Periphytic diatoms growing on aquatic turtle carapaces provide an interesting example of biofouling on an animal substrate. This study dealt with the question of the specificity of epizoic diatom communities for the case of the European pond turtle (Emys orbicularis) and across five water bodies in South-Eastern France. 375 diatom taxa have been identified on the European pond turtle carapace. The results showed that the epizoic communities of the five sites were significantly different from each other. The epizoic diatom communities could be clearly distinguished from epilithic and epiphytic communities only in two out of five sites. The differences in composition at the two sites resulted from the greater abundance of some species and life forms. However, the characteristic pattern of diatom communities on the carapaces was not the same at the two sites. It therefore appeared that the European pond turtle’s carapace did not harbour specific diatom communities and can rather be considered a neutral substrate.