Course:CONS200/2023/Protecting Coral Reefs from Crown-of-Thorns Starfish

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Introduction

Red Crown-of-Thorns Starfish eating coral causing it to bleach in Tanzania (2008). Photo by Matt Kieffer

The Crown-of-Thorns Starfish (COTS) is a pervasive echinoderm that is diminishing coral populations in the Great Barrier Reef (GBR)[1]. It is a large concern to Australian scientists and researchers because of the magnitude of damage it inflicts to the GBR[2]. One COTS Has the ability to consume 10 square meters of coral in a given year, making it a major liability to the already dwindling health and biodiversity of the reefs[1]. COTS is an extremely prolific species for a variety of reasons, the most notable of which is its rate of reproduction; a mature female COTS can release up to 60 million eggs per spawning season, making overall population reduction a hefty task[3]. The proliferation of COTS is further exacerbated by several environmental and biological factors, including increasing ocean acidification, low-frequency ocean currents, connectivity networks, and physical aggregation[4][5][6][7].

The current management system in practice uses specific vessels containing professionally-trained crews to manually reduce the abundance of COTS populations using a lethal injection of bile salts or household vinegar[8]. This method has proven to be effective when correctly administered, but its breadth has limitations given its manual nature[9]. As such, scientists are exploring a new method centered around the Giant Triton Snail (GTS), a mollusk that feeds almost exclusively on COTS and whose smell has also been shown to repel the starfish[10]. The snails are currently low in population numbers due to overfishing in the 1950s and 60s, allowing the COTS population to skyrocket, so scientists and researchers are effortfully trying to repopulate the GBR with GTS as both a COTS predator and repellant[11].

History of Effects of COTS on the Great Barrier Reef (GBR)

Crown of Thorns starfish

The COTS is a species of starfish native to the Indo Pacific region, and has been identified as a major contributor to the decline of coral reefs in the Great Barrier Reef in Australia[12]. Since as early as the 1960s, the COTS has drastically changed and reduced the vast biological diversity of coral reefs[13]. The COTS begin their life as a herbivore; however, once the starfish reaches a size of more than 0.008 m in diameter, taking about 4-6 months, they transition to a corallivorous stage[14]. The adults can grow up to a meter in diameter, and can have up to 21 arms which are flexible and allow them to easily consume coral[15]. COTS are nocturnal species and can travel up to 20 meters per hour[15][16].

A single adult starfish can consume approximately 10 square meters of coral per year, and outbreaks can impact the surrounding environment for more than a decade[17]. COTS can cause significant mortality in coral reefs, making it harder for them to recover from other stressors such as global warming and tropical cyclones[18]. Corals are the backbone of the GBR and their loss can lead to a phase shift, in which the ecosystem shifts to an algae dominated ecosystem with soft corals and sponges covering dead corral debris[19][14].

The economy of the GBR, specifically the tourism industry, has been greatly affected by the COTS[15][20]. Due to the COTS outbreaks and resulting loss of coral cover, there has been a decrease of almost 50% in visitors, which may result in the loss of several thousand jobs[15][20][21]. Since 2012 - 2020 the Australian Government has invested nearly 35 million dollars into controlling COTS on the GBR[20][22]. In 2017 alone, 14.4 million Australian dollars were allocated to fund a control vessel for marine park authorities[20].

Current Management Methods

Dr Sven Uthike with an adult COTS at the National sea Simulator in Townsville

The excessive quantity and fiercely negative effects of the crown-of-thorns starfish pose a significant threat to the health of coral reefs, acting as one of the primary drivers of coral degradation in the Great Barrier Reef[2]. Therefore, precise and urgent the mitigation must be taken to quell the COTS population in order to maintain the long-term health of the GBR ecosystem[23]. In 2015, the Australian government's Department of Climate Change released the “2050 Long-Term Sustainability Plan”, and the “Great Barrier Reef Blueprint for Resilience”, which offer several action plans for COTS mitigation and subsequent management to help alleviate the harm the COTS are inflicting on the GBR[24].

