A large coal spillage on the Great Barrier Reef would kill coral and stunt the growth of fish and seagrass, a new study suggests.
Scientists say their research demonstrates the likely effects of a coal tanker accident on the World Heritage listed reef.
Researchers exposed a range of marine species to varying levels of coal dust, and found coral subjected to the highest concentrations died within two weeks.
Corals exposed to lower concentrations of coal lasted longer, but most of them also died after a month.
Some fish and seagrass also died but the coal dust mostly stunted their growth by half compared to those in clean water.
There has never been a major coal spillage on the reef, but the grounding of the Chinese ship Shen Neng 1 off the central Queensland coast in 2010 highlighted the risks posed by mining-related shipping activities.
The ship didn't lose its load of 60,000 tonnes of coal when it hit Douglas Shoal, but it gouged a three kilometre-long scar into the sea bed and spilt about four tonnes of heavy fuel oil from a ruptured tank.
Researcher Dr Andrew Negri says the likelihood of a major coal spill on a coral reef or seagrass meadow is low.
But he says the study gives authorities a much clearer idea about what the environmental consequences would be.
The study, by scientists from the ARC Centre of Excellence for Coral Reef Studies and the Australian Institute of Marine Science, has been published in the journal Nature Scientific Reports.
