Developing and testing spatial indicators of ecosystem stability for subtidal seascapes
Predicting upcoming changes in ecosystems has become one of the priorities of current ecological research and conservation. This is especially crucial for ecosystems where large, durable ecological shifts – hereafter regime shifts – may occur following an increase in stressors (e.g. ocean temperature) or after perturbation events (e.g. hurricanes, fisheries). Because experimentally investigating regime shifts in ecosystems often requires large, impractical disturbance experiments, mathematical models have been used to investigate the factors underpinning such shifts, and predict where and when they might occur in a given ecosystem. This research effort has led to the development of indicators (metrics) based on the observed spatial structure of an ecosystem, which can inform on the proximity of a regime shift. While this approach has been explored for terrestrial ecosystems, virtually no work has been done to apply it to marine ecosystems, and in particular sub-tidal systems (e.g. coral reefs, algal beds). Yet, at least 500 million people depend on these ecosystems at global scale, and their potential for regime shifts in the current context of global changes has been extensively reported by the scientific and global policy literature. This project aims at opening a new research avenue by extending the previous approaches designed for terrestrial ecosystems to develop novel indicators of upcoming regime shifts for sub-tidal systems. We will do so by successively (1) develop a realistic, spatially-explicit model of ecological dynamics, using the coastal ecosystems of Easter Island as model systems; (2) derive indicators of upcoming shifts in coral reefs and algal beds and validate them on empirical data, and; (3) implement our results in widely-available software. Achieving these goals will advance our ability to predict regime shifts and ultimately provide globally-applicable indicators of ecosystem fragility for sub-tidal systems.