期刊
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
卷 370, 期 1659, 页码 -出版社
ROYAL SOC
DOI: 10.1098/rstb.2013.0269
关键词
phase-shift; hysteresis; kelp beds; sea urchin barrens; alternative stable states; tipping point
类别
资金
- Academic Career Development Scholarship, University of Tasmania
- Australian Research Council funds & Future Fellowship
- Natural Sciences & Engineering Research Council of Canada (NSERC)
- Tula Foundation
- Norwegian Research Council
- FONDECYT National Fund for Scientific & Technological Development
- Ministerio de Ciencia e Innovacion & CEI-Canarias, Campus Atlantico Tricontinental & Ministerio de Educacion
- University of Cape Town
- National Research Foundation
- Directorate For Geosciences [1232779] Funding Source: National Science Foundation
- Division Of Ocean Sciences [1232779] Funding Source: National Science Foundation
A pronounced, widespread and persistent regime shift among marine ecosystems is observable on temperate rocky reefs as a result of sea urchin overgrazing. Here, we empirically define regime-shift dynamics for this grazing system which transitions between productive macroalgal beds and impoverished urchin barrens. Catastrophic in nature, urchin overgrazing in a well-studied Australian system demonstrates a discontinuous regime shift, which is of particular management concern as recovery of desirable macroalgal beds requires reducing grazers to well below the initial threshold of overgrazing. Generality of this regime-shift dynamic is explored across 13 rocky reef systems (spanning 11 different regions from both hemispheres) by compiling available survey data (totalling 10 901 quadrats surveyed in situ) plus experimental regime-shift responses (observed during a total of 57 in situ manipulations). The emergent and globally coherent pattern shows urchin grazing to cause a discontinuous 'catastrophic' regime shift, with hysteresis effect of approximately one order of magnitude in urchin biomass between critical thresholds of overgrazing and recovery. Different life-history traits appear to create asymmetry in the pace of overgrazing versus recovery. Once shifted, strong feedback mechanisms provide resilience for each alternative state thus defining the catastrophic nature of this regime shift. Importantly, human-derived stressors can act to erode resilience of desirable macroalgal beds while strengthening resilience of urchin barrens, thus exacerbating the risk, spatial extent and irreversibility of an unwanted regime shift for marine ecosystems.
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