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As coral cover in the Great Barrier Reef (GBR) continues to degrade, pressure is growing for direct interventions to assist the recovery of corals. A range of coral restoration and assisted recovery techniques have been trialed overseas and in Australia, however there has not to date been an evaluation of what will work best in GBR conditions. This project was established in 2017 to: (1) Review coral restoration methods around the world and assess the evidence of their success, (2) trial the most promising coral restoration techniques in GBR conditions, and (3) bring together knowledge of coral restoration techniques for best practice guidelines for the GBR. In this report we summarise the outputs and outcomes of the National Environmental Science Program Tropical Water Quality Hub Project 4.3 ‘Best practice coral restoration for the Great Barrier Reef’ (December 2017 - December 2020).
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Final Report
Best Practice Coral Restoration for
the Great Barrier Reef
Synthesis of Results
Ian M. McLeod, David Bourne, Daniela M. Ceccarelli, Lisa Boström-Einarsson,
Nathan Cook, Stella E. Fulton, Boze Hancock, Peter Harrison, Margaux Hein,
Agnès Le Port, Roima Paewai-Higgins, Hillary A. Smith and Adam Smith
Best Practice Coral Restoration for
the Great Barrier Reef
Synthesis of Results
Ian M. McLeod1, David Bourne2,3, Daniela M. Ceccarelli4, Lisa Boström-Einarsson1,5,
Nathan Cook6, Stella E. Fulton2, Boze Hancock7, Peter Harrison1,8, Margaux Hein1,9,
Agnès Le Port1, Roima Paewai-Higgins2, Hillary A. Smith2, Adam Smith1,6
1TropWATER, James Cook University, Townsville, Qld, Australia
2College of Science and Engineering, James Cook University, Qld, Australia
3Australian Institute of Marine Science, Townsville, Qld, Australia
4Marine Ecology Consultant, Nelly Bay, Qld, Australia
5Lancaster Environment Centre, Lancaster University, UK
6Reef Ecologic, Townsville, Qld, Australia
7The Nature Conservancy, ℅ URI Graduate School of Oceanography, Narragansett, Rhode Island, USA
8Marine Ecology Research Centre, School of Environment, Science and Engineering,
Southern Cross University, Lismore, New South Wales, Australia
9Marine Ecosystem Restoration (MER) Research and Consulting, Monaco
Supported by the Australian Government’s
National Environmental Science Program
Project 4.3 Best practice coral restoration for the Great Barrier Reef
© James Cook University, 2020
Creative Commons Attribution
Best practice coral restoration for the Great Barrier Reef Final report: Synthesis of results is licensed by James
Cook University for use under a Creative Commons Attribution 4.0 Australia licence. For licence conditions see:
https://creativecommons.org/licenses/by/4.0/
National Library of Australia Cataloguing-in-Publication entry:
978-1-925514-72-8
This report should be cited as:
McLeod, I.M. et al. (2020) Best practice coral restoration for the Great Barrier Reef: Synthesis of results. Report to
the National Environmental Science Program. Reef and Rainforest Research Centre Limited, Cairns (36pp.).
Published by the Reef and Rainforest Research Centre on behalf of the Australian Government’s National
Environmental Science Program (NESP) Tropical Water Quality (TWQ) Hub.
The Tropical Water Quality Hub is part of the Australian Government’s National Environmental Science Program
and is administered by the Reef and Rainforest Research Centre Limited (RRRC). The NESP TWQ Hub addresses
water quality and coastal management in the World Heritage listed Great Barrier Reef, its catchments and other
tropical waters, through the generation and transfer of world-class research and shared knowledge.
This publication is copyright. The Copyright Act 1968 permits fair dealing for study, research, information or
educational purposes subject to inclusion of a sufficient acknowledgement of the source.
The views and opinions expressed in this publication are those of the authors and do not necessarily reflect those
of the Australian Government.
While reasonable effort has been made to ensure that the contents of this publication are factually correct, the
Commonwealth does not accept responsibility for the accuracy or completeness of the contents, and shall not be
liable for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the
contents of this publication.
Cover photographs: (front) Snorkeler investigating a coral nursery. Image: Grumpy Turtle Productions; (back)
Macroalgae removal and coral larval seeding experimental plots on Magnetic Island. Image: Ian McLeod.
This report is available for download from the NESP Tropical Water Quality Hub website:
http://www.nesptropical.edu.au
Best practice coral restoration for the Great Barrier Reef
i
CONTENTS
Contents .................................................................................................................................. i
List of Figures ......................................................................................................................... ii
Acronyms .............................................................................................................................. iii
Acknowledgements ............................................................................................................... iv
Executive Summary .............................................................................................................. 1
1.0 Introduction ................................................................................................................. 3
2.0 Global Reviews of Coral Restoration Techniques ....................................................... 5
2.1 Coral restoration A systematic review of current methods, successes, failures and
future directions ................................................................................................................. 5
2.2 Macroalgae removal .................................................................................................... 7
2.3 Substrate stabilisation .................................................................................................. 8
3.0 Coral Restoration in Australia ....................................................................................10
3.1 Coral gardening ..........................................................................................................11
3.2 Substrate stabilisation .................................................................................................14
3.3 Coral repositioning ......................................................................................................16
3.4 Macroalgae removal ...................................................................................................16
3.5 Coral larval propagation ..............................................................................................20
4.0 Best Practice Coral Restoration .................................................................................22
4.1 Coral restoration planning and design .........................................................................23
4.2 Coral reef restoration as a strategy to improve ecosystem services: A guide to coral
restoration methods ..........................................................................................................24
4.3 GBR toolkit for local-scale coral restoration.................................................................25
5.0 Summary and Future Directions ................................................................................27
5.1 Conclusion ..................................................................................................................28
References ...........................................................................................................................30
Appendix 1: Publications ......................................................................................................33
Appendix 2: NESP TWQ Hub Project 4.3 Involvement in GBR Coral Restoration Projects ...36
McLeod et al.
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LIST OF FIGURES
Figure 2.1: Summary of the main findings from Boström-Einarsson et al. (2020). ............. 7
Figure 2.2: Decision tree showing considerations to take in rubble stabilisation
interventions. From Ceccarelli et al. (2020). .................................................... 9
Figure 3.1: The locations of some recent in-water coral restoration projects in the GBR. 10
Figure 3.2: Coral restoration projects in the GBR, (a) CoralClip®, (b) assisted evolution
research undertaken by AIMS, (c) coral bommie repositioning, (d) macroalgae
removal, (e) larval propagation, (f) substrate stabilisation, (g) coral gardening,
(h) an underwater vacuum used to assist with macroalgae removal, (i) larval
propagation and macroalgae removal experiments. Images provided by Marie
Roman/AIMS, Ian McLeod, Nathan Cook/Reef Ecologic, Ross Miller, Margaux
Hein, David Suggett and Neil Mattocks. .........................................................11
Figure 3.3: The coral gardening process. ........................................................................12
Figure 3.4: Transplanted corals growing on mesh at Agincourt Reef. ..............................15
Figure 3.5: The mean height of macroalgae canopy over time in Arthur Bay and Florence
Bay. Grey bars indicate removal events; blue bar indicates the Townsville Flood
(February 2019). ............................................................................................17
Figure 3.6: The mean number of Sargassum spp. holdfasts per square meter over time in
Arthur Bay and Florence Bay. Grey bars indicate removal events; blue bar
indicates the Townsville Flood (February 2019). ............................................18
Figure 3.7: Total number of natural coral recruits per settlement tile surface in control and
removal plots across Florence and Arthur Bays, Magnetic Island, following the
2018 spawning event. ....................................................................................19
Best practice coral restoration for the Great Barrier Reef
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ACRONYMS
AIMS ............ Australian Institute of Marine Science
COTS ............ Crown-of-thorns Starfish
GBR ............. Great Barrier Reef
GBRF ........... Great Barrier Reef Foundation
GBRMP ........ Great Barrier Reef Marine Park
GBRMPA ..... Great Barrier Reef Marine Park Authority
ICRI .............. International Coral Reef Initiative
JCU .............. James Cook University
NESP ........... National Environmental Science Program
QPWS .......... Queensland Parks and Wildlife Service
RRRC ........... Reef and Rainforest Research Centre Limited
RTP .............. Reef Trust Partnership
TWQ .............. Tropical Water Quality
UNEP ............ United Nations Environment Programme
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ACKNOWLEDGEMENTS
The authors gratefully acknowledge the contribution of many collaborators and contributors to
this project including: Jennifer Loder, Danielle Koopman, David Suggett, David Wachenfelt,
Line Bay, David Mead, David Souter, Elizabeth Shaver, Gabriel Grimsditch, Tali Vardi, Daniela
Ceccarelli, Russell Babcock, Elisa Bayraktarov, Naomi Gardiner, Phoebe J. Stewart-Sinclair,
Tali Vardi, Elissa Mastroianni, Stewart Christie, Gary McKenna, Maxine Newlands, Alexander
Elms, Karen Vella, Sebastian Ferse, Gemma Molinaro, Al Songcuan and Neil Mattocks. We
thank Julie Carmody, Hulton King and Damien Burrows for their advice on milestone delivery
and support with end-user engagement. We thank Eric Lawrey and Suzannah Babicci for their
technical advice and eAtlas support.
The authors acknowledge the support of many tourism, citizen science, research and linking
organisations including: Reef Restoration Foundation, Quicksilver Connections, Red Cat
Adventures, Ocean Rafting, True Blue Sailing, Pro Sail Whitsundays, Whitsundays Regional
Council, Great Barrier Reef Foundation, the United Nations Environment Program, Southern
Cross University, Earthwatch Institute Australia, the International Coral Reef Initiative Ad Hoc
Committee for Reef Restoration, the University of Queensland, Queensland University of
Technology, the Coral Restoration Consortium, the Reef Resilience Network and the Reef
Restoration and Adaptation Program.
This project was funded through the Australian Government’s National Environmental Science
Program Tropical Water Quality Hub.
Best practice coral restoration for the Great Barrier Reef
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EXECUTIVE SUMMARY
As coral cover in the Great Barrier Reef (GBR) continues to degrade, pressure is growing for
direct interventions to assist the recovery of corals. A range of coral restoration and assisted
recovery techniques have been trialled overseas and in Australia, however there has not to
date been an evaluation of what will work best in GBR conditions.
