Settlement and colonization of epi-endobenthic communities on calcareous substrata in an underwater archaeological site.

Underwater archaeological sites represent assets of great value that are subjected to physical and biological stresses. The study of biological settlement on calcareous substrata is the first step to understanding the biodeterioration processes that take place on man-made structures (marble, statues, columns and other architectonic elements) in marine environments. To accomplish this objective, calcareous panels (30 x 30 cm) were immersed for 3, 6, 9 and 12 months along a north-south transect in marine protected areas of Baia (Naples). Both epilithic and endolithic assemblages were analyzed: the latter was observed by scanning electron microscope after the cast-embedding tech-nique had been used. After 1 year the epilithic community was still changing, with algae and pioneer species overgrown by encrusting organisms, and the endolithic assemblage dominated by cyanobacteria/chlorophyte traces. Changes of epilithics lead changes on endolithics. The initial phototrophic borers were replaced by more sciaphilous and competitive species; moreover, the first macroboring organisms arrived after the settlement of grazers. After 12 months of immersion, the rate of bioerosion was high, the material was deeply bored and all of the limestone surface was heavily covered.