A diver manually injecting a Crown-of-Thorns Starfish with a lethal chemical. Photograph by Greg McFall, National Oceanic and Atmospheric Administration, 2014, FlickrCommons. Public Domain

Physical Removal

Manual removal of crown-of-thorns starfish from coral reefs has been the primary eradication method for the majority of time that COTS removal has been around. This method is fairly rustic and simple, entailing the usage of some physical object (such as a metal rod, wooden stick, PVC pipe, or boat hook) by an experienced diver to manually pry the starfish off of the coral reefs they are feeding on[25]. The divers then must place all acquired COTS into a canvas bag to be brought back to shore [26]. While generally effective when performed, this method is quite slow and taxing to the diver, as challenges arise when the COTS are positioned in small crevices, hiding under larger reef structures, or securely stuck onto their environment via their suction-like arms[26]. It is also quite a dangerous method, particularly for more inexperienced divers, as each of COTS' many arms host sharp spines that contain potent and dangerous neurotoxins, poisonous to the surrounding marine life and to humans if come into contact with[27]. The COTS venomous spines can deliver a strong potent sting, which causes pain and swelling, and require surgical excision to remove the broken spine[16]. Although removal of the starfish can be facilitated using small boats and snorkel gear for shallow water, scuba gear is generally more effective as COTS largely reside in the deeper parts of the ocean floor[26].

Chemical Injection

The more modern method of COTS removal from reefs is chemical injection, implemented by organizations such as the Great Barrier Reef Marine Park Authority[28]. This technique involves injecting chemicals into the starfish, the most common of which are Oxgall and Bile Salts harvested from oxen as a slaughterhouse byproduct[29][8]. This method has proven highly effective, as most COTS slow down and begin to disintegrate and die within 24 hours of the oxbile injection[30]. It is also safer for the divers performing the injections, as the device that administers the bile salts involves a long needle that separates the diver from the COTS' poisonous spines and takes just one shot to inject each starfish, minimizing the risk that the divers experience[29]. Overall, this method has proven significantly more effective than manual removal of the COTS, though it still has drawbacks, as the cost and acquisition of the bile salts is a laborious and costly task[29]. Additionally, if the injection is not administered with correct placement (that being at the base of an arm), the starfish can simply shed and regenerate their arms, preventing the chemical spreading to the rest of their body and allowing them to evade death[30]. The most recently explored method is the injection of vinegar as an alternative to bile salts[30]. Vinegar is, unsurprisingly, much cheaper and more accessible than bile salts, and furthermore has shown to have no effect on other marine organisms that consume the dead or decaying COTS after injection[28]. Studies on the usage of vinegar in place of bile salts have shown that an injection of just 25 ml of the liquid incapacitates the starfish within 24 hours and induces full mortality within 48 hours[29][30].

Despite the relative effectiveness of manual removal and the increased effectiveness of lethal chemical injections as methods of removing COTS from coral reefs, these methods both rely on human engagement with every single targeted starfish. As a result, new COTS eradication methods are being explored that involve less of a dependence on humans[9].

Heavily Protected Areas

Australia has the one of the largest marine jurisdictions across the globe, having an area of about 14 million square kilometers[31] Due to the substantial amount of revenue brought about by reef tourism in Australia, popular underwater tourist sites are often the most heavily protected[31]. More resources have been funneled to these areas in an effort to preserve this vital industry. Ever since the COTS control program was conceived by the Australian government, its implementation was delivered in partnership with the reef tourism industry through the Association of Marine Park Tourism Operators (AMPTO)[32]. Along with job creation, the positive impacts on underwater tourism made by the COTS control program have been the most noticeable social and economic benefits for Australians[33][32]. Scientists note that affording heightened protection to some key areas over others is not necessarily a negative thing, as it provides control locations to measure against the overall impact of COTS, especially since protecting all areas would be too resource intensive to be done effectively[11].

Prolific Reproduction

Despite only reproducing once a year in December-January, female COTS are known to produce tens of millions of eggs in a single breeding season, due to their high fecundity[34]. Female COTS can have an individual GSI (gonad mass as a proportion of total body mass) of around 22, which is the highest recorded of any tropical sea star[34]. Other highly fecundity reproductive qualities of the COTS include the uniquely large masses of gametes released as well as regenerative arms that contain developed gonads inside the armpits. Because of this, COTS that lose arms to predators have little to no decrease in reproductive capacity[34].