This project was established in 2017 to:
Review coral restoration methods around the world and assess the evidence of their
success (Section 2)
Trial the most promising coral restoration techniques in GBR conditions (Section 3)
Bring together knowledge of coral restoration techniques for best practice guidelines
for the GBR (Section 4)
In this report we summarise the outputs and outcomes of the National Environmental Science
Program Tropical Water Quality Hub Project 4.3 ‘Best practice coral restoration for the Great
Barrier Reef’ (December 2017 - December 2020). These outputs included three book chapters,
nine peer-reviewed journal articles, and six reports (listed in Appendix 1) including:
A global review of coral restoration techniques with 407 unique case studies from
around the world
A published review of the efficacy of macroalgae removal for reef recovery
A published review of methods for substrate stabilisation for reef recovery and their
efficacy
A book chapter summarising coral restoration in Australia to date
An interactive visualisation of an open access database we created to allow for
customised interrogation
This project also supported a series of in-water experiments and pilot studies (summarised in
Section 3), including:
Helping to establish Australia's first coral nursery and assistance with early monitoring
and reporting for the Reef Restoration Foundation
Establishing a long-term experiment at Magnetic Island investigating the efficacy of
macroalgae removal and larval propagation to enhance coral recovery in partnership
with the Earthwatch Institute Australia and other organisations
Supporting the project planning and monitoring for coral restoration trials at Agincourt
Reef (offshore from Cairns) and the Whitsunday Islands.
One of the primary goals of this project was to produce best-practice guidelines for GBR coral
restoration projects. We worked with a broad team of national and international collaborators
to produce best practice guidance, including:
Producing content to update the Reef Resilience Network’s restoration section on their
website (https://reefresilience.org/restoration/)
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Producing content for the Reef Resilience Network’s online restoration course and
helping to facilitate the mentored version of the course
Co-authoring the major global report ‘A Manager’s Guide to Coral Reef Restoration
Planning and Design’ and mentoring teams from Guam and the Northern Mariana
Islands local government to plan restoration in their waters using the guide
Co-authoring the major global report with UNEP and ICRI ‘Coral reef restoration as a
strategy to improve ecosystem services. A guide to coral restoration methods’
Producing webinars and consolidating the best available best practice guidance to
create the ‘GBR toolkit for local-scale coral restoration’ in partnership with GBRF and
RRAP.
The novelty of the many intervention strategies presented here represent an important shift in
the use of coral restoration - away from assessing the feasibility and efficacy of individual
techniques, towards developing practical solutions with specific objectives linked to long-term
outcomes in a changing climate. Many of the current projects present coral restoration as one
of many strategies to strengthen the resilience of Australian coral reefs in the face of rising
anthropogenic and climate change associated pressures. Restoring reefs to some arbitrary
historical baseline is not the goal, rather, much of the research is focused on how restoration
can be used in the context of adaptation to forecast disturbances such as increases in sea-
surface temperatures. This approach requires research partnerships that extend beyond
traditional coral reef science to include engineers, social scientists, citizen scientists,
modellers, economists, infrastructure development experts, and project managers.
Coral restoration using existing methods in Australia is therefore best applied at the local reef
scale where there is sufficient evidence of successful outcomes in terms of coral growth and
survival. The RRAP is focused on producing an innovative suite of safe, acceptable, and cost-
effective interventions to help protect the GBR from climate change, and increase the
scalability of options. However, current techniques and methods used at a smaller-scale, such
as a popular dive site, can bring about socio-cultural and economic benefits valuable to local
livelihoods and communities. Further, while existing methods may not match the scale of the
crisis facing coral reefs in a climate impacted future, restoration and adaptation techniques
could be key to maintain remnant live reefs, effectively buying time as the world takes urgent
global action on climate.
Best practice coral restoration for the Great Barrier Reef
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1.0 INTRODUCTION
Coral reefs surround much of Australia’s tropical coastline and make an important contribution
to the nation’s identity and economy through associated cultural values, fisheries, tourism, and
recreation. The Great Barrier Reef (GBR) is the world’s largest coral reef system, extending
along 2,300km of the east coast of Australia. The economic contribution of the GBR to Australia
through reef-dependent industries such as tourism and fishing was estimated at AUD 6.4 billion
for 2015-2016 (Deloitte Access Economics, 2017).
Despite world-leading research and management, including in large Marine Protected Areas,
the GBR is following global trends of declining coral health (De’ath et al., 2012; Dietzel et al.,
2020). Until recently, management of reefs in the Great Barrier Reef Marine Park (GBRMP)
has focused on reducing stressors such as overfishing (through management and zoning),
coastal development (through permitting and mitigation), and on improving water quality
(through improved land and wastewater management) to facilitate natural resilience and
recovery. Until recently, in-water restoration was not commonly undertaken; however,
terrestrial-based restoration activities such as replanting land cleared for agriculture, riparian
planting to stabilise riverbanks and engineering projects to restore water movement in
wetlands are established approaches used to improve water quality from GBR catchments.
Similarly, islands within the GBRMP have been actively managed through actions such as
weed control, removal of pest animal species, and replanting of native species. Recently, more
active management tools such as crown-of-thorn starfish (COTS) control have become an
important part of reef management, with large-scale control on the GBR beginning in 2012
(GBRMPA, 2020).
In the last five years, there have been a series of damaging events such as large-scale coral
bleaching, COTS outbreaks and cyclones that have caused further rapid declines in live coral
cover in shallow waters (Cheal et al. 2017, Hughes et al. 2017). In 2017, seventy scientists,
managers, Traditional Owners and stakeholders came together for a ‘Reef Summit’ to discuss
what could be done to help address coral health decline. Following the summit, a ‘Reef
Blueprint for Resilience’ was produced, in which reef restoration was highlighted for the first
time as a potential tool to improve the resilience of the GBR (GBRMPA, 2017). The ‘Reef
Blueprint for Resilience’ included a vision for 2020 with one component being Coordinated
restoration trials are in place at demonstration sites, providing opportunities to test, evaluate
and - where appropriate - scale up restoration methods to ecologically relevant scales”.
Coral restoration is relatively new to Australia, but has been used around the world for
decades. This project was established in 2017 to:
1. Review coral restoration methods around the world and assess the evidence of their
success (Section 2)
2. Trial the most promising coral restoration techniques in GBR conditions (Section 3)
3. Bring together knowledge of coral restoration techniques for best practice guidelines
for the GBR (Section 4)
In addition to this project, many other research projects, programs and pilot restoration projects
began around the same time with coral restoration and adaptation becoming a primary
research focus in Australia between 2018 and 2020. Our team collaborated widely with
McLeod et al.
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relevant scientists, managers, restoration practitioners, stakeholders, and end-users in
Australia and around the world to make sure resources were used most efficiently and
knowledge gained shared as widely as possible.
The largest investment in this space has been the Reef Restoration and Adaptation Program
(RRAP). The initial RRAP program objectives (2018) were to assess existing restoration
techniques, and to develop new interventions and delivery methods to assist the GBR to
recover from major disturbances and to assist its adaptation to a changing climate. The
present project partnered with RRAP as there were shared goals of reviewing coral restoration
tools used around the world, evidence of their success and their potential suitability for the
GBR. This collaboration facilitated earlier delivery of the global review for coral restoration
methods and allowed for the inclusion of an online interactive visualisation of the coral
restoration database. https://www.gbrcoralrestoration.org/restoration-database
At the commencement of this project, there had been some early experiments and pilot studies
investigating the efficacy of restoration to facilitate coral recovery in the GBR. These included
transplanting corals, removing overgrown macroalgae and larval propagation (McLeod et al.
In Press). The GBR Restoration Symposium was held in Cairns in July 2018 and was attended
by over 300 people (Burrows et al. 2019), with several members of this project on the
organisational committee. There have been a growing number of coral restoration projects in
Australia over the last three years, with many having direct input from our project. These are
described in Section 3.
Interest in coral restoration increased globally at the same time. The US National Oceanic and
Atmospheric Administration commissioned the National Academy of Science to review
interventions to increase the resilience of coral reefs (A/Prof David Bourne from this project
was a member of the assembled NAS expert panel that produced two main reports from this
review). The Coral Restoration Consortium, a community of practice composed of scientists,
managers, coral restoration practitioners and educators hosted the Reef Futures conference
in Florida in December 2018 with over 500 attendees. In late 2018, Australia joined Monaco
and Indonesia to provide Secretariat services for the International Coral Reef Initiative (ICRI).
ICRI is a partnership between Nations and organisations which strives to preserve coral reefs
and related ecosystems around the world. In 2019, an ICRI ad-hoc committee on reef
restoration was formed Co-Chaired by Ian McLeod from this project (McLeod et al. 2019a).
This has served as one of the primary coordinating bodies for coral restoration around the
world.
In 2019, the United Nations Environment Assembly passed resolution 4/13 on “Sustainable
coral reefs management”. Following this resolution, the United Nations Environment
Programme (UNEP) supported the development of a compilation of best practices for coral
reef restoration. Our project has worked closely with UNEP on these, and Margaux Hein from
this project worked as a full-time consultant for UNEP to lead the creation of best practice
guidance material (e.g. Hein et al. In Press). A summary of best practice information drawing
from our reviews and pilot studies is included in Section 4.
This report summarises the learnings from our research and in-water experiments, and reviews
early coral restoration projects in the GBR, including ours. Section 5 shares best practice
guidance from these reviews and projects and Section 6 discusses future directions.
Best practice coral restoration for the Great Barrier Reef
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2.0 GLOBAL REVIEWS OF CORAL RESTORATION
TECHNIQUES
At the start of this project there was a lack of detailed reviews of restoration methods and their
success in different environments. We collaborated with a wide range of scientists and
managers from around the world to help to fill this critical knowledge gap. Our main review
included 407 unique coral restoration case studies from peer-reviewed journal articles, an
online survey, government and consultancy reports, and online sources. This information was
shared in a range of ways including:
A NESP TWQ Hub report ‘Coral restoration in a changing world: A global synthesis of
methods and techniques’ (Boström-Einarsson et al. 2018)
A database shared on the project website and hosted on Dryad (Dryad Digital
Repository. doi:10.5061/dryad.p6r3816)
A review contributed as part of the RRAP Investment Case (Hardisty et al. 2019) that
was awarded AU $100 million in funding
An interactive visualisation of the review data built using Tableau and hosted on the
project website
A peer-reviewed open-access journal article (Boström-Einarsson et al. 2020) that was
recommended to F1000 as a top-quality article. This article had been cited 29 times
within ten months of publishing. It has an Altmetric score of 195 (a measure of attention
received by research articles), placing it in the top 5% of research outputs.
