Gulf of Carpentaria’s record mangrove dieback is a case study of extremes
One of the worst instances of mangrove forest dieback recorded globally struck Australia’s Gulf of Carpentaria in the summer of 2015-16. A combination of extreme temperatures, drought and lowered sea levels likely caused this dieback, according to our investigation published in the journal Marine and Freshwater Research. The dieback, which coincided with the Great Barrier Reef’s worst recorded bleaching event, affected 1,000km of coastline between the Roper river in the Northern Territory and Karumba in Queensland. About 7,400 hectares, or 6%, of the gulf’s mangrove forest had died. Losses were most severe in the NT, where around 5,500ha of mangroves suffered dieback. Some of the gulf’s many catchments, such as the Robinson and McArthur rivers, lost up to 26% of their mangroves. The Gulf of Carpentaria is a continuous sweep of wide tidal wetlands fringed by mangroves, meandering estuaries, creeks and beaches. Its size and naturalness makes it globally exceptional. An apron of broad mudflats and seagrass meadows supports thousands of marine turtles and dugongs. A thriving fishing industry worth at least $30m ultimately depends on mangroves. Mangroves and saltmarsh plants are uniquely adapted to extreme and fickle coastal shoreline ecosystems. They normally cope with salt and daily inundation, having evolved specialised physiological and morphological traits, such as salt excretion and unique breathing roots. But in early 2016, local tour operators and consultants doing bird surveys alerted authorities to mangroves dying en masse along entire shorelines. They reported skeletonised mangroves over several hundred kilometres, with the trees appearing to have died simultaneously. They sent photos and even tracked down satellite images to confirm their concerns. The NT government supported the first investigative surveys in June 2016.
Posted by admin
on Mar 14 2017. Filed under Climate change.
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