Corallivorous Fish Have Reduced Population Sizes and Altered Foraging Behaviour on a Recently Restored Coral Reef

Area of Science:

• Marine biology
• Ecosystem restoration
• Coral reef ecology

Background:

• Ecosystem restoration globally prioritizes biodiversity recovery.
• Current coral reef restoration often focuses solely on coral cover, neglecting broader ecosystem impacts.
• Trophic networks and community development are crucial for assessing restoration success.

Purpose of the Study:

• To investigate the re-establishment of reef fish trophic groups following coral restoration.
• To assess the impact of rapid coral recovery on fish community development.
• To understand the recovery dynamics of specialist corallivores in restored reef systems.

Main Methods:

• Monitoring coral cover and fish abundance at a large-scale coral restoration project.
• Comparing fish trophic groups (herbivores, planktivores, omnivores, corallivores) between restored and reference reefs.
• Conducting feeding observations to analyze dietary selectivity of butterflyfish (Chaetodon octofasciatus).

Main Results:

• Coral cover recovered to reference levels within 4-6 years.
• Herbivore, planktivore, and omnivore fish abundances rapidly recovered.
• Corallivore abundance increased but remained at half that of reference sites.
• Butterflyfish exhibited higher dietary selectivity and larger foraging areas on restored reefs due to reduced availability of preferred coral morphotaxa.

Conclusions:

• Rapid coral cover recovery does not guarantee immediate re-establishment of all fish trophic groups, especially specialists.
• The slower recovery of specific, slower-growing coral morphotaxa limits specialist corallivore recovery.
• Achieving full trophic complexity and ecological balance in restored coral reefs requires extended timeframes beyond initial coral regrowth.