Eucampia zodiacus

General Close


(diatoms) Having radial symmetry, i.e., cell is shaped like a coin or a tuna can or a soup can.

Shape Eliptical cylinder, curved
Size Width 8 - 100 μm, height 8 - 60 μm
Colour Yellow-brown
Connection Two blunt Close


A natural projection or appendage on an organism.

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.

Numerous small discs
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.

Information not available
Harmful effects Bleaches "nori"
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.

except in polar regions
Seasonal Winter to early spring in Harima-Nada, Japan
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).

25 - 36
Temperature -2 - 29 °C (optimal)


Eucampia nodosa Schmidt 1888 Close


A difference in type. In naming species, a heterotypic synonym is one that comes into being when a taxon becomes part of a different taxon. Compare to homotypic.

Eucampia britannica Smith 1853 (heterotypic)
(Guiry and Guiry 2011)


Empire Eukaryota
Kingdom Chromista
Subkingdom Harosa
Infrakingdom Heterokonta
Phylum Ochrophyta
Subphylum Khakista
Class Mediophyceae
Subclass Biddulphiophycidae
Order Hemiaulales
Family Hemiaulaceae
Genus Eucampia
Species E. zodiacus Ehrenberg 1839

(Guiry and Guiry 2011)


Photosynthetic. Reproduces sexually and asexually (Guiry 2011).


Cells flattened, usually in helical chains, connected by two blunt processes. In Close


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

-view the cell is elliptical to linear. The valve face is concave. Close


"In some diatoms, the space between the valves of adjacent cells in chains" (Horner 2002).

are fairly wide, angular, elliptical to square. Chloroplasts are numerous small discs (Horner 2002). Cell is yellow-brown in colour (Guiry 2011).

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
located in the centre of the valve depression. Close

Costate ocellus

"A plate of silica pierced by closely packed pores" with siliceous ribs between each row of pores (Tomas 1997).

Costate ocelli
located at ends of blunt processes (Kraberg et al. 2010). "Valves are distinctly sculptured, with Close


(plural: puncta) A sharp tip or small point on any part of an organism's anatomy.

in roughly regular Close


(symmetry) Describing a shape that many axes of symmetry. That is, it does not have a left and right like humans do (bilateral symmetry), but can be divided into equal halves no matter where you place the axis. Some examples of radially symmetrical organisms include sea stars and centric diatoms like Thalassiosira.

rows running outward from center toward processes. Sculpturing on Close

Intercalary bands

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

intercalary bands
is visible only under high magnification. Tiny, highly refractive, colorless granules are present in ends of processes. (Cupp 1943).


Width Close


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

axis): 8 - 100 μm
Height 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
): 8 - 60 μm
Puncta on valve: 16 - 20 in 10 μm
Puncta on intercalary bands: 28 - 33 rows in 10 μm
Valve Close


In diatoms, the regularly repeated hexagonal holes on the valve walls (HPP 2003).

: 10 - 20 in 10 μm
(Cupp 1943, Hasle and Syvertsen 1997, Kraberg et al. 2010)

Similar species


Harmful effects

Blooms can lead to growth restrictions and poorer quality of the aquacultured seaweed nori (known as "bleaching"), due to consumption of most of the available 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.

(especially nitrogen) (Nishikawa et al. 2009). May be harmful to salmon (Martin et al. 2007).


Neritic (Cupp 1943).


Cosmopolitan except in polar regions (Horner 2002). Distribution is centered in temperate to warm waters (Kraberg et al. 2010).
Consistently blooms from winter to early spring after size-restoration in the fall in Harima-Nada, Japan (Nishikawa et al. 2007). High concentrations are usually found in the fall in the Bay of Fundy, although appearances and abundances are highly variable (Martin et al. 2007). Most abundant during spring and summer in Northern European seas (Kraberg et al. 2010).
"South temperate species. Very widely distributed. Often abundant off southern California, especially from March through July, and in Gulf of California. Common as far north as Scotch Cap, Alaska" (Cupp 1943).

Growth conditions

In the laboratory, growth rate increases with increasing temperature (from 9 °C to 20 °C) (Nishikawa and Hori 2004), with maximum rate at 25 °C and salinity of 25 (Nishikawa 2002). In nature, blooms usually occur when the average temperature is 8 - 9 °C (Nishikawa 2006).
Capable of efficient nitrogen uptake at low temperatures, but is less competitive for phosphate than other diatoms (Nishikawa et al. 2009). Larger numbers at low temperatures may also be due to a weaker grazing pressure by copepods (Honda and Yoshimatsu 2007).
May be favoured under high nitrogen to phosphorous ratios (> 100) (Hori et al. 1998). Can grow under very limiting nutrient conditions (Nishikawa and Hori 2004, cited in Nishikawa et al. 2009). May benefit from 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).

