Macroalgae may be a misleading indicator of coral reef health

Climate change and human disturbance threatens coral reefs across the Pacific, yet even within the field of marine conservation, there is little consensus on what characterizes a “healthy” reef. Benthic cover, particularly... [ view full abstract ]

Climate change and human disturbance threatens coral reefs across the Pacific, yet even within the field of marine conservation, there is little consensus on what characterizes a “healthy” reef. Benthic cover, particularly low coral cover and high macroalgae cover, are often used as an indicator of reef degradation, despite uncertainty about the typical algal community compositions associated with either near-pristine or damaged reefs. In this study, we assess taxa-level response to human disturbance, past heat stress and exposure by contrasting 25 sites along a gradient of human disturbance in Majuro and Arno Atolls of the Republic of the Marshall Islands. The results show that total macroalgae cover indicators of reef degradation may mask the influence of local human disturbance. Instead, identifying macroalgae to a lower taxonomic level (e.g. the genus level) would provide a more accurate measure of Pacific coral reef health, which is critical for the effective conservation of coral reefs.