Monday 5
Marine regime shifts around the globe : theory, drivers, and impacts
Norström Albert
› 11:05 - 18:00 (6h55)
› IFREMER Sète
Managing resilience to reverse phase shifts in coral reefs
Nicholas Graham  1, *@  , David Bellwood, Joshua Cinner, Terry Hughes, Albert Norström, Magnus Nyström, Shaun Wilson, Aaron Macneil@
1 : James Cook University
* : Corresponding author

Phase shifts (or regime shifts) from live coral dominance to fleshy macroalgae dominance have been well documented on Caribbean coral reefs, but are thought to be less problematic for Indo-Pacific coral reefs. Here we present empirical evidence of a widespread coral to algal phase shift on a system of Indo-Pacific coral reefs. Specifically, using data covering the entire granitic Seychelles and spanning nearly 2 decades, we document the unfolding of phase shifts on 9 out of 21 reefs following a major climate disturbance, and assess why some reefs are returning to coral dominance, whereas others have shifted to macroalgae systems. Building on this empirical example, we present a conceptual framework for reversing phase shifts in marine systems, with a focus on coral reefs. This framework recognizes that both coral-dominated and degraded coral reef ecosystems can be resistant to change. Typically, research and management has focussed on maintaining coral dominance and avoiding phase shifts to other species compositions, rather than weakening the resilience of coral reefs that are already degraded to return them to a coral-dominated state. Reversing degraded coral reef states will involve reducing local chronic drivers, such as fishing pressure and water quality. Reversals will also require innovative management of key ecological processes that both weaken the resilience of the degraded state and strengthen the resilience of the coral-dominated state. If human impacts are reduced and key ecological processes are enhanced, pulse disturbances, such as extreme weather events, and ecological variability may provide opportunities for a return to a coral-dominated state. Critically, achieving these outcomes will require a diverse range of integrated approaches to alter human interactions with reef ecosystems. Most approaches to coral reef management at present are small scale, and do not embrace the full range of social-ecological governance and management strategies available. We present some emerging strategies to manage reef resilience at large scales.

 

 This abstract is one of the listed talks in session proposal: " Marine regime shifts around the globe: theory, drivers, and impacts"


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