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Chaetoceros radicans

Classification
General Close

Centric

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

Centric diatom
Description
Shape Elliptic cylinder
Size Large diameter 6 - 25 μm
Colour Yellow-brown
Connection Crossing of adjacent Close

Spine

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

spines
Covering Silica Close

Frustule

In diatoms, the hard and porous silica cell wall (Horner 2002).

frustule
Close

Flagellum

(plural: flagella) A tail-like projection that sticks out from the cell body and enables movement.

Flagella		 None
Close

Chloroplast

An organelle in the cell that contains the cell pigments (Horner 2002). This is where photosynthesis occurs. A chloroplast is a specialized chromatophore.

Chloroplast		 One
Behaviour
Lifestyle Close

Photosynthesis

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.

Photosynthetic. Sexual/asexual. Close

Resting spore

In diatoms, a cell that requires a dormancy period prior to germination and can survive for several years; usually developed to survive adverse conditions. They are commonly observed in centric but not pennate diatoms. The morphology of the spore may be similar or different from a vegetative cell; they usually have heavily silicified walls and are rich in storage products (Horner 2002).

Resting spores present
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Bloom

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.

Bloom		 Information not available
Harmful effects None known
Distribution
Habitat Close

Neritic

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).

Neritic
Geographic Close

Cosmopolitan

Widely distributed; occurring in many parts in the world.

Cosmopolitan
Seasonal Summer
Growth Conditions
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Salinity

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).

Salinity		 31 - 36
Temperature -2 - 29 °C

Synonym(s)

Chaetoceros scolopendra Cleve 1896
(Guiry and Guiry 2012)

Classification

Empire Eukaryota
Kingdom Chromista
Subkingdom Harosa
Infrakingdom Heterokonta
Phylum Ochrophyta
Subphylum Khakista
Class Bacillariophyceae
Subclass Coscinodiscophycidae
Order Chaetocerotales
Family Chaetocerotaceae
Genus Chaetoceros
Species C. radicans Schütt 1895

(Guiry and Guiry 2012)

Lifestyle

Photosynthetic. Reproduces sexually and asexually (Guiry 2012). Resting spores present (see Description; Cupp 1943).

Description

Cells are connected in long, twisted chains that are straight or slightly curved. Cells are longer than wide, with rounded corners. Internal spines are thin and covered with numerous small spines, arising from just within the Close

Margin

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

margins and extending out roughly perpendicularly to the chain (Cupp 1943). These spines are often covered in detritus. Terminal spines are smooth and not covered in small spines (Hasle and Syvertsen 1997). Close

Aperture

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

Apertures are roughly elliptical with a slight constriction in the middle. One chloroplast per cell (Cupp 1943). Cells are yellow-brown in colour.
Resting spores are paired and without apertures, and have smooth, thick spines that are initially fused, then split and wrap back around the cell (Cupp 1943).

Measurements

Large diameter Close

Apical

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

(apical axis): 6 - 25 μm
(Hasle and Syvertsen 1997)

Similar species

None.

Harmful effects

None known.

Habitat

Neritic (Cupp 1943).

Distribution

Geographic:
Cosmopolitan (Hasle and Syvertsen 1997).
Seasonal:
Forms blooms in austral summer (November) and fall (April - May) around Antarctica (Perissinotto 1992).
Local:
One of the dominant species in the summer in Saanich Inlet (Sancetta and Calvert 1988). Most abundant in spring and late summer off California (Cupp 1943).

Growth conditions

May be favoured by conditions of high N:P ratios (> 80; Yoshida et al. 1998).

Environmental Ranges

Depth range (m): 0 - 128
Temperature range (°C): -1.697 - 29.468
Nitrate (μmol L-1): 0.056 - 18.784
Salinity: 30.920 - 35.801
Oxygen (mL L-1): 4.500 - 9.192
Phosphate (μmol L-1): 0.062 - 1.722
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).

Silicate (μmol L-1): 0.754 - 34.819
(OBIS 2012, cited in EOL 2012)

Bloom characteristics

Information not available.

References

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). 2012. Chaetoceros radicans. http://eol.org/pages/912020/overview. Accessed 31 Mar 2012.

Guiry, M. D. 2012. Chaetoceros radicans Schütt, 1895. http://www.marinespecies.org/aphia.php?p=taxdetails&id=163112. Accessed 31 Mar 2012.

Guiry, M. D. and Guiry, G. M. 2012. Chaetoceros radicans F. Schütt. http://www.algaebase.org/search/species/detail/?species_id=37456. Accessed 31 Mar 2012.

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.

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

Ocean Biogeographic Information System (OBIS). 2012. Chaetoceros radicans. http://www.iobis.org/mapper/?taxon_id=419688. Accessed 31 Mar 2012.

Perissinotto, R. 1992. Mesozooplankton size-selectivity and grazing impact on the phytoplankton community of the Prince Archipelago (Southern Ocean). Marine Ecology Progress Series. 79: 243-258.

Sancetta, C. and Calvert, S. E. 1988. The annual cycle of sedimentation in Saanich inlet, British Columbia: implications for the interpretation of diatom fossil assemblages. Deep Sea Research Part A. Oceanographic Research Papers. 35(1): 71-90.

Yoshida, Y., Mishima, Y. and Sato, M. 1998. Relationships between the dominant phytoplankton and DIN:DIP ratios in the inner part of Tokyo Bay. Nippon Suisan Gakkaishi. 64(2): 259-263.


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