2021 International COTS Control Forum

Program & Abstracts29-30 March 2021

Pullman Reef Hotel Casino, Cairns

# cots2021

Welcome

Like many reefs around the world, the Great Barrier Reef is suffering from the combined effects of many threats and disturbances, including mass coral bleaching, pollution and storm damage. Outbreaks of crown-of-thorns starfish (COTS) on the Great Barrier present an additional threat with a capacity to greatly reduce coral cover on reefs, both established and recovering. Their impacts are significant, but also amenable to local or regional-scale intervention, restoration and management.

The International Crown-of-Thorns Starfish Control Forum is a collaborative effort between the Reef Trust Partnership within the Great Barrier Reef Foundation (GBRF) and the Reef and Rainforest Research Centre (RRRC). The forum has brought those currently involved in COTS control, from researchers, rangers, vessel operators, industry, and experts, both domestic and abroad, together to review and discuss the current state of knowledge for COTS Integrated Pest Management (IPM) control and to share and discuss opportunities for future innovation in this area.

Future success for an IPM framework will rely on the manual control of outbreaks at specific sites to incorporate any ongoing improvements that may extend beyond current methods. This is a collaborative opportunity to identify and discuss these potential improvements to current methods and the pathways to incorporate them into practice effectively.

Participants are encouraged to sign into Slido on their mobile device (accessed at sli.do) for the event, as questions, polls and comments will be collected via this platform and discussed throughout.

A special welcome is extended to our International delegates (contributing remotely) and all Traditional Owner and Indigenous Rangers. Your participation and engagement will lead to positive future stewardship and ongoing use of the Reef for communities that depend on its health.

On behalf of all our partners, thank you for your time and participation in working towards a better protected Great Barrier Reef.

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07.30 Registration opens

08.45 Welcome to Country Gudju Gudju, Gimuy Walubarra Yidinji and Gavin Singleton, Yirrganydji

Context – The Problem at HandConvener: Theresa Fyffe, Great Barrier Reef Foundation (GBRF)

09.00 History of the Integrated Pest Management (IPM) approach and the future information required Sheriden Morris, Reef and Rainforest Research Centre (RRRC)

09.20 Putting the COTS threat in perspective. What does the future look like for the GBR, including COTS?

Richard Quincey, Great Barrier Reef Marine Park Authority (GBRMPA)

09.40 Introduction to the COTS Control Innovation Program (CCIP) Mary Bonin, GBRF

COTS Control on the GBR TodayConvener: Rickard Abom, C2O Consulting

10.00 Integrated Pest Management and control of the crown-of-thorns starfish: what can a manual control program achieve on the Great Barrier Reef?

David Westcott, CSIRO

10.15 Crown-of-thorns starfish management to achieve Reef 2050 goals for the Great Barrier Reef Roger Beeden, GBRMPA

10.30 Strategic targeting of crown-of-thorns starfish control effort in the Great Barrier Reef Marine Park

David Williamson, GBRMPA

10.45 Panel Discussion

11.00 Morning Tea

11.15 In-field observations from Townsville-Mackay region COTS Control Operator Alejandro Usobiaga, Pacific Marine

11.30 In-field observations and perspectives from Blue Planet Marine Group Dan Godoy, Blue Planet Marine

11.45 In-field observations and perspectives from INLOC Group Rickard Abom, C2O Consulting

12.00 Reviewing COTS control effects 2012-2019: adaptive management leads to continuous improvement

Chad Hewitt, Murdoch University

12.15 Panel discussion

12.30 Lunch

Perspectives from Further Afield Convener: Johanna Johnson, C2O Pacific

13.30 Distribution expansion and historical population outbreak patterns of crown-of-thorns starfish for the last 100 years; additional insights into secondary outbreaks

Nina Yasuda, University of Miyazaki, Japan

Day 1 – Monday 29th March

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Day 1 – Monday 29th March continued

13.45 Okinawa’s comprehensive research program on crown-of-thorns starfish outbreaks Ken Okaji, Coralquest Inc., Japan

14.00 Controlling crown-of-thorns starfish in a small island developing nation: using collaboration and innovation to overcome resource limitations

David Welch, C2O Pacific

14.15 COTS vs COTS: Overcoming threats in the sea by tackling crown-of-thorns starfish with coordination of team

I Dewa Kadek Wira Sanjaya, Coral Triangle Center (CTC), Indonesia

14.30 Perceptions of risk, burden and trust in the release of a biological agent to control European carp in Australian waterways: lessons for COTS integrated pest management

Lucy Carter, CSIRO

14.45 Panel discussion

15.10 Afternoon Tea

Traditional Owners and Tourism Operators Convener: Sheriden Morris, RRRC

15.25 Traditional Owner management and involvement in reef work including COTS and reef restoration

Gavin Singleton and selected Yirrganydji Rangers, Dawul Wuru Aboriginal Corporation

15.40 Traditional Owner aspirations for COTS management in the future Duane Fraser and Liz Wren, RRRC/GBRF

15.55 Long-term juvenile crown-of-thorns starfish control and research at a high value tourism site with implications towards outbreak prediction and suppression

Eric Fisher, Reef Magic

16.10 Panel discussion

Opportunities for Innovation (CCIP) / Panel Discussion Convener: Mary Bonin, GBRF

16.25 What does the future look like for COTS management on the Great Barrier Reef? What research should we prioritise to realise that vision?

Facilitated panel session with selected presenters from the COTS Control Innovation Program. The panel will share the preliminary findings of their work to identify priority areas for research and seek feedback from the audience via Slido™

17.10 Wrap up

Social Function 18.00 - 21.00

Please join us at the Pullman Reef Hotel Casino, Pool Deck, for social drinks, canapés and music. Visual Media and COTS Artwork on display

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07.30 Registration opens

08.30 Revision of Day 1 Summing up and focusing on the definition of success, areas for improvements and introducing the

sessions focused on latest research and challenges Sheriden Morris, RRRC

Ecology and Biology of COTSConvener: Suzanne Long, RRRC

08.45 New insights into the behavioural ecology of crown-of-thorns starfish Morgan Pratchett, James Cook University (JCU)

09.00 Filling missing pieces in the crown-of-thorns puzzle (COTS life-cycle traits) Maria Byrne, University of Sydney (USYD)

09.15 Linking crown-of-thorns starfish abundance to environmental variables using statistical modelling Dan Gladish, CSIRO

09.30 Morphological and molecular analyses reveal COTS ‘brain’ novelty Scott Cummins, Southern Cross University (SCU)

09.45 Reproductive biology of COTS and implications for management of outbreaks Ciemon Caballes, JCU

10.00 Ocean warming and changes in the behaviour and physiology of crown-of-thorns starfish Bethan Lang, JCU

10.15 Panel discussion

10.30 Morning Tea

Monitoring and SurveillanceConvener: David Williamson, GBRMPA

10.45 Monitoring Designed for the COTS Control Program David Westcott, CSIRO

11.00 AIMS Long-term coral reef monitoring: putting COTS into context Mike Emslie, Australian Institute of Marine Science (AIMS)

11.15 Genetic larval quantification to improve understanding of outbreaks Sven Uthicke, AIMS

11.30 Environmental DNA (eDNA) for the detection of adult COTS in water samples Jason Doyle, AIMS

11.45 Quantifying patterns of COTS settlement Peter Doll, JCU

12.00 Vertigo3: a modernised approach to manta towing Brett Kettle, CSIRO

12.15 Use of AI in COTS monitoring and surveillance Matt Dunbabin, Queensland University of Technology (QUT)

12.30 Panel discussion

12.40 Lunch

Day 2 – Tuesday 30th March

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Day 2 – Tuesday 30th March continued

Population Control – Dealing With Causes and Established OutbreaksConvener: Jane Waterhouse, C2O

13.40 Terrestrial runoff and crown-of-thorn starfish outbreaks on the Great Barrier Reef Frederieke Kroon, AIMS

13.55 Biologically based technologies for crown-of-thorns starfish control Lone Hoj, AIMS

14.10 Acoustic tracking of a large predatory marine gastropod, Charonia tritonis, on the Great Barrier Reef

Cherie Motti, AIMS

14.25 Identifying and managing fish predators to mitigate crown-of-thorns starfish outbreaks Frederieke Kroon, AIMS

14.40 Strategies for genetic control of the crown-of-thorns starfish (COTS) Owain Edwards and Maciej Maselko, CSIRO

14.55 Panel discussion

15.05 Afternoon Tea

Modelling and Decision Support ToolsConvener: Cedric Robillot, Great Barrier Reef Foundation

15.20 An ecologically-based operational strategy for crown-of-thorns starfish control on the Great Barrier Reef: Integrated decision making from the site to the regional scale

Cameron Fletcher, CSIRO

15.35 Connectivity and spatial prioritisation of COTS control efforts Karlo Hock, University of Queensland (UQ)

15.50 Insights for COTS management from reef-scale models of intermediate complexity (MICE) Eva Plaganyi, CSIRO

16.05 Quantifying COTS manual control efficacy to promote coral cover Jacob Rogers, UQ

16.20 Evaluating COTS control strategies for the Great Barrier Reef using a systems modelling approach

Scott Condie, CSIRO

16.35 The COTS Data Lifecycle: connecting on-water collection to adaptive management of COTS on the GBR

Sam Matthews, GBRMPA

16.50 Panel discussion

17.00 Wrap up & close Sheriden Morris, RRRC

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Field TripAn optional field trip is on offer to all delegates following the forum. Delegates are given the opportunity to visit the Reef Magic Pontoon at Moore Reef. Here, guided talks by a Master Reef Guide will take place alongside snorkelling, demonstration of control techniques by trained divers, and tours of a COTS vessel. Aside from being a great opportunity to see some of the Great Barrier Reef while in Cairns, this experience also will provide a close-up insight into the monitoring and control methods currently being used.