Additional collaborative reviews led by this team:
Supporting coral reef recovery with small structures and substrate stabilisation: State
of knowledge, considerations for management and implementation (Ceccarelli et al.
2020)
Rehabilitation of coral reefs through removal of macroalgae: state of knowledge and
considerations for management and implementation (Ceccarelli et al. 2018).
In addition to these outputs, we also collaborated with a wide range of authors in Australia and
around the world to co-author two other reviews:
Motivations, success, and cost of coral reef restoration (Bayraktarov et al. 2019)
Optimizing returnoneffort for coral nursery and outplanting practices to aid restoration
of the Great Barrier Reef (Suggett et al. 2019).
A short description of the main findings from these reviews follows.
2.1 Coral restoration A systematic review of current methods,
successes, failures and future directions
We conducted a systematic literature review of peer-reviewed journal articles, a review of grey
literature, and an online survey of coral restoration practitioners. More than 40 separate
categories of data were recorded from each case study including data on (1) the information
source, (2) the case study particulars (e.g. location, duration, spatial scale, objectives), (3)
McLeod et al.
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specific details about the methods, (4) coral details (e.g. genus, species, morphology), (5)
monitoring details, and (6) the outcomes and conclusions. The first phase of this review was
completed in 2018 and was published as a NESP report with a supporting online database,
and an open-access journal article (Figure 2.1). A second phase was completed in October
2020, and included another round of practitioner’s surveys and a review of all literature
published until 30th June 2020, bringing the total to 407 coral restoration projects reviewed.
Ten main coral restoration methods or techniques were identified. The effectiveness of each
method, and techniques associated with each intervention were evaluated. We found that coral
restoration projects were generally short-term, with the median of 12 months of monitoring
being reported. Most projects were relatively small, with a median size of restored area of 100
m2. A surprising result was how many coral taxa were used in projects, with 251 different
species from 79 coral genera with 10 different growth morphologies found to be used. Overall,
coral restoration projects focused on fast-growing branching corals (61% of studies), and
reported survival between 60 and 70%. There were challenges associated with getting useful
information because projects typically had 1) a lack of clear and achievable objectives, 2) a
lack of appropriate and standardised monitoring and reporting and, 3) poorly designed projects
in relation to stated objectives.
Bayraktarov et al. (2019) reviewed scientific studies published in peer-reviewed and grey
literature on the motivations for, costs and successes of coral reef restoration. They found that
the main motivations to restore coral reefs were to further ecological knowledge and improve
restoration techniques, with coral growth, productivity, and survival being the main variables
measured. The median project cost was US $400,000/ha (2010 USD), ranging from US
$6,000/ha for the nursery phase of coral gardening to US $4,000,000/ha for substrate addition
to build an artificial reef.
Best practice coral restoration for the Great Barrier Reef
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Figure 2.1: Summary of the main findings from Boström-Einarsson et al. (2020).
2.2 Macroalgae removal
Macroalgae are part of a healthy reef ecosystem and have both positive and negative effects
on corals (Ceccarelli et al. 2018; Fulton et al. 2019). Removal of macroalgae has been
proposed as an active intervention measure to aid reef recovery through increasing available
substrate for coral settlement, and reducing competition. However, the effects (positive and
negative) of removing macroalgae have not been rigorously tested. We reviewed and
synthesised available knowledge of the ecological role of macroalgae on coral reefs and the
potential benefits and risks associated with their active removal and published this as a journal
article, ‘Rehabilitation of coral reefs through removal of macroalgae: state of knowledge and
considerations for management and implementation’ (Ceccarelli et al. 2018). This also
included appendices on (1) the distribution and abundance of macroalgae on the GBR, (2) the
chemical role played by macroalgae on reefs, and (3) case studies of macroalgae removal on
coral reefs. This review complemented the in-water macroalgae removal experiments at
Magnetic Island as described in Section 3.
This review showed that the following considerations should guide the evaluation of algae
removal as a management tool:
McLeod et al.
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1. Establishing the need for the removal by demonstrating a phase shift or “threshold”
abundance of macroalgae
2. Interaction with herbivory: Re-introducing or protecting herbivores prior to removing
algal stands can allow the herbivores to establish control by consuming the juvenile
macroalgae, and prevent macroalgal stands regenerating within a few months
3. Methods and logistics: Seasonality of macroalgae is likely to affect the success of
removal; removal during the early growing season may be more effective than late in
the growth period. The effects of climate change on algal seasonality will also need to
be taken into account. The success of removal methodologies will depend on biological
characteristics that can vary extensively among algal morphs and species
4. Potential negative effects of macroalgae removal: Removal of algal holdfasts may
disturb or damage the substrate and may injure corals and other benthic organisms.
The removal of plant biomass and physical structure may result in declines in the
abundance of other taxa such as fishes. These potential risks should be considered
and assessed prior to large-scale macroalgae removal on coral reefs
5. Response of corals to macroalgae removal and controlling chronic stressors: Algal
reduction is not expected to translate into a uniform response in coral recruitment,
growth, and survival. The success of removal projects may be enhanced by
simultaneous interventions to enhance coral recruitment, and will also depend on the
control of chronic stressors
6. Measures of success: The performance indicators for restoration success should be
clearly defined and measured with standard scientific principles.
2.3 Substrate stabilisation
Substrate stabilisation involves the direct physical restoration and implementation of artificial
substrates over areas of loose, unconsolidated reef rubble. The project team, with a wide range
of collaborators, reviewed and synthesised 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 and published it as an
open-access journal article (Figure 2.2, Ceccarelli et al. 2020). We found that there are
fundamental knowledge gaps in this field, including baseline levels of rubble and the structural
complexity of reef habitats in space and time. Methods ranged from using artificial structures
or large rocks to laying down mesh or netting over the rubble to prevent further movement
(Ceccarelli et al. 2020). Substrate stabilisation can also be complemented with coral
transplantation to further assist reef recovery. However, there is a limited understanding of
natural recovery processes and the potential for this type of active intervention to successfully
restore local coral reef structures. The RRAP research will further investigate where and when
it is appropriate to intervene (Hardisty et al. 2019).
Best practice coral restoration for the Great Barrier Reef
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Figure 2.2: Decision tree showing considerations to take in rubble stabilisation interventions. From
Ceccarelli et al. (2020).
McLeod et al.
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3.0 CORAL RESTORATION IN AUSTRALIA
Alongside RRAP and other research programs, there is a growing number of coral restoration
trials in the GBR (Figures 3.1, 3.2). This section presents an overview of newly-implemented
in-water projects. See Appendix 2 for a table showing how NESP TWQ Hub Project 4.3 was
involved in these restoration projects.
Figure 3.1: The locations of some recent in-water coral restoration projects in the GBR.
Best practice coral restoration for the Great Barrier Reef
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Figure 3.2: Coral restoration projects in the GBR, (a) CoralClip®, (b) assisted evolution research
undertaken by AIMS, (c) coral bommie repositioning, (d) macroalgae removal, (e) larval propagation, (f)
substrate stabilisation, (g) coral gardening, (h) an underwater vacuum used to assist with macroalgae
removal, (i) larval propagation and macroalgae removal experiments. Images provided by Marie
Roman/AIMS, Ian McLeod, Nathan Cook/Reef Ecologic, Ross Miller, Margaux Hein, David Suggett and Neil
Mattocks.
3.1 Coral gardening
Coral gardening describes asexual coral propagation methods in which coral fragments are
transplanted back onto a degraded reef after an intermediate nursery phase (Rinkevich 1995,
Figure 3.3). It is the most widely used coral restoration method around the world (Boström-
Einarsson et al. 2020). Coral fragments are either harvested from donor colonies or from
fragments generated through natural or human disturbances, typically known as ‘corals of
opportunity’ (sensu Rinkevich 1995). These are placed into land-based or in-water nurseries
to recover and grow. The nursery phase allows for an exponential increase in coral branches
McLeod et al.
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available for outplanting generated by repeated fragmentation. This becomes coral restoration
when they are successfully transplanted back onto reefs.
Figure 3.3: The coral gardening process.
Since 2017, four coral gardening projects have been established within the GBRMP including
projects at Opal Reef, offshore from Port Douglas, Fitzroy Island, near Cairns, and at two reefs
in the Whitsundays region (Figure 3.1). The first coral gardening project to be established on
the GBR was led by the Reef Restoration Foundation (RRF) at Fitzroy Island. The project used
the ‘coral tree’ nursery design developed by the Coral Restoration Foundation, in the Florida
Keys, USA (Nedimyer et al. 2011). The original installation was supported with funding and
assistance from this project. Six coral nursery trees were installed in December 2017 (Cook et
al. 2018). Twenty four sections of coral colonies were harvested from two fringing reefs around
Fitzroy Island; Hidden Beach and Shark Fin Bay. The species collected were visually identified
as Acropora nobilis, A. digitifera, A. muricata, and A. nasuta. Coral sections were fragmented
and attached to the coral tree nurseries. Ninety percent of the fragments survived resulting in
246 coral colonies. In July 2018, four more coral trees were installed. In September 2018, 192
corals from the nurseries were planted in the northern end of Welcome Bay, Fitzroy Island.
These were planted into six 16m2 plots at a density of two corals/meter. The fate of individually
planted corals was not systematically monitored and there was no significant effect of coral
planting on live coral cover after 12 months (Cook et al. 2020).
Coral gardening efforts at six major tourism reefs, close to Cairns-Port Douglas, were the
largest-scale coral restoration project on the GBR to date. There, researchers from the
Best practice coral restoration for the Great Barrier Reef
13
University of Technology Sydney (UTS) in partnership with local tourism company, Wavelength
Reef Cruises, established two coral nurseries at Opal Reef (Figure 3.2g), and developed a
new attachment device (Coralclip®, Figure 3.2a) to outplant both coral fragments and larval
settlement devices in a targeted but versatile manner across reef terrains (Suggett et al. 2020).
From 2018 to 2019 the team outplanted over 3500 coral fragments (Suggett et al. 2019). By
October 2020 the team had outplanted over 5500 corals, comprising 23 species, among sites
(D. Suggett pers. comm.). Despite the need for further testing, Coralclip® has proven to be
fast (0.3-1.9 coral fragments per diver per minute), cheap (USD 0.6-3.0 per coral deployed)
and successful (≤15% failure rate of clips deployment method after 3-7 months, Suggett et al.
2020).
