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Thalassiosira nordenskioeldii/aestivalis/pacifica

(These species are grouped together as they are difficult to distinguish apart with Close

LM

(light microscopy) "Using a microscope in which a beam of light passes through optical lenses to view an image of the specimen" (MCM LTER 2010).

LM.)
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 Drum-shaped
Size Diameter 7 - 56 μm
Colour Yellow-brown
Connection Single, central, thin, organic thread
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		 Numerous, small, plate-like
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.
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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 May produces chemicals that can inhibit copepod reproduction
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 Sometimes contributes to spring and fall blooms
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		 19 - 36
Temperature -2 - 25 °C

Synonym(s)

None.

Classification

Empire Eukaryota
Kingdom Chromista
Subkingdom Harosa
Infrakingdom Heterokonta
Phylum Ochrophyta
Subphylum Khakista
Class Coscinodiscophyceae
Subclass Coscinodiscophycidae
Order Thalassiosiranae
Family Thalassiosirales
Genus Thalassiosira
Species T. nordenskioeldii Cleve 1873
Species T. aestivalis Gran 1931
Species T. pacifica Gran and Angst 1931

(Guiry and Guiry 2012)

Lifestyle

Photosynthetic. Reproduces sexually and asexually.

Description

Cells are drum-shaped with threads extending from the Close

Margin

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

margins. Adjacent cells are connected in chains by a single and thin central thread. Corners of cells are often bevelled, and the Close

Valve

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

valve centre is usually concave (Cupp 1943).

Measurements

Diameter: 7 - 56 μm
(Hasle and Syvertsen 1997)

Similar species

Information not available.

Harmful effects

May produce polyunsaturated aldehydes (PUAs) that can inhibit copepod reproduction (Wichard et al. 2005).

Habitat

Neritic (Cupp 1943).

Distribution

Geographic:
Cosmopolitan, except in polar regions (Hasle and Syvertsen 1997).
Seasonal:
Sometimes contributes to spring and fall blooms.
Local:
See above.

Growth conditions

Information not available.

Environmental Ranges

Depth range (m): 0 - 470
Temperature range (°C): -1.948 - 24.625
Nitrate (μmol L-1): 0.335 - 28.983
Salinity: 18.564 - 35.801
Oxygen (mL L-1): 4.838 - 9.192
Phosphate (μmol L-1): 0.048 - 1.909
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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 - 43.816
(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. Thalassiosira. http://eol.org/pages/12082/overview. Accessed 17 Mar 2012.

Guiry, M. D. and Guiry, G. M. 2012. Thalassiosira Cleve, 1873: 6. http://www.algaebase.org/search/genus/detail/?genus_id=43768. Accessed 26 Feb 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.

Ocean Biogeographic Information System (OBIS). 2012. Thalassiosira. http://www.iobis.org/mapper/?taxon_id=518563. Accessed 17 Mar 2012.

Wichard, T., Poulet, S. A., Halsband-Lenk, C., Albaina, A., Harris, R., Liu, D. and Pohnert, G. 2005. Survey of the chemical defence potential of diatoms: Screening of fifty one species for α, β, γ, δ-unsaturated aldehydes. Journal of Chemical Ecology. 31(4): 949-958.