Field trip fee will cover all transfers, lunch, snorkelling equipment, as well as all guided tours (excluding SCUBA). Guided SCUBA dives will also be organised on the day for those wishing to spend more time underwater. These will incur an additional cost on top of the field trip fee.

Field trip detailsWednesday, March 31, 2020Cairns Marina & Moore Reef

Itinerary08:30 Check-in at Reef Fleet Terminal09:00 Boat departs for Moore Reef10:30 Arrival at Moore Reef10:35 Pontoon activities, guided tour and demonstration of control vessel operations15:30 Boat departs Pontoon17:00 Arrival at Cairns CostDelegates are offered a 40% Discount on this trip by using the code: “RRRC” when calling to make abooking. The cost of the full day trip is $167.30 including discount. Making a bookingPlease call +61 (0)7 4031 1588 (between 08:00-17:00 AEST) to secure a spot on this very special trip.

Day 3 – Wednesday 31st March

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ABSTRACTSAbstracts are presented in the running order of the forum program timetable

Introduction to the COTS Control Innovation Program (CCIP)Mary C. Bonin1

1COTS Control Innovation Program, Great Barrier Reef Foundation, Brisbane, QLD, Australia

Outbreaks of coral-eating crown-of-thorns starfish (COTS) are a major cause of coral decline on the Great Barrier Reef and future COTS outbreaks are almost certain. Managing these damaging outbreaks is a critical priority to improve the health of the Great Barrier Reef World Heritage Area. Effective management of COTS outbreaks is also a necessary complement to research and innovation that helps the Great Barrier Reef resist, adapt to, and recover from the impacts of climate change. The overarching goal of the COTS Control Innovation Program (CCIP) is to create a step change that will accelerate the development of innovative control and surveillance methods, while continuing to improve the efficacy and efficiency of current methods. The program is being delivered as a collaborative partnership between AIMS, CSIRO, James Cook University, University of Queensland, and the Great Barrier Reef Foundation, with a total investment of $9.8m through the Reef Trust Partnership. In Phase 1 of the program (2020-21), 43 multidisciplinary experts are assessing the feasibility and benefit of a broad range of possible research investment opportunities across six research theme areas. This initial design phase will deliver recommendations for an integrated 3-year research and innovation program (2021-24). Outcomes of this research program will advance our capacity to proactively detect and suppress primary outbreaks and manage COTS at scale on the Great Barrier Reef.

Integrated Pest Management and control of the crown-of-thorns starfish: what can a manual control program can achieve on the Great Barrier Reef?

David Westcott1, Cameron Fletcher1, Scott Condie2, Dan Gladish3, Mary Bonin4, Sheriden Morris5

1CSIRO Land and Water, Australia2CSIRO Oceans and Atmosphere, Australia3CSIRO Data61, Pullenvale, QLD, Australia

4COTS Control Innovation Program, Great Barrier Reef Foundation, Brisbane, QLD, Australia5Reef and Rainforest Research Centre, Cairns, QLD, Australia

Crown-of-thorns starfish (COTS) are a significant contributor to hard coral loss throughout the Indo-Pacific Region. Since the 1960s, on the Great Barrier Reef (GBR) and across the Indo-Pacific Region, 10s of millions of dollars have been spent on COTS control. Despite this significant investment the general consensus has been that control has had only limited success. During the current outbreak on the GBR a new approach to manual control has been implemented with the introduction of a coordinated control program and a strategic approach to control based on integrated pest management (IPM) principles. The IPM Program identifies program objectives and the key tasks that must performed, it optimises how these are achieved, and then applies a structured approach to decision making at each of the relevant scales: the site, the individual reef, the region and the GBR as a whole. This structured approach to decision making integrates an understanding of the processes underpinning COTS population dynamics, fleet and dive operations logistics and control program objectives across these scales.

In this presentation we use data from the IPM Program’s operations to address the following four questions:

1) How effective is the program in achieving COTS control at the scale of the site, the individual reef and the region?

2) How reliable are the decision criteria used to guide decision making?

3) What does this tell us about the potential of the current program for responding to the next outbreak?

Our results indicate that the program is far more effective than was initially anticipated and suggest that a modestly funded program, operating under our IPM principles, could significantly modify the dynamics of the next COTS outbreak on the GBR.

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Crown-of-thorns starfish management to achieve Reef 2050 goals for the Great Barrier Reef

Darren Cameron1, Roger Beeden1, Jo Baker1, Mary Bonin2, Dylan Horne1, Anya Jaeckli1, Sam Matthews1, Tristan Simpson1, Daniel Schultz1, David Williamson1

1Reef Interventions, Great Barrier Reef Marine Park Authority, Townsville, QLD, Australia2COTS Control Innovation Program, Great Barrier Reef Foundation, Brisbane, QLD, Australia

The Reef 2050 Plan identifies crown-of-thorns starfish (COTS) outbreaks as a significant threat to the health of the Great Barrier Reef ecosystem. It calls on us to work collaboratively across government, research and industry bodies to reduce the impact of COTS in the Great Barrier Reef World Heritage Area. These outbreaks compound the damage caused by tropical cyclones and coral bleaching events, and mitigating their impact is one of the most scalable and feasible on-ground management interventions currently available to enhance Reef resilience and recovery in the face of climate change. The COTS Control Program is delivered as part of the Great Barrier Reef Marine Park Authority’s management strategy to address the COTS threat. The Program’s manual in-water control component is delivered through a strategic partnership between the Great Barrier Reef Foundation (GBRF), Great Barrier Reef Marine Park Authority (GBRMPA) and the Reef and Rainforest Research Centre (RRRC). Since its inception, the COTS Control Program has been carried out in collaboration with tourism industry and research partners to ensure the best available science and local knowledge are incorporated into on-ground action. The goal of the COTS Control Program is to protect coral by culling starfish down to ecologically sustainable levels that promote coral growth and recovery. We are not attempting to stop the outbreaks or eradicate the starfish; these are not feasible goals given the limitations of current control methods. The Program strategically focuses its resources on individual reefs of high ecological and economic value across the Marine Park using dedicated vessels and trained crews. With the expansion of the program in 2018, we implemented an innovative new approach to pest management in collaboration with our research partners in the National Environmental Science Program. Crews on board the fleet of vessels are now trained to use targeted surveillance, intensive culling, and reef health surveys to achieve sustainable starfish numbers that promote coral growth and recovery. To support this new approach, the Marine Park Authority has developed data capture apps and visualisation tools to support adaptive and data-driven decision making. The expanded COTS Control Program is protecting coral from COTS impacts on a network of >100 high value reefs across the Marine Park. The COTS Control Program has undergone significant improvement since its inception, and we strive to maintain this momentum, delivering world-leading, science-based, adaptive management of COTS on the Great Barrier Reef looking forward to 2050.

Strategic targeting of crown-of-thorns starfish control effort in the Great Barrier Reef Marine Park

David Williamson1, Joanne Baker1, Roger Beeden1, Darren Cameron1, Dylan Horne1, Anya Jaeckli1, Sam Matthews1, Daniel Schultz1, Mary Bonin2

1Reef Interventions, Great Barrier Reef Marine Park Authority, Townsville, QLD, Australia2COTS Control Innovation Program, Great Barrier Reef Foundation, Brisbane, QLD, Australia

Outbreaks of crown-of-thorns starfish (COTS) periodically occur on reefs throughout the Indo-Pacific and typically result in broad-scale declines in hard coral cover and shifts in benthic community structure. On the Great Barrier Reef, COTS are a major driver of systemic coral decline and efforts to mitigate their impact have been amplified in recent years through an expanded COTS Control Program. The COTS Control Program employs a data-driven strategic approach to decide where, when and how to undertake starfish management across the expanse of the Great Barrier Reef Marine Park. These decisions are underpinned by several innovative tools designed to provide decision-makers (i.e. Marine Park managers and control vessel crews) with the information required to allocate program resources efficiently and effectively. The Program is being adaptively managed in close partnership with science and industry partners, and it is currently delivered through a fleet of five vessels with professional crews trained to undertake COTS surveillance, culling and reef health surveys. This talk will provide an overview of our strategic approach to vessel allocation across Marine Park management regions, reef prioritisation within regions, and rank for action amongst prioritised reefs. We will provide insight into the successes and challenges we have faced

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along the way, highlighting key knowledge gaps and areas for scientific innovation from a management perspective. The Marine Park Authority is committed to working collaboratively with our science, industry and stakeholder partners to apply the best available knowledge and experience to understand and effectively manage COTS populations and deliver real-world benefits for the health of the ecosystem and for the people that utilise it.

