Etude de l’effet des facteurs du milieu sur la distribution des bactéries entériques dans la lagune de Bizerte (nord -Tunisie)

Abstract

The focus of the present study was to evaluate the effect of hyrobiological parameters on the spatial distribution of enteric bacteria (total coliform (TC) and fecal enterococci (FE)) in Bizerte lagoon (northern Tunisia). Thus, a seasonal survey (November 2004, April 2005, may 2005 and august 2005) of the total fecal pollutants was dealt simultaneously to measures of hydrobiological parameters within 41 stations, covering the entire surface of the lagoon. The climatic
parameters were provided by a meteorological station nearby the lagoon. The results obtained, showed high fecal bacterial counts in the sediment during all the period of survey. The sediments seemed to be the most favourable environment for survival and growth of enteric bacteria and it must be controlled with
the same degree as the water. Besides, we noted high loads in TC and FE for the entire coastal areas of the lagoon especially in front of the urban and
agricultural zones. The incoming of these bacteria were linked to (i) the rainfall, during the wintry season and to (ii) the increase of sewage discharge in summer due to the increasing in anthropogenic activities. Thus, statistical study revealed a positive correlation of TC and FE with temperature, salinity and sunshine period. The persistence of the indicator organisms notably during the summer season presents a sanitary risk on the shellfish as well as on the swimmers.