摘要：The structure, diversity and spatial distribution of the amphipod fauna associated with Posidonia oceanica meadows were studied along the Tunisian coasts in 2007. Samples were collected in nine different meadows at 2 m depth. A total of 44 species belonging to 12 families were collected. The most common species in terms of abundance were Ampithoe helleri , Hyale camptonyx and Ericthonius punctatus . The highest values of abundance and species richness and the lowest values of diversity and equitability were found in meadows with high epiphyte biomass. Multivariate analyses of data indicated that epiphyte biomass and geographical position were major determinants of the distribution and composition of amphipod assemblages along Tunisian coasts. The presence of two lessepsian amphipod species in one of the southern Posidonia oceanica meadows modified the structure of assemblage.
