Chemical pollution of estuaries often affects the different compartments of this ecosystem. Pollutants are in water, sediment and biocenosis. Anthropogenic activity, responsible for this pollution, continues to grow. Thus, the assessment of the degree of this pollution has become a necessity.

In the present work, we have evaluated the content of four metallic elements (Fe, Zn, Cu, Pb) in the sediment of one of the most polluted estuaries of Morocco: the estuary of Sebou. At the same time we estimated the contents of these metallic elements in the muscle of two fish harvested in the same estuary: Anguilla anguilla L. and Mugil cephalus L.

The results showed that, for the four metal elements studied, the concentrations noted in the sediment vary from one season to another. Similarly, organ tissues of the species studied show concentrations of all metals evaluated. These contents differ according to the metals and according to seasons. These are the gills that bioaccumulate more metal followed by the liver and most often it is the muscle that bioaccumulates metal month. In addition, the degree of bioconcentration of iron and zinc in the tissues studied does not differ significantly among species. However, the concentration of copper seems to be higher in Anguilla anguilla and that of lead seems to be higher in Mugil cephalus.

The classification of the concentrations of the metals studied ranked in descending order of the average concentrations is the same as that noted in the sediment: Fe> Zn> Pb> Cu.