Abstract .– The distribution of the marine biotic index (BI) and the trophic groups is proposed in this paper to assess the impact of environmental factors on the macro-zoobenthic assemblages of Tunis bay. The first approach is based on the subdivision of benthic fauna into five ecological groups. This subdivision is related to the degree of sensitivity to an environmental stress gradient. This enables to characterize the assemblages and the degree of dependence of their health on the disturbances. On the other hand, the spatial distribution of trophic groups gives a general tendency of population evolution. The method of functional groups shows that Tunis bay seems to be in a good state, except some areas which are more affected by disturbances and which could constitute, in the future, a potential threat if the environmental conditions get worse.