Seabirds boost coral reef resilience

Area of Science:

• Marine biology
• Ecology
• Climate change science

Background:

• Global climate change and increasing anthropogenic nutrients threaten tropical coral reefs.
• The impact of natural nutrient flows, like those from seabirds, on reef recovery is understudied.
• Invasive species, such as rats, can disrupt vital seabird-derived nutrient subsidies.

Purpose of the Study:

• To investigate how seabird-derived nutrient subsidies influence coral reef recovery mechanisms and patterns.
• To assess the effects of nutrient loss and restoration on reef resilience following a marine heatwave.
• To determine the role of natural nutrient pathways in coral growth and community dynamics.

Main Methods:

• Multiyear field experiments involving coral transplantation between islands with and without seabird influence.
• Repeated surveys to monitor coral growth, cover, and benthic community composition.
• Bayesian modeling to analyze nutrient assimilation and recovery trajectories.

Main Results:

• Transplanted corals rapidly assimilated seabird nutrients, acclimating within 3 years.
• Increased seabird-derived nutrients doubled coral growth rates at individual and reef scales.
• Seabird presence correlated with faster recovery of Acropora coral cover (<4 years) and more dynamic benthic communities.

Conclusions:

• Restoring seabird populations and their nutrient pathways can significantly enhance coral reef resilience.
• Seabird-derived nutrients promote coral growth and accelerate recovery rates, offering a viable restoration strategy.
• Natural nutrient subsidies are critical for mitigating the impacts of climate change on coral reef ecosystems.