[SYDNEY] A major coal spill on Australia's Great Barrier Reef could kill some colourful corals within two weeks and stunt the growth of fish and seagrass, a new study revealed on Tuesday.
While coal spills are rare, environmentalists have been increasingly concerned about the risks to the reef from ships carrying the commodity mined in Queensland state through its waters.
The study, published in Nature Scientific Reports, is the first to examine the effects of fine coal particles on tropical marine organisms.
"Results demonstrate that chronic coal exposure can cause considerable lethal effects on corals, and reductions in seagrass and fish growth rates," it said.
In experiments in which marine species were exposed to varying levels of fine coal particles, the researchers found that it had a "smothering" impact on corals, co-author Mia Hoogenboom told AFP.
Ms Hoogenboom, from Australia's Centre of Excellence for Coral Reef Studies, said there was a stickiness to coal dust which formed a film on coral which light struggled to penetrate.
"From our study it was the coral that was the most vulnerable where we saw extensive mortality of the coral tissue," she said.
"For the sea grass and the fish we saw lower levels of mortality but we did see significant impacts on their growth rates." Kathryn Berry, who led the experimental research, said corals exposed to the highest concentrations of coal dust died within two weeks.
"Corals exposed to lower concentrations of coal lasted longer, but most of them also died after four weeks of exposure," she said in a statement.
Ms Berry said while some fish and seagrass died from coal dust exposure, in most cases it stunted their growth by half compared to how they would have grown in clean water.
The reef is suffering its worst bleaching in recorded history with 93 per cent of corals affected due to warming sea temperatures, and a coal spill would add to problems caused by farming run-off, development and the coral-eating crown-of-thorns starfish.
A catastrophe was avoided when the Chinese-registered coal carrier Shen Neng 1 foundered in the marine park in 2010, but the huge ship gouged a 3km-long scar in the reef and was stranded for nine days before salvagers could refloat it.