Australia's iconic Great Barrier Reef has lost half its coral since 1985 and around 40 percent of this is believed to be down to the venomous Crown of Thorns starfish.

Scientists believe that a combination of global warming and nitrogen-based fertilisers from on-shore agriculture may have created the perfect conditions for the coral munching starfish, which are breeding in massive numbers.

Tamara Sheward heads to the Great Barrier Reef to meet divers culling the starfish – a painstaking process in which the creature’s stomach and each of its limbs is injected with a dry acid.

She also meets Dr Jairo Rivera Posada from James Cook University in Townsville, who has developed a potential new weapon against the starfish – a protein solution derived from Ox bile and which kills the starfish in just one hit.

earthrise can be seen each week at the following times GMT: Tuesday: 2230; Wednesday: 0930; Thursday: 0330; Friday: 1630; Saturday: 2230; Sunday: 0930; Monday: 0330; Tuesday: 1630. 

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Source: Al Jazeera