A method for gathering data pertaining to ecologically significant biological components of a reef habitat over small spatial scales. Because the method provides a quick “snapshot” of major reef biota during a single dive or snorkel survey, it is particularly useful in assessing remote areas that are only rarely visited and where little time can be spent. REA is usefully employed by Coral Reef Ecosystem Division (CRED) at the NMFS Pacific Island Fisheries Science Center. During research cruises to these remote areas, teams of CRED divers survey the reef communities in a comprehensive manner, recording species abundance, diversity, and spatial distribution simultaneously for four key components of the ecosystem: fishes, corals, other invertebrates, and algae. Specific protocols are followed for field work and subsequent laboratory analyses .