After female COTS produce larvae, the larvae are often transported by ocean currents before settling on coral, which perpetuates the spread of the starfish, making the high rate of reproduction even more dangerous, although it is debatable how long COTS larvae can survive planktonically before settling[11]. A mean density of roughly 14 adult COTS per 1,000 square meters of reef has been found sufficient to kill most of the hard-coral cover in just 2.5 years[11]. When combined with the high fecundity of COTS as well as the inability of hard coral to recolonize affected areas, this lethal effect poses a dire threat to the health of the underwater ecosystem.

Future Method - Giant Triton Snail

A giant triton sea snail devours a crown of thorns starfish on the Great Barrier Reef (Courtesy of Australian Institute of Marine Science)

The Giant Triton Snail (Charonia tritonis) is one of the largest marine predatorial gastropods that has shown promising potential as a natural solution for controlling the exponentially increasing COTS population in coral reefs[35]. Giant Triton snails (GTS) have a very developed ospharium which uses chemoreceptors to detect odors from possible prey[36]. The COTS can detect the GTS causing the COTS to rapidly move away; however, they are no match for the speed of the snail[10][37]. Once a triton has caught the COTS, the triton will grab it with its muscular foot, and probe the starfish with its proboscis, and discharge toxins into the COTS[36]. The toxins that the giant triton snail injects into the COTS immobilize the starfish as well as neutralize the neurotoxin within the thorn like spines enabling the snail to have a safe to eat snack[38].

The Decline in the GTS population, due to overexploitation for the trophy of their massive shells, is believed to be a large factor in contributing to the multiple outbreaks of COTS by allowing the starfish to take grown and multiply its populations tenfold[39]. Aquaculture is proving to be a fruitful option in increasing the GTS population[39]. However many factors regarding their life cycle including factors that control the GTS reproduction are still unanswered[39]. The Giant triton snail is protected in many countries such as Australia, but did not make the Convention of International Trade in Endangered Species of Wild Fauna and Flora (CITES) due to lack of data regarding its illegal trade and population numbers[40][41].

Exacerbating Factors

There are several reasons that explain why the Crown of Thorns Starfish has such a chokehold over the coral reefs of the GBR.

Aggregation

In the breeding season, usually in early to mid summer, COTS begin to aggressively congregate on a section of coral reef and release gametes simultaneously, which results in high rates of egg fertilization[36]. This is the primary means by which COTS reproduce since they do not engage in physical copulation[42]. This synchronized spawning allows for massive amounts of gametes to interact in the same area of water at the same time, drastically increasing the chance of fertilization and culminating in hundreds of millions of fertilized eggs from just one aggregation[36]. COTS are made aware of nearby aggregations in progress via a water-borne hormone that is released when the starfish aggregate[7][39]. This hormone, consisting of signaling factors and coral-disintegrating enzymes, causes the starfish to move rapidly and become significantly more sexually motivated than usual[39]. This combination of increased writhing plus the hermaphroditic starfish effectively being 'in heat' has been found to lead the starfish to feed both in the day and night (whereas a COTS on its own will generally feed exclusively during the night) which causes increased coral consumption and thus, reef degradation[7][43].

Ocean Acidification

Another factor that increases the successful survival and reproduction of COTS is increased ocean acidification[4]. A 2017 study of the effects of various pH levels on the development of COTS found that starfish consumption levels peaked when the starfish were reared in low pH water and fed Crustose coralline algae (CCA) that, too, was grown in low pH water[4]. This particular type of algae is what juvenile COTS consume most of before maturing and graduating into the coral-eating stage of life[44]. Low pH causes a reduction of the C:N ratio in the CCA as well as lower levels of carbonate, correlating with a weakening in the algae's defense system in addition to the algae being more palatable and more nutritious for consumption by COTS[4][45]. Better and more feeding early on in a Crown of Thorns Starfish's lifetime raises the probability that it will survive adolescence and progress to adulthood, where it will gorge on coral and display profound fecundity[4] .

Connectivity Networks

A third source of exacerbation of the reef damage caused by COTS is the connectivity networks between reefs and thus, populations of the starfish[6]. Connectivity networks can best be thought of as highway systems that connect various reef hotspots (which can be thought of as nodes) to one another, allowing for efficient spread between nodes[6]. For COTS, these connectivity networks can facilitate major outbreaks. Through repeated study and analysis of historical outbreaks, it has been found that areas where COTS epidemics occur can be predicted based on their high local and system-wide connectivity[6]. Such areas are generally nexuses of reef clusters, thus having high potential for larval exchange - the perfect recipe for a COTS population explosion[14].

