Etude de la structure et de la dynamique des populations phytoplanctoniques des eaux marines côtières de la région de Mostaganem et d’Alger

Abstract

The principal goal of this study is to contribute to the quantitative and qualitative evaluation, in order to explore the diversity of the phytoplankton community of three station of the Algerian coastal shallow waters areas: ["les Trois Suisses "; "le Vivier" (Algiers) and Stidia (Mostaganem)] and to confirm the production capacity of these organism. The studied physico-chemical parameters (salinity, temperature, ammonium, nitrites, nitrates and phosphorus), showed little differences between the studied stations. The contents of the analyzed nutrients are relatively low during all the studied period, and remain always lower than 0.2mg/l, suggesting an important consumption of the nutrients by the autotrophic phytoplankton species. Also, during all the study period, a total of 103 species were identified, with a specific richness slightly more important at the station «le Vivier" compared to the " Trois Suisses" station. The three stations are characterized by abundance of diatoms (69%), followed by dinoflagellates (31%). In addition, in May, in the site of Ouillis, dinoflagellates are mainly represented with more than 89%, followed by diatoms with a percentage of 11%. Contrary, at the station "le Vivier" , the diatoms are the most dominant species (76%). However, in the "Trois Suisses" station, both diatoms and dinoflagellates are present in equal values with a percentage of 50% each. The monthly comparison of the monthly ―row-frequency‖ diagrams of the phytoplankton identified in the two stations " le Vivier " and " Trois Suisses ", allowed to highlight a pioneer communities which appear each time at the stage 1, therefore, a generating beginning of succession characterized by species, which are in the majority diatoms, only for May at the station " le Vivier". In addition, the two phytoplanctonic blooms identified in spring (May) and in summer (July-August) are characterized by the predominance of the diatoms at the both station of Algiers.