Contribution a l’étude d’une algue toxique « Ostreopsis Ovata » des côtes oranaises (Algérie occidentale)

Abstract

Ostreopsis Ovata is a unicellular microalgae, producing palytoxin, which usually lives in waters of tropical seas. It belongs to the group of dinoflagellates. The presence of this microalga has been reported several times including in the Mediterranean sea, in Spain in 2004, Italy in 2005 and Algeria in 2009, causing the intoxication of almost 200 people. Some changes in the conditions of the marine environment very favorable (high atmospheric pressure, calm sea or presence of artificial barriers (dams and jetties), high water temperature (about 25 ° C), sea winds, ect ...) have Ostreopsis Ovata allowed to grow in our climate. The main objective of our work is to acquire to gather relevant scientific knowledge, namely a literature review on the identification of the species Ostreopsis Ovata and conditions for its development to have a more objective, and as concrete as possible, sensitive areas and the hazards posed by the proliferation of this species on human health, flora and fauna. During blooms (technically called bloom) the concentration of these toxic cells free in the water exceeds the threshold of 4000 cells per liter of Ostreopsis Ovata "early warning" or 30 000 cells per liter "alert", generates a health impact on coastal users. Concentrations Ostreopsis Ovata in water are highly variable in space (preferably harbor and rocky beaches), and in time (the highest concentration is in the summer or the temperature).