MOLLUSCAN HARD-SUBSTRATE ASSOCIATIONS IN THE NORTHERN RED-SEA

The mollusc associations of 29 hard-substrate localities in the Northe rn Bay of Safaga (Red Sea, Egypt) were studied. The hard substrates we re classified into 7 types: reef flats, intertidal rock bottom, very s hallow subtidal conglomerate, Porites carpel, faviid carpet, platy scl eractinian association, Sarcophyton carpet. Based on a cluster analysi s the molluscs of these hard substrates can be classified into 5 group s: Group A is dominated by Dendropoma maxima, Chamoidea and Tridacna m axima, group B by Pedum spondyloideum, T. maxima and Coralliophila ner itoidea, group C by Chamoidea and Cerithium ruppelli, group D by Modio lus auriculatus, Chamoidea, Morula granulata and Nerita albicilla and group E by Chamoidea and Pitar hebraea. The latter group contains only samples which are generally poor in molluscs. Group A molluscs are di agnostic for reef flats, group B for Porites and faviid carpets, group C for Sarcophyton carpets and group D for tidal/shallow subtidal rock substrates. The different hard substrates are therefore characterized by diagnostic mollusc associations and some of them could also be ide ntified in the fossil record.