Projects in the Whitsundays (Figure 3.1) were a result of government funding to support
tourism values following Cyclone Debbie in March 2017. In November 2018, two coral
gardening projects were established at Blue Pearl Bay and Manta Ray Bay by environmental
consultants (Reef Ecologic) in partnership with a tourism promotion organisation (Tourism
Whitsundays) and Daydream Island Resort. At each location, two types of coral nursery were
trialled, (1) rope nurseries where coral fragments were fixed between strands of rope and
attached to a frame suspended off the seafloor, and (2) table nurseries where coral fragments
were attached to cement discs fixed to a tray suspended in mid-water. Each nursery held 700-
1000 coral fragments, with approximately 50% of fragments surviving until being planted (N.
Cook, unpublished data). In May 2019, 164 corals were planted in Blue Pearl Bay and 497 at
Manta Ray Bay. Overall, 50% of outplanted corals survived until November 2019 (N. Cook,
unpublished data). In June 2020 a further 955 corals were planted across both sites. Monitoring
is ongoing.
A range of techniques were trialled as part of the Whitsundays project, with the following
observations (N. Cook, pers. obs):
Underwater putty and cement were effective adhesives for attaching corals to areas of
bare rock, Coralclips® were not as effective in this project, and using silicone as an
adhesive caused substantial mortality of outplanted corals;
Biodegradable rope degraded too quickly for use in coral nurseries;
Branching corals should be at least 10cm in length when outplanted so they can have
some live coral tissue above the substrate;
Coral bleaching caused mortality on coral nurseries, although the effects were partially
mitigated by shading and water depth;
Multi-storey nurseries provided more space for corals to grow and options to grow
corals at the most advantageous depth;
Coral gardening and associated research and monitoring can be done through
community-based projects/ citizen scientists;
Sedimentation needs to be taken into account when deciding outplant locations as
areas with large amounts of sediment deposition were linked to lower survival rates of
outplanted corals;
Unexpected observed drivers of outplanted coral mortality included overgrowth by
macroalgae (Padina spp.), and predation by bumphead parrotfish (Bolbometapon
muricatum).
McLeod et al.
14
All of the above projects have involved extensive consultation with management and
community stakeholders to ensure their support. For example the Whitsundays reef restoration
project had over 678 individual interactions (meetings, presentations, phone calls and emails)
engaging over 2850 people over an 18 month period (N. Cook pers. comm.) Volunteers have
provided a substantial amount of in-kind time, labour and support for implementation,
monitoring and maintenance. While more time and monitoring is necessary to evaluate the
effectiveness of each of these techniques, site specificity will likely influence the choice of
methods both in terms of ecological characteristics, and needs and capacities of the
stakeholders and partners involved in the project.
3.2 Substrate stabilisation
The addition of structure for coral attachment has been trialled on cyclone damaged reefs
around Agincourt 3, a diving platform at Agincourt Reef, offshore from Port Douglas (Figure
3.1). The primary goal for this trial was to improve the coral cover and aesthetics of a patch of
rubble close to where divers enter the water. In 2018, Reef Ecologic, in partnership with the
pontoon operator, Quicksilver Connections, installed six 4.5m2 sheets of reinforcing steel mesh
with a low-voltage electrical current applied to three panels (Figures 3.2f, 3.4). The electrical
current was added in the hope that it would increase the growth rates and resilience of corals.
Two panels were installed on top of a rubble patch and four on the sloping sides that were also
dominated by unconsolidated rubble. Forty-eight coral fragments were then attached to each
of the panels. Marine biologists working for Quicksilver Connections conducted regular
maintenance of the system and corals, reattaching and realigning loose fragments and
removing predatory snails (Drupella spp.). Overall, 37% of the coral fragments were alive after
12 months, with no difference in coral survival between the powered and unpowered panels.
In August 2019, 294 additional coral fragments were attached to the frames and the power
supply adjusted to lower the voltage delivered to the frames. This proved to be technically
challenging and the power supply was switched off in December 2019. Ongoing husbandry
and assessments were being conducted until early 2020 when COVID-19-related travel
restricted opportunities to visit the site. In October 2020 monitoring began again. Live coral
cover was estimated to have increased from 5% to 8.3% in control plots and from 0.9% to
46.8% on the panels (N. Cook, unpublished data). The panels on top of the rubble pile had the
highest amount of live coral cover in October 2020 (over 70% each for both panels). Project
proponents were generally happy with the result (G. Burns, pers. comm., Fig. 3.4).
Best practice coral restoration for the Great Barrier Reef
15
Figure 3.4: Transplanted corals growing on mesh at Agincourt Reef.
Reef Stars are hexagonal sand-coated steel structures that provide a stable base for coral
fragments to grow. The following two projects using Reef Stars are recent and have not been
formally written up, but the following information has been shared by the project proponents
for this report.
Mars Sustainable Solutions (part of Mars Incorporated), and Reef Magic Cruises, a tourism
company, installed Reef Stars at Moore Reef, 40 km offshore from Cairns (Figure 3.1) in two
installations during June and October 2020. This project will investigate the effectiveness of
Reef Stars to stabilise coral rubble and includes positive and negative controls. The restoration
area was 20m x 30m and the proponents expected to fill this area in over the course of the
next five years (A. McArdle, pers. comm.). As of October 2020, a total of 148 Reef Stars
populated with fragments of broken coral from nearby reefs have been deployed over two
installations (A. McArdle, pers. comm.). The first installation included 29 species of corals from
five families, the second 26 species from four families, with most of the species coming from
the Acroporidae family (E. Fisher, pers. comm.). Monitoring has begun and three maintenance
trips have been undertaken. Transplanted coral fragments from the first installation had high
survivorship (99.9%) within the first three months (A. McArdle, pers. comm.).
Another recent trial (November 2020) at Green Island, close to Cairns, is a collaboration
between the GBRMPA, QPWS, Mars Incorporated, Great Adventures, Big Cat Green Island
Cruises, the Coral Nurture Program and Gunggandji Traditional Owners. It included attaching
more than 2600 coral fragments to a web of 165 Reef Stars on an area of unstable dead coral
rubble and connecting an additional 200 coral fragments to adjacent suitable hard substrate
using Coral Clips®. This project allowed for extensive engagement between Marine Park
McLeod et al.
16
managers and other stakeholders, thereby enabling the continued development of new
partnerships (a key focus of the GBRMPA produced ‘Great Barrier Reef Blueprint for
Resilience’).
3.3 Coral repositioning
Severe Tropical Cyclone Debbie impacted the Whitsunday Islands in March 2017 and resulted
in widespread damage to island infrastructure and fringing reef habitats (McLeod et al. 2019b).
The cyclone dislodged a large number of 1-3 m diameter Porites spp. bommies from the reef
slope at Manta Ray Bay and rolled them high into the intertidal zone of the reef flat. The QPWS
and GBRMPA, repositioned the bommies to the subtidal reef flat in June 2017. The objectives
of this activity were to restore coral reef habitat, improve aesthetics and access to the beach,
provide substrate for future coral larvae settlement, increase habitat complexity, and
demonstrate the value of proactive management (McLeod et al. 2019b). Experienced
machinery operators repositioned the bommies subtidally by rolling them over the reef flat
during a very low tide. A long-arm excavator then pushed them over the reef crest onto the
reef slope, using the full 10m extension of the excavator arm. A compact track loader equipped
with a grab bucket was also used to push coral rubble and smaller bommies into the subtidal
area of the reef flat. An estimated 100 cubic metres (400 tonnes) of dead coral substrate was
repositioned, at an estimated cost of AUD 30,000.
The repositioning of the Porites bommies has delivered positive environmental and social
benefits. Boat access has been restored to the beach, corals have recruited to the repositioned
bommies, and some remnant coral tissue survived on most bommies. Further, the bommies
provide three-dimensional habitat structure on the outer reef flat, supporting reef fishes and
other marine life. As the coral community re-colonises the surface of the bommies, it's
expected that the shallow-water snorkeling experience for tourists will improve (McLeod et al.
2019b). The coral bommies were last surveyed in December 2019. Seventeen of the 23 coral
bommies surveyed had live coral tissue (mean of 4.9%, range 0-20%) and there were 232
coral recruits on 21 repositioned coral bommies, up to 15 cm in diameter (D. Ceccarelli,
unpublished data).
3.4 Macroalgae removal
Removal of macroalgae has been proposed as an active intervention measure to aid reef
recovery through increasing available substrate for coral settlement and reducing competition
for coral recruits. Macroalgae removal trials began at Magnetic Island, close to Townsville in
2016. Initial trials were led by Reef Ecologic. Two methods of macroalgae removal were tested,
a plastic scraper to remove holdfasts, and hand removal (Figure 3.2g). Macroalgae cover was
reduced from 38% to 7% from 2m x 2m plots immediately following removal, with no difference
in speed or efficacy between methods (McLeod et al. In Press). There was no follow up
monitoring from these early trials.
The project team, in collaboration with Earthwatch Institute Australia and a range of other
partners, built on this work to quantify the ecological effects of macroalgae removal on reefs
at Magnetic Island. In October 2018, 12 permanent 5m x 5m experimental plots were
Best practice coral restoration for the Great Barrier Reef
17
established across two sites (Florence Bay and Arthur Bay). In half of these plots, fleshy
macroalgae, predominantly Sargassum spp., was removed just prior to coral spawning, whilst
the remaining plots acted as controls. In July 2019, the number of experimental plots was
doubled, expanding the area of experimental intervention (24 permanent 5m x 5m
experimental plots). In addition, removal of macroalgae was conducted more frequently
(approximately every 3 months) to maintain low biomass in the experimental plots. Monitoring
of the plots included measurement of algal biomass (measured as number of holdfasts and
height of algal thalli), counting coral recruits (juveniles) on both settlement tiles and natural
substrata, measuring sediment deposition and turf algae dynamics, quantifying changes in
benthic cover, examining changes in the number and function of fish communities (e.g.
juveniles, herbivores), and tracking bleaching susceptibility between control and algae-removal
plots. After initial surveying of benthic composition, macroalgae were removed by hand
(freediving and on SCUBA, see Mastroianni 2019 for detailed methodology on removal and
monitoring). Consistent with other published work, we found that macroalgae growth follows a
seasonal pattern, reaching its peak abundance in summer (Smith and Bourne 2019). With
repeated removals, a 43% reduction in summer canopy height in removal plots was achieved
in Arthur Bay compared to control plots, even given four months of regrowth (Figure 3.5).
Figure 3.5: The mean height of macroalgae canopy over time in Arthur Bay and Florence Bay. Grey bars
indicate removal events; blue bar indicates the Townsville Flood (February 2019).
