At what spatial scales are alternative stable states relevant in highly interconnected ecosystems?

Area of Science:

• Marine ecology
• Ecological modeling
• Conservation biology

Background:

• Alternative stable states (ASS) are crucial for ecosystem resilience but lack empirical evidence in interconnected systems.
• High species interconnectedness and dispersal may homogenize ecosystem states, eroding local ASS.
• Understanding ASS dynamics in complex, open systems is vital for effective conservation.

Purpose of the Study:

• To investigate the role of interconnectedness and local feedbacks in maintaining alternative stable states in temperate rocky reef ecosystems.
• To model the spatial scales at which alternative stable states can persist despite regional dispersal.
• To identify key drivers, such as environmental variation and local human impacts, that influence the duration and extent of alternative stable states.

Main Methods:

• Developed dynamical models of California rocky reef communities, incorporating kelp-urchin-predator interactions.
• Included environmental stochasticity and feedback loops affecting disperser settlement.
• Analyzed the influence of interconnectedness and spatial scales on the emergence and persistence of alternative stable states.

Main Results:

• Models predicted the potential for localized alternative stable states in highly interconnected reef systems.
• Feedbacks at the disperser settlement stage were identified as critical for maintaining local ASS.
• Regional analysis revealed a mosaic of alternative stable states spanning 10-20 km, despite long-distance dispersal.
• Environmental variation and local dynamics, like fishing, significantly influenced the spatial scale and duration of these states.

Conclusions:

• Alternative stable states can persist in interconnected marine ecosystems due to local settlement feedbacks.
• These feedbacks create regional mosaics of community states, challenging the homogenizing effect of dispersal.
• Model predictions align with observed community structures in California rocky reefs, offering insights for managing similar systems globally.