Epi- and endobiont faunal communities on an Egyptian Mediterranean rocky shore: Species composition and their competition for space

Abstract

The exposed calcareous rocky area of the Abu Qir Headland, east of Alexandria, Egypt whichrange from coarse grains, through pebbles, cobbles, and boulders to rocky platforms, was significantlycolonized by sclerobionts (epibionts and endobionts). The epibiont species diversity was comparativelyhigher than that of endobionts. Epibiont communities included bryozoans (the anascan-grade cheilostomeBiflustra savartii), serpulid (Hydroides elegans, Spirobranchus cf. tetraceros, Vermiliopsis striaticepsand Protula or Apomatus) and spirorbid (Spirorbis) wormtubes, and balanoid barnacles (Amphibalanusamphitrite, Balanus trigonus, and Perforatus perforatus). The cheilostome bryozoan colonies, whichdeveloped extensive sheets, proliferated on the study rocky shore either encrusting the bioeroded basementdirectly, or encrusting other epilithic taxa, particularly balanoid barnacles and serpulid worms. Encrustersdisplayed a remarkable marginal competitive interaction (overgrowth and stand-off) for space on the studyrocky shore. On the other hand, endobionts were not well represented on the studied rocky shore exposure.It was possible to identify three ichnotaxa: Gastrochaenolites, Maeandropolydora, and Finichnus. Thefindings documented represent a significant contribution to our knowledge of sclerobionts composition,sequence of their colonization and/or bioerosion, and their mutual relationships on the intertidal rocky shoreof the Abu Qir Headland.