Definition and Importance:
Live coral cover refers to the percentage of a reef's surface covered by living hard corals. It is a primary indicator of reef health, as corals are foundational species that provide essential habitat, structure, and biodiversity. High live coral cover suggests a healthy reef ecosystem capable of supporting diverse marine life, protecting coastlines, and sustaining local fisheries and tourism.

While each reef has its unique characteristics, coral cover offers valuable insights, a “healthy” reef in the Mesoamerican Reef (MAR) region generally should exhibit:

• A relatively high percentage (more than 20%) of live stony coral cover, preferably from reef building species such as branching or massive boulder ones.
• A moderate percentage of crustose coralline, calcareous, and short turf algae.
• A low percentage of fleshy macroalgae.

A rapid decline in coral dominance can signal ecosystem stress and the loss of numerous ecosystem services.

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How Do We Measure it?
Using the Atlantic and Gulf Rapid Reef Assessment AGRRA protocol, live coral cover is measured using the point intercept transect method. Divers lay a transect line along the reef and record the substrate type at regular, predefined intervals (e.g., every 10 cm for 10m on each of six benthic transects per site). At each defined point along the transect line the species or taxa directly underneath that point is recorded.  The percentage of these points that include live coral provides the estimate of coral cover. This method provides a quantitative and replicable measure of coral cover across different reef sites.