Queensland's Citizen Science Hub

Crown of Thorns Starfish On the Great Barrier Reef: Evaluating Control Programs and Funding Opportunities in Australia

By Alicia Dunn, Down Deep Drones and Member, The Royal Society of Queensland 

The Crown of Thorns Starfish (COTS), Acanthaster planci, has posed a significant and increasing threat to the Great Barrier Reef (GBR) since the 1960s [1, n.d.] These large starfish feed on coral polyps and cause extensive degradation of coral and also affect biodiversity generally. According to Australian Institute of Marine Studies (AIMS) the “Crown-of-thorns starfish are native to the Great Barrier Reef but can occur in plague proportions. Where numbers are high they consume vast amounts of living coral, dramatically reducing coral cover.”[2, n.d.] Over the past thirty years, control programs funded by government grants have aimed to mitigate these impacts. However, the efficacy of these programs and the management of funds has been open to frequent debate. Please view the table below. This article reviews the impact of COTS on the GBR, and evaluates the efficacy of funding and looks at the prospect of introducing new methods of control to supplement existing efforts.

On the Great Barrier Reef there are many industries dependent on healthy reefs including tourism and fishing. According to the Great Barrier Reef Foundation, the social, economic and icon value of the reef is $56 billion.[3] When there have been recurrent outbreaks of COTS, densities can exceed 30 starfish per hectare – double the number of COTS that can cause significant reef damage.[4] These outbreaks lead to a loss of coral and also biodiversity.[5]

There have been localised successes in reducing COTS populations; however the nature of the outbreaks and the frequent recurrence suggest inefficiencies in the control strategies currently used. Peaks in COTS populations in study areas are thought to coincide with either funding delays or variations in control measures (Status of Coral Reefs of the World, 2020). There are many limitations and challenges concerning COTS control.[6]

Some control methods that have been proposed and implemented include manual removal by divers, manually injecting the COTS by divers and biological control. Divers are funded by programs such as by the Great Barrier Reef Marine Park Authority (GBRMPA) and the Reef Trust. Due to the rapid reproduction of COTS these methods also are ineffective (Pratchett et al., 2008).

Using divers to control COTS is very labour-intensive and comes with its own set of environmental stressors including the impact of multiple vessels and potential damage to the reef. Divers are prone to decompression sickness and are exposed to hazards including hostile marine life, poor visibility and strong currents, as well as the possibility of being spiked by a COTS. COTS are cryptic, more active at night whereas most control programs are conducted during the day. There is a large economic cost with employing divers and insuring them, and workplace health and safety regulations restrict the length of time that divers can remain on the bottom.

In an article published by The Guardian newspaper in 2023, Dr Roger Beeden from the GBRMPA said that using the $41 million spent on direct intervention of COTS, 320,000 starfish had been killed in 43,000 diver hours. This equates to 7 starfish being killed per hour at $953 per hour (a staggering $136 per starfish!)[7]

There are many control programs and some rely on short-term funding causing fragmented and inconsistent efforts. As there are so many stakeholders with their own control programs, there is the possibility of duplicated efforts and a lack of coordination, resulting in gaps in coverage or other inefficiencies, including the manner in which results are being reported and the accuracy of these results.

With so much funding there is the potential for diving companies or research institutions to depend on this income and this is at risk of creating a disincentive to finding solutions on a permanent basis.

COTSbot and Rangerbot

With the technological advancements of underwater drones, Queensland University of Technology developed an underwater drone “COTSbot”, designed to autonomously detect and inject bile salts and other lethal substances into COTS. Underwater drones can also be known as Remotely Operated Vehicles (ROVs) and operate in deeper and less accessible waters than divers, they work longer hours, can be used continuously, can be operated at night, have a once-off cost and are less environmentally disruptive than using divers. Underwater drones could potentially be a game-changer in controlling COTS outbreaks, with the COTSbot primed for success. The QUT COTSbot was designed to “search the reef for up to eight hours at a time, delivering more than 200 lethal shots.”[8] However, the author has found no video evidence online of COTSbot or RangerBot actually injecting any COTS. “Widespread deployment of the RangerBot has not yet occurred”, (Queensland University of Technology, 2018). “RangerBot has achieved a 99.4% accuracy rate in detecting COTS and a 100% success rate in delivering coral larvae to damaged reefs during trials.[9] These high success rates demonstrate the robot’s capability in performing critical reef management tasks effectively (QUT Centre for Robotics, 2024),[10] but reference to the RangerBot online makes no mention of delivering injections to COTS after 2018.