McLeod et al.
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Figure 3.6: The mean number of Sargassum spp. holdfasts per square meter over time in Arthur Bay and
Florence Bay. Grey bars indicate removal events; blue bar indicates the Townsville Flood (February
2019).
Other studies (summarised in Ceccarelli et al., 2018) described the importance of removing
holdfasts to reduce macroalgal regrowth. In our study, there were significant reductions in the
number of holdfasts following some, but not all removal events (Smith and Bourne 2019).
Despite the variation in successful removal of holdfasts, given the significant reduction in
canopy, it may not be necessary to fully remove holdfasts to gain the desired effect. Further
monitoring is required to determine how the number of holdfasts changes with repeated
removal events, and how this impacts coral recovery dynamics.
Terracotta settlement tiles are often used to quantify coral recruitment through soaking field-
deployed tiles in bleach solution and counting resulting coral skeletons. Here, we installed such
tiles to test for the effect of macroalgae removal on natural coral recruitment. In the first year
of the project, we observed a significant increase in the number of coral juveniles on tiles from
Florence Bay plots where macroalgae had been removed following the 2018 coral spawning
event, particularly to the bottom surface of settlement tiles (Figure 3.7). However, the pattern
was not as distinct in Arthur Bay, with the highest number of settlers recruiting to the upper
surfaces of the settlement tiles in control plots. There was no difference in the size of juvenile
corals between removed and control plots, suggesting there is no benefit to growth of settlers;
however this will be monitored into the future. At the time of writing, time-consuming data
collection is still in progress to examine settlement tiles deployed prior to the 2019 spawning
event. These tiles were retrieved in two lots, in February and April 2020 to assess recruitment,
survival, and growth of coral juveniles. Initial in situ observations have detected increased
numbers of coral recruits in removal plots, however ongoing monitoring is planned.
Best practice coral restoration for the Great Barrier Reef
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Figure 3.7: Total number of natural coral recruits per settlement tile surface in control and removal plots
across Florence and Arthur Bays, Magnetic Island, following the 2018 spawning event.
One of the known benefits of macroalgae is providing shade to corals living below algal
canopies, as such it is possible that removal of algae may stress cohabiting corals by
increasing harmful UV penetration to the benthos. During the mass bleaching event of March
2020, the opportunity arose to assess the relationship between bleaching severity in plots with
and without macroalgae removal. Unfortunately due to Covid-19 related travel restrictions, field
data collection was limited to target only those colonies that bleached, rather than a full
community census. Nonetheless, surveys found that bleaching incidence was greater in the
macroalgae-removed plots compared to the control plots. Despite this result, recovery was
significantly higher in the macroalgae-removed plots compared to the control plots four months
following the bleaching event. The absence of a dense macroalgal canopy in the removal plots
may, therefore, allow corals the opportunity to expend more energy on recovery as opposed
to competition. If further acute thermal events arise in the future, a more thorough examination
of these processes will be undertaken in the experimental plots at Magnetic Island.
In addition to quantifying coral recruitment, which is seen as a major indicator of restoration
success, current work by JCU, and AIMS is also investigating the impact of macroalgae
removal on sediment deposition, resuspension and turf algae dynamics, which are likely to be
important factors influencing coral settlement and recruitment. Planned future work will aim to
quantify coral host genetic parameters and changes to benthic microbial biofilm communities.
Importantly, citizen science forms a critical part of this project through ongoing partnership with
McLeod et al.
20
Earthwatch Institute Australia. A range of activities are completed by citizen scientists, with the
goal to develop the best way to incorporate local community action into macroalgae removal-
based projects into the future, should results support wide-scale implementation. To date, four
Earthwatch partnered expeditions have been conducted with citizen scientists participating in
a range of activities including removal of macroalgae and data collection.
A related project led by GBRMPA focused on testing logistics and feasibility of larger-scale
removal by removing macroalgae from three 20m x 20m plots in Florence Bay on Magnetic
Island by hand in 2018 and again in 2019 using hand removal and a suction device (Figure
3.2h, N. Mattocks pers. comm.). Pre-removal assessments of coral and fish populations were
undertaken, with further surveys planned.
3.5 Coral larval propagation
Coral larval propagation aims to increase the rates of larval settlement and recruitment on
damaged reef areas using large numbers of coral larvae, thereby increasing the rate of
recovery (dela Cruz and Harrison 2017). The methods are designed to exploit the high
fecundity of corals and maximise fertilisation and larval rearing rates for increasing larval
supply on damaged reefs, mimicking the natural pulses of high larval supply and recruitment
following major spawning events on healthy reefs. Larvae are either reared in water within
floating enclosures on reefs or in laboratories or aquaculture facilities to optimise production
and retain them for restoration, rather than allowing them to be dispersed in currents away
from target reef areas. When larvae are visually assessed as competent to settle they are
released onto reef areas using various methods, including temporarily contained under mesh
sheets for small scale manipulative experiments, or released as larval clouds directly onto
damaged reef areas at larger scales.
Initial larval propagation trials in the GBR began on Heron Island reef patches in 2016, using
three densities of Acropora larvae settled in replicate 2m x 2m plots and larvae reared from
wild spawn slicks. In 2017, larval enhancement experiments were initiated on replicated 10m
x 10m patch reefs at Heron Island and One Tree Island reefs using multispecies mixes of
Acropora spp. and Diplora spp. coral larvae, with significantly increased larval settlement in
larval propagation reef plots compared with controls reliant on low natural larval settlement
rates (Harrison 2018).
More recently, larger-scale reef trials were successfully initiated on reefs in the central and
northern GBR using combinations of larger floating spawn catchers and floating larval pools to
contain multispecies coral spawn slicks, and rearing millions of larvae in floating pools and
laboratory culture tanks that were settled onto degraded reef areas with low coral cover
(Harrison 2018, Harrison et al. 2019, and unpublished data). For example, over 150 million
larvae were successfully reared in larval nets moored on Moore Reef, off Cairns (Harrison et
al. 2019).
An experiment at Moore Reef included larval propagation and the inoculation with heat tolerant
Symbiodinium. Twelve 30 m2 experimental plots with four plots for larvae without symbionts,
four plots for settlement of larvae cocultured with symbionts, and four plots as controls. In
addition to the planned project laboratory and reef experiments, they also successfully
deployed ~5.5 million 7day old larvae over a patch reef using a newly trialled gravity fed and
Best practice coral restoration for the Great Barrier Reef
21
divercontrolled larval release method (Harrison et al. 2019). Monitoring of longer-term
recruitment and coral restoration outcomes is ongoing for all of these projects.
Recently, macroalgae removal and larval propagation have been combined in a fully crossed
field experiment, building on the algal removal experiments at Magnetic Island. Within the 12
established quadrats, three quadrats are assigned to each of four treatments (control, algae
removal only, larval propagation only, and combined algae removal with larval propagation).
Adult colonies of Acropora tenuis were removed from the reef and allowed to spawn in the
National Sea Simulator at AIMS. Gametes were fertilised, larvae cultured, and then
approximately 3 million larvae were returned to the reef in specially-designed 5m x 5m mesh
tents to target delivery of larvae onto the experimental plots. This process was completed
during the 2019 spawning for Arthur Bay, and repeated in 2020 for both Arthur and Florence
Bays. In February 2020 (following the 2019 spawning), live coral recruits were counted on
settlement tiles from Arthur Bay, with significantly increased numbers of recruits in the
combined treatment quadrats (i.e. larval propagation with algal removal), however all three
other treatments (control, larval propagation only, algae removal only) had similar numbers of
recruits. Recruit counts were repeated in September 2020, with the combined treatment again
showing most recruitment, followed by algae removal plots, followed by larval propagation
plots, followed by control. Monitoring is ongoing for this project.
McLeod et al.
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4.0 BEST PRACTICE CORAL RESTORATION
One of the primary goals of this project was to produce best-practice guidelines for GBR coral
restoration projects. Our team worked with a broad team of national and international
collaborators drawing on global expertise to produce these guidelines. The main relevant
outputs included:
Producing content to update the Reef Resilience Network’s restoration section on their
website, including providing a case study about coral bommie repositioning, and
content to update the substrate stabilisation and macroalgae removal website sections
(to be incorporated in early 2021). https://reefresilience.org/restoration/
Producing content for the Reef Resilience Network’s online restoration course and
helping to facilitate the mentored version of this course.
https://reefresilience.org/online/
Co-authoring the major global report ‘A manager’s guide to coral reef restoration
planning and design’ and mentoring teams from Guam and the Northern Mariana
Islands local governments to plan restoration in their waters using the guide
Co-authoring the major global report with UNEP and ICRI ‘Coral reef restoration as a
strategy to improve ecosystem services. A guide to coral restoration methods’ (to be
released in January 2021)
Producing webinars and consolidating the best available best practice guidance to
create a ‘GBR toolkit for local-scale coral restoration’ in partnership with GBRF and
RRAP.
A summary of two of the most important global reports that this project contributed to, and the
GBR toolkit for local-scale coral restoration follows:
Best practice coral restoration for the Great Barrier Reef
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4.1 Coral restoration planning and design
A manager’s guide to coral reef restoration planning and design (Shaver et al. 2020) supports
the needs of reef managers seeking to begin restoration or assess their current restoration
program. Based on global best practices - and tested with managers from Hawaii, Guam,
American Samoa, and the Commonwealth of the Northern Mariana Islands - the guide was
developed for reef managers and practitioners and anyone who plans, implements, and
monitors restoration activities. From this project, Ian McLeod, Margaux Hein and Lisa Boström-
Einarsson were authors of the report and Ian McLeod helped mentor the teams from Guam
and the Northern Mariana Islands.
As managers embark on restoration activities to combat reef degradation and enhance
resilience, careful planning is required to improve the chances that restoration will be
successful. Effective planning includes working with local experts, stakeholders, and decision-
makers to determine how, when, and where restoration will be conducted, and how it can
complement existing coral reef conservation and management strategies.
Together with a suite of tools and templates, the guide maps out a six-step, iterative process
to help users gather relevant data, ask critical questions, and have important conversations
about restoration at their location. Use of the guide culminates in the creation of a Restoration
Action Plan to enhance reef resilience and recovery.
McLeod et al.
