North Stradbroke Island wetland probe turns up ice age scientific finds

STRADDIE WETLANDS: A movie crew works as the sun sinks on wetlands at North Stradbroke Island. Photo: Hing Ang.
STRADDIE WETLANDS: A movie crew works as the sun sinks on wetlands at North Stradbroke Island. Photo: Hing Ang.

AN investigation of wetlands on North Stradbroke Island has the potential to rewrite what scientistS know about climate change in Australia since the last ice age, say scientists.

Government scientists, working with University of Adelaide, have found a trove of climate and biodiversity data on Brisbane’s doorstep, reaching back an astonishing 200,000 years.

Science Department principal scientist Jonathan Marshall said the core-dating investigations he and his colleagues conducted on North Stradbroke Island (Minjerribah) indicated there have been persistent wetland areas on the island for at least 40,000 years, and probably longer.

“Through our collaborative work … we have discovered that North Stradbroke Island is an Australian exception,” Dr Marshall said.

“We cored and dated 16 wetlands on the island and found six dating to the Last Glacial Maximum or earlier, with one being more than 200,000 years old.”

The bulk of Redlands drinking water is drawn from water tables on North Stradbroke, with conservationists and scientists having warned previously about the danger of drawing too much from the island.

Last week Seqwater announced that it was too expensive to restore the gates to the Leslie Harrison Dam, a move that reduces its contribution to local drinking water supplies and cuts dam supplies by about 50 per cent. 

Straddie wetland project leader Dr John Tibby said the persistence of island wetlands suggested that for much of the past 40,000 years, and for perhaps much longer, the local environment had remained relatively moist.

“This may partly be due to links between these wetlands and the island’s groundwater systems, which act as water reservoirs during periods of rainfall deficit,” Dr Tibby said.

“During what was otherwise a particularly dry period in Australia’s ancient past, these persistently moist regions are thought to have played a unique role in maintaining biodiversity.

“This unique and remarkably long and uninterrupted record of climatic conditions in south-east Queensland will greatly improve our understanding about the drivers of both local and regional climate variability.”

Quandamooka Yoolooburrabee Aboriginal Corporation traditional owner Darren Burns said the scientific evidence confirmed the existence of local natural resources, which the Quandamooka people would have utilised to enable them to live on the island.

“Coupled with the existence of the Pleistocene sites, this study demonstrates the long and extensive connection Quandamooka people have to our ancient land,” Mr Burns said.

Science Minister Leeanne Enoch said that by studying cores taken from freshwater lakes and swamps on Straddie, the team had made a world-class contribution to climate science.

“I’d like to acknowledge the paradigm-changing work of the team, led by Dr John Tibby from the University of Adelaide, and including DSITI scientists Drs Jonathan Marshall, Glenn McGregor and Tim Page,” she said.

“As a Quandamooka woman originally from North Stradbroke Island, I am proud of the fact Minjerribah Moorgumpin elders assisted in the coordination of the extensive field work required for this detailed scientific investigation.

“The significance of this research is that it greatly adds to our understanding of the ancient climatic changes that shaped our country, our wildlife and our first peoples.

“Until now, few Australian sites had offered detailed information about what was happening at wetlands since the last great ice age, which peaked around 15,000 years ago.”