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Ceccarelli DM, McLeod IM, Boström-Einarsson L, Bryan SE, Chartrand KM, Emslie MJ, Gibbs MT, Gonzalez Rivero M, Hein MY, Heyward A, Kenyon TM, Lewis BM, Mattocks N, Newlands M, Schläppy ML, Suggett DJ, Bay LK. Substrate stabilisation and small structures in coral restoration: State of knowledge, and considerations for management and implementation. PLoS One 2020; 15:e0240846. [PMID: 33108387 PMCID: PMC7591095 DOI: 10.1371/journal.pone.0240846] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Coral reef ecosystems are under increasing pressure from local and regional stressors and a changing climate. Current management focuses on reducing stressors to allow for natural recovery, but in many areas where coral reefs are damaged, natural recovery can be restricted, delayed or interrupted because of unstable, unconsolidated coral fragments, or rubble. Rubble fields are a natural component of coral reefs, but repeated or high-magnitude disturbances can prevent natural cementation and consolidation processes, so that coral recruits fail to survive. A suite of interventions have been used to target this issue globally, such as using mesh to stabilise rubble, removing the rubble to reveal hard substrate and deploying rocks or other hard substrates over the rubble to facilitate recruit survival. Small, modular structures can be used at multiple scales, with or without attached coral fragments, to create structural complexity and settlement surfaces. However, these can introduce foreign materials to the reef, and a limited understanding of natural recovery processes exists for the potential of this type of active intervention to successfully restore local coral reef structure. This review synthesises available knowledge about the ecological role of coral rubble, natural coral recolonisation and recovery rates and the potential benefits and risks associated with active interventions in this rapidly evolving field. Fundamental knowledge gaps include baseline levels of rubble, the structural complexity of reef habitats in space and time, natural rubble consolidation processes and the risks associated with each intervention method. Any restoration intervention needs to be underpinned by risk assessment, and the decision to repair rubble fields must arise from an understanding of when and where unconsolidated substrate and lack of structure impair natural reef recovery and ecological function. Monitoring is necessary to ascertain the success or failure of the intervention and impacts of potential risks, but there is a strong need to specify desired outcomes, the spatial and temporal context and indicators to be measured. With a focus on the Great Barrier Reef, we synthesise the techniques, successes and failures associated with rubble stabilisation and the use of small structures, review monitoring methods and indicators, and provide recommendations to ensure that we learn from past projects.
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Affiliation(s)
- Daniela M. Ceccarelli
- Marine Ecology Consultant, Nelly Bay, QLD, Australia
- ARC Centre of Excellence for Coral Reef Studies, Townsville, QLD, Australia
- * E-mail: (DMC); (IMM)
| | - Ian M. McLeod
- TropWATER (Centre for Tropical Water and Aquatic Ecosystem Research), James Cook University, Townsville, Queensland, Australia
- * E-mail: (DMC); (IMM)
| | - Lisa Boström-Einarsson
- TropWATER (Centre for Tropical Water and Aquatic Ecosystem Research), James Cook University, Townsville, Queensland, Australia
- Lancaster Environment Centre, Lancaster University, Lancaster, United Kingdom
| | - Scott E. Bryan
- School of Earth & Atmospheric Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Kathryn M. Chartrand
- TropWATER (Centre for Tropical Water and Aquatic Ecosystem Research), James Cook University, Townsville, Queensland, Australia
| | - Michael J. Emslie
- Australian Institute of Marine Science, PMB 3 Townsville MC, Townsville, Queensland, Australia
| | - Mark T. Gibbs
- Australian Institute of Marine Science, PMB 3 Townsville MC, Townsville, Queensland, Australia
- Division of Business Development, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Manuel Gonzalez Rivero
- Australian Institute of Marine Science, PMB 3 Townsville MC, Townsville, Queensland, Australia
| | - Margaux Y. Hein
- TropWATER (Centre for Tropical Water and Aquatic Ecosystem Research), James Cook University, Townsville, Queensland, Australia
| | - Andrew Heyward
- Australian Institute of Marine Science, Indian Ocean Marine Research Centre, University of Western Australia, Crawley, Western Australia, Australia
| | - Tania M. Kenyon
- Marine Spatial Ecology Lab, The University of Queensland, St. Lucia, Queensland, Australia
| | - Brett M. Lewis
- School of Earth & Atmospheric Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Neil Mattocks
- Reef Joint Field Management Program, Great Barrier Reef Marine Park Authority, Townsville, Queensland, Australia
| | - Maxine Newlands
- TropWATER (Centre for Tropical Water and Aquatic Ecosystem Research), James Cook University, Townsville, Queensland, Australia
- School of Social Science, James Cook University, Townsville, Queensland, Australia
| | - Marie-Lise Schläppy
- Australian Institute of Marine Science, PMB 3 Townsville MC, Townsville, Queensland, Australia
- Faculty of Engineering, Oceans Graduate School, The University of Western Australia, Crawley, WA, Australia
