A critical evaluation of benthic phase shift studies on coral reefs

• Published in: Marine environmental research 2022-06, Vol.178, p.105667-105667, Article 105667
• Main Authors: Crisp, Samantha K., Tebbett, Sterling B., Bellwood, David R.
• Format: Article
• Language: English
• Subjects: Animals; Anthozoa; Barrier reefs; Benthic cover; Benthos; Coral Reefs; Ecosystem; Ecosystem function; Ecosystem management; Literature reviews; Marine ecology; Regime shift; Resilience; Variability
• ISSN: 0141-1136; 1879-0291
• DOI: 10.1016/j.marenvres.2022.105667

Coral reef decline has accelerated in the last two decades resulting in substantial research into the phenomenon of ‘phase shifts’ or ‘regime shifts’. However, the conclusions drawn from this research have been varied. Some of this variability may stem from methodological approaches, although the extent to which these factors have shaped our understanding remain largely unexplored. To examine this, we conducted a systematic review of the literature. In doing so, we revealed marked variability in the approaches used for studying phase shifts. Notably, very few studies clearly defined what they meant by phase shifts. Therefore, we developed a clarified definition of phase shifts, which specifically defined persistence and dominance. The applicability of this definition was tested on multi-decadal benthic composition data on the Great Barrier Reef. The number of shifts depended critically on the definition selected, suggesting that this may be a primary reason underpinning the variability in past results. [Display omitted] •Benthic phase shifts are a major sign of coral reef degradation.•Identifying phase shifts is challenging; no uniform, quantifiable thresholds exist.•A rigorous phase shift framework reveals phase shifts may be rare on coral reefs.•Our revised ‘phase shift’ definition is quantifiable and ecologically relevant.•Phase shift reversals may occur relatively frequently on coral reefs.