A diver injects vinegar into crown-of-thorns starfish as part of a culling program.
CSIRO
A culling program has successfully protected key areas of the Great Barrier Reef from voracious coral-eating starfish. Scientists who analyzed the results say efforts need to be scaled up to further protect coral reefs.
Crown-of-thorns starfish (COTS) are persistent predators of almost all types of coral within Australia’s Great Barrier Reef. Each starfish reaches a diameter of 1 meter and eats 10 square meters of coral reef each year.
Starfish live on coral reefs, and it is believed that increased nutrient input into reef waters due to agriculture and other human factors is increasing their numbers and exacerbating coral destruction. Between 1985 and 2012, they accounted for 40 percent of coral losses in the region.
When starfish erupted across the reef from 2012 to 2022, the Great Barrier Reef Marine Park Authority conducted a massive culling program. A team of divers injects the starfish with a single shot of vinegar or cow bile, which kills the starfish and prevents it from releasing its larvae.
Roger Beeden The Park Service and colleagues found that in areas where timely removals were carried out, outbreaks were limited and coral cover recovered and increased by up to 44%. Where no culling occurred, coral losses were severe. The study also confirmed that by preventing outbreaks on strategically important coral reefs, the larvae do not spread to other reefs on ocean currents, reducing further outbreaks.
To date, the program has focused on 500 of the marine park’s 3,000 reefs scattered throughout the park, which have significant value to the tourism industry or are home to starfish. were chosen because they are known to be important for the spread of
“The results we found in this study are the result of using integrated pest management. [the starfish] Just like managing plague locusts and other pest species, it needs to be done at the right time and on the right reef,” says Beeden.
But researchers recommend expanding the program from the current fleet of five to seven ships to 10 to 15 ships. “At any given time, about a third to a half of his 500 cases are involved in the current outbreak,” Beeden said.
Terry Hughes Researchers at James Cook University in Townsville do not agree that culling programs are worthwhile. “It is becoming increasingly clear that attempts to protect Great Barrier Reef corals by culling crown-of-thorns starfish on a few reefs are just a drop in the ocean,” he says.
Mr Hughes said geographical differences in starfish numbers and coral abundance – which the study attributed to levels of culling in different parts of the Great Barrier Reef – could be explained by which areas had suffered from recent cyclones and coral mass destruction. Events they say could be explained by who is most affected by large-scale bleaching. Professor Beeden acknowledges that it is difficult to separate these factors from the effects of selection, but he says: “Our results are strengthened and are not confounded by the fact that the increase in coral cover in the Townsville region was achieved despite two large-scale bleaching events in 2020 and 2022. do not have” “
Instead, Hughes says the priority should be to tackle global warming, which is accelerating the frequency and intensity of coral bleaching. “Each time there is a bleaching event, the Australian government announces additional funding to eliminate starfish from some coral reefs, shifting the focus away from addressing the causes of these outbreaks and reducing Australia’s greenhouse gas emissions.” he says.
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Source: www.newscientist.com