Low Frequency Currents

The final explanation for COTS' abundance in the Great Barrier Reef is low frequency currents[5]. Studies have shown that hydrodynamic conditions associated with El Niño-Southern Oscillation cause a decrease in ocean current velocities which correlates with an increased success rate in larval recruitment, leading to heightened gamete fertilization and a subsequent population increase[5]. This may be due to the calmer frequencies disrupting the larger "regional" connectivity networks in the GBR, instead breaking the apart into smaller, "local" reef clusters, around which the COTS can coalesce and take over[2]. This is largely due to local retention of dispersed larvae (often after events of aggregation) within the eddy-induced zone around a reef, creating a calmer area for the newly fertilized larvae to develop[5]. At this point, they will first feed off of CCA and if they make it to adulthood, will begin aggressive consumption of coral[44].

Conclusion

Crown-of-thorns starfish may not take center stage in the public discussion of environmental threats, but they are one of the primary causes of coral degradation, particularly in the Great Barrier Reef and reef formations in the Indo-Pacific at large[1]. COTS have the ability to reproduce rapidly through aggregation behavior, causing frequent and unpredictable outbreaks that lead to mass destruction of coral reefs[46]. Significant effort is being put forth by scientists, oceanic researchers, and conservationists to manually remove and kill individual starfish on the GBR through physical removal efforts as well as chemical injection, and while effective, the manual nature of these techniques makes them unrealistic for enacting population reduction on a large scale[25][28]. Newer approaches such as the idea of proliferating the Giant triton snail around coral reefs to disperse and repel COTS show promising projections, though the behind-the-scenes effort to restore the waning snail populations are proving to be a challenge in and of itself[39].

The strong correlation found between human-driven environmental factors, such as increasing ocean acidification, and increases in COTS outbreaks highlights yet another reason that mitigating the effects of global warming is imperative and urgent [46]. Because of the vast range of factors driving COTS outbreaks and pervasiveness, a multifaceted approach is needed to significantly reduce population numbers. Unfortunately, just as is the case with the reproductive habits of the giant triton snail, many of the fundamental scientific queries needed to move research and action remain unanswered[46].