In-field observations from Townsville-Mackay region COTS Control OperatorJack Strickland1, Alejandro Usobiaga1, Enrique Mosquera1

1Pacific Marine Group Pty Ltd, Townsville, QLD, Australia

Pacific Marine Group (PMG) is working for GBRMPA to control the COTS population on high value reefs in the Marine Park Townsville to Mackay area, between Townsville and the Whitsundays (latitudes -18.9’ S and -21.1’ S). As a COTS control operator, PMG’s aim is to reduce COTS densities to allow for coral growth to outpace COTS feeding capacities as determined by CSIRO (Babcock et al. 2014), as well as undertaking reef Surveillance, Reef Health Impact Surveys and supporting research activities.

In 18 months of ongoing operations PMG have visited three reefs. Two of which were categorized to be in ‘Severe Outbreak’ from the COTS/Tow observed on the first visit with since over 52,000 COTS removed. According to the most recent Surveillance both reefs are categorized as ‘No Outbreak’ status.

To date we have spent over 300 operational days and more than 7,000 dive hours on the reefs and will share PMG learnings and how the activities have evolved since the early trips to date, covering an insight into the successes, challenges, limitations and constraints faced along the way from the operator’s perspective. We aim to provide an insight view of a COTS control dive operation with a comprehensive overview on all the field aspects including; decision making processes, dive planning and tactics, equipment, environmental considerations, safety aspects, helpful tools and resources.

Finally, whilst notable impact has been made over the past 18months on the COTS densities on two reefs, PMG acknowledges that COTS management is still an ongoing operation far from completion and our efforts so far are to be replicated across the 28 Priority Reefs assigned to PMG’s working area. We are optimistic regarding the future of our culling operations but will strive to demonstrate COTS management is a dynamic operation requiring a close working relationship between all stakeholders from operators, scientific community and policy makers.

In-field observations and perspectives from Blue Planet Marine GroupDan Godoy1, Dave Paton1, Michael Civiello1, Tom Taylor-Latt1

1Blue Planet Marine, Canberra, ACT, Australia

As part of the Great Barrier Reef Marine Park Authority’s (GBRMPA) crown-of-thorns starfish (COTS) control program, Blue Planet Marine (BPM) has been engaged to undertake COTS Control and research activities within several regions of the Great Barrier Reef Marine Park (GBRMP). Within the prescribed scope of work, BPM have undertaken operations across a vast expanse of the GBRMP, extending from the Lockhart River in the Far North region down to the Bunker Group at the southern extremity of the Marine Park. Since operations commenced in November 2018, BPM have spent 355 days at sea undertaking surveillance, culling, reef health surveys, and providing COTS research support. Overall, BPM have completed more than 7,800 surveillance manta tows extending over 1,650 km across 102 ecologically and economically important priority target reefs. In addition, BPM have established more than 600 permanent Reef Health and Impact Survey (RHIS) sites and controlled over 13,000 COTS. With the support of the GBRMPA COT Management Team, these significant achievements by our dedicated team has resulted in the collection and provision of highly valuable coral cover and health indices, while substantially reducing the impact of COTS in support of the GBRMPA Reef Blueprint for Resilience initiative. Ultimately, being at the interface between sound management principals developed under the National Environmental Science Program (NESP) Integrated Pest Management Program and the utilisation of operational methodologies to achieve those established management targets, BPM are delighted to share a unique insight through our experiences, challenges and successes.

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In-field observations and perspectives from INLOC GroupRickard Abom1

1C2O Consulting, QLD, Australia

The Great Barrier Reef Foundation’s Reef Trust Partnership (RTP) crown-of-thorns starfish (COTS) Control Program aims to reduce coral damaged caused by COTS in the Great Barrier Reef (GBR) Marine Park. The Great Barrier Reef Foundation (GBRF) is partnering with the Reef & Rainforest Research Centre (RRRC) and the Great Barrier Reef Marine Park Authority (GBRMPA) to deliver this program, in collaboration with Integrated Pest Management (IPM) research activities delivered through the National Environmental Science Program (NESP) Tropical Water Quality (TWQ) Hub.

During the reporting period (1 July to 31 December 2020), the three INLOC COTS control vessels were operating – MV Hero, MV Tura and MV Venus II – in coordinated surveillance, reef health impact surveys (RHIS) and culling activities on target reefs across an area of the GBR between Lizard Island and Airlie Beach. The vessel crew also provide research support to NESP and other research programs. In summary:

• The three INLOC vessels conducted 32 voyages of generally 10-days each but varying between 5 and 19 days due to weather and logistics.

• These voyages signify 331 days of COTS control activities in the GBR Marine Park with a total of 3,665 hours of dive time conducting surveillance, RHIS and culling activities over 67 different reefs (including 3 non-priority reefs).

• A total of 13,841 COTS were culled from 3,090 ha of the GBR Marine Park. These reefs represent 64 of the 123 priority reefs in the Lizard Island to Airlie Beach region allocated to 2020/2021 workplan.

• Our teams provided 122 hours of research support through the NESP TWQ Hub and other research programs, contributing to closing the IPM loop between science and impact for the COTS Control Program.

Reviewing COTS control efforts 2012-2019: adaptive management leads to continuous improvement

Chad L Hewitt1, Marnie L Campbell1

1Murdoch University, Murdoch, WA, Australia

The Great Barrier Reef (GBR) holds an iconic place in the Australian psyche and represents unique and outstanding values to Australia and the global community as acknowledged through its World Heritage listing in 1981. Despite numerous protections, the GBR has been under increasing stress from numerous threats resulting in decreases in hard coral cover. These include impacts from tropical cyclones, oceanic heatwaves, increased nutrient inputs, fishing pressures and coral predation by the natural predator crown-of-thorns starfish (COTS) particularly during cyclic ‘outbreaks’.

COTS outbreaks have some degree of predictability, particularly within the cycle of an outbreak, leading to opportunities for intervention to minimise or even prevent coral loss. When a new outbreak was detected in 2010 (the fourth outbreak cycle since the 1960s), several parties including tourism operators, reef managers and key members of the public lobbied for significant efforts to minimise COTS impact. In 2012 the Australian Government provided significant funding for manual COTS control at key economic assets between 2012 and June 2018, and additional funding for an expanded program between July 2018 to June 2020.

An independent review has examined the COTS Control Program between 2012/13 and 2018/19. Here we report the high level findings of the review, specifically: insights to the changes in the Control Program through time; the extent to which key stakeholder concerns with Control Program efforts have been incorporated or addressed in improvements; whether the current surveillance and control data collections are commensurate with Control Program objectives to optimise investment and control effort; and, critical review of the effectiveness of manual control in reducing COTS density and size at control sites.

In general, the Control Program has shifted from reactionary (tactical) response almost entirely focused on economic values to a more strategic response focused on core environmental values that also have economic benefits. This shift has been driven by changes in strategy (e.g. methods of site/reef selection; Integrated Pest

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Management strategy in 2016), application of best available scientific evidence (e.g. definition of outbreak threshold densities; determination of control targets; efficiency of control methods), and increasing incorporation and timeliness of data driven decision-making. We find that adopting an IMP approach to inform knowledge acquisition and decision-making in the current Expanded Control Program is likely to achieve wider benefits to the GBR and create greater preparedness for response to future outbreaks.

Distribution expansion and historical population outbreak patterns of crown-of-thorns starfish for the last 100 years; additional insights into secondary outbreaks

Nina Yasuda1

1Department of Marine Biology and Environmental Science, Faculty of Agriculture, University of Miyazaki1-1 Gakuen Kibanadai-nishi, Miyazaki 889-2192, Japan

The distribution and population outbreak records of the crown-of-thorns starfish (COTS), Acanthaster cf. solaris, in Japan from 1912to 2015 was reviewed and analyzed. The literature survey suggests that COTS distribution has been extending northwards since 1945 from Amami Ohshima (its previous northernmost distribution) to Miyake Island and Goto Island. Genetic homogeneity within Japanese COTS populations indicates that larval dispersal has likely caused this poleward migration. Water temperatures have significantly increased in the temperate area of Japan, implying that climate change is partly responsible for this poleward migration. More frequent and intense population outbreaks in temperate areas were also observed, possibly in relation to increased water temperatures and successive larval dispersal from the south. Overall, complex and persistent patterns were observed fortwo major successive population outbreaks in Japan: from 1969 to 1991 and from 1995 to now. The evidence suggests that the western Okinawa populations are the most likely origin for secondary outbreaks within Japan. The Amami population is also likely to be an important source for outbreaks intemperate regions. However, no records of intensive population outbreaks were found until 2015 for least in two regions: Ogasawara and the Ohsumi Islands. Ogasawara is located approximately 1,000 km south of the Kuroshio Current, so infestation via larval dispersal from other populations is more limited than in other Kuroshio regions. The Ohsumi Islands are, however, located in the middle of the Kuroshio Current, implying that insufficient corals are available for the growth of COTS or that unknown environment factors suppress recruitment and juvenile survival.