, shallower water, and mixing of the Close

Water column

Referring to a water system from the surface to the bottom sediments. This can be used to understand processes of stratification, mixing and their relationship to nutrient transport. Temperature, salinity, pH, and nutrient levels often vary along the length of the water column.

water column
(Martin et al. 2007). Minimum cell Close


(as in, cell quota for a nutrient) The amount of a macro- or micronutrient required by an organism to fulfill its life cycle.

of nitrate, phosphate, 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).

at 20 °C and 9 °C, respectively: 1.0 and 1.6 pmol-N cell-1, 0.16 and 0.24 pmol-P cell-1, and 2.6 and 3.8 pmol-Si cell-1 (Nishikawa and Hori 2004). Capable of significant growth with 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 μmol m-2 s-1 and higher, and saturated at 150 μmol m-2 s-1 (Nishikawa 2002).
The increase in depth range in early spring may favour bloom formation, as the reproductive cells are often found in deeper waters (Nishikawa and Yamaguchi 2006).

Environmental Ranges

Depth range (m): 0 - 133
Temperature range (°C): -1.679 - 29.468
Nitrate (μmol L-1): 0.056 - 28.280
Salinity: 25.320 - 36.128
Oxygen (mL L-1): 4.500 - 9.116
Phosphate (μmol L-1): 0.046 - 2.337
Silicate (μmol L-1): 0.754 - 59.039
(OBIS 2011, cited in EOL 2011)

Bloom characteristics

Information not available.


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). 2011. Eucampia zodiacus Ehrenberg. Accessed 07 Aug 2011.

Guiry, M. D. 2011. Eucampia zodiacus Ehrenberg, 1840. Accessed 07 Aug 2011.

Guiry, M. D. and Guiry, G. M. 2011. Eucampia zodiacus Ehrenberg. Accessed 07 Aug 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.

Honda, K. and Yoshimatsu, S. 2007. The grazing experiments with copepod Calanus sinicus BRODSKY and cultured Eucampia zodiacus EHRENBERG. Bulletin of the Akashiwo Research Institute of Kagawa Prefecture. 6: 1-11.

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.

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

Martin, J. L., Hastey, C. D., LeGresley, M. M. and Page, F. H. 2007. Temporal and Spatial Characteristics of the Diatom Eucampia zodiacus in the Western Isles Region of the Bay of Fundy. Canadian technical report of fisheries and aquatic sciences. 2705: iii + 22 p.

Nishikawa, T. 2002. Effects of temperature, salinity and irradiance on the growth of the diatom Eucampia zodiacus caused bleaching of seaweed Porphyra isolated from Harima-Nada, Seto Inland Sea, Japan. Bulletin of the Japanese Society of Scientific Fisheries. 68(3): 356-361.

Nishikawa, T. and Hori, Y. 2004. Effects of nitrogen, phosphorus and silicon on the growth of the diatom Eucampia zodiacus caused bleaching of seaweed Porphyra isolated from Harima-Nada, Seto Inland Sea, Japan. Bulletin of the Japanese Society of Scientific Fisheries. 70(1): 31-38.

Nishikawa, T., Hori, Y., Tanida, K. and Imai, I. 2007. Population dynamics of the harmful diatom Eucampia zodiacus Ehrenberg causing bleachings of Porphyra thalli in aquaculture in Harima-Nada, the Seto Inland Sea, Japan. Harmful Algae. 6(6): 763-773.

Nishikawa, T., Tarutani, K. and Yamamoto, T. 2009. Nitrate and phosphate uptake kinetics of the harmful diatom Eucampia zodiacus Ehrenberg, a causative organism in the bleaching of aquacultured Porphyra thalli. Harmful Algae. 8(3): 513-517.

Nishikawa, T. and Yamaguchi, M. 2006. Effect of temperature on light-limited growth of the harmful diatom Eucampia zodiacus Ehrenberg, a causative organism in the discoloration of Porphyra thalli. Harmful Algae. 5(2): 141-147.

Ocean Biogeographic Information System (OBIS). 2011. Eucampia zodiacus. Accessed 07 Aug 2011.

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