CONICET | Buscador de Institutos y Recursos Humanos

Salinity is one the major stress factors that controls the biotic activities in marine environments. Ingeneral, the mixture with fresh-water has been mention as a great stress factor, but the opposite, i.e.high-salinity conditions, is less developed in the ichnological literature. Along the Al-Khafji coastline,Saudi Arabia, hard substrates (constituted by gastropods, bivalves and coral skeletons) contain diverseand abundant bioerosion traces and associated encrusters. Field and laboratory observations allowed therecognition of eight ichnospecies belong to the ichnogenera Gastrochaenolites, Entobia, Oichnus, Caulostrepsisand Trypanites, which can be attributed to various activities produced by bivalves, sponges, gastropodsand annelids. The borings demonstrate two notable ichnological boring assemblages, namely,Entobia-dominated and Gastrochaenolites-dominated assemblages. The highly diversified bioerosion andencrustation in the studied hard organic substrate indicate a long exposition period of organic substratewith slow to moderate rate of deposition in a restricted (high-salinity) marine environment. This bioerosionstudy shows that high-salinity, at least for the study area, is not an important controlling factorfor ichnology.