Tropical coral reefs are under pressure from a suite of global and local stressors. In this article, Anthony and colleagues present a quantitative model for the resilience of benthic coral reef communities under combinations of ocean acidification, global warming, overfishing and nutrification. Projections for a high CO2 emission scenario alone can drive reefs from coral to macroalgal dominance, but such community phase shifts are likely to occur faster and more dramatically under herbivore overfishing and nutrient enrichment. Safeguarding coral reefs in the 21st century will require urgent solutions to the global carbon problem as well as strong management of local disturbances.
Photo courtesy of Jeff Maynard

Photo courtesy of Guillermo Diaz-Pulido

Photo courtesy of Guillermo Diaz-Pulido

Grazing Herbivores
Photo courtesy of GBRMPA image library

Healthy reef, Lady Elliot Island
Photo courtesy of Paul Marshall

• Impacts from increasing atmospheric carbon dioxide and pressures from other man-made stressors like overfishing and reduced water quality can in combination push coral reefs from spectacular places of biodiversity to species-poor areas covered in seaweeds.
• The recent modeling study by Anthony and colleagues show that vigilant protection of coral reefs from overfishing and pollution can buy reefs some time until carbon emissions are reduced.
• Elimination of local stressors can not compensate for the increasing stress on reefs from CO2 driven warming and acidification, however.
• Reduced global carbon emissions as well as vigilant management of local-scale stressors is the only recipe for healthy coral reefs in the 21st century.

Photos courtesy of Paul Marshall and Ken Anthony

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