Mangrove expert says it is the most extreme “dieback” he has ever seen! The mangrove deaths happened across a 700 km distance. International mangroves expert Dr Norm Duke said he had no doubt the “dieback” was related to climate change. “It’s a world-first in terms of the scale of mangrove that have died,” he told the ABC He described the scene as the most “dramatic, pronounced extreme level of dieback that I’ve ever observed.
Close to 10,000 hectares of mangroves have died across a stretch of coastline reaching from Queensland to the Northern Territory.
International mangroves expert Dr Norm Duke said he had no doubt the “dieback” was related to climate change.
“It’s a world-first in terms of the scale of mangrove that have died,” he told ABC.
Dr Duke a world expert in mangrove classification and ecosystems, based at James Cook University, flew 200 kilometres between the mouths of the Roper and McArthur Rivers in the Northern Territory last month to survey the extent of the dieback. He described the scene as the most “dramatic, pronounced extreme level of dieback that I’ve ever observed”.
Until that time he and other scientists had been focused on mangrove dieback around Karmuba, Queensland, at the opposite end of the Gulf. “Images were compelling. They were really dramatic, showing severe dieback of mangrove shoreline fringing — areas just extending off into infinity”.
The area the Northern Territory photos were taken in was so remote the only way to confirm the extent and timing of the mangrove dieback was with specialist satellite imagery.
“I have not seen such imagery anywhere before, from all over the world. I work in many places around the world and I look at damaged mangroves as part of my work all the time. These are the most shocking images of dieback I’ve ever seen.”
Dr Duke said the cause of such extensive damage was not immediately evident. “Like a large oil spill, like a cyclone or severe storm — none of those things had occurred in the region in recent times,” he said.
“But in that mix of things that were going on at the same time we’re starting to hear about coral bleaching … [and] hot water on the east coast.” The coincident timing of coral bleaching on the Great Barrier Reef and the dieback of mangroves in the north led Dr Duke to look at climatic factors.
The wet season was only one month long in the year before. Usually the wet season in the Northern Territory in that area is three or four months long. Unusually low rainfall in the 2014 wet season and elevated temperatures likely led to the massive mangrove dieback. A lack of fresh water and increased water and atmospheric temperatures stressed the plants beyond their tolerance.
Satellite imagery pinpoints the damage to a period of around four weeks in September-October 2015.
The health of mangroves has a significant impact on the fishing industry in Australia. Mangroves are essential breeding grounds for fish stock including prawns, crabs and, in the north of Australia, fin fish such as barramundi. http://mobile.abc.net.au/news/2016-07-10/unprecedented-10000-hectares-of-mangroves-die/7552968