Coral reefs develop in shallow tropical waters around the calcareous structures built by coral animals that harbor photosynthesizing algal cells within their bodies. Corals thrive under conditions of high light, stable warm temperatures, clear water, low nutrient supply, and vigorous grazing that removes competing algae. Coral reefs are often referred to as ‘rainforests of the sea’, harboring diverse communities of all types of organisms. Coral reefs are also very important to people, providing services in the form of fisheries, shoreline protection, and tourism revenues estimated at 30 - 172 billion U.S. dollars per year. Thriving reefs require a narrow set of environmental conditions that are changing rapidly under human impact, primarily as a result of climate warming, coastal development, and overfishing.
MarineGEO protocols, listed below, provide a standardized set of measurements for characterizing the changing structure and health of coral reef communities, including coral cover and physical structure, coral demography and disease, and community composition of corals and fishes. The data collected are meant to be inter-comparable with those of other major reef monitoring programs, including the Global Coral Reef Monitoring Network (GCRMN), Reef Life Survey, and the Atlantic and Gulf Rapid Reef Assessment (AGRRA).
Coral reef community sampling has several components: (1) photoquadrat-based measurements of benthic species composition (corals and other sessile organisms) and percent cover; (2) rugosity or structural complexity; and (3) diver visual censuses of fishes. Detailed protocols are provided in the linked modules below.