Mechanisms of resilience: empirically quantified positive feedbacks produce alternate stable states dynamics in a model of a tropical reef

Alternate stable states (ASS) theory is a dominant conceptual framework for understanding processes that support resilience of ecological communities in the face of multiple anthropogenic disturbances. For decades, coral reefs have been cited as a classic example of ASS, yet this position remains highly controversial, largely because convincing empirical evaluations have been elusive.

Using a combination of empirical measurements of positive feedback processes and simulation modelling, we assessed ASS in coral reefs of the Eastern Tropical Pacific (ETP) by identifying the potential for multiple basins of attraction from a mechanistic perspective.

Using bioassays of algal growth and consumption, we quantified two spatially localized positive feedback mechanisms on coral reefs: increasing herbivore activity associated with higher coral abundances and amelioration of nutrient limitation leading to higher algal growth in areas with higher algal abundance.

Analysis of a model of ben...