Forecasting intensifying disturbance effects on coral reefs.

Area of Science:

• Marine ecology
• Coral reef ecosystems
• Climate change impacts

Background:

• The Great Barrier Reef (GBR) faces significant threats from climate change, leading to rapid shifts in hard coral (HC) communities.
• While HC responses to disturbances are documented, other benthic communities' reactions remain poorly understood.

Purpose of the Study:

• To statistically model the effects of climate-related disturbances on benthic communities in the GBR.
• To predict the future structure of these communities under increasing disturbance frequencies and interactions.

Main Methods:

• Utilized a multivariate statistical model parameterized with 145,000 benthic observations from the northern GBR (2012-2017).
• Analyzed data from reefs impacted by tropical cyclones and heat stress events to assess disturbance effects.

Main Results:

• Discrete disturbances promoted algae over HC.
• The interaction between cyclones and heat stress was the primary driver for increased soft corals (SC) relative to algae and HC.
• Disturbance scenarios predict variable increases in algae versus SC based on frequency and interaction types.

Conclusions:

• Combined disturbances significantly alter coral reef benthic community structure.
• Further research is needed to understand algae and SC responses to HC decline and the uncertainty in predicting community composition under multiple stressors.
• Developing models for multiple disturbance impacts is essential for coral reef management and predicting future ecosystem states.