Sampling state and process variables on coral reefs

Area of Science:

• Marine Ecology
• Coral Reef Ecology
• Population Dynamics

Background:

• Coral reefs face disturbances across various scales, impacting their survival and recovery.
• Current monitoring often focuses on state variables (e.g., benthic coverage) but neglects crucial ecological processes.
• Understanding these processes is key to accurate predictive models for coral population trajectories.

Purpose of the Study:

• To outline a sampling strategy that captures both state and process variables in coral reefs.
• To examine spatial and temporal patterns in coral population size-frequency distributions.
• To determine major population processes (recruitment, mortality) and their relationship with state variables.

Main Methods:

• A nested sampling strategy was developed, with stations (10^3 m scale) nested within sites (10^4 m scale).
• Randomly selected quadrats (16 m^2) within stations track processes over time.
• Random belt-transects assess state variables, with re-randomization at each sampling event.

Main Results:

• The strategy enables capturing both state and process variables at a large spatial scale (tens of kilometers).
• It allows for the assessment of coral population size-frequency distributions and key processes like recruitment and mortality rates.
• The nested design facilitates comparisons of population performance and processes across disturbance events and regions.

Conclusions:

• This nested sampling strategy effectively captures critical population stages and performance metrics.
• It provides a framework for comparing ecological processes through disturbance events and across different regions.
• The approach enhances our ability to understand and predict coral reef population dynamics.