Definition and Importance:
The Reef Health Index (RHI) is a comprehensive metric used to assess the overall health of coral reef ecosystems. It combines four key indicators: coral cover, fleshy macroalgae cover, commercial fish biomass, and herbivorous fish biomass. By evaluating these indicators together, the RHI provides a holistic view of reef condition and resilience. Each indicator is assigned a condition rating on a scale from one (critical) to five (very good), allowing managers and interested community members  to easily understand the health status of a reef. This index is vital for guiding conservation efforts, informing management decisions, and monitoring changes in reef ecosystems over time.

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How It’s Measured:
The RHI is calculated by first measuring the four individual indicators using established survey methods, such as point intercept transects for coral and macroalgae cover, and fish belt transects for commercial and herbivorous fish biomass. The average values for each indicator are then converted into condition ratings using specific data ranges developed by a scientific review committee. These ranges are based on extensive data from the Atlantic and Gulf Rapid Reef Assessment (AGRRA) database, which includes information from over 800 reef sites across the Wider Caribbean. The RHI reflects a balanced approach, aiming to represent a realistic assessment of reef health by considering both ideal "pristine" conditions and what is currently achievable under present-day environmental and anthropogenic pressures.