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Global regime shift dynamics of catastrophic sea urchin overgrazing
Citation
Ling, SD and Scheibling, RE and Rassweiler, A and Johnson, CR and Shears, N and Connell, SD and Salomon, AK and Norderhaug, KM and Perez-Matus, A and Hernandez, JC and Clemente, S and Blamey, LK and Hereu, B and Ballesteros, E and Sala, E and Garrabou, J and Cebrian, E and Zabala, M and Fujita, D and Johnson, LE, Global regime shift dynamics of catastrophic sea urchin overgrazing, Royal Society of London. Philosophical Transactions. Biological Sciences, 370, (1659) Article 20130269. ISSN 0962-8436 (2015) [Refereed Article]
Copyright Statement
Copyright 2014 The Authors
DOI: doi:10.1098/rstb.2013.0269
Abstract
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.
Item Details
| Item Type: | Refereed Article |
|---|---|
| Keywords: | regime shift, marine ecology, overgrazing, temperate reefs, kelp beds, sea urchins |
| Research Division: | Biological Sciences |
| Research Group: | Ecology |
| Research Field: | Marine and Estuarine Ecology (incl. Marine Ichthyology) |
| Objective Division: | Environment |
| Objective Group: | Flora, Fauna and Biodiversity |
| Objective Field: | Marine Flora, Fauna and Biodiversity |
| Author: | Ling, SD (Dr Scott Ling) |
| Author: | Johnson, CR (Professor Craig Johnson) |
| ID Code: | 97071 |
| Year Published: | 2015 |
| Web of Science® Times Cited: | 42 |
| Deposited By: | IMAS Research and Education Centre |
| Deposited On: | 2014-12-02 |
| Last Modified: | 2016-09-04 |
| Downloads: | 0 |
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