Caractérisation hivernale de la lagune de Bizerte

Abstract

This work concerns the winter characterization of the lagoon of Bizerte based on series of measurement taken in January 2004 (winter season). This sampling has interested 17 stations distributed in the lagoon and a reference marine station. Each sample was the subject of in-situ measurements (Temperature, Salinity, Conductivity, Transparency, Suspended matter, Acidity and dissolved Oxygen) and of the analyses in the laboratory (NO sub(3), NO sub(2) , NT, PO sub(4) , Chlorophyll-a, Pheopigment and MES). For better characterizing the state of the lagoon a statistical analysis was applied to the hydrobiological data obtained. This analysis consists in applying the technique of Principal Components Analysis (ACP) and the technique of the Ascending Hierarchical Clustering (CAH) with flexible bonds. The last stage consists in using the Method of the Equivalent Vectors (EVM) in order to identify the significant hydrobiological parameters. This study showed that the space distribution of the parameters is strongly related to the contributions of fresh waters. With the opposition to mineral phosphorus the total nitrogen content shows a significant space variation. The analysis of the spatial distribution of the nutriments on the one hand and chlorophyll-a on the other hand suggests a close connection between the quantity of the phytoplankton and the availability of mineral phosphorus. The statistical analysis made it possible to distinguish five areas the Narrow part, the conchylaceous zone, the littoral zone, the eastern, the western part and the central part.