References

  1. ↑ 1.0 1.1 1.2 Crown of Thorns Starfish (COTS) - Living Oceans Foundation. (2015). Retrieved from Living Oceans Foundation website: https://www.livingoceansfoundation.org/science/crown-of-thorns-starfish/
  2. ↑ 2.0 2.1 2.2 Woolridge, Scott; Brodie, Jon (April 2023). "Environmental triggers for primary outbreaks of crown-of-thorns starfish on the Great Barrier Reef, Australia". Marine Pollution Bulletin. 110: 805–815 – via Elsevier.
  3. ↑ DeLaCour, Sophie (11/14/2006). "Introduced Species Summary Project". Columbia. Retrieved 02/11/2023. Check date values in: |access-date=, |date= (help)
  4. ↑ 4.0 4.1 4.2 4.3 4.4 Kamya, Pamela; Byrne, Maria; Mos, Benjamin; Hall, Lauren; Dworjanyn, Symon (14 June 2017). "Indirect effects of ocean acidification drive feeding and growth of juvenile crown-of-thorns starfish, Acanthaster planci".
  5. ↑ 5.0 5.1 5.2 5.3 Black, Kerry; Moran, Peter; Burrage, Derek; De'ath, Glenn (September 14 1995). "Association of low-frequency currents and crown-of-thorns starfish outbreaks". Check date values in: |date= (help)
  6. ↑ 6.0 6.1 6.2 6.3 Hock, Karlo, Nicholas H. Wolff, Scott A. Condie, Kenneth R. N. Anthony, and Peter J. Mumby. “Connectivity Networks Reveal the Risks of Crown-of-Thorns Starfish Outbreaks on the Great Barrier Reef.” Journal of Applied Ecology 51, no. 5 (2014): 1188–96. http://www.jstor.org/stable/24032556.
  7. ↑ 7.0 7.1 7.2 Rogers, J. G. D., Pláganyi, É. E., & Babcock, R. C. (2017). Aggregation, Allee effects and critical thresholds for the management of the crown-of-thorns starfish Acanthaster planci. Marine Ecology Progress Series, 578, 99–114. Retrieved from https://www.jstor.org/stable/26403708
  8. ↑ 8.0 8.1 Crown-of-thorns starfish control program. gbrmpa. (n.d.). Retrieved April 13, 2023, from https://www2.gbrmpa.gov.au/our-work/programs-and-projects/crown-thorns-starfish/Crown-of-thorns-starfish-control-program#:~:text=The%20program%20uses%20dedicated%20vessels,of%2Dthorns%20Starfish%20Control%20Program.
  9. ↑ 9.0 9.1 Kenchington, R., & Kelleher, G. (1992). Crown-of-thorns starfish management conundrums. Coral Reefs, 11(2), 53–56. https://doi.org/10.1007/bf00357422
  10. ↑ 10.0 10.1 "The Triton that ate the Crown-of-Thorns". Australian Institute of Marine Science. 12/04/2014. Retrieved 02/11/2023. Check date values in: |access-date=, |date= (help)
  11. ↑ 11.0 11.1 11.2 11.3 Endean, Robert; Stablum, William (Winter 1975). "Population Explosions of Acanthaster planci and Associated Destruction of the Hard-coral Cover of Reefs of the Great Barrier Reef, Australia". Evironmental Conservation, Cambridge University Press. 2: 10 – via JSTOR.
  12. ↑ Birkeland, Andrew. (1982). Terrestrial runoff as a cause of outbreaks of Acanthaster planci (echinodermata: Asteroidea) - marine biology. SpringerLink. Retrieved April 13, 2023, from https://link.springer.com/article/10.1007/BF00396897
  13. ↑ Australian Institute of Marine Science. "Crown-of-thorns starfish".
  14. ↑ 14.0 14.1 14.2 Deaker, D. J., & Byrne, M. (2022). Crown of thorns starfish life-history traits contribute to outbreaks, a continuing concern for coral reefs. Emerging Topics in Life Sciences, 6(1), 67–79. https://doi.org/10.1042/etls20210239
  15. ↑ 15.0 15.1 15.2 15.3 Crown of Thorns Starfish. (n.d.). Retrieved from Great Barrier Reef Foundation website. Retrieved from: https://www.barrierreef.org/the-reef/threats/Crown-of-thorns%20starfish#:~:text=%23Facts%20about%20crown%2Dof%2D
  16. ↑ 16.0 16.1 All About the Crown of Thorns Starfish - AquaViews. (2020, January 3). Retrieved from Aquaviews - SCUBA Blog website: https://www.scuba.com/blog/explore-the-blue/crown-of-thorns-starfish/
  17. ↑ Miller, I., Sweatman, H., Cheal, A., Emslie, M., Johns, K., Jonker, M., & Osborne, K. (2015, March 26). Origins and implications of a primary crown-of-thorns starfish outbreak in the Southern Great Barrier Reef. Journal of Marine Sciences. Retrieved March 10, 2023, from https://www.hindawi.com/journals/jmb/2015/809624/
