Coral reef ecosystems are among the most threatened ecosystems on Earth. Climate change and anthropogenic disturbances erode their resilience whereas the complexity of the systems challenges our capacity to secure their future. Managing coral communities in a rapidly changing environment requires understanding and predicting how coral species interact and respond (i.e., resist and recover) to disturbances. Simulation models can help better understand and predict ecosystems dynamics under different environmental scenarios. However, existing models usually only implement a limited number of processes and do not capture the high functional diversity typical of coral reefs. This constrains their applicability to real-world systems, and also limits the types of questions that can be addressed. We argue that more complex models are required for simulating important ecosystem characteristics such as emergent dynamics, tipping points, and chaotic behaviours in a context of increasing anthropogenic pressures and climate change.
Results/Conclusions
Here we introduce a spatially explicit and mechanistic agent-based model that simulates the dynamics of functionally diverse coral communities under different environmental conditions. The model represents processes at different spatiotemporal scales, their interactions, and the contribution of species functional diversity to ecosystem dynamics. It is the first model to implement numerous processes with such a degree of ecological details, both for species resistance and recovery as well as interspecific spatial competition. The model can be used to predict species composition under diverse scenarios of disturbance and to conduct experiments to explore the relationship between functional diversity and resilience. The model enables manipulation of the intensity and frequency of hydrodynamic (i.e., waves and cyclones) and thermal (i.e., bleaching) disturbances as well as grazing pressure, larval connectivity and sedimentation. The simulated coral community is completely configurable to represent real or fictitious reef systems and can be assembled by sampling species from their functional trait space. Ten functional traits are used to determine how each species grows, reproduces, competes and responds to disturbances. Most of the parameter values and submodels of ecological processes we implemented are based on empirical studies. The model has been calibrated and validated using empirical datasets of three Caribbean reefs and successfully reproduces interspecies dynamics and reef responses to bleaching and cyclone events. We present here some of the ecological processes and details implemented as well as the model calibration and validation.