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Synonym(s)
Gonyaulax tamarensis Lebour 1925
Gonyaulax exccavata (Braarud) Balech 1971
Gonyaulax tamarensis var. excavate Braarud 1945
Gessnerium tamarensis (Lebour) Loeblich and Loeblich 1979
Protogonyaulax tamarensis (Lebour) Taylor 1979
Protogonyaulax excavate (Braarud) Taylor 1979
Alexandrium excavatum (Braarud) Balech and Tagen 1985
(Smithsonian 2011, Kraberg et al. 2010)
Classification
Empire Eukaryota
Kingdom Protozoa
Subkingdom Biciliata
Infrakingdom Alveolata
Phylum Dinoflagellata
Subphylum
Class Dinophyceae
Subclass Peridniphycidae
Order Gonyaulacales
Family Gonyaulacaceae
Genus Alexandrium
Species A. tamarense (Lebour) E. Balech 1985
(Guiry and Guiry 2011)
Lifestyle
Alexandirum tamarense is a photosynthetic dinoflagellate. It has a number of orange-brown chloroplasts. It reproduces asexually by binary fission, although it can also reproduce sexually through joining of dissimilar
Close Gamete A reproductive cell (sperm or ovum) that can combine with another reproductive cell to create a new individual.
Close Anisogamous Sexual reproduction involving two dissimilar gametes, e.g. sperm and egg.
Close Cyst "A thick-walled dormant cell" (Horner 2002).
Description
Alexandrium tamarense cells are relatively small. Cell size can range from 22 - 51 μm, with cells almost as wide as they are long (EOL 2011). Cells are spherical and have
Close Epitheca In thecate dinoflagellates, the anterior part of a dinokont cell above the cingulum. The equivalent of epicone for naked dinoflagellates.
Close Hypotheca In thecate dinoflagellates, the posterior part of a dinokont cell above the cingulum. The equivalent of a hypocone for naked dinoflagellates.
Measurements
Length: 22 - 51 μm
Width: 17 - 44 μm
Similar species
Alexandrium tamarense is similar to A. catenella but A. catenella does not have a
Close Ventral Relating to the underside of an organism; abdominal.
Harmful effects
Alexandrium tamarense causes paralytic shellfish poisoning (PSP). This is a potent neurotoxin, which can block sodium channels within cells, inhibiting transmission of nerve impulses (Armi et al. 2011). This toxin is observed to accumulate in shellfish (Armi et al. 2011) and can accumulate up the food chain killing fish, seabirds, affecting human health and causing economic loss (Smithsonian 2011). PSP toxins caused several massive fish kills (Atlantic herring, rainbow trout and salmon) resulting from fish feeding on zooplankton that had accumulated large amounts of PSP toxins (Smithsonian 2011). Resting cysts can harbor toxins and are even thought to contain more toxins (10x) than the motile stage (Smithsonian 2011). There are also strains of Alexandrium tamarense that are not harmful (Horner 2002). For example, all known strains in the southern North Sea are non-toxic (Kraberg et al. 2010).
Habitat
Coastal and estuarine. (Horner 2002).
Distribution
Geographic:
Alexandrium tamarense is mostly found in coastal cold temperate waters of North America, Europe and Japan (Smithsonian 2011). It is broadly distributed in the North Atlantic and southern North Sea (Kraberg et al. 2010). It has also been reported in warm Mediterranean waters off northern Africa (Armi et al. 2011). Non-toxic strains of Alexandrium tamarense have been reported in Australia and the Gulf of Thailand (Smithsonian 2011).
Seasonal:
Summer (July to August).
Growth conditions
A study conducted by Amri et al. (2011) in Lake Tunis in North Africa recorded the highest Alexandrium tamarense cell concentration in the summer (above 29 °C). Alexandrium tamarense can adapt to a wide range of nitrate concentrations. A. tamarense can survive in salinities between 21 - 30, however, high cell growth is observed only when salinity is < 24 (Fauchot et al. 2005). In the Bay of Fundy, Canada, sea surface temperatures above 10 °C encouraged growth of Alexandrium tamarense populations (Medcof 1985).
Environmental Ranges
Depth range (m): 0 - 175
Temperature range (°C): -1.770 - 27.590
Nitrate (μmol L-1): 0.275 - 4.405
Salinity: 21.680 - 30
Oxygen (mL L-1): 4.600 - 8.712
Phosphate (μmol L-1): 0.071 - 1.153
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).
Bloom characteristics
Localized blooms of Alexandrium tamarense occur in brackish, shallow and restricted embayments and lagoons. Widespread blooms occur in open salty coastal waters and large estuaries (Anderson 1998).
References
Anderson, D. M. 1998. Physiology and Bloom Dynamics of Toxic Alexandrium Species, with Emphasis on Life Transitions. Physiological Ecology of Harmful Algal Blooms. G: 41.
Armi, Z., Milandri, A., Turki, S., Hajjem, B. 2011. Alexandrium catenella and Alexandrium tamarense in the North Lake of Tunis: bloom characteristics and the occurrence of paralytic shellfish toxin. African Journal of Aquatic Science. 36(1): 47-56.
Encyclopedia of Life (EOL). 2011. Alexandrium tamarense (Lebour) E. Balech 1985. http://eol.org/pages/910083/overview. Accessed 05 Nov 2011.
Fauchot, J., Levasseur, M., Roy, S., Gagnon, R. Weise, M. 2005. Environmental Factors Controlling Alexandrium tamarense (Dinophyceae) growth rate during a red tide event in the St. Lawrence estuary (Canada). Phycological Society of America. 41: 263-272.
Guiry, M. D., Guiry, G. M. 2011. Alexandrium tamarense (Lebour) E. Balech 1985. http://www.algaebase.org/search/species/detail/?species_id=40299&sk=0&from=results. Accessed 05 Nov 2011.
Horner, R. A. 2002. A Taxonomic Guide To Some Common Phytoplankton. Biopress Limited, Dorset Press, Dorchester, UK. 200.
Kraberg, A., Baumann, M., Durselen, C. D. 2010. Coastal Phytoplankton Photo Guide for Northern European Seas. Verlag Dr. Friedrich Pfeil, Munchen, Germany.203.
Medcof, J. C. 1985. Life and death with Gonyaulax, an historical perspective. In: Anderson, D. M., White, A. W., Baden, D. G. (eds.) Toxic Dinoflagellates. Elsevier, New York, 1-8.
Smithsonian Institution. 2011. Alexandrium tamarense (Lebour) E. Balech 1985. http://botany.si.edu/references/dinoflag/Taxa/Atamarense.htm. Accessed 06 Nov 2011.
