Protoceratium reticulatum

General Dinoflagellate
Shape Rounded polygon
Size Length 28 - 43 μm, width 25 - 35 μm
Colour Dark brown
Connection None (solitary)
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.

Many dark brown chloroplasts
Lifestyle Close


An organism that cannot convert inorganic carbon into a usable energy source. Instead, it consumes other organisms to obtain organic carbon for growth.

. 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.

Blooms in bays and coastal waters
Harmful effects Produces various toxins
Habitat Coastal and Close


Of or relating to estuaries.

Geographic Cold temperate to subtropical waters
Seasonal Spring to 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).

5 - 35
Temperature -2 - 27 °C


Peridinium reticulatum Claperede and Lachmann 1859
Protoceratium aceros Bergh 1882
Gonyaulax grindleyi Reinecke 1967
(Horner 2002, Kraberg et al. 2010)


Empire Eukaryota
Kingdom Protozoa
Subkingdom Biciliata
Infrakingdom Alveolata
Phylum Dinoflagellata
Class Dinophyceae
Subclass Peridiniphycidae
Order Gonyaulacales
Family Gonyaulacaceae
Genus Protoceratium
Species P. reticulatum (Claperede and Lachmann) Butschli 1885

(Guiry and Guiry 2011)


P. reticulatum is a heterotrophic dinoflagellate. It reproduces asexually (Smithsonian 2011).


Protoceratium reticulatum cells are oval to polygonal (Smithsonian 2011). Both the Close


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

and Close


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

are oval to bowl-shaped. The cell surface is highly Close


Resembling a net or having a pattern that resembles a net.

and cell has numerous brown chloroplasts (Smithsonian 2011).


Length: 28 - 43 μm
Width: 25 - 35 μm
(Smithsonian 2011)

Similar species


Harmful effects

This species produces disulfated polyethers, a Close


(YTXs) A group of toxins produced by some dinoflagellates, including Protoceratium reticulatum. Researchers have observed toxic effects in mice but little is known about it effects on humans or how the toxins work. These toxins do not break down with freezing or cooking, which has lead some countries to regulate the amount of YTXs allowed in shellfish (EFSA 2008).

(YTX), that present risks to human health, aquaculture development and coastal environments (Mitrovic et al. 2004). YTX was first isolated from the scallop Patinopecten yessoensis in Japan 1986 (Paz et al. 2006). YTX produced by P. reticulatum has been reported in New Zealand, Japan, USA, Spain and Norway thus it is a wide-spread toxin (Mitrovic et al. 2004). Blooms of P. reticulatum can cause problems to shellfish producers and consumers because YTX concentrates in many bivalves (clams, oysters, scallops). Although it does not induce diarrhetic effects and does not inhibit protein phosphatases, YTX is still considered to cause diarrheic shellfish poisoning (DSP; Mitrovic et al. 2004). The mode of action and toxic effect of YTX is still not clearly understood. When 100 μg kg-1 of the toxin were injected into the bodies of mice, the mice died. On the other hand, when it was orally administered, the toxins showed a reduced effect (Mitrovic et al. 2004).


Coastal and estuarine (Horner 2002).


This species is widely distributed in temperate and tropical areas and has been reported in Close


Relating to the area immediately south of the Arctic.

locations in the summer (Smithsonian 2011). P. reticulatum is also found in North and South Atlantic, Pacific and Indian Oceans and in their associated seas (e.g. Red Sea; Smithsonian 2011).
Spring and summer (Smithsonian 2011).

Growth conditions

Laboratory experiments have shown that P. reticulatum can survive in a wide variety of environmental conditions: temperatures of -4 - 24 °C, salinities of 1 - 40 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 10 - 150 μmol photons m-2 s-1 (Paz et al. 2006). Seamer (2001) established that the most rapid growth of P. reticulatum occurs at salinity of 35, temperature of 21 °C and irradiance of 45 μmol photons m-2 s-1 (Paz et al. 2006). Iron and selenium availability have effects on the growth rate and number of cells of P. reticulatum (Mitrovic et al. 2004). Paz et al. (2006) found that light levels had the biggest impact on the growth of P. reticulatum and on YTX production. At light levels of 50 - 90 μmol photons m-2 s-1, the highest levels of toxins were produced (Paz et al. 2006).

Environmental Ranges

Depth range (m): 0 - 270
Temperature range (°C): -1.893 - 27.583
Nitrate (μmol L-1): 0.041 - 22.805
Salinity: 27.165 - 39.081
Oxygen (mL L-1): 4.586 - 8.589
Phosphate (μmol L-1): 0.085 - 1.771

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): 0.780 - 34.056
(EOL 2011)

Bloom characteristics

Blooms were observed from late June to July in Japan immediately following a Dinophysis bloom (Koike et al. 2006). P. reticulatum flourishes under salinities 30 - 32 and the highest cell densities were observed in the surface layer (0 - 5 m depth; Koike et al. 2006). This bloom was initiated by two factors: a decrease in salinity caused by rainfall and an enchanced Close


The act of forming a cyst.

due to a massive bottom-layer inflow of cold oceanic water in the bay (Koike et al. 2006).


Encyclopedia of Life (EOL). 2011. Protoceratium reticulatum (Claperede and Lachmann) Butschli 1885. Accessed 15 Nov 2011.

Guiry, M. D. and Guiry, G. M. 2011. P. reticulatum (Claperede and Lachmann) Butschli 1885. Accessed 16 Nov 2011.

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

Koike, K., Horie, Y., Suzuki, T., Kobiyama, A., Kurihara, K., Takagi, K., Kaga, S. N. and Oshima, Y. 2006. Protoceratium reticulatum in northern Japan: environmental factors associated with seasonal occurrence and related contamination of yessotoxin in scallops. Journal of Plankton Research. 28(1): 103-112.

Kraberg, A., Baumann, M. and Durselen, C. D. 2010. Coastal Phytoplankton Photo Guide for Northern European Seas. Verlag Dr. Friedrich Pfeil, Munchen, Germany.203.

Mitrovic, S. M., Amandi, M. F., Mckenzie, L., Furey, A. and James, J. K. 2004. Effects of selenium, iron and cobalt addition to growth and yessotoxin production of the toxic marine dinoflagellate Protoceratium reticulatum in culture. Journal of Experimental Marine Biology and Ecology. 313: 337-351.

Paz, B., Riobo, P., Fernandez, M. L., Fraga, S. and Franco, J. M. 2006. Study of the effect of temperature, irradiance and salinity on growth and yessotoxin production by the dinoflagellate Protoceratium reticulatum in culture by using a kinetic and factorial approach. Marine Environmental Research. 62: 286-300.

Seamer, C. 2001. The production of yessotoxin by Protoceratium reticulatum. M.Sc. Thesis, Victoria University of Wellington, New Zealand.

Smithsonian Institution. 2011. Protoceratium reticulatum (Claperede and Lachmann) Butschli 1885. Accessed 16 Nov 2011.

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