Okinawa’s comprehensive research program on crown-of-thorns starfish outbreaksKen Okaji1, Kei Ogasawara1, Eiji Yamakawa2, Makoto Kitamura2, Naoki Kumagai3,

Nobuyuki Nakatomi4, Shuichi Yamamoto4, Ryota Nakajima5, Koichi Kinjo6, Masako Nakamura7, Nina Yasuda8

1Coralquest Inc., 1-34-10 Asahicho, Atsugi, Kanagawa 2430014, Japan 2Incorporated Foundation Okinawa Prefecture Environment Science Center,

720 Kyozuka, Urasoe, Okinawa 901-2111, Japan 3National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki, 305-8506, Japan

4Graduate School of Engineering, Soka University, 1-236 Tangimachi, Hachioji, Tokyo 1920003, Japan 5JAMSTEC, 2-15, Natsushimacho, Yokosuka, Kanagawa 2370061, Japan6Environmental Preservation Division, Okinawa Prefectural Government,

1-2-2 Izumizaki, Naha, Okinawa 9008570, Japan 7School of Marine Science and Technology, Tokai University, 3-20-1 Orido,

Shimizu, Shizuoka city, Shizuoka, 424-8610, Japan 8Department of Marine Biology and Environmental Science, Faculty of Agriculture,

University of Miyazaki1-1 Gakuen Kibanadai-nishi, Miyazaki 889-2192, Japan

Repeated outbreaks of crown-of-thorns starfish (COTS) have devastated Okinawa’s coral communities during the past five decades. For identifying the important causal factors of outbreaks and developing a new management policy, Okinawa Prefectural Government implemented its first ever comprehensive research program on this species between 2012 and 2018. The program involved water quality observation, larval nutrition, larval dispersal simulation, and juvenile ecology. The results of the program suggested the following: 1) food availability for COTS larvae quickly increases to the level at which larval growth

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and survival is supported after heavy rainfall; 2) in addition to phytoplankton, COTS larvae are able to utilize particulate organic matter such as detritus and coral mucus as supplemental food sources; 3) COTS larval dispersion leading to successful recruitment is likely a local-scale event; 4) the prediction of COTS outbreaks by monitoring the density of alga-eating juveniles is considered to be feasible. On the basis of these results, the Okinawa Prefectural Government proposes water quality improvement in the coastal catchment areas as a long-term target as well as continued physical removal of COTS in limited areas for short-term management.

Controlling crown-of-thorns starfish in a small island developing nation: using collaboration and innovation to overcome resource limitations

Johanna Johnson1,2, David Welch1,2, Peter Whitelaw3, Christina Shaw4, Pascal Dumas5, Rocky Kaku6, Owen Drew7, Kehana Andrew8

1C2O Pacific, Port Vila, Vanuatu2College of Science and Engineering, James Cook University, Cairns, QLD

3Sailaway Cruises4Big Blue Scuba; Vanuatu Environmental Science Society

5IRD, Noumea, New Caledonia6Vanuatu Fisheries Department

7Tranquility Island Resort8Vanuatu Department of Tourism

Vanuatu is an archipelago of 83 islands with the majority of the population living in coastal areas based on a subsistence lifestyle that relies on healthy coral reef ecosystems for sustainable fisheries, small-scale livelihoods and reef tourism. Vanuatu has experienced crown-of-thorns starfish (COTS) outbreaks numerous times, and previous COTS outbreaks documented in 2006, 2008 and 2014 caused significant reef habitat declines (Dumas et al. 2014, Johnson et al. in press). There is currently an active outbreak of COTS in Vanuatu that has been observed on fringing reefs around the main island of Efate and nearby islands of Lelepa, Moso, Ifira and Hideaway, areas of high to very high coral cover (Johnson et al. 2016, 2018). There are also reports of COTS on fringing reefs around islands to the north – Nguna, Pele, Espiritu Santo – as well as islands in the south of the country – Tanna. Due to limited resources and high accessibility of fringing reefs, COTS control is haphazard through a voluntary program, and only some data (e.g. number of COTS culled) are documented using an online reporting system1. Marine tourism operators and community groups are leading the initiative using injector kits to cull COTS, and remote villages without kits are removing COTS manually and burning or burying them. Critically, a network of committed marine stakeholders are reporting sightings of COTS in high densities and responding accordingly with collective culling efforts. Communities have also used a ‘bounty’ system as incentive to remove COTS, with Pele Island addressing a recent outbreak and protecting their high-value eco-tourism reefs. An intensive 6-months of control in 2020 removed over 5,600 COTS and identified hotspot areas around Pango Peninsula and in Mele Bay. Observations that COTS outbreaks are becoming more frequent is of great concern to the tourism and fishing sectors, and future successful COTS control will require a more strategic and coordinated approach that is locally appropriate.

COTS vs COTS: Overcoming threats in the sea by tackling crown-of-thorns starfish with coordination of team

I Dewa Kadek Wira Sanjaya1, Kitty Currier1, Hesti Handayani Widodo1, Made Sudarsana2

1Coral Triangle Center (CTC), Jl. Bet Ngandang II No. 88-89 Sanur, Denpasar, Indonesia 802282Authority of Marine and Fishery of Bali Province, Jl. Patimura no 77, Denpasar, Bali, Indonesia 80234

Pressure on the coast and the sea in Bali is increasing and increasingly complex. Various efforts in dealing with threats have also been carried out by various parties, whether organized or conducted sporadically. One of the threats in the Bali sea that almost every year becomes a problem is the outbreak of crown-of-thorns starfish (COTS). Desktop studies show that several regions in Bali, namely Pemuteran and Menjangan Island in Bali Barat National Park, have recorded large numbers of COTS every year. During June and November,

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COTS are often found at these locations, although the actual number of COTS in these outbreaks is uncertain because the information recorded is based on the number of COTS removed opportunistically. At Menjangan Island, which has an area of around 17 hectares, more than 7.500 COTS were removed during one outbreak in 2017 and more than 700.000 COTS removed on 1997 in Bali Barat National Park, and in Pemuteran, more than 100 individuals were found at one dive site. It seems that COTS can often be found in these two locations at any time. COTS outbreak prevention efforts at these locations have been carried out since monitoring for outbreaks began in 1996.

COTS are removed manually by snorkelers or divers using a steel hook and then put into a net bag and brought to the surface and buried near the beach. Alternatively, vinegar injection is used to kill the COTS. The COTS outbreak phenomenon in Bali (Pemuteran and Menjangan Island) continues to occur every year, so it is deemed necessary to coordinate all parties to address this threat, not only in the COTS outbreak locations but also in other locations so that local communities will be prepared if the need ever arises.

Therefore, the formation of a coordinated team to address this threat is important and proposed as a solution to monitor conditions in the field, coordinate response efforts, and prepare response teams at different locations as necessary. Another important consideration is how to allocate available resources to jointly prevent, reduce and overcome the threats that exist in each location and prevent the spread to other places.

Perceptions of risk, burden and trust in the release of a biological agent to control European carp in Australian waterways: lessons for COTS integrated pest management

Lucy Carter1, Aditi Mankad1, Matt Curnock1

1CSIRO Land and Water, Brisbane, QLD, Australia

The European or common carp, Cyprinus carpio L., is considered a major threat to the sustainability of Australian freshwater systems. The Australian government’s Fisheries Research and Development Corporation (FRDC) has been tasked with determining the economic, social and ecological feasibility of releasing Cyprinid herpesvirus 3 under the National Carp Control Plan (NCCP).

Previous research on stakeholder perspectives has focussed on the opinions of experts or peak body representatives. Under social science research commissioned by the NCCP, the CSIRO sought to gather insights from individuals living in situ to a potential release or clean-up site. Our qualitative analysis reports specifically on the issues faced by rural and regional communities who rely on local social networks and institutions for their livelihoods and wellbeing. The risk perspectives of these communities to a virus release reveal a sophisticated understanding of both ecological complexity and experience of current and past institutional failings.

Our findings indicate that public trust in the governance of the control program, how the problem is defined and communicated and the quality of engagement with local communities were key issues of significance. We suggest that these considerations may also be of relevance to the roll-out of a COTS control program. Our findings reflect a) the value of engaging closely with local communities and b) efforts to build trust and engage meaningfully are two important drivers for garnering local support for the release of a biological agent. Engagement methods which respect and value the uniqueness of individual communities will serve decision-makers well.

Traditional Owner management and involvement in reef work including COTS and reef restoration

Gavin Singleton1 & Selected Yirrganydji Rangers1

1Dawul Wuru Aboriginal Corporation, Cairns, QLD, Australia

Two Yirrganydji rangers were graduates from the AMPTO/Gempearl COTS program. And they have since been involved in reef restoration work. Selected rangers will provide their views on their experience in COTS control, including challenges, lessons learnt, and the opportunities and aspirations for GBR Traditional Owner groups in this space.

