Few ecosystems on earth are as vulnerable to the impacts of climate change as coral reefs. While it will take a concerted global effort to address a global issue, Great Barrier Reef Marine Park Authority Chief Scientist Dr Roger Beeden explains the future sustainability of the world’s most complex marine ecosystem also relies, in part, on household vinegar!
Of all the incredible marine species found on the Great Barrier Reef – over 9,000 at last count, and likely many more - there is arguably none more surprising, and ultimately misunderstood, than the crown-of-thorns starfish (COTS).
Contrary to popular belief, Pacific crown-of-thorns starfish (Acanthaster cf. solaris) are native to Australian waters and, as their name suggests, can be found across much of the Indo-Pacific Region, including the Great Barrier Reef Marine Park which stretches more than 2,300km along the Queensland coastline.
They feed exclusively on live coral and can consume an area equivalent to half of their ‘dinner plate’ sized bodies every day. When their numbers are low, their presence helps to maintain the diversity of coral communities and natural balance of the ecosystem.
However, under the right conditions COTS numbers can explode to plague proportions known as outbreaks. When this occurs their taste for coral becomes a significant problem as their combined appetite can lead to rapid coral loss and degradation of reef habitats.
Research indicates that fishing, coastal development and farming can all influence how often COTS outbreaks occur and how severe they get. Rising sea temperatures, driven by increased greenhouse gas emissions, may lengthen the COTS spawning season – which, generally occurs during the warmer summer months – when a single female can release over 100 million eggs.
Against these incredible numbers, it should come as no surprise that previous COTS outbreaks, which typically span about 15 years and impact hundreds of reefs, have caused significant declines in coral cover across the entire Marine Park.
While the Reef is a complex network of estuaries, seagrass beds, mangroves, wetlands and deep ocean areas, coral is the foundation on which Australia’s greatest natural wonder is built. As the climate changes, and the Reef becomes more vulnerable to disturbances, that foundation is increasingly under pressure.
Targeted and systematic control of COTS outbreaks is a demonstrated effective management action to protect corals and their future generations. It’s a clear global example of best practice ‘resilience-based management’.
Since the expansion of the COTS Control Program in 2012, we have invested more than 130,000 diver hours to cull over 1.2 million starfish and protect more than 800,000 hectares of coral reef habitat from COTS predation.
FACT: A single 20ml injection of household vinegar is enough to safely cull COTS without harming other reef inhabitants.
Supressing COTS outbreaks protects both the growth of existing coral communities and their recovery from other less directly manageable disturbances such as climate driven coral bleaching events.
Building on previous reef protection successes, the COTS Control Program has received a $161.5 million funding allocation from the Australian Government to deliver on-water operations from 2022 to 2030. Moreover, the Program has partnered with four companies, including Indigenous business Malu Ventures, to enhance on-water operations through to 2027. This partnership is groundbreaking. It ensures that the remote Far Northern region of the Marine Park will receive sustained starfish control while also employing and training Reef Traditional Owners and enabling expanded work opportunities on Sea Country.
Over the next three years, the COTS Control Program aims to deliver more than 3,370 days at sea and 55,117 diver hours, targeting up to 200 reefs annually to protect coral from starfish predation and support the Reef ‘s natural resilience and adaptability.
The Great Barrier Reef is Australia’s greatest natural wonder; it transcends national boundaries and is a source of collective pride for all Australians. For almost 50 years the Reef Authority has been charged with managing the Reef for its long-term health and protection.
The COTS Control Program is just one example of targeted management actions making a real difference through a genuine commitment to strategic innovation, strong partnerships… and a few teaspoons of household vinegar.
Dr Roger Beeden
Chief Scientist