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4.2 Coral reef restoration as a strategy to improve ecosystem
services: A guide to coral restoration methods
In anticipation of the coming UN Decade on Ecosystem Restoration, and as a response to the
UNEP Assembly resolution 4/13 adopted in 2019, the UNEP assembled a team of experts to
produce a report on coral reef restoration as a strategy to improve ecosystem services. This
team was led by Margaux Hein (Margaux was employed as a UNEP consultant to lead this
report) and Ian McLeod along with collaborators from around the world. The report (Hein et al.
In Press) presents an overview of current methods, and the best-available knowledge in the
field of coral reef restoration. A set of recommendations are also provided to assist key actors
such as managers, practitioners, policy makers, and funding agencies to make informed
decisions in applying coral reef restoration more broadly as an integrated reef management
strategy. Specifically, the report includes two comprehensive recommendation tables, one
method and one goal-based, highlighting expert views on strengths and weaknesses of
existing methods, and key recommendations and challenges depending on the overarching
goal of a restoration project. A suitability-index matrix was also created to match specific
methods to goals and assist the decision-making process in the early planning phases. The
report along with a policy brief and an animated video are expected to be released in January
2021. A peer-reviewed publication highlighting key concepts of the report (Hein et al. In
Review) is in-review in the journal Frontiers in Marine Science as part of a special issue on
Coral Reef Restoration in a Changing World: Science-based Solutions.
Best practice coral restoration for the Great Barrier Reef
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4.3 GBR toolkit for local-scale coral restoration
This toolkit is hosted on the RRAP website with the following text and content:
RRAP’s aim is to create an innovative suite of safe, acceptable interventions to help the Great
Barrier Reef resist, adapt to, and recover from the impacts of climate change. The Program
supports the eventual deployment, if required, of at-scale integrated restoration and adaptation
interventions. We recognise that local engagement in restoration work has the potential to
enhance and be an innovative scaling approach for intervention deployment.
But what is available now? The resources listed here provide users with quick access to a
range of key Great Barrier Reef coral restoration guidance material and links to find out more
about coral restoration efforts around the world
The toolkit will be published mid-December 2020 and can be accessed at:
https://gbrrestoration.org/resources/coral-restoration-toolkit/
The toolkit will include the following sections when launched and all website links will be
available through the web address above:
GBR Restoration
Background Reading
Best practice coral restoration for the Great Barrier Reef: Synthesis of results (McLeod
et al. 2020)
Tourism and restoration motivations, opportunities and challenges (Hein et al. 2020)
Infographic - what is coral gardening ?
Great Barrier Reef blueprint for resilience (GBRMPA, 2017)
Watch and Learn
Webinar: Overview of NESP products and findings
Webinar: Coral gardening in Australia
Webinar: Permitting processes for GBR coral restoration projects
Webinar: Why do tourism operators engage in coral restoration?
Guides
GBRMPA permitting processes
Global Coral Restoration
Background Reading
Coral restoration: A review
Coral restoration and adaptation: Mapping current and future priorities
Motivations, success, and cost of coral reef restoration
Coral reef rehabilitation through removing macroalgae
Supporting coral reef recovery with small structures and substrate stabilisation
Guides
A manager’s guide to coral reef restoration planning and design
Coral reef restoration monitoring guide
McLeod et al.
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Reef rehabilitation manual
A guide to coral restoration methods
Reef resilience network coral restoration training course
Guide to ecological engineering: The restoration of coral reefs and associated
ecosystems
Resources
Global coral restoration database
Coral restoration image library
Best practice coral restoration for the Great Barrier Reef
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5.0 SUMMARY AND FUTURE DIRECTIONS
Since 2017, there has been a rapidly growing field of research into coral restoration and
adaptation, and a growing number of in-water projects. This project has systematically
reviewed restoration techniques used around the world to date, and synthesised the results
and recommendations into three book chapters, nine peer-reviewed journal articles, and six
reports. These outputs have already been cited 68 times in the scientific literature (as of 15
September 2020 Google Scholar) and read over 4000 times (as of 15 September 2020,
ResearchGate). The legacy of this project not only comes from these and subsequent
publications, but from the broad collaboration and engagement through the process including
hundreds of phone calls and meetings, and scores of presentations and media and social
media posts. Through co-creating an online training course with the Reef Resilience Network
and an in-person Coral Restoration and Leadership Workshop with Reef Ecologic (four
workshops of up to four days during 2018-2020), we also shared the learnings of this project
with hundreds of people. Many of the co-investigators have moved into leadership roles in the
field of restoration, for example senior leadership roles in RRAP, and the CRC. As coral
restoration is a long-term process, only interim results can be included in this report. As the
NESP ends in December 2020, these experiments have been handed over to collaborators or
funded through other sources to continue monitoring and reporting.
The heightened interest in coral restoration and adaptation over the three years of the project
has been supported by increased funding. For example, Australia’s first Restoration Hub has
been launched in the Cairns-Port Douglas region with AUD 1.1 million in funding for projects
in the initial round. The RRAP R&D Phase was launched with AUD 130 million in dedicated
funding for the first four years. These efforts and investments reflect an increasing sense of
urgency for action to confront the coral reef crisis and management appetite for
implementation, including a new GBRMPA Policy on GBR Interventions being developed
(https://elibrary.gbrmpa.gov.au/jspui/retrieve/1a949699-19b8-4aee-8b73-271feb19eab1/v0-
Interventions-Great-Barrier-Reef-Policy.pdf). Generally, there has been a collaborative,
positive spirit, and coral restoration has brought together stakeholders who rarely work
together (Burrows et al. 2019). However, many of these projects are new and will experience
challenges, and some may not meet their objectives as there are few examples of large-scale
success through existing coral restoration techniques around the world (Boström-Einarsson et
al. 2020).
In general, there has been a shift in the use of coral restoration. Projects are becoming less
focused on assessing the feasibility and efficacy of individual restoration techniques and more
focused on developing practical, scalable solutions with specific objectives linked to long-term
outcomes in a changing climate. This approach requires research partnerships that extend
beyond the coral research space to include engineers, social scientists, modellers,
economists, infrastructure development experts, and project managers (Anthony et al. 2020).
The RRAP is the largest investment in restoration and adaptation of a marine ecosystem
globally. RRAP aims to deliver an integrated, properly governed and executed 10-year R&D
program to provide a level of health insurance for the GBR by developing safe and effective
new interventions before they become critically needed. The R&D Program is designed to be
responsive to the range of possible climate outcomes and the range of the Reef’s ecological
responses to this changing environment. It aims to reduce critical uncertainty, improve
McLeod et al.
28
understanding of the system and quickly narrow a set of optimal interventions. These
interventions would provide an integrated, three-point approach:
Cooling and shading reefs to help protect them from the impacts of climate change
Assisting reef species to adapt to a changing environment
Assisting recovery of damaged and degraded reefs
The envisaged final phase of RRAP would be an implementation phase which could overlap
with the R&D Phase as early as five years from commencement depending on the specific
intervention in question. This would include commercial transfer of the reduced set of candidate
measures, including the construction and deployment of scaled-up systems.
Currently, considerable effort, including RRAP, is focused on developing methods and testing
efficacy with the goals of increasing the scale and reducing the costs of interventions. While
there is an urgent need to scale-up interventions to match the scale of threats and degradation,
there is also value in small scale interventions. If project objectives include increasing
community engagement, then approaches that allow for hands on participation may be the
most appropriate. Between 2017 and 2019, ten tourism organisations were actively involved
in coral restoration projects on the GBR (Hein et al. 2020). Since then many more organisations
have become involved and interest is growing rapidly across the sector (J. Lodder, pers.
comm.). This involvement is often motivated by the desire to be proactive in improving the
condition of the reefs they use. For example, crown-of-thorns starfish control, macroalgae
removal, or coral restoration using corals of opportunity may be appropriate to be applied at
small scales to improve the health of local reefs, such as at popular dive sites. Tourism
operations also recognise the value of coral restoration programs in educating the general
public and providing opportunities for reef stewardship (Hein et al. 2020). Until very recently
this type of hands-on reef stewardship would have been difficult or impossible due to strict
permitting requirements. However, a shift in appetite for active interventions by management
agencies has now opened a pathway for these kinds of reef stewardship activities.
5.1 Conclusion
Australia has thousands of hectares of coral reef area, and none of the current coral restoration
techniques are able to be scaled up towards even a fraction of this area (nor do they claim to).
Coral restoration and adaptation is new in Australia and the novelty of the concept has in some
instances led to a narrative that these approaches can ‘save our reefs’. This mismatch in the
scale of the problem, the scale of existing restoration techniques and the expectation set by
such misleading messages can be damaging to the trust in restoration practitioners and
managers. Therefore it is critical to stress that restoration is (1) not a quick fix, but rather a
long-term investment, and (2) not a solution on its own, but rather one of the tools in a reef
manager’s toolbox to assist the recovery and adaptation of reefs to current and projected
climate conditions.
Coral restoration using existing methods in Australia is therefore best applied at the local reef
scale where there is sufficient evidence of successful outcomes in terms of coral growth and
survival. The RRAP is focused on producing an innovative suite of safe, acceptable, and cost-
effective interventions to help protect the GBR from climate change, and increase the
Best practice coral restoration for the Great Barrier Reef
29
scalability of options. However, it is important not to discount techniques and methods with a
local focus as even small-scale actions can support socio-cultural and economic benefits
valuable to local livelihoods and communities. Further, while existing methods may not match
the scale of the crisis facing coral reefs in a climate impacted future, restoration and adaptation
techniques could be key to maintain remnant live reefs, effectively buying time as the world
takes urgent global action on climate.
Such a multi-pronged approach is likely to be the best strategy for maintaining resilient reefs
in a complex future. The rapid progress in trialling coral restoration in Australia builds on
decades of overseas experience. Australia is at the cusp of investing considerable time and
money into developing new interventions and are an emerging leader in this space. There are
great advantages to continuing to actively collaborate with researchers internationally and with
other sectors not currently involved in coral reef management as this can save on costs and
bring in new ideas. This could be facilitated through coordinating communication with
practitioners through organisations and networks such as the Coral Restoration Consortium,
and the Reef Resilience Network, scientific collaborations through RRAP, and the International
Coral Reef Society, and outreach to governments and funding agencies though the United
Nations, and the International Coral Reef Society.
McLeod et al.
30
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Cook, N., Smith, A., Sartori, G., Songcuan, A. (2020) Fitzroy Island coral restoration: project
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Hardisty, P., Roth, C.H., Silvey, P.J., Mead, D., Anthony, K.R.N. (2019). Reef Restoration and
Adaptation Program Investment Case. A report provided to the Australian Government
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Harrison, P.L. (2018). Coral larval restoration on the GBR, Final project report, Great Barrier
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Harrison, P.L, Chartrand, K., Suggett, D. (2019). Coral Abundance Challenge Proof of
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Great Barrier Reef Foundation. 30 pp.
