Australia: Remote ecosystem suffers 7000 hectare dieback

Drew Creighton Sydney Morning Herald 9 Jul 16;

A 700 kilometre stretch of mangrove shoreline in the southern reaches of the Gulf of Carpentaria has died, sparking fears of deeper implications for the ecosystem.

The dieback encompasses about 7000 hectares of land and was the result of the El Nino conditions that affected the region during the warmer months.

James Cook University Professor Norm Duke said that was about the extent of their 'hard data' around the problem ranging from Kurumba in Queensland to the Roper River in the Northern Territory.

"We know from the remote sensing we have in the area that the dieback occurred late November, December last year," Professor Duke said.

"That was the end of an unusually long dry period, that is probably the major contributing factor, the change of climate such that there was virtually no wet season last year.

"It's been so severe in many locations that the whole of the shoreline fringe of mangrove has been killed or at least defoliated.

"The question is, how much if any will recover?"

That question may go unanswered if research funding to send scientists to the area is not forthcoming.

"Everything that's happening at the moment is happening without funding, everything is being done by people as individuals, this is not driven by government agenda or contract.

"At the end of the day, it's going to need a proper injection of funding to get to the bottom of what's going on and to properly check the repercussions."

Professor Duke said the remoteness of the the damaged area was a huge inhibitor to solving the problem and shining light on what should be 'international news'.

"If 700 kilometres of shoreline had been affected in such a way on the east coast of Australia, this would be international news, it's a major event in a habitats response to an adjustment in climate.

"There would be a lot of people or industry hoping they weren't to blame for it if it happened around a port area."

The death of 7000 hectares of mangrove trees is a large event, but it may be just the beginning of a chain of events caused by the rotting of the trees' roots.

"One of the mangroves roles is that they prevent erosion of mud banks and as they've died, a lot of the sediment is going to be released and make the water dirtier and that will kill seagrass and coral.

"If it involves seagrass then the implications extend much more broadly, you're talking about turtles and dugongs, but we don't know for sure.

"One report from indigenous rangers in the area on the Northern Territory side at least, there was lots of dead seagrass floating up that has never done that before - it needs to be checked.

"There could be other repercussions on other habitats that we have even less of an idea of."

The little help Professor Duke and his researcher have received has been pivotal in what he has been able to study.

"I've been talking to the rangers who are observing locally what's going on, they're telling me they've seen lots of dead leaves and the shellfish living under the trees are now dying or dead.

"All this is anecdotal at that level and we don't have data from scientific or industry types about what is happening there.

"We don't have any hard data, but the observations and the expectations are that there are effects."