  18. ↑ Ortiz, Juan-Carlos (July 2018). "Impaired recovery of the Great Barrier Reef under cumulative stress". National Library of Medicine. 4: 1–8 – via PubMed Central.
  19. ↑ Cooker, Darren; Wilson, Shaun; Pratchett, Morgan (August 2013). "Importance of live coral habitat for reef fishes". Reviews in Fish Biology and Fisheries. 24: 89–126 – via Springer Link.
  20. ↑ 20.0 20.1 20.2 20.3 Kwai, I. (2018, January 5). A voracious starfish is destroying the Great Barrier Reef. The New York Times. Retrieved April 13, 2023, from https://www.nytimes.com/2018/01/05/world/australia/starfish-coral-great-barrier-reef.html#:~:text=Normally%2C%20the%20starfish%20contribute%20to,than%20the%20coral%20can%20reproduce  
  21. ↑ Perry, N. (2018). What's the economic value of the Great Barrier Reef? it's priceless. The Conversation. Retrieved April 13, 2023, from https://theconversation.com/whats-the-economic-value-of-the-great-barrier-reef-its-priceless-80061
  22. ↑ "CROWN-OF-THORNS STARFISH CONTROL". Great Barrier Reef Foundation. 2023. Retrieved April 2023. Check date values in: |access-date= (help)
  23. ↑ Crown-of-thorns starfish management | gbrmpa. (2019). Retrieved from Gbrmpa.gov.au website: https://www2.gbrmpa.gov.au/our-work/programs-and-projects/crown-thorns-starfish-management
  24. ↑ The Reef 2050 Plan - DCCEEW. (2022). Retrieved from Dcceew.gov.au website: https://www.dcceew.gov.au/parks-heritage/great-barrier-reef/protecting/reef-2050-plan
  25. ↑ 25.0 25.1 foursiteadmin. (2020, March 20). The devastating effects of a Crown of Thorns Starfish outbreak. Retrieved April 14, 2023, from ICRI website: https://icriforum.org/the-devastating-effects-of-a-crown-of-thorns-starfish-outbreak/#:~:text=The%20best%20and%20most%20successful
  26. ↑ 26.0 26.1 26.2 Khaled bin Sultan Living Oceans Foundation. (2015). Managing a COTS Outbreak - Living Oceans Foundation. Retrieved from Living Oceans Foundation website: https://www.livingoceansfoundation.org/science/crown-of-thorns-starfish/managing-cots-outbreak/
  27. ↑ Lee, C.-C., Tsai, W.-S., Hsieh, H., & Hwang, D.-F. (2013). Hemolytic activity of Venom from crown-of-thorns starfish Acanthaster planci spines. Journal of Venomous Animals and Toxins Including Tropical Diseases, 19(1), 22. https://doi.org/10.1186/1678-9199-19-22
  28. ↑ 28.0 28.1 28.2 Boström-Einarsson, L., Bonin, M. C., Moon, S., & Firth, S. (2018). Environmental impact monitoring of household vinegar-injections to cull crown-of-thorns starfish, Acanthaster spp. Ocean & Coastal Management, 155, 83–89. https://doi.org/10.1016/j.ocecoaman.2018.01.023
  29. ↑ 29.0 29.1 29.2 29.3 Einarsson, L. B. (2015, October 12). Vinegar - controlling Crown-of-Thorns Starfish at half the cost. Retrieved April 15, 2023, from Lizard Island Reef Research Foundation website: https://lirrf.org/vinegar-controlling-cots/#:~:text=The%20oxbile%20injection%20method&text=A%20long%20needle%20separates%20the
  30. ↑ 30.0 30.1 30.2 30.3 Rivera-Posada, J., Pratchett, M. S., Aguilar, C., Grand, A., & Caballes, C. F. (2014). Bile salts and the single-shot lethal injection method for killing crown-of-thorns sea stars (Acanthaster planci). Ocean & Coastal Management, 102, 383–390. https://doi.org/10.1016/j.ocecoaman.2014.08.014
  31. ↑ 31.0 31.1 Grech, A., Edgar, G., Fairweather, P., Pressey, R. L., & Ward, T. (2015). Australian marine protected areas. Retrieved from: https://www.researchgate.net/profile/Alana-Grech/publication/293079951_Australian_marine_protected_areas/links/5849eee408ae686033a76cbc/Australian-marine-protected-areas.pdf
  32. ↑ 32.0 32.1 "Crown-of-thorns starfish control program". Great Barrier Reef Marine Park Authority. 2022. Retrieved 02/11/2023. Check date values in: |access-date= (help)
  33. ↑ "Tourism Reef Protection Initiative". Great Barrier Reef Marine Park Authority. Aug 2022. Retrieved April 2023. Check date values in: |access-date= (help)
