Coral reef baselines: how much macroalgae is natural?

John F Bruno, William F Precht, Peter S Vroom & Richard B. Aronson
Identifying the baseline or natural state of an ecosystem is a critical step in effective conservation and restoration. Like most marine ecosystems, coral reefs are being degraded by human activities: corals and fish have declined in abundance and seaweeds, or macroalgae, have become more prevalent. The challenge for resource managers is to reverse these trends, but by how much? Based on surveys of Caribbean reefs in the 1970s, most reef scientists believe that the average...