Some 7,000 hectares (17,300 acres), or nine per cent of the mangroves in the Gulf of Carpentaria, perished in just one month according to researchers from Australia's James Cook University, the first time such an event has been recorded.
The so-called dieback -- where mangroves are either dead or defoliated -- was confirmed by aerial and satellite surveys and was likely to have been the result of an extended drought period, said Norm Duke, a mangrove ecologist from James Cook University.
"The reason that there's dieback now is because of this drought. Droughts are normal, but not so severe, and that's the difference," he said.
Local rangers told scientists they were seeing creatures like shellfish, which need the shade of the trees, dying and that turtles and dugongs that are dependent on the ecosystem could "be starving in a few months", he added.
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Duke said researchers believe the event took place in the semi-arid region in late November or early December last year.
He added that "by all accounts, the climate is going to become more erratic, so we can expect these type of events to become more common".
Some of the mangroves suffering "dieback" were defoliated, meaning they were not yet dead but had lost their leaves, and could recover. But most "won't recover, and will be dead", with satellite images matching ground surveys, said Duke.