Oakford Offshore

In 2016 Oakford Offshore Pty Ltd was issued a marine permit by GBRMPA to operate a field test of a modified remotely operated vehicle (ROV) with an injector arm to inject COTS. This was to ascertain if culling COTS with an underwater drone was possible. The permit stipulated that Environmental Site Supervision of the initial trial was necessary. Oakford Offshore could not select their own area and had an area selected for them. They worked alongside the divers responsible for injecting the COTS, in the vessel Venus II used for COTS control by Association Marine Parks Tourism Operators (AMPTO). The trial was conducted in February. It does not appear that this was a fair and impartial field study due to the following reasons:

  • the area was selected for Oakford Offshore and had few COTS;
  • the vessel was provided by AMPTO who were running COTS control programs – a conflict of interest;
  • divers on the boat were contracted to AMPTO; the divers, crew and project manager may not have been impartial.[10A]

John Lawrie of Oakford Offshore has advised as follows:

The existing culling program seemed to be run competently and was giving an opportunity to the young people involved in the diving activities. What I was proposing was a stand alone culling program on our own vessel that can run 24/7 and also operate in deeper waters while conducting monitoring operations at the same time.

Funding for our research study and the connections to GBRMPA came from Steven Miles who was Minister for Environment and Heritage Protection at the time and who was enthusiastic for my study. GBRMPA didn’t have the funding to give out, that’s all with the Reef Trust. GBRMPA just gives the necessary permits to operate on the reef.

A ROV-based culling operation will work very well, better than anything currently operating, it’s just a matter of getting funding to prove it. A standalone vessel with the right equipment and two weeks at sea will easily get all the data needed.

I was obliged to use the dive boat for the trial because the funding I received was only $30k so it wasn’t enough to charter my own vessel. 

During this experimental study, we saw only two COTS. We were told that there were hundreds the week before. It became obvious that AMPTO was regarding the voyage as a monitoring one, to check on the previous cull.[10B]

Down Deep Drones

Founder of Australian firm Down Deep Drones (ABN 92 411 458 189), robotics engineer John Griffiths, has developed a prototype for injecting COTS. This first prototype was made in 2017 and Down Deep Drones travelled to Cairns in 2018 with the underwater drone COTS injector, a prototype, for the purpose of testing it in field conditions and to gift  the underwater drone to an organisation involved in culling the Crown of Thorns Starfish. Griffiths constructed the underwater drone for just over $6,000. GBRMPA, the responsible department of James Cook University and the Reef and Rainforest Foundation did not respond to the offer. In 2018, the underwater drone was taken to Projects Global which advised that there was limited space onboard their vessel and working with the underwater drone on the vessel would interfere with the work of the divers controlling COTS. An approach to CSIRO also received no follow-up reply.

This year 2024, Down Deep Drones have a prototype COTS injector on an off-the-shelf underwater drone manufactured by QYSEA. QYSEA have been market leaders in underwater drones since their first release in 2018. With affordable underwater drones for hobbyist, researcher and environmental stewards, they have a sophisticated electronics system and user-friendly interface. One of the benefits of these underwater drones is their reliability, ease of use and adaptability. Down Deep Drones make custom tools for QYSEA underwater drones to combat a range of environmental issues, including attachments for culling rogue urchins, cutting ghost nets, spearing lion fish and injecting COTS, with spearguns mounted on the drone to reduce incidental bycatch. As the underwater drone with the COTS injector is not autonomous, it can be bought for less than $5000. These underwater drones are easy to operate and can be mastered after one or two hours of training. They are accessible to citizen scientists, school children and volunteers of all ages. By contrast, diving is a specialised vocation and executed after considerable training needing expensive equipment, something outside the capabilities of most people.

