To better understand the impacts of biofouling on the biological processes of the basibiont, the effects of epibiotic
barnacles on the relative growth and reproductive indices of Stramonita haemastoma (Linnaeus, 1767) were assessed.
A total of 1035 specimens were collected monthly for one year from Bizerta Channel (northern Tunisia). Endobiotic species
comprised the lithophagous bivalves Lithophaga aristata and Rocellaria dubia of different sizes, communicating with the
outside through tiny perforations. Intra-shell tunnels and galleries also sheltered annelids and sipunculids. Epibiotic species
comprised algae and highly diversified invertebrates represented by crustaceans, polychaetes, molluscs, echinoderms, ascidians,
sponges, bryozoans and sipunculids, with barnacles being the most common group. Comparison of growth features
between non-fouled and fouled S. haemastoma revealed higher growth in non-fouled specimens. Differences in reproductive
condition indices were detected in few months, being mostly higher in non-fouled snails, but showed no asynchrony in the
spawning period for either fouled or non-fouled gastropods hosts.