Characterising the effectiveness of coral restoration to build reef resilience: a socio-ecological perspective

Hein, Margaux Yvonne Sophie (2018) Characterising the effectiveness of coral restoration to build reef resilience: a socio-ecological perspective. PhD thesis, James Cook University.

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Abstract

Coral restoration is rapidly becoming a mainstream strategic reef management response to address dramatic declines in coral cover worldwide. Restoration success can be defined as increased resilience of the restored reef areas leading to improved ecosystem services, with multiple socio-cultural and economic benefits. However, there is often a mismatch between the objectives of coral restoration programs and the measures used to assess their effectiveness. In particular, scales of ecological benefits currently assessed are limited in both time and space, and very few studies account for potential socio-cultural and economic benefits. The research presented in this thesis explores the effectiveness of current long-term restoration programs across the socio-ecological spectrum and provides best-practice recommendations on how coral restoration can be used to improve reef resilience.

In Chapter 2, I review the literature to identify current measures of coral restoration success. I found that current measures of coral restoration effectiveness are largely limited to evaluating the short-term, biological responses of coral fragments to transplantation. Over 50% of current studies measure coral restoration success solely through two indicators: fragment survival and growth. Additionally, 53% of these studies monitor restoration outcomes for only one year post-transplantation at most; only 5% of studies monitored outcomes for longer than five years. To address the lack of measures assessing the success of restoration programs against key socio-ecological principles, I developed an integrated scale of coral restoration effectiveness based on ten indicators of reef and social resilience. These were: three ecological indicators linked to the structural integrity of reefs (benthic cover, structural complexity, and coral diversity); three ecological indicators linked to the functional integrity of reefs (coral recruitment, coral health, and fish biomass); and four socio-cultural and economic indicators of social resilience (satisfaction, stewardship, capacity building, and economic benefits). In Chapters 3 to 6, I test the efficacy of these indicators by evaluating the overall socio-ecological effectiveness of four well-established coral restoration programs in Thailand, the Maldives, the Florida Keys, and St Croix in the US Virgin Islands. All four programs have practiced coral restoration for eight to 12 years, but use different coral restoration methodologies, including a variety of artificial structures (Thailand), transplantation onto steel-frames (the Maldives), and direct transplantation onto the reef substrata (Florida Keys and Virgin Islands). The four programs are located in different reef regions, each with specific socio-economic settings, making them good case studies to evaluate the effectiveness of coral restoration.

In Chapters 3 and 4, I explore the effect of restoration practices on the structural and functional integrity of reefs, both of which are integral to improving ecosystem services. At the four program locations, I compare coral assemblages (Chapter 3) and fish communities (Chapter 4) at restored sites with those at neighbouring degraded sites and at nearby control reference sites. I found that hard coral cover and structural complexity were consistently greater at restored compared to unrestored (degraded) sites. However, patterns in coral diversity, coral recruitment and coral health among restored, unrestored and reference sites varied across locations, highlighting differences in methodologies among restoration programs. Altogether, differences in program objectives, methodologies and the state of nearby coral communities were key drivers of variability in the responses of coral assemblages to restoration.

It is a common assumption that coral restoration efforts will result in an increase in both the abundance and diversity of reef fishes, thereby improving ecosystem function and restoring some ecosystem services. However, very few studies have specifically looked at the response of the fish assemblage to coral restoration. Results presented in Chapter 4 demonstrate that the responses of fish assemblages are more complex than expected, with location-, site- and size-specific responses. Overall, I found that fish communities did not show overly strong and/or clear responses to the outcomes of any of the restoration programs.

The results for the six ecological indicators varied across my four study locations, highlighting the varied potential for coral restoration to improve ecological resilience. I found positive results for structural indicators at all four locations, but indicators linked to functional integrity only improved in response to the Thailand program, particularly in response to steel structures and concrete reef balls that held a diversity of corals above the substratum. Comparisons among programs revealed that the limited diversity in the corals used in restoration was an issue for the ecological resilience of restored sites in the Maldives, and high disease susceptibility of monospecific stands of target species of Acropora was an issue in both the St Croix and Florida Keys programs. Factors likely to affect fish colonisation of restored sites, such as connectivity to healthy fish populations, timing of colonisation, and complexity and coral diversity at the restored sites, require further consideration.

