Associations of coral and boring bivalves: Lizard Island (Great Barrier Reef, Australia) versus Safaga (N Red Sea)

Although certain coral and Lithophaga species are present in both areas, the respective associations differ regionally distinctively in L. laevigata and L. simplex. Most bivalve species have a variety of hosts, but a few seem to be restricted to a single coral genus. Different genera of bivalves may be found in the same host specimen. In contrast to coral rock, where several different boring bivalves can occur next to each other, rarely more than one Lithophaga species is found per host colony, although it happens in both areas. On the other hand, the same coral species may be inhabited by one species of Lithophaga in one area and (mainly) by another in the other area. In Lithophaga, more associations are established at Lizard than at Safaga, while in Pedum it is the other way round. Altogether, more different associations can be noted than equal ones. Generally, coral-bivalve associations are regionally stable and do not overlap. Thus, host determination should yield the bivalve identity, too.