Hein, M., Newlands, M., Elms, A., Vella, K., McLeod, I.M. (2020) Why do Great Barrier Reef
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opportunities, and challenges. Report to the National Environmental Science Program.
Reef and Rainforest Research Centre Limited, Cairns (24 pp.). [1, 30]
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Grimsditch G (In Press) Coral Reef Restoration as a strategy to improve ecosystem
services- A guide to coral restoration methods. United Nations Environment Program,
Nairobi, Kenya. 64 pp.
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(In Review). Perspectives on the use of coral reef restoration as a strategy to support
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Mastroianni, E. (2019). Macroalgal removal on inshore reefs of the Great Barrier Reef.
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Einarsson L. (In Press). Coral restoration in Australia: An overview. Advances in Marine
Biology. Volume 84.
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(2019a). Mapping current and future priorities for coral restoration and adaptation
programs: International Coral Reef Initiative Ad Hoc Committee on Reef Restoration
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32
McLeod, I.M., Williamson, D.H., Taylor, S., Srinivasan, M., Read, M., ... Ceccarelli, D.M.
(2019b), Bommies away! Logistics and early effects of repositioning 400 tonnes of
displaced coral colonies following cyclone impacts on the Great Barrier Reef. Ecological
Management & Restoration, 20: 262-265.
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manager’s guide to coral reef restoration planning and design. NOAA Coral Reef
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Best practice coral restoration for the Great Barrier Reef
33
APPENDIX 1: PUBLICATIONS
Book chapters
1. McLeod, I.M., Hein, M.Y., Babcock, R., Bay, L., Bourne, D.G., Cook, N., Doropoulos,
C., Harrison, P., van Oppen, M.J.H., Mattocks, N., Smith, A., Smith, H., Suggett, D.,
Taylor, B., Wachenfeld, D., Boström-Einarsson L. (In Press). Coral restoration in
Australia: An overview. Advances in Marine Biology. Volume 84.
2. Smith, A., Hancock, B., Cook, N, Vaughn, D (In Press). History and overview. In
‘Active coral restoration: techniques for a changing planet’ (Ed. David Vaughan).
3. Smith, A., Cook, N, Gaskell, J (In Press). ‘Case study - Australia’. In ‘Active coral
restoration: techniques for a changing planet’ (Ed. David Vaughan).
Peer-reviewed journal articles
1. Hein, M., Mohammed, A., Boström-Einarsson, L., Grimsditch, G., Pioch, S., Shaver,
E., Vardi, T., McLeod, I.M. (In Review) Perspectives on the use of coral reef restoration
as a strategy to support and improve reef ecosystem services. Frontiers in Marine
Sciences
2. Ceccarelli, D.M., McLeod, I.M., BoströmEinarsson, L., Bryan S.E., Chartrand, K.M.,
Emslie, M.J., Gibbs, M.T., Gonzalez-Rivero, M., Hein, M.Y., Heyward, A., Kenyon,
T.M., Lewis, B., Mattocks, N., Newlands, M., Schläppy, M., Sugget, D.J., Bay, L. (2020).
Supporting coral reef recovery with small structures and substrate stabilisation: State
of knowledge, considerations for management and implementation. PLoS ONE.
3. Anthony KRN, Helmstedt KJ, Bay LK, Fidelman P, Hussey KE,. McLeod IM.. et al.
(2020) Interventions to help coral reefs under global change - A complex decision
challenge. PLOS ONE 15(8): e0236399. https://doi.org/10.1371/journal.pone.0236399
[0, 140]
4. Boström-Einarsson, L., Babcock, R.C., Bayraktarov, E., Ceccarelli, D.M., Cook N.,
Ferse, S.C.A., Hancock, B., Harrison, P., Hein, M., Shaver, E., Smith, A., Suggett, D.,
Stewart-Sinclair, P.J., Vardi, T., McLeod, I.M. (2020) Coral restoration A systematic
review of current methods, successes, failures and future directions. PLoS ONE 15(1):
e0226631. https://doi.org/10.1371/journal.pone.0226631 [19, 506]
5. McLeod, I.M., Williamson, D.H., Taylor, S., Srinivasan, M., Read, M., Boxer, C.,
Mattocks, N. and Ceccarelli, D.M. (2019), Bommies away! Logistics and early effects
of repositioning 400 tonnes of displaced coral colonies following cyclone impacts on
the Great Barrier Reef. Ecological Management & Restoration, 20: 262-265.
doi:10.1111/emr.12381 [1, 83]
6. Burrows, D.W., Purandare, J., Bay, L., Cook, N., Koopman, D., Long, S., Lundgren,
P., Mead, D., Morris, S., Newlands, M., Roth, C., Wachenfeld, D., Smith, A.K. and
McLeod et al.
34
McLeod, I.M. (2019), Symposium report: Great Barrier Reef restoration symposium,
2018. Ecological Management & Restoration, 20: 175-178. doi:10.1111/emr.12368 [0.
92]
7. Bayraktarov, E., StewartSinclair, P.J., Brisbane, S., BoströmEinarsson, L.,
Saunders, M.I., Lovelock, C.E., Possingham, H.P., Mumby, P.J. and Wilson, K.A.
(2019), Motivations, success, and cost of coral reef restoration. Restoration Ecology,
27: 981-991. doi:10.1111/rec.12977 [11, 352]
8. Suggett, D.J., Camp, E.F., Edmondson, J., BoströmEinarsson, L., Ramler, V., Lohr,
K. and Patterson, J.T. (2019), Optimizing returnoneffort for coral nursery and
outplanting practices to aid restoration of the Great Barrier Reef. Restoration Ecology,
27: 683-693. doi:10.1111/rec.12916 [10, 179]
9. Ceccarelli, D.M., Loffler, Z., Bourne, D.G., Al MoajilCole, G.S., BoströmEinarsson,
L., EvansIllidge, E., Fabricius, K., Glasl, B., Marshall, P., McLeod, I.M., Read, M.,
Schaffelke, B., Smith, A.K., Jorda, G.T., Williamson, D.H. and Bay, L. (2018),
Rehabilitation of coral reefs through removal of macroalgae: state of knowledge and
considerations for management and implementation. Restoration Ecology, 26: 827-
838. doi:10.1111/rec.12852 [14, 2002]
Reports
1. Shaver EC, Courtney CA, West JM, Maynard J, Hein M, Wagner C, Philibotte J,
MacGowan P, McLeod I M, Böstrom-Einarsson L, Bucchianeri K, Johnston L, Koss
J. (2020). A Manager’s Guide to Coral Reef Restoration Planning and Design. NOAA
Coral Reef Conservation Program. NOAA Technical Memorandum CRCP 33, 128 pp.
2. Hein MY, McLeod IM, Shaver EC, Vardi T, Pioch S, Boström-Einarsson L, Ahmed
M, Grimsditch G (In Press) Coral Reef Restoration as a strategy to improve ecosystem
services- A guide to coral restoration methods. United Nations Environment Program,
Nairobi, Kenya. 64 pp.
3. Hein, M., Newlands, M., Elms, A., Vella, K., McLeod, I.M. (2020) Why do Great Barrier
Reef tourism operators engage in coral restoration? An exploration of motivations,
opportunities, and challenges. Report to the National Environmental Science Program.
Reef and Rainforest Research Centre Limited, Cairns (24 pp.). [1, 30]
4. McLeod IM, Newlands M, Hein M, Boström-Einarsson L, Banaszak A, Grimsditch G,
Mohammed A, Mead D, Pioch S, Thornton H, Shaver E, Souter D, Staub F. (2019).
Mapping Current and Future Priorities for Coral Restoration and Adaptation Programs:
International Coral Reef Initiative Ad Hoc Committee on Reef Restoration 2019 Interim
Report. 44 pages. Available at icriforum.org [1, 167]
5. Boström-Einarsson L, Ceccarelli D, Babcock R.C., Bayraktarov E, Cook N, Harrison
P, Hein M, Shaver E, Smith A, Stewart-Sinclair P.J, Vardi T, McLeod I.M. (2018).
Coral restoration in a changing world - A global synthesis of methods and techniques,
Best practice coral restoration for the Great Barrier Reef
35
Report to the National Environmental Science Program. Reef and Rainforest Research
Centre Ltd, Cairns (63pp.). [11]
6. Cook, N., Smith, A., McLeod, I.M., Boström-Einarsson, L., Christie, S., McKenna,
G. (2018). Fitzroy Island coral installation and baseline report. Report to the National
Environmental Science Program. Reef and Rainforest Research Centre Limited,
Cairns, Australia. 26 pp. [0, 578]
Thesis
1. Mastroianni, E. (2019). Macroalgal removal on inshore reefs of the Great Barrier Reef.
Honours Thesis (1st Class). Supervisors DG Bourne, HA Smith, L Boström-
Einarsson, P Harrison
McLeod et al.
36
APPENDIX 2: NESP TWQ HUB PROJECT 4.3
INVOLVEMENT IN GBR CORAL RESTORATION
PROJECTS
Project
NESP TWQ Hub Project 4.3 Involvement
Fitzroy Island coral gardening
Assistance and funding with establishment of first coral
nurseries, assistance with monitoring and project
evaluation.
Agincourt Reef rubble
stabilisation
Advice and assistance with planning and monitoring
Whitsundays Islands coral
gardening
Advice and assistance with planning and monitoring
Magnetic Island macroalgae
removal and coral larvae
propagation
Co-leadership and co-funding with Earthwatch Institute
Australia, Southern Cross University and the Australian
Institute of Marine Science
Coral Nurture Program
(coral gardening and direct
transplantation, six reefs in the
Cairns/ Port Douglas region)
Assistance with monitoring and data management
planning
Mars Inc. Reef Star Installations
Early discussions and advice
Reef Restoration and
Adaptation Program
Collaboration and co-funding of global coral restoration
review
Manta Ray Bay coral bommie
redeployment
Assistance with monitoring as publishing results
www.nesptropical.edu.au
... Cultiver du corail pour reproduire les mêmes expériences en nourrissant les acanthasters avec du corail vivant serait une amélioration intéressante. Il existe de nombreuses méthodes pour cultiver du corail à bas coût telles que la micro-fragmentation, le clonage, etc (pour revue, voirMcLeod et al., 2020). Une autre alternative serait de pouvoir reproduire ces expériences dans des centres de recherche qui disposent déjà de coraux (ex : AIMS). ...