There has been substantial funding and challenges in controlling COTS outbreaks, but this new technology of using underwater drones has the potential to supplement current control methods. There is a higher efficiency rate with underwater drones and also lower operational cost than with divers. Divers are limited by how long they can spend underwater in ‘bottom time’ and historically this has been forty minutes, four times a day “for logistical and Occupational Health and Safety reasons”.[Cited in 11] Maximum operating time for an underwater drone is dependent on battery life, but an underwater drone with surface power is available from around $12,000 AUD. This can allow for continuous injections of COTS not limited by divers’ time at the bottom. Down Deep Drones aims at a rate of one injection every two minutes in areas of greatest density of the starfish, or ten every 20 minutes. According to GBRMPA, between 2023 and 2024, 50,227 COTS starfish were culled in 16,657 hours.[12] This equates to only one starfish culled every 20 minutes! These figures are different from those quoted by Dr. Beeden, but the figures could be still be accurate and may be from different time periods.

As stated by QUT “Currently human divers are equipping themselves and eradicating this starfish from targeted sites, however there aren’t sufficient divers to cover all the COTS hotspots across the Great Barrier Reef.”[13] Additionally “the scale of COTS outbreaks on reefs across the GBR far exceeds the resources that are available.”[11]

Areas of the GBR are surveyed for COTS using a ‘manta tow’. This is when a diver is towed behind a vessel for observational purposes, and then assesses the extent of impact from a COTS outbreak and records the data. An underwater drone could be towed by a vessel and complete the survey quicker, with greater accuracy, without potential injury and with 4K video evidence.

Conclusions: Advantages of citizen science using drones

Greater community engagement could be fostered with the use of the underwater drone for COTS control, providing a sense of ownership and responsibility towards reef conservation. The technique also allows for continuous monitoring and rapid response to outbreaks. The inclusion of 4K video capabilities and real-time streaming to YouTube allows unparalleled monitoring and data collection. This transparency and real-time data relay can engage and inform the public, increase accountability and provide valuable information for ongoing research and adaptive management strategies. By leveraging advanced technology, cost-effective production, and widespread community engagement, it offers a scalable and sustainable solution to a persistent environmental challenge.

This is a draft article currently undergoing peer review. Critical feedback is invited. For more information on underwater drones, read https://scienceqld.org/2024/07/26/underwater-drones/

References

[1] DCCEEW (Department of Climate Change, Energy, the Environment and Water). (n.d.). Crown-of-thorns starfish control program: Great Barrier Reef. Retrieved from https://www.dcceew.gov.au/parks-heritage/great-barrier-reef/case-studies/crown-of-thorns/

[2] AIMS (Australian Institute of Marine Science). (n.d.). Causes of crown-of-thorns starfish outbreaks. Retrieved from https://www.aims.gov.au/research-topics/environmental-issues/crown-thorns-starfish/causes-crown-thorns-starfish-outbreaks

[3] Great Barrier Reef Foundation. (n.d.). The value of the Great Barrier Reef. Retrieved from https://www.barrierreef.org/the-reef/the-value

[4] The Nature Conservancy. (2003). Crown-of-thorns starfish (COTS) management. Retrieved from https://www.reefresilience.org/pdf/COTS_Nov2003.pdf

[5] Grimm, V., & Berger, U. (2023). Analyzing and Modeling the Dynamic Response of Marine Ecosystems to Environmental Change. Environmental Modelling & Software, 166, 105429. Retrieved from https://www.sciencedirect.com/science/article/pii/S0304380023001746

[6] Pratchett, M. S., Caballes, C. F., Rivera-Posada, J. A., & Sweatman, H. P. A. (2014). Limits to understanding and managing outbreaks of crown-of-thorns starfish (Acanthaster spp.). Oceanography and Marine Biology, 52, 133-200. doi:10.1201/b17143-4

[7] Readfearn, G. (2022, February 13). Australia is spending billions on the Great Barrier Reef – will it do any good? The Guardian. Retrieved from https://www.theguardian.com/environment/2022/feb/13/australia-is-spending-billions-on-the-great-barrier-reef-will-it-do-any-good

[8] “RangerBot: An Autonomous Underwater Robot for COTS Control.” Queensland University of Technology. https://research.qut.edu.au/qcr/Projects/cotsbot-eliminating-invasive-reef-species/ , accessed 23 July, 2024. QUT.

