Dinophyta

Ecology

Dinoflagellés make party of the Plancton of fresh water and especially of marine water. Certain species are also found in snow. Other species, the Zooxanthelle S, live in symbiosis with Protiste S or Invertébré S sailors (sponges, Coraux, Towards dishes, Mollusque S, Crustacé S). The chlorophyllian species carry out the Photosynthèse thanks to plastids. The not pigmented species nourish plankton. There exist bioluminescent forms as Noctiluca which uses a Enzyme, the Luciférase, and a substrate, the Luciférine. The accumulation of Noctiluca miliaris and Noctiluca scintillans involves efflorescences and red phenomena of tides under certain conditions.

Dinoflagellés and Phycotoxines

Certain species of planktonique algae, primarily of the Dinoflagellés and the Diatoms, can secrete Phycotoxine S (toxins algales) in certain badly known circumstances, in particular at the time of the sudden multiplications (one speaks then about located efflorescences, English bloom). These toxins would be means of protection and of limitation of the predation by the phytophagous ones (Zooplancton, Coquillage S filterers).
Ces toxins causes various disorders, bases classification:

• diarrheal toxins (in English DSP, Diarrheic Shellfish Poison), produced by Dinoflagellés of the kinds Dinophysis and Prorocentrum , whose type is the okadaïque acid. They cause diarrhea and vomiting quickly (into 30 mn at 2 a.m. after the ingestion of contaminated shells), reassigning spontaneously into 2 to 3 days, without after-effects. One associates with it the hepatotoxic pectenotoxines, the yessotoxines without proven toxicity and the azaspiracides diarrheal. The standards selected are of 160 µg/kg for the okadaïque acid and the azaspiracides, and 1 mg/kg for the pectenotoxines. One preferentially uses a biological test on mouse. These food poisonings are relatively common, on all the coasts, often with the changes of season (spring, autumn).
• paralyzing toxins (in English PSP, Paralytic Shellfish Poison), produced by Dinoflagellés of the kinds Alexandrium , Gonyaulax , Gymnodinium and Pyrodinium , whose type is the saxitoxine. They quickly cause after the ingestion of contaminated shells a brutal paraesthesia (into 5 to 30 mn) of the lips, face, arms then legs. Serious cases are announced with a driving incoordination, inconsistency, and a risk of death by respiratory paralysis. The standards selected are of 800 µg/kg for the saxitoxine. It is about the first known phycointoxication (retrospectively) in British Columbia (Canada) in 1798. Efflorescences of Alexandrium are located time with other the summer along the French coasts, but no intoxication was still declared in France.
• toxins amnésiantes (in English ASP, Amnesic Shellfish Poison), produced by the Diatoms of the kind Pseudo-nitzschia , whose type is the domoïque acid. They quickly cause after the ingestion of contaminated shells gastro-enteritis (diarrhea and vomiting into 2 with 24:00) then neurological symptoms, with cephalgias, confusion, confusion, and in the serious cases, amnesia, then mortal coma. The children and the elderly are most sensitive. The standards selected are of 20 mg/kg for the domoïque acid. Efflorescences of Pseudo-nitzschia are regularly located the summer along the French coasts, but no intoxication was still declared in France. All the shells can be contaminated (Huître S, mould S, Pecten ), but also certain fish (anchovy), which poison the piscivorous birds then.
• cutaneous toxins, produced by Dinoflagellé Ostreopsis ovata , whose type is the palytoxine. It is about a neurotoxine likely to cause cutaneous irritations, fever and a respiratory embarrassment, the contamination being done by contact or inhalation of the spray (marine aerosols, charged in phycotoxines), and consumption of the fishery products contaminated. The species is Benthique (in the marine sediments), but goes up on the surface for flowering, and the toxin can then concentrate in the food chain. There were some toxic episodes in Italy (1998), and an alarm in Marseilles in 2006.
• Ciguatera, produced by Dinoflagellé Gambierdiscus toxicus , whose types are the cigatoxines and the maïtotoxines. It is about a food poisoning by consumption of contaminated fish flesh (ichtyosarcotoxism). The alga multiplies on the skeleton of the Corail died, and is grazed by the Poisson parrots. These fish can in their turn contaminate their predatory. The principal symptom is the " gratte" , intense cutaneous itching, with gastro-enteritis and a paraesthesia of the face. The spontaneous cure is more or less fast, with sometimes neurological after-effects. Often associated with others phycotoxines (palytoxine). It is the standard and well-known intoxication tropical seas, but of the cases however were declared recently in the east of the Mediterranean.
• Pfiesteria piscicida also releases from the neurotoxines. This disease especially becomes alarming in North Carolina where the Man poisons himself by consuming fish.

The production and the fishing of the edible shells, in the majority of the countries, are placed under the control of an authority, responsible for the monitoring with marine water and produced shells, in order to guarantee the harmlessness of the food products (Maritime businesses and Veterinary services in France, with the technical support of the IFREMER).

However, the majority of the species of Dinoflagellés are not toxic and are at the base of the nutrition of many species: Zooplancton, Poisson S.

Paleontology

With reading

phylogenetic Classification of alive the by Guillaume Lecointre and Herve Guyader with the editions Belin

List of Dinoflagellés (2200 S known)

• Alexandrium minutum
• Ceratium hirundinella
• ''Dinophysis'' spp. (200 known species)
• Dinophysis triptos
• Erythropsidinium pavillardii
• Gonyaulax tamarensis
• Gymnodinium microadriaticum
• Nematodinium lebourae
• Noctiluca miliaris
• Noctiluca scintillans
• Syndinium rostratum
• Peridinium cinctum
• Polykrikos schwartzii
• '' Pyrocystis '' spp.
• Pyrocystis lunula capable of Bioluminescence.
• Pyrocystis nociluca capable of Bioluminescence.

Internal bonds

• Dinoflagellata (phylogenetic classification)

References

• Course of Eucaryote Microbiology of University of Paris VII