Thesis
Full-text available
Outbreaks of the coral-eating starfish Acanthaster sp. represent one of the most severe threats to coral reefs in the Indo-Pacific zone. Despite significant research efforts over the last three decades, the factors behind the initiation of these outbreaks remain poorly understood. Recent work proposes that processes related to climate change, notably ocean warming and acidification, could favour certain life stages in particular the pelagic larval phase, which is considered a bottleneck for population dynamics. In this context, we studied the effects of ocean warming and acidification predicted by the end of the century according to the classical IPCC business-as-usual scenario (+2°C; pH 7.75) on the reproductive performances of acanthasters after exposing the adults to different conditions. The reproductions were carried out in vitro before studying the following biological processes from fertilization to the final larval stages. Replicating the experiments two years in a row made it possible to specify the optimal reproduction period in New Caledonia, which seems to be in December when the water temperature exceeds 26°C. Our results showed that future modifications of the physico-chemical parameters of the water could have contrasting effects according to the life stages and especially according to the seasonality of reproduction. As one moves away from the optimal reproduction period, the effects become particularly deleterious, with a fertilization success divided by three under heated conditions, associated with an increase in mortality (+25%) as well as in the abnormality rate (up to 100%) of the larvae under acidified conditions. Our results suggest that global warming could lead to an advancement of the breeding period of acanthasters, then a lengthening to approach the period observed at lower latitudes. On the other hand, during the optimal breeding period, we observed weak to moderate effects of temperature on eggs, RGS, fertilization rates, and size of early larval stages. We also showed that all larvae were consistently larger in acidified treatments, regardless of larval stage. In addition, we detected delays in larval development caused by temperature and pH, which could result in a lengthening of the larval cycle in nature, associated with a decrease in the number of recruits. Nevertheless, no significant mortality was shown on larvae resulting from breeding during the optimal period, suggesting possible acclimation of adults to future conditions. Adding an acclimation phase to modified temperature and pH conditions had never been done on acanthasters, and the differences in results between the doctoral project and previous studies that omitted this phase underline its importance for future work. Although our work was carried out over a specific period of time under controlled conditions, which are different from natural conditions, it seems that the acanthasters acclimatized to the modified conditions and produced resistant larvae. Since climate change is a slow phenomenon, it is very likely that acanthasters will acclimatize to future conditions and that population dynamics will not be affected. Our work has increased knowledge of the effects of climate change on acanthasters and clarified the optimal breeding period in New Caledonia.
... There are also opportunities to increase removal efficiency through technology. For example, underwater pumps to remove algae have been trialled in Hawaii and in Australia (Neilson et al. 2018;McLeod et al. 2020). ...
Article
Declining coral cover on tropical coral reefs often results in a concomitant increase in macroalgae. When proliferation of macroalgae persists outside of regular seasonal growth, it can shift the ecosystem dominance away from corals into a permanently altered system. Such an altered system is unlikely to recover naturally, despite ample supply of coral larvae, as coral settlement and survival is reduced by the presence of macroalgae. Physical removal of macroalgae has been proposed to overcome this biotic barrier to recovery, though empirical evidence demonstrating the effects of removal on phase-shifted reefs is lacking. Here, we manually removed macroalgae from twelve 25 m² experimental plots (88.5 ± 6.2 kg wet weight per plot; 90% benthic cover decrease) on a degraded reef prior to coral mass spawning across two years and recorded the number of coral recruits to settlement tiles and natural substrata. Four months after each spawning event, we found a three-fold increase in coral recruits to tiles in plots where macroalgae had been removed (n = 12 plots; February 2019: mean 45.9 ± 12.7 recruits per tile; February 2020: mean 53.9 ± 5.9 recruits per tile) compared to control plots where macroalgae remained (n = 12 plots; February 2019 mean: 13.6 ± 2.8 recruits per tile; February 2020 mean: 17.5 ± 3.5 recruits per tile). These results suggest that, at small scales, macroalgae removal may be a useful intervention to boost recruitment on degraded reefs. Longer-term monitoring is needed to document if coral survivorship, growth, and subsequent reef recovery occurs. This article is protected by copyright. All rights reserved.
Article
Full-text available
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 PLOS ONE PLOS ONE | https://doi.org/10.1371/journal.pone.
Article
Full-text available
Climate change is impacting coral reefs now. Recent pan-tropical bleaching events driven by unprecedented global heat waves have shifted the playing field for coral reef management and policy. While best-practice conventional management remains essential, it may no longer be enough to sustain coral reefs under continued climate change. Nor will climate change mitigation be sufficient on its own. Committed warming and projected reef decline means solutions must involve a portfolio of mitigation, best-practice conventional management and coordinated restoration and adaptation measures involving new and perhaps radical interventions, including local and regional cooling and shading, assisted coral evolution, assisted gene flow, and measures to support and enhance coral recruitment. We propose that proactive research and development to expand the reef management toolbox fast but safely, combined with expedient trialling of promising interventions is now urgently needed, whatever emissions trajectory the world follows. We discuss the challenges and opportunities of embracing new interventions in a race against time, including their risks and uncertainties. Ultimately, solutions to the climate challenge for coral reefs will require consideration of what society wants, what can be achieved technically and economically, and what opportunities we have for action in a rapidly closing window. Finding solutions that work for coral reefs and people will require exceptional levels of coordination of science, management and policy, and open engagement with society. It will also require compromise, because reefs will change under climate change despite our best interventions. We argue that being clear about society’s priorities, and understanding both the opportunities and risks that come with an expanded toolset, can help us make the most of a challenging situation. We offer a conceptual model to help reef managers frame decision problems and objectives, and to guide effective strategy choices in the face of complexity and uncertainty.
Technical Report
Full-text available
Active coral restoration is a new endeavour on the Great Barrier Reef (GBR) with the first projects starting in 2017. Methods used in these early projects include coral gardening, direct transplantation, larval enhancement, substrate addition and substrate enhancement. Although many of these projects are led by or involve the tourism industry, there has been little research into the motivations, opportunities, and challenges for the tourism industry associated with their involvement. To address this knowledge gap, we conducted semi-structured interviews with ten tourism industry operators about their motivations to get involved with coral restoration and their experience. Interviews were transcribed and thematically analysed. Although the number of interviewees was small, they represented most of the tourism companies involved in coral restoration in the GBR at the time. Biotic considerations (wanting to improve coral cover and resilience at the tourism sites) were primary motivators for coral restoration by tourism operators. Idealistic motivations (passion for the reef) and an opportunity to use restoration as a way to improve public awareness of current threats to coral reefs were also reported as motivations. One operator identified a pragmatic motivation to use coral restoration as a way to improve the satisfaction of customers. Protecting the reef from increasing pressures was also a common motivation. Three key challenges were identified by tourism operators, (1) regulatory systems and approvals; (2) uncertainties and challenges linked to weather and climate events; and (3) perceived risk that coral restoration may cause more damage to both the reef and their businesses. This report provides an initial first look at tourism industry motivations and experiences with coral restoration on the GBR as well as insights into how the industry can better be integrated in large-scale efforts supported by the Reef Restoration and Adaptation Program (RRAP) and the Great Barrier Reef Foundation (GBRF). Restoration projects may not be stand-alone activities as they are in other countries. In the GBR they may be integrated with other on-going site stewardship activities such as coral predator and macroalgae control, diver education, pollution reduction and reef monitoring in an attempt to improve the health and aesthetics of the reefs tourist operators use. The tourism industry may offer opportunities to grow the capacity for coral restoration on the GBR. Current challenges to their involvement could be improved through further developing collaborations among restoration practitioners, with regulators, and with the scientific community. A follow-up of their motivations and perspectives, and those of operators not involved in coral restoration activities will be valuable as the coral restoration industry matures.
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Coral reef ecosystems have suffered an unprecedented loss of habitat-forming hard corals in recent decades. While marine conservation has historically focused on passive habitat protection, demand for and interest in active restoration has been growing in recent decades. However, a disconnect between coral restoration practitioners, coral reef managers and scientists has resulted in a disjointed field where it is difficult to gain an overview of existing knowledge. To address this, we aimed to synthesise the available knowledge in a comprehensive global review of coral restoration methods, incorporating data from the peer-reviewed scientific literature, complemented with grey literature and through a survey of coral restoration practitioners. We found that coral restoration case studies are dominated by short-term projects, with 60% of all projects reporting less than 18 months of monitoring of the restored sites. Similarly, most projects are relatively small in spatial scale, with a median size of restored area of 100 m². A diverse range of species are represented in the dataset, with 229 different species from 72 coral genera. Overall, coral restoration projects focused primarily on fast-growing branching corals (59% of studies), and report survival between 60 and 70%. To date, the relatively young field of coral restoration has been plagued by similar ‘growing pains’ as ecological restoration in other ecosystems. These include 1) a lack of clear and achievable objectives, 2) a lack of appropriate and standardised monitoring and reporting and, 3) poorly designed projects in relation to stated objectives. Mitigating these will be crucial to successfully scale up projects, and to retain public trust in restoration as a tool for resilience based management. Finally, while it is clear that practitioners have developed effective methods to successfully grow corals at small scales, it is critical not to view restoration as a replacement for meaningful action on climate change.
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Coral reef restoration is an increasingly important part of tropical marine conservation. Information about what motivates coral reef restoration as well as its success and cost is not well understood but needed to inform restoration decisions. We systematically review and synthesise data from mostly scientific studies published in peer‐reviewed and grey literature on the motivations for coral reef restoration, the variables measured, outcomes reported, the cost per hectare of the restoration project, the survival of restored corals, the duration of the project and its overall spatial extent depending on the restoration technique employed. The main motivation to restore coral reefs for the projects assessed was to further our ecological knowledge and improve restoration techniques, with coral growth, productivity and survival being the main variables measured. The median project cost was 400,000 US$ ha‐1 (2010 US$), ranging from 6,000 US$ ha‐1 for the nursery phase of coral gardening to 4,000,000 US$ ha‐1 for substrate addition to build an artificial reef. Restoration projects were mostly of short duration (1‐2 years) and over small spatial extents (0.01 ha or 108 m²). Median reported survival of restored corals was 60.9%. Future research to survey practitioners who do not publish their discoveries would complement this work. Our findings and database provide critical data to inform future research in coral reef restoration. This article is protected by copyright. All rights reserved.