[9] Queensland University of Technology. (n.d.). RangerBot: Environmental monitoring using robot vision. Retrieved from https://research.qut.edu.au/qcr/Projects/rangerbot

[10] Queensland University of Technology. (n.d.). COTSbot: Eliminating invasive reef species. Retrieved from https://research.qut.edu.au/qcr/Projects/cotsbot-eliminating-invasive-reef-species/

[10A] COTS Culling ROV Field Test. (2014). Atlas of Living Australia. https://fieldcapture.ala.org.au/project/index/d9a27e47-9277-4609-8c11-ce95803373ed

[11] Fletcher C. S., Bonin M. C, Westcott D. A. (2020). An ecologically-based operational strategy for COTS Control. Reef and Rainforest Research Centre Limited NESP Tropical Water Quality Hub. Retrieved from https://nesptropical.edu.au/wp-content/uploads/2020/04/NESP-TWQ-Project-3.1.1-Technical-Report-2.pdf

[12] Great Barrier Reef Marine Park Authority. (n.d.). Crown-of-thorns starfish control program. Retrieved from https://www2.gbrmpa.gov.au/our-work/programs-and-projects/crown-thorns-starfish/Crown-of-thorns-starfish-control-program

[13] Biopixel. (n.d.). COTSbot: Robo reef protector to save the reef from the crown-of-thorns starfish. Retrieved from https://biopixel.tv/cotsbot-robo-reef-protector-to-save-the-reef-from-the-crown-of-thorns-starfish/

Table of Funding for Crown of Thorns Starfish Control: Total $255,050,000

 Disclaimer: The funding amounts presented in this table may not reflect the entire funding received for COTS control and also may contain inaccuracies (E. & O. excepted).

Date Funding  (AUD) Funding Organization Purpose Notes
2012 N/A GBRMPA Establishment of COTS Control Program   Response to outbreaks
2014 N/A James Cook University (JCU) Development of bile salts single-shot injection method Improved efficiency of culling
2015 750,000 Google Impact Challenge Development of COTSbot AUV for COTS detection
2018 57,800,000 Reef Trust Partnership Large-scale intervention program for COTS control The funding in 2020 of $28,600,000 came from this initial  amount Australian Government
2020 (28,600,000) National Environmental Science Program (NESP) Manual culling, deployment of additional 5 vessels over 2 years Enhanced GBRMPA’s COTS Control Program
2020 1,500,000 Great Barrier Reef Foundation Feasibility study for new COTS control options COTS Control Innovation

 

? 9,800,000 Great Barrier Reef Foundation

Reef Trust

Delivering innovation to provide a solution to COTS to suppress and prevent future outbreaks. CCIP
? 7,500,000 Research Partners Delivering innovation to provide a solution to COTS to suppress and prevent future outbreaks. CCIP
2020 5,970,000 Australian Institute Marine Science COTS Tactical Control over 3 years for 1 vessel on high value tourist reefs Australian Government
2020 8,300,000 Great Barrier Reef Foundation Development and testing of new control technologies Early warning systems
2020 5,800,000 Great Barrier Reef Foundation Support for Traditional Owners in COTS control Traditional Owner engagement
2020 100,000 Great Barrier Reef Foundation Community-driven control initiatives Community engagement and support
2022 162,000,000 Great Barrier Reef Marine Park Authority COTS Control Program 7 vessels 150 people over 8 years Indigenous divers with bile salts
2023 9,800,000 Great Barrier Reef Foundation COTS Control Innovation Program AIMS CSIRO JCU UQ

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