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Traditional Owner aspirations for COTS management in the futureDuane Fraser1, Liz Wren2

1Reef and Rainforest Research Centre, Cairns, QLD, Australia2Great Barrier Reef Foundation, Brisbane, QLD, Australia

Traditional Owners are co- designing delivery of an innovative COTS Control Program on the Great Barrier Reef that aims to elevate leadership and participation from GBR Traditional Owners. Such a program will include pathways for specialised, culturally grounded and culturally appropriate employment, training and leadership opportunities. This work also considers and respects the Reef as a cultural landscape and the association with Traditional Owners’ cultural heritage values associated with COTS control work. Surrounding this, there are additional aspirations to develop cultural guidelines for adoption by key partners in current COTS research, surveillance and control. This is an achievable goal for sea country groups, and one which can provide a number of co-benefits to existing business models.

Long-term juvenile crown-of-thorns starfish control and research at a high value tourism site with implications towards outbreak prediction and suppression

Eric Fisher1

1Experience Co., Cairns, QLD, Australia

Crown-of-thorns starfish (COTS) are a coral predator and large populations on individual coral reefs ultimately reduce hard coral cover to low levels. At tourism sites in the Great Barrier Reef Marine Park, high levels of coral cover are maximised through various efforts to improve customer appreciation of a world heritage area but also participate in building a coral reef resilience network. Ongoing COTS control programs are an example of one initiative tourism operators utilise to preserve and protect live coral cover. Cairns tourism Operator Reef Magic Cruises has a site at the north west aspect of Moore Reef and extensive, reef health monitoring surveys around this site revealed increasing COTS abundance in 2009. A multi-shot injection programme was conducted between 2010 and 2012 which removed 650 Adults and 2,060 juvenile COTS from this site. This programme identified key habitat areas that experience repeatable high recruitment rates. In 2014 the programme was refined to focus on locating and collecting juvenile COTS using belt transects. From 2014 too present, 11,049 juvenile COTS between 5 and 150mm in size have been removed. This has also provided quantifiable information on juvenile densities, ontogenetic shifts in coral diet and size structure of juvenile population over time. Sampling designs that focus on juvenile COTS abundance combined with other early detection methods could be incorporated into an early warning system to predict future outbreaks in the initiation region of the Great Barrier Reef. This long term juvenile research programme provides information on juvenile COTS ecology that may be useful to innovative programmes involved with suppression of future outbreaks.

New insights into the behavioural ecology of crown-of-thorns starfishMorgan Pratchett1

1ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD, Australia

Crown-of-thorns starfish (Acanthaster spp.) are among the most extensively studied single species on coral reefs, largely owing to their devastating impacts on live coral cover during population irruptions. There remain however, considerable gaps in our understanding of their behavioural ecology. In this presentation, I will outline the latest advances in our efforts to better understand and manage population irruptions of crown-of-thorns starfish, focussing mainly on their movement and diel patterns of behaviour. We have measured movement at a range of spatiotemporal scales using a variety of different techniques, showing that adult crown-of-thorns starfish can be extremely site attached and move very little if they have good access to coral prey, and especially Acropora spp. Interestingly, crown-of-thorns starfish may exhibit distinct homing behaviour as has been previously reported in urchins, and return to the same resting location after feeding bouts. Our research on the behaviour of crown-of-thorns starfish in the field has also revealed distinct changes in the behavioural mode of starfish at different times throughout the day, which will have important implications of detecting and culling starfish.

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Filling missing pieces in the crown-of-thorns puzzle (COTS life-cycle traits)Maria Byrne1, Dione Deaker1, Tyler Carrier2, Jon Allen3, Symon Dworjanyn4,

Ben Mos4, Vanessa Guerra5, Nina Yasuda6, Mike Hart4

1University of Sydney, NSW, Australia2GEOMAR Helmholtz Centre for Ocean Research, Kiel

3College of William and Mary, Williamsburg, Virginia4Southern Cross University, QLD, Australia

5Simon Fraser University, Burnaby, British Columbia 6Univserity of Miyazaki1-1 Gakuen Kibanadai-nishi, Miyazaki 889-2192, Japan

The crown-of-thorns starfish (COTS) is one of the most influential invertebrates in tropical reef systems. The specific traits across the life cycle stages of COTS that drive outbreaks and convey its superstar keystone ecological role are important to understand and are best identified in context with the evolution and phenotypic plasticity of the Asteroidea. As characteristic of tropical starfish larvae, the larvae of COTS show a propensity for cloning and thus have the potential to be ‘eternal’ and also have a distinct microbiome including photobacteria that may contribute to their nutrition. The dynamics of the early herbivorous juvenile stage of COTS, a likely mortality bottle neck, is important to understand and we investigated the impact of a delay in diet transition from herbivory to corallivory in cohorts reared on coralline algae for 10 months and 6.5 years. Our results show the inherent resilience and growth plasticity of the juveniles and the marked age-size disconnect that is typical of the Asteroidea. The implication of the juveniles ‘in waiting’ hypothesis is the possibility that the current killing programs used to manage COTS may trigger a feedback mechanism promoting the herbivory-corallivory transition as juveniles are released from adult competition. For the adults, non-gender specific expression of gamete binding proteins and occurrence of hermaphrodites suggests the potential for reproductive assurance through self-fertilization. This find has implications for management of COTS populations and initiation of outbreaks in consideration of their massive fecundity. The pieces of the COTS puzzle contributed in this research in larval plasticity, the resilience of the herbivorous juvenile stage to coral scarcity and the potential that COTS may be micro-hermaphrodites, adds to the suite of remarkable traits of COTS and the unappreciated complexity of COTS boom-bust dynamics.

Linking crown-of-thorns starfish abundance to environmental variables using statistical modelling

Dan Gladish1

1CSIRO Data61, Pullenvale, QLD, Australia

While knowledge about the preferred habitat for crown-of-thorns starfish (COTS) has increased in recent times, there is still high uncertainty in understanding the environmental factors and conditions of COTS habitat and abundance. Some efforts have focused on statistical models, accounting for random effects. In this work, we present efforts in linking different environmental factors to COTS through generalized linear mixed modelling. In particular, we analyse the effects of bleaching and coral cover in explaining the habitat of COTS. Our focus is on data at the site and reef scales during a recent bleaching event on the Great Barrier Reef. This analysis is funded by NESP TWQ Hub.

Morphological and molecular analyses reveal COTS ‘brain’ noveltyScott Cummins1

1Southern Cross University, Australia

What are COTS actually thinking? To help answer this question, it is critical to look deep in into the neural system of the animal. The starfish neural system has no central ‘brain’, yet comprises of a circumoral ring linked to radial nerve cords that together coordinate movement, growth, regeneration, reproduction, defence, olfaction and more. Over the past five years, we have investigated the COTS radial nerve cords to establish new knowledge into their make-up at the anatomical and molecular levels. I will describe some of the major findings (published and unpublished), inclusive of the identification of unique neural structures and neurohormones that provide a framework for establishing COTS neuroscience approaches and manipulating COTS behaviour.

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Reproductive biology of COTS and implications for management of outbreaksCiemon Caballes1

1ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD, Australia

Population outbreaks of the coral-eating crown-of-thorns starfish (COTS) often result in extensive coral mortality with highly extended recovery times, thereby contributing significantly to sustained and ongoing declines in coral cover across the Indo-Pacific. Long-term or permanent solutions depend on filling crucial gaps in our knowledge of the biology of COTS, particularly its reproductive biology and early life history, to understand the initiation and spread of outbreaks. Populations of COTS are typically predisposed to outbreaks due to inherent life history characteristics such as high fecundity and high fertilization rates. However, COTS densities vary enormously in space and time, pointing to major fluctuations in reproductive success. The over-arching question therefore is: What limits recruitment success in COTS?

Small environmental perturbations that trigger life-stage-specific responses can have pronounced effects on recruitment success and hence, on the dynamics of adult populations of COTS. My research explored the role of environmental factors on gametogenesis and reproductive timing, as well as on spawning induction and synchronicity. Environmental factors significantly influenced variability in reproductive behaviour and output. Taken together, these results demonstrate that variable sensitivity of early life history stages and processes to environmental factors can have flow-on effects that disproportionately impact recruitment success and population replenishment in COTS.

Ocean warming and changes in the behaviour and physiology of crown-of-thorns starfishBethan Lang1

1James Cook University, Townsville, QLD, Australia

Crown-of-thorns starfish (Acanthaster cf. solaris.; COTS) and climate change are two of the most prominent threats to the Great Barrier Reef, however there is currently a lack of knowledge regarding how COTS may fare in a warmer ocean. Some studies have demonstrated that the immature stages of COTS are sensitive to warming, potentially a result of the relatively stable thermal environment they experience in the tropics. Adult COTS may also be highly thermosensitive as a result of the high energetic demands associated with reproduction, as observed in other echinoderm species. Over the coming months I will be conducting laboratory-based experiments in order to answer questions regarding the thermal tolerance and sensitivity of COTS. I will investigate how COTS respond to warming in terms of locomotion, neuromuscular coordination, metabolic rate and survival. I will also conduct acute thermal challenge experiments in order to establish the temperature-induced aerobic scope and also the metabolic enzyme activity, with the aim of determining the reliance on aerobic vs. anaerobic metabolism at different temperature points. This study will enable us to better predict how future climate change will affect populations of COTS, and their effects on corals and reef ecosystems.