Understanding local stakeholders' perceptions of restoration success is critical to better integrate their needs in the planning, management and ultimately the long-term sustainability of restoration efforts. In Chapters 5 and 6, I evaluate the socio-cultural and economic indicators of restoration success by evaluating local stakeholders' perceptions of their respective restoration programs. In Chapter 5, I use semi-structured interviews to identify the perceived benefits and limitations of coral restoration efforts. Respondents were stratified across groups of people involved first-hand in the restoration efforts and members of the local community. Stakeholders' perceptions of coral restoration effectiveness encompassed far more than just ecological considerations, suggesting that coral restoration can be a powerful tool to enhance agency, hope and stewardship, thereby strengthening coral reef conservation strategies. Respondents also revealed key points likely to improve the outcomes of coral restoration efforts, such as the need to better embrace socio-cultural dimensions in goal setting, evaluate ecological outcomes more broadly, secure long-term funding and improve management and logistics of day-to-day practices.

In Chapter 6, I use semi-structured interviews to assess local stakeholders' perceptions of the socio-cultural and economic outcomes of coral restoration across the four socio-cultural indicators developed in Chapter 2. I firstly examine the subjectivity and context dependencies of people's perceptions about program success. Results revealed complex perceptions that varied among locations and groups of respondents. Secondly, I compare their perceptions of ecological outcomes to the ecological results my underwater surveys revealed about the responses of coral and fish assemblages to restoration (Chapters 3 and 4). Altogether, stakeholders generally perceived that the outcomes of coral restoration are highly important across all four socio-cultural and economic indicators of social resilience. In particular, the importance of restoration for two metrics, reef stewardship and user satisfaction, were consistently rated as very high at all four locations, highlighting the strong potential for coral restoration to improve the resilience of local communities. Responses suggest that increased involvement of local communities and improved communications of objectives and results could maximise the successful delivery of socio-cultural and economic outcomes within the respective local communities.

Finally, I integrate the physical and social results from this study to develop best-practice recommendations for the use of coral restoration as a management strategy to improve reef resilience across the socio-ecological spectrum. Recommendations for maximising ecological components of resilience include designing restoration structures to maximise complexity and coral diversity, selecting sites to maximise biological connectivity and site qualities like water quality and depth. Recommendations for improving the socio-cultural benefits of restoration include increasing and sustaining engagement of local communities and key stakeholders, securing long-term funding, and providing strong leadership.

This thesis demonstrates that the potential for coral restoration efforts to improve the socio-ecological resilience of degraded reef systems is high but complex, as potential can vary across restoration programs with different objectives, designs and management strategies. The ten indicators of coral restoration effectiveness synthesised and tested herein are practical tools for improving the long-term monitoring of such efforts. While climate action is needed first and foremost to address dramatic, climate-change driven declines in the world's coral reefs, results from this thesis demonstrate that coral restoration can be used as a valuable tool to improve the resilience of both coral reefs and the local communities that rely on them.

Item ID: 59793
Item Type: Thesis (PhD)
Keywords: coral restoration, ecosystem services, resilience, socio-ecological systems, sustainability
Related URLs:
Copyright Information: Copyright © 2018 Margaux Yvonne Sophie Hein
Additional Information:

Publications arising from this thesis are available from the Related URLs field. The publications are:

Chapter 2: Hein, Margaux Y., Willis, Bette L., Beeden, Roger, and Birtles, Alastair (2017) The need for broader ecological and socioeconomic tools to evaluate the effectiveness of coral restoration programs. Restoration Ecology, 25 (6). pp. 873-883.

Chapter 5: Hein, Margaux Y., Birtles, Alastair, Willis, Bette L., Gardiner, Naomi, Beeden, Roger, and Marshall, Nadine A. (2019) Coral restoration: socio-ecological perspectives of benefits and limitations. Biological Conservation, 229. pp. 14-25.

Date Deposited: 13 Aug 2019 05:10
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050207 Environmental Rehabilitation (excl Bioremediation) @ 40%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050205 Environmental Management @ 40%
16 STUDIES IN HUMAN SOCIETY > 1608 Sociology > 160802 Environmental Sociology @ 20%
SEO Codes: 96 ENVIRONMENT > 9612 Rehabilitation of Degraded Environments > 961299 Rehabilitation of Degraded Environments not elsewhere classified @ 50%
96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960507 Ecosystem Assessment and Management of Marine Environments @ 50%
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