| | - David J. Suggett
- Climate Change Cluster, University of Technology Sydney, Sydney, NSW, Australia
| | - Line K. Bay
- Australian Institute of Marine Science, PMB 3 Townsville MC, Townsville, Queensland, Australia
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Chartrand KM, Szabó M, Sinutok S, Rasheed MA, Ralph PJ. Living at the margins - The response of deep-water seagrasses to light and temperature renders them susceptible to acute impacts. Mar Environ Res 2018; 136:126-138. [PMID: 29503105 DOI: 10.1016/j.marenvres.2018.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 02/05/2018] [Accepted: 02/08/2018] [Indexed: 06/08/2023]
Abstract
Seagrasses inhabit environments where light varies at different timescales, nonetheless are acutely sensitive to reductions in light beyond some conditional bounds. Two tropical deep-water seagrasses, Halophila decipiens and Halophila spinulosa, from the Great Barrier Reef were tested for their response to defined light and temperature regimes to identify their growth requirements and potential thresholds of mortality. Species were exposed to two light intensities, saturating (75 μmol photons m-2 s-1) and limiting (25 μmol photons m-2 s-1) light and two temperature treatments (26 °C and 30 °C) over a four-week period. Wavelength-specific parameters of PSII photochemistry were evaluated for seagrass leaves, as well as shoot density, gas exchange, and pigment content. Both species were sustained under saturating light levels (3.2 mol photons m-2 d-1) while limiting light led to decreased shoot density for H. decipiens and H. spinulosa after two and four weeks, respectively. Wavelength-specific photochemistry was also affected under light-limiting treatments for both species while the functional absorption cross section was highly conserved. Photoacclimation and physiological adjustments by either species was not adequate to compensate for reduced irradiance suggesting these plants reside at the margins of their functional limits. As such, relatively short periods of light attenuating events, like dredging or flood plumes, may be detrimental to deep-water seagrass populations.
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Affiliation(s)
- Kathryn M Chartrand
- Centre for Tropical Water & Aquatic Ecosystem Research, James Cook University, Cairns, Queensland, Australia; Climate Change Cluster, University of Technology Sydney, Broadway, New South Wales, Australia.
| | - Milán Szabó
- Climate Change Cluster, University of Technology Sydney, Broadway, New South Wales, Australia; Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Sutinee Sinutok
- Climate Change Cluster, University of Technology Sydney, Broadway, New South Wales, Australia; Faculty of Environmental Management, Prince of Songkla University, Hat Yai, Thailand; Coastal Oceanography and Climate Change Research Center, Prince of Songkla University, Hat Yai, Thailand
| | - Michael A Rasheed
- Centre for Tropical Water & Aquatic Ecosystem Research, James Cook University, Cairns, Queensland, Australia
| | - Peter J Ralph
- Climate Change Cluster, University of Technology Sydney, Broadway, New South Wales, Australia
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Unsworth RKF, Rasheed MA, Chartrand KM, Roelofs AJ. Solar radiation and tidal exposure as environmental drivers of Enhalus acoroides dominated seagrass meadows. PLoS One 2012; 7:e34133. [PMID: 22479541 PMCID: PMC3315502 DOI: 10.1371/journal.pone.0034133] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 02/22/2012] [Indexed: 11/22/2022] Open
Abstract
There is strong evidence of a global long-term decline in seagrass meadows that is widely attributed to anthropogenic activity. Yet in many regions, attributing these changes to actual activities is difficult, as there exists limited understanding of the natural processes that can influence these valuable ecosystem service providers. Being able to separate natural from anthropogenic causes of seagrass change is important for developing strategies that effectively mitigate and manage anthropogenic impacts on seagrass, and promote coastal ecosystems resilient to future environmental change. The present study investigated the influence of environmental and climate related factors on seagrass biomass in a large ≈250 ha meadow in tropical north east Australia. Annual monitoring of the intertidal Enhalus acoroides (L.f.) Royle seagrass meadow over eleven years revealed a declining trend in above-ground biomass (54% significant overall reduction from 2000 to 2010). Partial Least Squares Regression found this reduction to be significantly and negatively correlated with tidal exposure, and significantly and negatively correlated with the amount of solar radiation. This study documents how natural long-term tidal variability can influence long-term seagrass dynamics. Exposure to desiccation, high UV, and daytime temperature regimes are discussed as the likely mechanisms for the action of these factors in causing this decline. The results emphasise the importance of understanding and assessing natural environmentally-driven change when interpreting the results of seagrass monitoring programs.
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Affiliation(s)
- Richard K F Unsworth
- Centre for Sustainable Aquatic Research, College of Science, Swansea University, Swansea, Wales, United Kingdom.
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