Monitoring Designed for the COTS Control ProgramDavid Westcott1

4CSIRO Land & Water, Atherton, QLD, Australia

The IPM COTS Control Program (IPM CCP) has evolved dramatically since 2013. Moving into the next outbreak cycle, however, it will need to evolve even more. The recent evolution of COTS control has been driven by a shift to strategic decision making focused on where and when to invest resources to best achieve management objectives. This shift has placed a premium on up-to-date and reliable monitoring of CoTS density and distribution. The importance, and the required scope, of monitoring will only increase in the future as the IPM CCP evolves to meet the challenges of the next outbreak cycle. In this talk I review monitoring and surveillance in the IPM CCP and consider how the role of monitoring, and the monitoring needs themselves, will change moving forward. I outline monitoring strategies that underpin our capacity to effectively manage CoTS into the future and consider their implications for the IPM CCP.

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AIMS Long-term coral reef monitoring: putting COTS into contextMike Emslie1

1Australian Institute of Marine Science PMB No 3, Townsville, QLD, Australia

The Great Barrier Reef (GBR) is under increasing pressure from a range of natural and anthropogenic pressures. The Long-Term Monitoring Program (LTMP) of the Australian Institute of Marine Science has been monitoring of the status and trends of coral reef communities for over three decades. This represents a vast repository of ecosystem-scale knowledge such as the composition and condition of benthic and reef fish assemblages, counts of adult COTS and processes such as coral recovery. LTMP data has shown that hard coral cover on the GBR has been in long-term decline, and that COTS are one of the top three natural disturbances to have contributed to this decline. Recent analyses show that while the climate driven disturbances of mass coral bleaching and cyclones have increased in spatial scale and frequency in recent years, the probability of a reef being impacted by COTS has remained constant throughout the 35-year span of LTMP data. However, the cumulative nature of disturbances has continued to cause declines in hard coral cover and shifts in coral assemblage structure across much of the GBR, which have flow on effects on other reef associated organisms, like reef fishes. LTMP data on reef fish dynamics has revealed that COTS have a lesser short-term effect on reef fish assemblages than storms and multiple concurrent disturbances, however they may exhibit lagged responses as dead coral skeletons slowly erode. Much of the data collected by LTMP are highly relevant for the understanding of the COTS phenomenon and to support adaptive management action. Information on reef fish assemblages has enabled investigations into the role of predatory fishes in controlling COTS numbers, and preliminary results reveal variable evidence for any top-down control among different groups of reef fishes on COTS populations. Recently, there has been a significant investment in manual COTS culling to preserve coral assemblages on high value reefs. However, on many LTMP survey reefs in the central GBR, reef wide coral cover has continued to decline, despite COTS culling effort. This is likely attributable to impacts of other disturbances, notably mass coral bleaching, and the timing of culling commencement. LTMP data are highly relevant to inform future COTS management, especially for “suppress & contain” actions during the initiation phase of primary outbreaks by providing i) trends in COTS counts to complement other early warning surveillance and ii) coral cover recovery and composition data contextualised within the disturbance history of individual reefs.

Genetic larval quantification to improve understanding of outbreaksSven Uthicke1, Frances Patel1, Jason Doyle1

1Australian Institute of Marine Science PMB No 3, Townsville, QLD, Australia

Coral predation by crown-of-thorns seastars (COTS) is a major contributor to the coral reef crises in the Indo-Pacific Region, with the 4th wave of outbreaks on the Great Barrier Reef (GBR) now well under way. New monitoring tools are needed to allow early detection, because early outbreak stages are difficult to detect using scuba or manta tow surveys. Early outbreak detection would allow early intervention, but also improve understanding of the exact initiation zone of the outbreaks. Environmental DNA (eDNA) approaches are now widely used in terrestrial and freshwater environments for detection of introduced pest species. In this three-part presentation, we present the application of specific COTS genetic markers and eDNA approaches to i) identify and quantify COTS larvae in the plankton and ii) detect the presence of post settlement COTS using ‘free eDNA’ from water samples, and iii) determine settlement trends of COTS. Supported by tourism operators and COTS culling teams over the last five years, we have obtained over 2500 plankton samples to date. This dataset can now be employed to i) detect the presence of COTS as early outbreak stages, ii) investigate small scale temporal variability during the summer season to obtain details about spawning time of COTS, iii) look at large scale inter-annual differences in larvae distribution and spread and iv) obtain cues about the relationship between COTS larvae and water quality (‘nutrient hypothesis of outbreaks’). We propose to integrate larval and post-settlement e-DNA monitoring into a large-scale COTS monitoring program for early outbreak detection and to assist efficient COTS control.

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Environmental DNA (eDNA) for the detection of adult COTS in water samplesJason Doyle1, Sven Uthicke1

1Australian Institute of Marine Science PMB No 3, Townsville, QLD, Australia

Monitoring of COTS densities and consequently defining outbreaks is typically done via manta tow or RHIS survey. COTS densities that exceed pre-defined outbreak thresholds have most likely been developing well before the outbreak was identified, thus the importance of pre-outbreak detection is crucial to implementing appropriate management strategies. We present an environmental DNA approach to early detection of COTS pre-outbreak populations.

In August 2018, we conducted an eDNA sampling trip from three reefs on the Great Barrier Reef along a COTS density gradient. To detect post-settlement individuals, replicate (> 40 per reef) 2.5L surface water samples were collected, filtered and preserved for DNA extraction. DNA extracts were then analysed via digital droplet PCR (ddPCR). We demonstrated that there is a relationship with both mtDNA copy numbers and overall number of positive samples to COTS densities. Follow up sampling at two of the three reefs in May 2019 revealed a shift in the COTS eDNA detections corresponding to a southward migration of the current outbreak.

By comparing data to in-water field surveys, we demonstrated that COTS densities below those classified as ‘outbreak levels’ can be detected using eDNA. We are currently fine tuning the method by simplifying workflow, testing for best sampling times and locations, testing automated samplers and testing for sample numbers needed.

Quantifying patterns of COTS settlementPeter Doll1, Vanessa Messmer1, Jason Doyle2, Sven Uthicke2, Morgan Pratchett1

1ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD, Australia2Australian Institute of Marine Science PMB No 3, Townsville, QLD, Australia

Changes in key demographic rates of COTS, in particular the rates of larval production and successful settlement, are fundamental to rapid increases in local abundance. Detecting high recruitment pulses as early as possible is key to improve the timing and effectiveness of control activities and limit the extirpation of many corals. We present an innovative approach to quantifying larval settlement using artificial collectors and eDNA that will contribute to early outbreak detection.

We used polymerase chain reaction (PCR) to quantify rates of COTS settlement into purpose-built settlement collectors deployed during the summer reproduction and settlement season. During a pilot study conducted on the GBR in 2017-2018, standard PCRs produced clear bands indicating the presence of COTS eDNA in 39.3% of retrieved samples. Our preliminary results suggest an apparent lack of depth preference in settlement and, although eDNA was detected at all reefs and sampling periods, spatial and temporal variation between reefs and sampling periods was apparent.

In-depth studies commenced in 2020 and will further address i) how rates of larval settlement vary among habitats, ii) whether settlement rates are related to larval, juvenile and adult densities, and iii) what the predominant settlement cues or inhibitors are and whether this can account for geographical variation in the incidence of population irruptions. These studies will improve our understanding of the patterns and drivers of COTS recruitment pulses and contribute to the development of an effective early warning system using eDNA detection of adults, larvae, and the settlement of COTS.

Vertigo3: a modernised approach to manta towingBrett Kettle1, Andy Steven2, Joshua Riddell3, Brano Kusy3

1Babel-sbf, Manly QLD and CSIRO Data61, Pullenvale, QLD, Australia2CSIRO Oceans and Atmosphere, St Lucia, QLD, Australia

3CSIRO Data61, Pullenvale, QLD, Australia

Manta towing (tow-boarding) was first used for crown-of-thorns starfish management 51 years ago, and with few modifications remains the staple for many reef monitoring initiatives. A modernisation program would seek to improve speed and depth range, apply geolocations to individual observations, adopt artificial

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intelligence / machine learning (AIML) to reduce latency in data analysis, archive vision for repurposing datasets to address future research questions, increase survey repeatability, and reduce personnel requirements. Vertigo3 achieves these objectives in a suitcase-sized ‘towed glider’, 650mm in wingspan and weighing 5kg. Vertigo3’s design philosophy focusses on overcoming four physical constraints: towing the robotic device behind a small boat provides the energy required to overcome the density of the medium and to combat tidal velocities; the absence of GPS signals or other reef-wide positioning systems is mitigated by calculating offsets from the vessel’s GPS, and by on-board sensors that allow image rectification and geo-referencing; underwater bandwidth limits are overcome by a reinforced fibre optic tow cable that provides gigabit bandwidth so that the surface operator sees live streaming vision with real-time AIML augmentation; and operations in topographically complex environments are facilitated by a strategy of small size and mass, authoritative 3-axis flight controls and fast fusion of terrain-following sensors. In its current incarnation Vertigo3 operates comfortably to 7kts and 15m depth, capturing 500,000 5MP images per day, with real-time ML models operating at 10 frames per second. The device autopilots with minimal inputs from the vessel coxswain, allowing for single-handed operations. AIML object detection skills have been demonstrated for temperate starfish, and seabed classification methods are currently being trialled for seagrass identification and density mapping. Vertigo3 appears amenable to adaptation for crown-of-thorns starfish management, with geolocation, immediacy of starfish detection, AIML and larger/faster survey footprints potentially offering opportunities to refine management field methods and productivity. Vertigo3 is intended to become an open-sourced tool for marine biophysical surveys, and its developers are currently seeking collaborations to build new use cases.

