Molluscan Hard‐Substrate Associations in the Northern Red Sea

The mollusc associations of 29 hard‐substrate localities in the Northern Bay of Safaga Red Sea, Egypt were studied. The hard substrates were classified into 7 types: reef flats, intertidal rock bottom, very shallow subtidal conglomerate, Porites carpet, faviid carpet, platy scleractinian association, Sarcophyton carpet. Based on a cluster analysis the molluscs of these hard substrates can be classified into 5 groups: Group A is dominated by Dendropoma maxima , Chamoidea and Tridacna maxima , group B by Pedum spondyloideum, T. maxima and Coralliophila neritoidea , group C by Chamoidea and Cerithium rüppelli , group D by Modiolus 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 diagnostic 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 identified in the fossil record.