Herbivory and Temperature Mediate Coral Reef Halo Dynamics

Area of Science:

• Marine ecology
• Reef ecosystems
• Grazing dynamics

Background:

• Reef halos are vegetation-free zones around reefs.
• Factors influencing reef halo prevalence and size are not fully understood.
• Biotic (herbivory) and abiotic (temperature, nutrients) factors are potential drivers.

Purpose of the Study:

• To investigate the impact of herbivore biomass, primary productivity, temperature, and nutrients on reef halo presence and width.
• To combine field observations with mechanistic modeling to understand halo dynamics.

Main Methods:

• Field study using artificial reef structures to observe halo formation.
• Development and application of a consumer-resource model incorporating environmental drivers.
• Analysis of interactions between herbivorous fish biomass and temperature.

Main Results:

• Reef halos were more prevalent with high herbivorous fish biomass.
• Halo size increased with higher temperatures.
• An interaction effect showed halos were more likely under low temperatures when herbivore biomass was high.
• Modeling indicated environmental drivers can induce temporal fluctuations in halo width and fish density.

Conclusions:

• Herbivore biomass and temperature significantly influence reef halo characteristics.
• Environmental drivers play a crucial role in grazing patterns and halo dynamics.
• Findings are vital for predicting reef ecosystem changes due to climate change.