Dinophysis acuminata

Classification
General Dinoflagellate
Description
Shape Clamshell shaped, oval
Size Length 30 - 35 μm, diameter 38 - 58 μm
Colour Reddish-brown
Connection None (solitary)
Covering Cellulose Close

Theca

(plural: thecae) Cell wall. In dinoflagellates, it is composed of cellulose plates within vesicles (Horner 2002).

theca
Close

Flagellum

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

Flagella
Two Close

Transverse flagellum

In dinoflagellates, one of the two flagella they possess; responsible for the rotation of the cell around its length axis. The two flagella are directed parallel to one another and together, the rotational components result in a helical swimming path (Fenchel 2001).

(transverse
and Close

Trailing flagellum

In dinoflagellates, one of two flagella they possess; responsible for the movement of the cell and due to its asymmetric arrangement it also causes a rotation of the cell around an axis perpendicular to the longitudinal axis. (Fenchel 2001).

trailing
)
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 red-brown chloroplasts present
Behaviour
Lifestyle Close

Mixotroph/mixotrophic

An organism that is both autotrophic (photosynthesizes or chemosynthesizes) and heterotrophic. That is, it can gain energy both from light (or chemical) energy and also by consuming other organisms. This allows such organisms to take advantage of different environmental conditions.

Mixotroph
. Asexual Close

Binary fission

A form of asexual reproduction where one cell divides into two identical cells. All prokaryotes and some eukaryotes reproduce in this manner. Compare with mitosis, where the nucleus must also divide, adding an extra step to the process.

(binary fission
)
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
Abundant in sheltered and enclosed areas such as fjords
Harmful effects Diarrhetic shellfish poisoning Close

Diarrhetic Shellfish Poisoning

(DSP) Mainly caused by okadaic acid, a toxin produced by some diatoms. When shellfish consume phytoplankton, they can bioconcentrate the toxin leading to non-life threatening symptoms that may include diarrhea, nausea, vomiting and cramps (Yasumoto et al. 1985).

(DSP
)
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 Warm to cold temperate waters worldwide
Seasonal Late spring to summer
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
28 - 34.5
Temperature 12 - 22 °C

Synonym(s)


Dinophysis borealis Paulsen 1949
Dinophysis lachmanii Paulsen 1949
Dinophysis boehmi Paulsen 1949
Dinophysis lachmanii Solum 1962
Dinophysis skagii Paulsen 1949
Dinophysis ellipsoides Kofoid 1907
(Kraberg et al. 2010)

Classification


Empire Eukaryota
Kingdom Protozoa
Subkingdom Biciliata
Infrakingdom Alveolata
Phylum Dinoflagellata
Subphylum
Class Dinophyceae
Subclass
Order Dinophysiales
Family Dinophyciaceae
Genus Dinophysis
Species D. acuminata Claperede and Lachman (1859)

(Guiry and Guiry 2011)

Lifestyle


Mixotrophic. Asexual reproduction by binary fission (Dodge 1982).

Description


In Close

Lateral

Relating to a side-to-side direction.

lateral
view, cells are clamshell, oval or elliptical in shape, with a crown on top, a wing or fin at the side, and a round Close

Posterior

The back end of a cell. Opposite of anterior.

posterior
. Posterior profile is round, sometimes with small Close

Ventral

Relating to the underside of an organism; abdominal.

ventrally
placed Close

Antapical

Referring to the most posterior point of a cell. The opposite of apical.

antapical
protuberances (Dodge 1982). Left Close

Sulcal list

(left and right) In dinokont dinoflagellates, a well-defined groove on the ventral surface that is supported by ribs.

sulcal list
is well developed and extends beyond the midpoint of the cell. Cells have three Close

Sulcus

"In dinokont dinoflagellates, the longitudinal area on the ventral surface that forms a furrow or depression and houses the longitudinal (trailing) flagellum" (Horner 2002).

sulcal
Close

Ribs

Features that provide support to other structures in the cell.

ribs
, with the third and longest pointing to the posterior (Kraberg et al. 2010). Cells have several large reddish-brown chloroplast that are associated with a posteriorly placed Close

Pyrenoid

Any of various protein granules that can be found in the chloroplast of some algae species. It is associated with the production of starch.

pyrenoid
. Cells have a centrally located Close

Nucleus

(plural: nuclei) In eukaryotic cells, a membrane-bound organelle that contains the cell's genetic information; the nucleus controls the activities of the cell by controlling gene expression.

nucleus
and a low Close

Epitheca

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

epitheca
that does not extend beyond Close

Cingulum

(dinoflagellates) "In dinokont dinoflagellates, a furrow encircling the cell one or many times" (Horner 2002). It is also known as the girdle or transverse groove and may be located at, above, or below the midpoint of the cell with the left and right ends meeting or displaced form one another (Horner 2002). In diatoms, this term describes the collective elements of a diatom girdle: "The cingulum is made up of delicate silica bands that join the two valves of a frustule. Most diatoms possess a cingulum, although some may not" (Spaulding et al. 2010).

cingular
list (Kraberg et al. 2010).

