Data came from a broader analysis on the effects of offshore gas production on the benthic macrofauna assemblages far from Crotone (Ionian Sea, Italy, data unpublished). Data were collected in June 2005. There were two gas platforms for each of the two bathymetric ranges (30-40m and 70-90m). Sampling locations were established at increasing distances from the four platforms (300 m, 1000 m, 3000 m). For each of the three distances, five sites were randomly selected and, at each site, samples were taken in three replicates with a 0.1 m2 van Veen grab. Samples were sieved through a 0.5 mm mesh, preserved in 5% buffered formalin, and stained with 1% Rose Bengal for later sorting and identification. For molluscs, the final dataset consisted of 219 species on a total of 8694 individuals.