A defender Pauline Hanson has maintained coral bleaching is a natural occurrence, in an exchange with the chief scientist of the Great Barrier Reef Marine Park Authority.
The Queenslander used a Senate hearing on Monday to question the link between heat waves and back-to-back mass coral bleaching events in 2016 and 2017.
"You're saying coral bleaching is affected by water temperatures," she told David Wachenfeld.
"Yet around Indonesia, closer to the equator … where water temperatures are 29 degrees, it is a known fact that coral actually grows faster and more prolific at warmer temperatures."
Dr Wachenfeld explained that corals live in a variety of water temperatures around the world, with significant differences even within the Great Barrier Reef.
Corals bleach when stressed – such as when exposed to warmer temperatures than normal – and die if stressed for prolonged periods, he told the senator.
"The fact that corals in Indonesia could withstand higher temperatures than corals on the Great Barrier Reef is of no use to corals in the Great Barrier Reef when they die."
But Senator Hanson was not swayed, asking how the authority planned to address both water temperatures and the "natural occurrence" of bleaching events with its taxpayer funding.
The GBRMPA is trying to stamp out crown-of-thorns starfish, improve water quality in catches while urging greater global action on climate change, Senator Hanson was told.
The authority recently released its latest five-year outlook for the reef, which found it to be "very poor" unless more action was taken to slow climate change.