Artificial sampling units (ASUs) allow for standardized sampling in the marine environment. We deployed ASUs at three sites in the Bay of Marseille for 14 months to measure the diversity and community composition of macroinvertebrates within and among sites. Invertebrates were identified morphologically to the class level. At this resolution, variability within sites was high enough to obscure differences among sites in both taxonomic diversity and community composition. Future work will use metabarcoding techniques to study diversity at the species level, both in the Bay of Marseille and other sites in the Mediterranean and more regional European seas.