Population outbreaks of the crown-of-thorns sea star (Acanthaster planci), remain one of the major causes of coral destruction and habitat degradation on coral reefs throughout the Great Barrier Reef (Grand, 2014) Given the threat posed by this poisonous echinoderm to coral reefs, significant investments have been made to reduce the number of Sea Stars and their effects on assemblages. New ongoing control programs have been introduced by scientists such as the bile salt injections to try and protect the ecosystem in the GBR. This report will investigate the new control theories and the effect of these methods on social, economical and environmental aspect of the GBF. Given that these control methods have been put in place to reduce the impact of the COTS this links to my SHE key concept of ‘development’.
Background of Biology:
The Crown of Thorns Starfish (COTS) are a destructive type of starfish that belong to the Echinodermata phylum. These starfish have been a major predator to the corals throughout the Indo-pacific region, the Pacific and Indian Oceans mainly. It’s full-body covering of its sharp, venomous spines, the Crown of Thorns Sea star has a reputation for its devastating impact on coral reef ecosystems. There have been 3 significant waves of major destruction from the COTS in the Great Barrier Reef that caused the Government to take some action. The Australian Government Marine institutes 2012 study showed these outbreaks were occurring of the Queensland coast and were responsible for 25% of the live coral loss in the GBR. When there is a dramatic increase of COTS it results in a major disturbance to the whole ecosystem, as the starfish are known to consuming coral faster than it can grow thereby drastically reducing coral cover.
From between 7-23 arms that radiate from a large central disk. These arms are covered in membranous skin which have hundreds of poisonous spines. The underside of each of its arms has a sequence of closely fitting suction cups which extend in rows to the mouth. The COTS are known for there ability to bend to fit around the corals. Geneses such as dolphins, turtles, sharks and dugong’s numbers have greatly reduced as a result of there food and habitat being destroyed.
A new control methods have been introduced in the recent years called the ‘single jab’ and the ‘multiple jab’ method. Bile salt and Sodium bisulphate are the to white powder’s that are injected into these starfish to reduce their numbers. These coral predators are now injected by divers with a dose a bile salt, which paralyses the nervous system of these animals causing their arms to drop off. When these starfish are injected it is important that the divers inject 10 mL dose especially in small sea stars. This dosage of bile salt has been tested to make sure that it does not effect the surrounding habitat. These new control methods and technologies have to be developed and tested, clearly linking to my development key concept through the formulation and testing of new theories.
Discussion
Many short term and long term control methods have been developed to reduce the effect of the Crown of Sea Stars on the Great Barrier Reef. The decline in coral cover in the Great Barrier Reef shows that COTS are a major threat to the long term viability of the coral reefs and the ecosystem. In relation to my key concept topic development, there has been many control methods that have been modified to improve the reduction of COTS of the GBF. A major breakthrough for controlling the COTS was made by the James Cook University by the discovery of the single shot method. This single injection of Bile salt causes the Sea star’s arms to fall off causing them to die off. When the first wave of COTS came in 1986 original methods such as cutting the A. Planci into pieces was the way scientists used to try and reduce the number on the GBF. Scientists found that within 3 days there was a 75% survivor rate from the sea stars with visible healing in the areas that were cut. Through this original control method scientist’s found that this theory of cutting the sea stars to reduce the number on the barrier reef was unsuccessful.
Not long after this a Crown of Thorns Targeted Control Program was developed with the project manager Steve Moon. As the increased waves were becoming more frequent Steve found new ways to improve scientific methods by modifying and replacing the old method through various tests. Steve Moon was the creator of the single shot injections that have revolutionised the decline in the COTS.
Through more testing a multi-shot method was introduced in 2010. This method required divers to inject a starfish with up-to 25 injections to make sure there would be no change of it surviving. Although this method was successful, it wasn’t the most efficient as the sodium bisulphate had to be stored and took much longer to prepare. However, bile salts only need to be injected once for the starfish to take affect. The single-shot bile salts injection were introduced in 2014 and have become is far more time efficient than the multi-shot method. ‘Through many trials of the single-shot method this indicate that it was three times more efficient than the multi-shot method’ (Craig, 2010).
According to the research by the Australian Institute of Marine Science the coral cover on the GBR between 1985 and 2012 declined by about 50 per cent over that period of time and the COTS were responsible for that for almost half of that decline. After the new injection control was introduced 500,000 COTS have been killed by injections from divers (Martin, 2015). This links to my She key concept of development as scientists found new ways to improve their methods by replacing the unsuccessful one’s and modifying them to successful methods.
Scientists and society also have a very strong role to play in reducing the impacts of the COTS of the Great Barrier Reef. COTS have hundreds of toxic spines covering their bodies, presenting a health threat to people who interact with them. The government has heavily invested money into the research for control methods as COTS are harming one of Australia’s biggest tourist attractions the Great Barrier Reef. In 2015 the Government invested $7 million purely to the COTS control program. These outbreaks of the COTS are of great concern to all GBF Marine park users, in particular the tourism industry.
Conclusion:
There have been many control methods that have been it in place to reduce the impact of Crown of Thorns Sea stars on the Great barrier reef. 500,000 sea stars have been killed by injections by divers. However, I think that we need a longer term approach for the protection of the whole of the Great Barrier Reef. This could be done by researching further methods into controlling the conditions that lead to outbreaks, and developing means for early control. My report is linked to my SHE key concepts as the development is shown through the old methods being analysed and modified to control the COTS on the Great Barrier Reef. Social and economic impacts such as the amount of money being invested and the development and control of new methods are all contributors to investing in new technology and theories to reduce the impact.