Measurements


Length: 30 - 35 μm
Diameter: 38 - 58 μm
(Horner 2002)

Similar species


Easily confused with D. sacculus, D. norvegica, D. ovum and D. punctata. Cell shape, sulcal list development and surface markings are possible ways to differentiate them, but there is still confusion between these species (Steidinger et al. 1997). The Close

Hypotheca

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

hypotheca
of Dinophysis acuminata has sides that are round or oval-shaped, unlike the straight side of Dinophysis acuta.

Harmful effects


Produces Close

Lipophilic

Having the ability to combine with or dissolve lipids.

lipophilic
toxins (okadaic acid derivatives and pectenotoxins) causing diarrhetic shellfish poisoning (DSP; Escalera et al. 2010). Toxin production is affected by light intensity. In a lab experiment, highest toxin production occurred at light levels below 65 μmol photons m-2 s-1. No toxins were produced in dark treatments or above 65 μmol photons m-2 s-1 (Tong et al. 2010).

Habitat


Neritic.

Distribution


Close

Cosmopolitan

Widely distributed; occurring in many parts in the world.

Cosmopolitan
in warm to cold temperate waters worldwide (Steidinger and Tangen 1997).

Growth conditions


Can live in a wide range of temperature, salinity and light conditions in varied geographical settings. This species has been observed to live at temperatures ranging from 12 - 22 °C and salinities from 28 - 34.5 (Tong et al. 2010). Increased cell densities have been observed in temperatures and light levels that benefit their prey (that is, better conditions for their food leads to more food and therefore more D. acuminata; Tong et al. 2010).

Environmental Ranges


Depth range (m): 0 - 270
Temperature range (°C): -1.203 - 21.917
Nitrate (μmol L-1): 0.738 - 10.982
Salinity: 27.165 - 37.775
Oxygen (mL L-1): 5.041 - 8.968
Phosphate (μmol L-1): 0.097 - 0.677
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): 1.190 - 39.813
(EOL 2012)

Bloom characteristics


Abundant in sheltered and enclosed areas such as fjords. High abundance coincides with thermal and haline 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
(Miota et al. 2006).

References


Dodge, J. D. 1982. Marine Dinoflagellates of British Isles. Her Majesty's Stationary Office, London, UK. 303.

Encylopedia of Life (EOL) 2012. Dinophysis acuminata Claperede and Lachman 1859. http://eol.org/pages/901407/details. Accessed 19 Mar 2012.

Escalera, L., Reguera, B., Miota, T., Pazos, Y. and Cerejo, M. 2010. Bloom dynamics of Dinophysis acuta in an upwelling system: in situ growth versus transport. Harmful Algae. 9(3): 312-322..

Guiry, M. D. and Guiry, G .M. 2011. Dinophysis acuminata Claperede and Lachman 1859 http://www.algaebase.org/search/species/detail/?species_id=52217. Accessed 05 May 2011.

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

Miota, M. T., Gonçalves, L. S., Oliveira, P. B. and Falcão, M. 2006. A bloom of Dinophysis acuta in a thin layer off north-west Portugal. African Journal of Marine Science. 28(2): 265 -269.

Reguera, B., Bravo, I. and Fraga, S. 1995. Autoecology and some life history stages of Dinophysis acuta Ehrenberg. Journal of Planktonic Research. 17(5): 999-1015.

Steidinger, K. A. and Tangen, K. 1997. Dinoflagellates. In: Tomas, C. R. (ed.) Identifying Marine Phytoplankton. Academic Press, Inc., San Diego. 429.

Tong, M., Kulis, D. M., Fux, E., Smith, J. L., Hess, P. 2010. The effects of growth phase and light intensity on toxin production by Dinophysis acuminata from the northeastern United States. Harmful Algae. 10(3): 254-264.


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