Sleeping functional group drives coral-reef recovery

Area of Science:

• Marine Biology
• Ecology
• Conservation Science

Background:

• Coral reefs worldwide face decline, shifting from coral to macroalgal dominance.
• This phase shift is linked to habitat loss and overfishing of herbivorous fish like parrotfish and surgeonfish.
• Enhancing coral reef resilience is a critical ecological challenge.

Purpose of the Study:

• To investigate the drivers of phase-shift reversal in coral reef ecosystems.
• To determine the role of herbivorous fishes in reversing macroalgal dominance.
• To identify key species for maintaining coral reef health and regeneration.

Main Methods:

• Conducted a large-scale, experimentally induced phase shift on a coral reef.
• Monitored changes in ecosystem state (coral vs. macroalgal dominance).
• Assessed the herbivory impact of various fish species, including parrotfish, surgeonfish, and batfish (Platax pinnatus).

Main Results:

• Rapid reversal from macroalgal to coral/epilithic algal dominance was observed.
• The reversal was primarily driven by the batfish (Platax pinnatus), previously thought to be an invertebrate feeder.
• Traditional herbivorous fishes (parrotfish, surgeonfish) played a minor role in the phase-shift reversal.

Conclusions:

• The resilience of complex ecosystems like coral reefs may depend on unexpected keystone species.
• Biodiversity alone may not guarantee protection or reversal of phase shifts in these ecosystems.
• Identifying and protecting specific functional groups, like the batfish, is vital for coral reef regeneration and conservation.