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Dictyocha fibula

Classification
General Silicoflagellate
Description
Shape Star-shaped
Size Length 10 - 45 μm (excluding 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)
Colour Yellow-brown
Connection None, solitary
Covering No covering, but with Close

Rhomboid/rhombic

Describing the geometric shape of the cell; a parallelogram in which adjacent sides are of unequal lengths and angles are oblique.

rhomboid silica skeleton
Close

Flagellum

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

Flagella		 One, Close

Anterior

The front. The part of the cell in the direction of movement. Opposite of posterior (HPP 2003).

anterior
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
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. Skeletal and Close

Naked

(athecate, unarmoured dinoflagellates) Without a theca. Referring to "cells without a cell wall" (Horner 2002). The opposite of thecate or armoured.

naked stages present.
Close

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 Physical obstruction of fish gills
Distribution
Habitat Coastal and oceanic
Geographic Warm to cold seas
Seasonal Most abundant during winter-spring transition
Growth Conditions
Close

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		 24 (optimal)
Temperature 10 °C (optimal)

Synonym(s)

None.

Classification

Empire Eukaryota
Kingdom Chromista
Subkingdom Chromobiota
Infrakingdom Heterokonta
Phylum Heterokontophyta
Subphylum
Class Dictyochophyceae
Order Dictyochales
Family Dictyochaceae
Genus Dictyocha
Species D. fibula Ehrenberg 1837

(Guiry and Guiry 2011)

Lifestyle

Photosynthetic. Sexual reproduction by Close

Isogamy

The simplest type of sexual reproduction between gametes that are similar in size and shape. Instead of being classified as male and female cells, organisms of different mating types (i.e., different size and shape of gamete) can fuse to form a zygote (Botany Dictionary 2002).

isogamy. Asexual reproduction by Close

Aplanospore

A thin-walled spore that relies on water currents for passive transport. It is produced by some phytoplankton (including Scenedesmus and Geminella species [phylum Chlorophyta]) as a means of asexual reproduction. Upon germination, it develops a new cell wall distinct from the parent cell. The production of aplanospores may be a hereditary feature or may be an adaptation to withstand unfavourable environmental conditions (Transeau 1916).

aplanospores and Close

Statospore

An internally formed spore in its resting stage. A thick-walled, resistant spore formed within the frustules of various centric diatoms.

statospores (Guiry 2011). Naked, swimming stage and non-swimming Close

Coenocyte

A multinucleate cell originating either from multiple nuclear divisions without accompanying cell division or from cellular aggregation and dissolution of the cell membranes inside the mass (DeWreede 2006).

coenocytes were found in clonal cultures at 15 °C (Van Valkenberg and Norris 1991).

Description

Cells are solitary, roughly spherical and are slightly flattened with one anterior flagellum. The external silica skeleton is composed of tubular elements and consists of four protruding spines and four windows, with the flagellum extending along one of the spines. Cells have many golden-brown, Close

Discoid

Disc-shaped.

discoid chloroplasts (Horner 2002).
The flagellum is as long as the cell or slightly shorter. The cell body is naked with multiple tentacles or Close

Pseudopodium/pseudopodia

A semi-permanent extension of the cytoplasm used for locomotion and feeding by some flagellate protozoans.

pseudopodia (Kraberg et al. 2010).

Measurements

Length: 10 - 45 μm (skeletal form), ∼90 μm with spines
(Kraberg et al. 2010)

Similar species

Dictyocha speculum, which has six spines protruding from a hexagonal ring, connected to another smaller hexagonal ring by six rods (Horner 2002).

Harmful effects

Harmful to fish gills at high concentrations (Vila and Maso 2005).

Habitat

Coastal and oceanic (Horner 2002).

Distribution

Geographic:
Warm to cold seas (Horner 2002).
Seasonal:
Most abundant during the winter-spring transition in Western Mediterranean (Rigual-Hernandez et al. 2010). Can be found occasionally throughout the year (Kraberg et al. 2010).
Local:
Information not available.

Growth conditions

Optimal growth conditions at 10 °C, salinity of 24, and 2.52 W m-2 (1720 Close

Lux

(abbreviated 'lx') Units for measuring light intensity in a given surface area.

lux) illumination in culture. D. fibula is unable to grow at temperatures above 15 °C (Van Valkenberg and Norris 1991).
Most abundant during winter-spring transition due to the Close

Nutrients

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.

nutrient-rich euphotic layer and the increase in solar radiation. Minimum abundances occur during the summer due to strong Close

Oligotrophic

Describing an aquatic ecosystem with low nutrient and organic matter accumulation and high dissolved oxygen content.

oligotrophic (low nutrients, high oxygen) and Close

Stratification

The development of distinct non-mixing layers in the water column resulting from a steep gradient in density, which is caused by differences in temperature and/or salinity.

stratification conditions. Also very sensitive to nutrient inputs, reaching maximums where river influence is important (Rigual-Hernandez et al. 2010).

Environmental Ranges

Depth range (m): 0 - 470
Temperature range (°C): -1.857 - 26.001
Nitrate (μmol L-1): 0.135 - 13.138
Salinity (PSU): 25.320 - 36.252
Oxygen (mL L-1): 4.705 - 9.002
Phosphate (μmol L-1): 0.048 - 1.562
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 - 33.908
(OBIS 2011, cited in EOL 2011)

Bloom characteristics

Information not available.

References

Encyclopedia of Life. 2011. Dictyocha fibula Ehrenberg. http://www.eol.org/pages/900748. Accessed 02 Jul 2011.

Guiry, M. D. 2011. Dictyocha fibula Ehrenberg, 1837. World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=157463 Accessed 02 Jul 2011.

Guiry, M. D. and Guiry, G. M. 2011. Dictyocha fibula Ehrenberg. http://www.algaebase.org/search/species/detail/?species_id=52816. Accessed 02 Jul 2011.

Haigh, N. 2010. Harmful Plankton Handbook. Nanaimo, BC, Canada. 52.

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.

Ocean Biogeographic Information System (OBIS). 2011. Dictyocha fibula. http://www.iobis.org/mapper/?taxon_id=434071. Accessed 02 Jul 2011.

Rigual-Hernandez, A. S., Barcena, M. A., Sierro, F. J., Flores, J. A., Hernandez-Almeida, I., Sanchez-Vidal, A., Palangues, A. and Heussner, S. 2010. Seasonal to interannual variability and geographic distribution of the silicoflagellate fluxes in the Western Mediterranean. Marine Micropaleontology. 77(1-2): 46-57.

Throndsen, J. 1997. The planktonic marine flagellates. In: Tomas, C. R. (ed.) Identifying marine Phytoplankton. Academic Press, Inc., San Diego, California, US. 591-730.

Van Valkenburg, S. D. and Norrise, R. E. 1970. The growth and morphology of the silicoflagellate Dictyocha fibula Ehrenberg in culture. Journal of Phycology. 6: 48-54.

Vila, M. and Maso, M. 2005. Phytoplankton functional groups and harmful algal species in anthropogenically impacted waters of the NW Mediterranean Sea. Scientia Marina. 69(1): 31-45.