Octocoral dynamics over a decade on Florida's coral reef

Area of Science:

• Marine Ecology
• Coral Reef Biology
• Benthic Ecology

Background:

• Octocorals are increasingly dominant on western Atlantic reefs, outcompeting scleractinians.
• Florida's Coral Reef (FCR) has abundant octocorals that show resilience to disturbances.
• Assessing octocoral resilience requires more than just cover; recruitment and survival are key.

Purpose of the Study:

• To investigate spatiotemporal trends in arborescent octocorals on FCR using multiple metrics.
• To analyze octocoral responses to disturbances, including marine heatwaves and hurricanes.
• To evaluate the role of recruitment and survival in octocoral population dynamics and resilience.

Main Methods:

• Utilized a decade-long dataset (2013-2023) of octocoral cover, density, and recruit density across FCR.
• Employed generalized mixed-effects models to analyze temporal and spatial trends.
• Correlated changes in octocoral metrics with major disturbance events like marine heatwaves and hurricanes.

Main Results:

• Octocoral cover slightly declined (1.67%) from 2013-2023, but density increased by 33.7%, indicating a community shift.
• Recruitment surged in the latter study half, boosting density in some areas beyond pre-disturbance levels.
• Hurricane Irma (2017) caused significant declines; recent disturbances (Hurricane Ian, 2022, and 2023 heatwave) impacted the Florida Keys.

Conclusions:

• Octocorals exhibit remarkable resilience on FCR, with rapid recovery via recruitment after acute disturbances.
• While density recovers quickly, achieving pre-disturbance percent cover requires sustained growth and survival.
• A multi-metric approach is crucial for understanding octocoral dynamics and their response to environmental stressors.