Coral reef baselines: how much macroalgae is natural?
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, some reef scientists believe that the average cover of seaweed was very low in the natural state: perhaps less than 3%. On the other hand, evidence from remote Pacific reefs, ecological theory, and impacts of over-harvesting in other systems all suggest that, historically, macroalgal biomass may have been higher than assumed. Uncertainties about the natural state of coral reefs illustrate the difficulty of determining the baseline condition of even well studied systems.
Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA. Electronic address: jbruno@unc.edu.
John F
JF
Bruno
Dial Cordy & Associates, Inc., 7310 Poinciana Court, Miami Lakes, FL 33014, USA.
William F
WF
Precht
Ocean Associates, contracted to NOAA Pacific Island Fisheries Science Center Coral Reef Ecosystem Division, 1125 B Ala Moana Boulevard, Honolulu, HI 96814, USA.
Peter S
PS
Vroom
Department of Biological Sciences, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901, USA.
Richard B
RB
Aronson
D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D018533:Biomass; D057894:Coral Reefs; D003625:Data Collection; D004463:Ecology; D012624:Seaweed / Q000254:growth & development*
Baseline; Coral reef; Macroalgae; Macroalgal cover; Phase shift; Seaweed