This species occurs in lagoons and bays and appears to be restricted to shallow, low-water motion environments.

This species is very rare in Kaneohe Bay, but used to be more abundant and occurred in large patches on some of the reef flats.

The main threats to M. dilatata include: 1) vulnerability to coral bleaching due to high temperatures (it was the first species to bleach during the 1996 event in Kaneohe Bay); 2) fresh water kills and exposure at extreme low tide; 3) habitat degradation and modification as a result of sedimentation, pollution, alien alga species (Gracilaria salicornia, Kappaphycus and Eucheuma spp.

The Hawaiian reef coral is a U.S. National Marine Fisheries Service Species of Concern.

[2] Coral collection is not allowed in the state waters of Hawaii without a research permit.