis, spine) The region of the apex or point. Refers to the most anterior point or region of the cell (HPP 2003).

pore plate has the characteristic fishhook-shaped Close


(plural: foramina) The space within an areolation or hole. Often used to describe features on diatom frustules and dinoflagellate thecae (Hasle and Syvertsen 1996).

(Montagnes 2006). The Close


In thecate dinoflagellates, the posterior part of a dinokont cell above the cingulum. The equivalent of a hypocone for naked dinoflagellates.

is roughly equal in size to the Close


In thecate dinoflagellates, the anterior part of a dinokont cell above the cingulum. The equivalent of epicone for naked dinoflagellates.

(Smithsonian 2012).


Length: 22 - 51 μm
Width: 17 - 44 μm
(Smithsonian 2012, Montagnes 2006)

Similar species

This species is similar to Alexandrium tamarense but A. tamarense has a Close


Relating to the underside of an organism; abdominal.

pore (Smithsonian 2012). A. catenella can occur in short chains while A. tamarense is solitary (Smithsonian 2012).

Harmful effects

This species produces neurotoxins that cause deadly paralytic shellfish poisoning (PSP) events in the Pacific Ocean (Dyhrman et al. 2010). The PSP toxins can cause human illness (Smithsonian 2012). Symptoms of PSP include numbness around the lips, muscular paralysis, choking sensation and death (Hallegraff 1991).


A. catenella is a coastal species (Smithsonian 2012).


A. catenella is found in cold temperate coastal waters (Smithsonian 2012). It has been observed off the west coast of North America, Chile, Argentina, western South Africa and Japan (Smithsonian 2012). Generally, populations of A. catenella have been found in the North Pacific, South Pacific and South Atlantic (Horner 2012). Blooms that are restricted to harbours and other constricted zones have been seen in the Mediterranean Sea (Laabir et al. 2011).
A. tamarense cells have been found in Puget Sound in late May and early June (Dyhrman et al. 2010).

Growth conditions

A. catenella is believed to bloom in temperatures ranging from 17 to 23 °C and salinities of 15 to 32 ( Montagnes 2006).

Bloom characteristics

This species blooms when surface water temperature exceeds 12 °C. In Chile, the highest cell concentrations (961 cells/mL) were found 14.5 °C and 15 salinity. The bloom led to several cases of human sickness and one fatality (Fuentes et al. 2008).


Dyhrman, S. T., Haley, S. T., Borchert, J. A., Lona, B., Kollars, N. and Erdner, D. L. 2010. Parallel Analyses of Alexandrium catenella Cell Concentrations and Shellfish Toxicity in the Puget Sound. American Society for Microbiology. 76(14): 4647-4654.

Fuentes, C., Clement, A. and Aguilera, A. 2008. Summer Alexandrium catenella Bloom and Impact on Fish Farming, in the X1 Aysen Region, Chile. International Society for the Study of Harmful Algae and Intergovernmental Oceanographic Commission of UNESCO. Copenhagen.

Guiry, M. D. and Guiry, G. M. 2012. A. catenella (Whedon and Kafoid) Balech 1985. Accessed 22 Jan 2012.

Hallegraff, G. M. 1991. A review of Harmful Algal Blooms and their Apparent Global Increase. Phycologia. 32(2): 79-99.

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

Laabir, M., Jauzein, C., Genovesi, B., Masseret, E., Grzebyk, D., Cecchi, P., Vaquer, A., Perrin, Y. and Collos, Y. 2011. Influence of temperature, salinity and irradiance on the growth and cell yield of the harmful red tide dinoflagellate Alexandrium catenella colonizing Mediterranean waters. Journal of Plankton Research. 33(10): 1550-1563.

Montagnes, D. 2006. Guide to Harmful Phytoplankton. University of Liverpool, UK. Accessed 22 Jan 2012.

Olenina, I. and Olenin, S. 2006. Delivering Alien Invasive Species Inventory for Europe. Accessed 27 Jan 2012.

Smithsonian Institution. 2012. A. catenella (Whedon and Kafoid) Balech 1985. Accessed 22 Jan 2012.

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