Use of AI in COTS monitoring and surveillanceMatthew Dunbabin1

1Queensland University of Technology, School of Electrical Engineering & Robotics, Brisbane, QLD, Australia

Artificial intelligence (AI) is transforming our ability to perform robust classification and segmentation of many different natural scenes to varying degrees of certainty (or uncertainty). These algorithms, when trained appropriately and optimised, can be run on-board current, low-power hardware for in-field real-time predictions that can be used for COTS control and surveillance. This presentation will provide an overview of how Deep Neural Networks (DNNs) has been used for real-time COTS detection. It will describe the process used to train the DNNs and COTS tracking algorithms, as well as provide insights into the challenges and performance results for field deployment. It will conclude by presenting our latest approaches to AI-enabled robotic systems for broader scale automated surveillance and real-time in-field decision systems for reef-based conservation activities.

Terrestrial runoff and crown-of-thorn starfish outbreaks on the Great Barrier ReefFrederieke Kroon1

1Australian Institute of Marine Science, Townsville, QLD, Australia

In this presentation, I will provide a summary of current scientific evidence and knowledge gaps linking land-based run-off with crown-of-thorns starfish (COTS) population outbreaks on the Great Barrier Reef (GBR), Australia. Population outbreaks of COTS are a periodic and reoccurring phenomenon on the GBR and a major cause for loss of coral cover. One of the foremost hypotheses proposed to account for COTS population outbreaks, the ‘terrestrial runoff’ hypothesis, states that high nutrient availability increases phytoplankton biomass, which in turn enhances COTS larval growth and survival leading to mass recruitment events and outbreaks. Despite ongoing scientific debate about the validity of this hypothesis, the postulated link between elevated terrestrial runoff and COTS outbreaks has become a central argument for policy and investment to improve GBR water quality. The summary of current scientific evidence and knowledge gaps will be presented in the context of catchment management actions around water quality improvement to reduce COTS recruitment and population outbreaks.

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Acoustic tracking of a large predatory marine gastropod, Charonia tritonis, on the Great Barrier Reef

Audrey Schlaff1, Patricia Menéndez1,2, Michael Hall1, Michelle Heupel1,3, Thomas Armstrong1, Cherie Motti1

1Australian Institute of Marine Science, Townsville, QLD, Australia2Department of Econometrics and Business Statistics, Monash University, Australia

3Integrated Marine Observing System, University of Tasmania, Australia

Crown-of-thorns starfish (COTS) outbreaks have been identified as a major cause of coral cover loss on the GBR since detailed observation records began three decades ago. The endangered giant triton snail, Charonia tritonis, is a natural predator of adult COTS. Although aquarium and field observations indicate the intensity of direct predation is inadequate to significantly mediate outbreaks, the mere presence of C. tritonis can elicit a chemically-induced sensory behavioural response – effectively a ‘landscape of fear’ - which may help to suppress COTS populations when in non-outbreak status. While there is increasing knowledge of the sensory biology of both species, little is known about how giant triton snails move and occupy space on coral reefs making it difficult to determine their true zone of influence and thus their capacity to disrupt COTS behaviour. Passive acoustic telemetry was used to examine short-term activity space and diel movement patterns of five individuals on the GBR. Results revealed localised movement and increased activity at night. Mean distance travelled by individuals during the day (1,078.58 m) was roughly half that observed at night (1,970.00 m) with an average cumulative distance of 3,050.83 m travelled over the 42-day study. Establishing short-term movement patterns of this natural COTS predator within a coral reef environment further supports its potential to mediate populations, i.e. through aggregation dispersal, and will inform future C. tritonis conservation and COTS management efforts.

Identifying and managing fish predators to mitigate crown-of-thorns starfish outbreaksFrederieke Kroon1, Mike Emslie1, Diego Barneche1

1Australian Institute of Marine Science, Townsville, QLD, Australia

The corallivorous crown-of-thorns starfish (Acanthaster spp.) has been linked with the widespread loss of scleractinian coral cover on Indo-Pacific reefs during periodic population outbreaks. Here, we re-examine the role of predation by coral reef fish species in mitigating the size and frequency of outbreaks of the Pacific crown-of-thorns starfish (COTS; Acanthaster cf. solaris), by combining (1) new evidence from COTS DNA detected in faecal and gut content samples collected from coral reef fish species on the Great Barrier Reef (GBR); (2) large-scale and long-term field data of coral reef fish and COTS presence and abundance on the GBR; and (3) results from statistical modelling investigating the relationship between GBR fisheries catches and COTS outbreaks. COTS DNA was detected in samples from 18 different coral reef fish species collected on reefs at various stages of COTS outbreaks in the GBR Marine Park, nine of which had not been previously reported to feed on COTS. These results strongly indicate that direct fish predation on COTS may well be more common than is currently appreciated, and may play a role in reducing COTS larval abundance, settlement and post-settlement survival. Preliminary results from the field data and the statistical modelling show that density and fisheries catches of certain fish groups appear to influence patterns in COTS outbreaks on the GBR. Overall, this work will inform COTS management by recommending specific management approaches to enhance predation on COTS by coral reef fishes, and to support the mitigation of COTS outbreaks and reverse declines in hard coral cover.

Biologically based technologies for crown-of-thorns starfish controlLone Hoj1, Maria Byrne2, David Westcott3

1Australian Institute of Marine Science, Townsville, QLD, Australia2University of Sydney, NSW, Australia

3CSIRO Land & Water, Atherton, QLD, Australia

Future integrated pest management strategies for COTS are likely to incorporate one or more biologically based control technologies such as semiochemicals, predator control, traditional biological control, and genetic biocontrol. As part of the NESP Tropical Water Quality Hub project on implementation of the COTS research

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strategy, we have outlined the history and current use of these approaches in pest control worldwide, with special reference to their use in aquatic systems. We furthermore considered their potential role for COTS control on the Great Barrier Reef. In this analysis, we considered factors such as the scale of potential use, the need for repeated applications, reversibility, environmental risk, perception and regulatory risks, financial risk and critical knowledge gaps. On this basis, we made recommendations with respect to the potential role of these approaches in an integrated pest management strategy for COTS and estimated a minimum lead time until each approach can be application ready. Our analyses should be regarded as a starting point for a more rigorous process involving broad stakeholder engagement, multi-disciplinary expert groups to formally assess risks, and modelling of promising strategies to clarify their potential efficiencies and stop-go criteria for further development.

Strategies for genetic control of the crown-of-thorns starfish (COTS)Maciej Maselko1, Owain Edwards2

1Applied Biosciences, Macquarie University 1Synthetic Biology Future Science Platform, CSIRO

The crown-of-thorns starfish (Acanthaster planci) is native in the Indo-Pacific region and is not harmful at low population densities. However, crown-of-thorns starfish (COTS) population booms are responsible for approximately 42 percent of observed cover loss in the Great Barrier Reef during an irruption and their populations are expected to grow as ocean temperatures increase

We propose to strategically release caged populations of transgenic male COTS for the purposes of biological control. Two options would be considered for biological control, both of which have been used effectively for landscape-wide control of insect pests. First, using the sterile male technique, male COTS would be caged at high density at locations where outbreaks are predicted to occur. Sperm release by these caged individuals carry a genetic system that renders them effectively sterile, and would compete with sperm from wild males for the fertilisation of eggs during spawning. Eggs fertilised by the SGI-carrying sperm would not develop, resulting in localised population suppression. Secondly, using a mating disruption approach, release COTS could also be engineered to release high levels of aggregation or alarm pheromone, and be strategically placed to disrupt local mating efficiencies.

