Vinegar offers hope in Barrier Reef starfish battle

Sydney : Coral-munching crown-of-thorns starfish can be safely killed by common household vinegar, scientists revealed Thursday in a discovery that offers hope for Australia's struggling Great Barrier Reef.

The predatory starfish is naturally-occurring but has proliferated due to pollution and run-off at the World Heritage-listed ecosystem, which is also reeling from two consecutive years of mass coral bleaching.

Until now other expensive chemicals such as bile salts have been used to try and eradicate the pest -- which consumes coral faster than it can be regenerated -- but they can harm other marine organisms.

Tests by James Cook University, in collaboration with the Great Barrier Reef Marine Park Authority (GBRMPA), showed vinegar was safe, effective and cheap. 

Study head Lisa Bostrom-Einarsson said crown-of-thorns were injected with vinegar at four sites on the reef over six weeks, causing them to die within 48 hours with no impact on other life.

"We recorded live coral cover, abundance of coral disease, fish abundance and diversity, fish diseases and the abundance of closely related invertebrates before, during and after the six-week study period and found no detrimental effects," she said.

Keeping crown-of-thorns under control however is a tough ask, with dive teams needing to individually inject each starfish before it dies and breaks-up.

But despite the labour-intensive job, it is far more efficient than extracting them from the water before killing them.

A major study of the reef's health published in 2012 showed cover had halved over the past 27 years and attributed 42 percent of the damage to crown-of-thorns starfish.