Coral associations and space competitors of Pedum spondyloideum (Gmelin, 1791) (Bivalvia, Pteriomorphia, Pectinidae) from the northeast coast of Sulawesi, Indonesia

On the northeast coast of Sulawesi, Indonesia, several species of scleractinian corals are used as hosts by the nestling and facultatively boring pectinid bivalve Pedum spondyloideum, including the previously unrecorded hosts Acropora robusta, Coeloseris mayeri, Montipora confusa, Porites monticulosa and P. evermanni. Porites is the favourite host genus and the maximum density (7 specimens) occurs in both Porites lutea and P. lobata. Pedum is restricted to shallow water (2-16 m depth) and there is no relationship between the number of individuals associated with scleractinian host corals and the depth. Local distribution indicates that Pedum is most common in sheltered areas; some exposed sites are completely devoid of individuals. Competitors (nestling and boring organisms) are only observed in massive colonies of the coral genus Porites (P. lutea and P. lobata).