An ecologically-based operational strategy for crown-of-thorns starfish control on the Great Barrier Reef: Integrated decision making from the site to the regional scale

Cameron Fletcher1, David Westcott1, Mary Bonin2

1CSIRO Land and Water, Atherton, QLD, Australia2Great Barrier Reef Marine Park Authority, Townsville, QLD, Australia

Crown-of-thorns starfish (COTS) are one of the major threats to coral resilience on the Great Barrier Reef (GBR) and around the Indo-Pacific. Moreover, unlike other significant threats, COTS can be managed directly to provide immediate protection of coral. This makes an effectively structured COTS control program a key strategy to conserve coral over the short and medium term. At the same time, however, the extent of COTS damage exceeds the management resources available. Making the most of these resources requires that efforts are targeted at high priority locations at an intensity sufficient to preserve coral cover.

It also requires that decisions made across the program are underpinned by a solid ecological understanding of the system being managed, and that they can generate ecologically-meaningful outcomes even when some management and population processes cannot be estimated accurately ahead of time. Ideally, decision makers would leverage the intensive data collected by a coordinated COTS control program to inform their decisions.

Here, we outline a hierarchy of three decision trees linking COTS ecology to the decisions that need to be made to run an on-water control program; including where within a reef to cull each day; how to target reefs during a voyage, and how to distribute resources across a region over a year. The framework leverages our best current understanding of the management and ecology processes driving the system but, importantly, is also designed to collect information at management-relevant scales to fill key knowledge gaps and improve the performance of the program in future.

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Connectivity and spatial prioritisation of COTS control effortsKarlo Hock1, Yves-Marie Bozec1, Mary Bonin2, Scott A Condie3, David Westcott4, Peter J. Mumby1

1Marine Spatial Ecology Lab, School of Biological Sciences, The University of Queensland, St Lucia, QLD, Australia2Reef Interventions, Great Barrier Reef Marine Park Authority, Townsville QLD, Australia

3CSIRO Oceans & Atmosphere, Hobart, TAS, Australia4CSIRO Land & Water, Atherton, QLD, Australia

Australia’s Great Barrier Reef (GBR) is a vast coral reef ecosystem consisting of 3800+ individual reefs. Ocean currents connect populations of coral and other benthic organisms by dispersing their larvae among the reefs. Connectivity is also a major driver of regional dynamics for coral-eating crown-of-thorns starfish (COTS), whose periodic population explosions have had devastating impacts on the health of the GBR. While large populations of adult starfish can devastate the coral community on a reef, dispersal of starfish larvae to other reefs leads to large-scale outbreak events and subsequent regional declines in coral cover. Efforts to control these outbreaks are exacerbated by the spatial scale of the GBR, and warrant targeted allocation of management resources at strategic locations. Here, we first used the oceanographic models to simulate the dispersal of both COTS and coral larvae among the reefs and obtain GBR-wide connectivity patterns. We then analysed these connectivity patterns in order to highlight reefs that will be more likely to either experience larval influx or spread the larvae to other reefs in the region. To test the capability of the connectivity models to capture the demographic processes on the GBR, we validated the model outputs against COTS field surveys, and found that the predictions of COTS larval connectivity correspond to reported adult abundances on reefs. We then used these outputs to define connectivity profiles of reefs that can then be used as a basis for designing regional control and management strategies. Importantly, in addition to identifying reefs important for COTS connectivity, this approach also identified potential sources of coral larvae that can support regional recovery processes, and do so consistently over multiple spawning seasons. Protecting these regionally important source reefs may be critical to help with the recovery of reefs that have not only already been damaged by COTS outbreaks, but also affected by other disturbances such as coral bleaching.

Insights for COTS management from reef-scale models of intermediate complexity (MICE)Éva E. Plagányi1, Jacob Rogers1, Russ C. Babcock1, Scott A. Condie2, Laura Blamey1,

Cameron S. Fletcher3, David A. Westcott3

1CSIRO Oceans and Atmosphere, Brisbane, QLD, Australia2CSIRO Oceans and Atmosphere, Hobart, TAS, Australia

3CSIRO Land and Water, Atherton, QLD, Australia

Extensive control programs on the GBR involve manual culling of COTS in the field, and research is needed to inform these management efforts. Models of Intermediate Complexity for Ecosystem assessments (MICE have been used to describe the trophic interactions between juvenile and adult COTS, and two groups of coral (fast- and slow-growing corals). By fitting to available data, the reef-scale models are able to quantify the outcomes for coral of different abundances of COTS as well as evaluate the efficacy of alternative levels and strategies for culling COTS. This approach has been used to underpin estimates of ecological thresholds, and how these vary with varying coral cover. Further model refinements are incorporating COTS reproductive features, movement behaviour, predators and habitat variables to further inform on optimal methods for controlling COTS at selected reefs.

Quantifying COTS manual control efficacy to promote coral coverJacob Rogers1, Éva E. Plagányi1, Russ Babcock1

1CSIRO Oceans and Atmosphere, Brisbane, QLD, Australia

Crown-of-thorns starfish (COTS) management primarily entails the deployment of divers at pre-specified locations where they manually cull individual starfish to reduce coral consumption by the species. However, COTS outbreaks may span large geographical regions – concurrently encompassing many reefs – across which a limited suite of control vessels and divers must be distributed. Success at the regional scale first demands success at the scale at which COTS control operates – the sub-reef spatial scale. Here we quantify management control efficacy as a basis for informing optimal control at the reef scale. Preliminary results from the implementation of a fine sub-reef scale Model of Intermediate Complexity for Ecosystem Assessment (MICE) for individual reefs of the GBR will

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be presented. MICE are well-suited to informing and quantifying such strategic and tactical management advice. Through a data-centric focus which only resolves key aspects of a system relevant to identified objectives, MICE can handle uncertainties whilst preserving an ecosystem context to inform specific questions. The model is fitted to the COTS control program data and coral cover from the Long Term Monitoring Program Data (for years 2013-2017). The model demonstrates the relative trade-off of alternative control strategies in different conditions. For example, our model results suggest that management limited the magnitude and duration of COTS population increases which likely led to higher coral cover in areas less severely impacted by bleaching. However, the impact of management was regulated by the pattern of larval.

Evaluating COTS control strategies for the Great Barrier Reef using a systems modelling approach

Scott A. Condie1, Russ C. Babcock2, Cameron S. Fletcher3, Éva E. Plagányi2, David A. Westcott3

1CSIRO Oceans and Atmosphere, Hobart, TAS, Australia2CSIRO Oceans and Atmosphere, Brisbane, QLD, Australia

3CSIRO Land and Water, Atherton, QLD, Australia

Regular outbreaks of coral-eating crown-of-thorns starfish (COTS) have combined with coral bleaching and tropical cyclones to severely deplete coral cover on the Great Barrier Reef (GBR) and this deterioration is likely to accelerate under the influence of climate change. Optimising COTS control strategies within such a complex system requires a systems-modelling approach. The Coral Community Network (CoCoNet) model represents major coral groups and age-structured COTS populations on more than 3750 reefs connected through ocean larval dispersal. It includes realistic environmental forcing (tropical cyclones, floods, and coral bleaching) and has been validated in terms of historical coral cover and the outbreak and propagation of COTS through the GBR network. Results suggest that recently developed control methods combined with existing vessel capacity could potentially reduce COTS populations below the ecological threshold (for net coral growth) on most GBR reefs. However, this will be achieved gradually over the next two decades and maintaining control capacity throughout the COTS boom-bust cycle will be critical to the success of the strategy.

The COTS Data Lifecycle: connecting on-water collection to adaptive management of COTS on the GBR

Sam Matthews1, Mary C. Bonin1, Tristan Simpson1, Daniel Schultz1, Jo Baker1, Anya Jaeckli1, Darren Cameron1

1Reef Interventions, Great Barrier Reef Marine Park Authority, Townsville, QLD, Australia

The COTS Control Program collects a vast array of ecological observations as well as program management data. While the volume and disparate nature of many datasets provides technical problems to overcome, improving the processes and data infrastructure to efficiently collect, quality check, store, analyse and visualise these data provides deep insight into the impact and management of COTS on the Great Barrier Reef. In recent years, the Marine Park Authority has made significant progress in improving the data management and analytical platforms we use to ensure high quality data is available to track the progression of COTS outbreaks, measure progress in pest management, and support our adaptive management of the COTS Control Program. Here we present the lifecycle of data in the COTS Control Program on the Great Barrier Reef. Observation data, including manta tow surveillance, culling and reef health surveys are collected on water by professionally trained vessel crews using custom built apps. These apps have been designed to include quality checks that reduce error rates, and they deliver data directly into the Marine Park Authority’s Eye on the Reef Database.

Once data is received from vessel crews, further quality checks are conducted and quality assurance reports are then delivered back to our contractors providing feedback on data collection and logistical considerations. Once checked, the data is synthesised and visualised in our analytics platform, the COTS Dashboard, providing an interactive interface to monitor the progress of the control program in achieving pest management goals on each reef and cull site being actioned, while also providing broader situational awareness of COTS outbreaks across the entire Marine Park. This analytics platform is the first of its kind for the Great Barrier Reef Marine Park Authority, allowing COTS management actions to be monitored, evaluated and improved upon in near real time. Adherence to best practice data management principles and ongoing investment in analytical capabilities provides provide a platform to manage the COTS Control Program in a data-driven and adaptive fashion.

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