  34. ↑ 34.0 34.1 34.2 Bos, Arthur; et al. (January 2013). "Management of crown-of-thorns sea star (Acanthaster planci L.) outbreaks: Removal success depends on reef topography and timing within the reproduction cycle". Ocean & Coastal Management. 71: 116–122 – via Elsevier Science Direct. Explicit use of et al. in: |last= (help)
  35. ↑ Mottia, Cherie; Cummins, Scott; Hall, Michael (2022). "A Review of the Giant Triton (Charonia tritonis), from Exploitation to Coral Reef Protector?". Diversity. 14: 1–35 – via Multidisciplinary Digital Publishing Institute.
  36. ↑ 36.0 36.1 36.2 36.3 Hall, M.R.; Motti, C.A.; Kroon, F. (2017). "The potential role of the giant triton snail, Charonia tritonis (Gastropoda: Ranellidae) in mitigating populations of the crown-of-thorns starfish" (PDF). Reef and Rainforest Research Centre: 58 – via Australian Institute of Marine Science. line feed character in |title= at position 55 (help) Cite error: Invalid <ref> tag; name ":3" defined multiple times with different content
  37. ↑ "Cephalopods, Crustaceans, & Other Shellfish - Giant Triton". OCEANA Protecting the World's Oceans. Retrieved April 2023. Check date values in: |access-date= (help)
  38. ↑ Jia, H.; Zhang, Gege; Zhang, Chenglong; Zhang, Hua; Yao, Gaoyou; He, Maoxian; Liu, Wenguang (2023). "Identification and Expression of the Conotoxin Homologous Genes in the Giant Triton Snail (Charonia tritonis)". Ocean University of China. 22: 213–220 – via Springer Link.
  39. ↑ 39.0 39.1 39.2 39.3 39.4 39.5 Klein, A. H.; Motti, C. A.; Hillberg, A. K.; Ventura, T.; Thomas-Hall, P.; Armstrong, T.; Barker, T; Whatmore, P; Cummins, S. F. (June 2021). "Development and Interrogation of a Transcriptomic Resource for the Giant Triton Snail (Charonia tritonis)". Marine Biotechnology. 23: 501–515 – via Springer Link. Cite error: Invalid <ref> tag; name ":20" defined multiple times with different content
  40. ↑ "Endangered Shells - Triton Trumpet Shell". Mamanuca Environment Society. Retrieved April 2023. Check date values in: |access-date= (help)
  41. ↑ "Amendments to Appendices 1 and 2 of the Convention" (PDF). CITES.
  42. ↑ ORMOND, R. F. G., CAMPBELL, A. C., HEAD, S. H., MOORE, R. J., RAINBOW, P. R., & SAUNDERS, A. P. (1973). Formation and Breakdown of Aggregations of the Crown-of-Thorns Starfish, Acanthaster planci (L.). Nature, 246(5429), 167–169. https://doi.org/10.1038/246167a0
  43. ↑ De’ath, G., & Moran, P. J. (1998). Factors affecting the behaviour of crown-of-thorns starfish (Acanthaster planci L.) on the Great Barrier Reef: Journal of Experimental Marine Biology and Ecology, 220(1), 83–106. https://doi.org/10.1016/s0022-0981(97)00085-3
  44. ↑ 44.0 44.1 Johnson, Craig; Sutton, D. C.; Olson, R. R.; Giddins, R. (April 11 1991). "Settlement of crown-of-thorns starfish: role of bacteria on surfaces of coralline algae and a hypothesis for deepwater recruitment" (PDF). Check date values in: |date= (help)
  45. ↑ Coral predators get a boost from climate change. (2017). Nature, 546, 330–330. https://doi.org/10.1038/d41586-017-00760-1
  46. ↑ 46.0 46.1 46.2 Pratchett, M.S.; Caballes, C.F.; Wilmes, J.C.; Matthews, S.; Mellin, C.; Sweatman, H.P.A.; Nadler, L.E.; Brodie, J.; Thompson, C.A.; Hoey, J.; Bos, A.R.; Byrne, M.; Messmer, V.; Fortunato, S.A.V.; Chen, C.C.M.; Buck, A.C.E.; Babcock, R.C.; Uthicke, S. Thirty Years of Research on Crown-of-Thorns Starfish (1986–2016): Scientific Advances and Emerging Opportunities. Diversity 2017, 9, 41. https://doi.org/10.3390/d9040041

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  1. ↑ Ian Miller ,Hugh Sweatman,Alistair Cheal,1Mike Emslie, Kerryn Johns, Michelle Jonker, Kate Osborne (March 2015). "Origins and Implications of a Primary Crown-of-Thorns Starfish Outbreak in the Southern Great Barrier Reef". Hindawi.CS1 maint: multiple names: authors list (link)
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