Reef science shows local impacts for Burnett—Mary catchment
THE Burnett Mary catchment does have an impact on the Great Barrier Reef, and much of the region’s run-off of dissolved inorganic nitrogen comes from sugarcane.
This is according to one of the leading writers behind the co-ordinated Scientific Consensus Statement, which has influenced the state and federal governments’ Reef 2050 Water Quality Improvement Plan, and the state government’s proposed reef management laws.
James Cook University TropWater researcher, Jane Waterhouse, said satellite imagery of the 2011 and 2013 Bundaberg floods proved that run-off from the area can reach the Great Barrier Reef.
Canegrowers and scientist Peter Ridd have noted that the Australian eastern current moves south, therefore reasoning that southern waterways could not impact the Great Barrier Reef.
Dr Ridd said there was limited testing done with sediments in the reef, which showed how much run-off impacted it.
But according to Ms Waterhouse, this was not true.
“River discharges from Queensland’s coastal rivers, including those in these areas, generally move in a northward direction,” Ms Waterhouse said.
“This is due to the prevailing currents and wind direction which is typically in a south easterly direction during the wet season.
“There are instances where we have observed different plume movements due to different wind conditions, such as in the Burdekin discharge this year where there was limited wind and the plume moved offshore.”
The Burnett Mary’s catchment was important for seagrass, which fed dugongs and turtles even outside of the World Heritage Area.
“The region contains one of the largest and most important seagrass areas along the whole GBR coast,” she said.
Ms Waterhouse said the Burnett Mary catchment was not considered a “high risk” to the reef when compared to the five other reef catchments, but it did contribute 11 per cent of the total dissolved inorganic nitrogen (DIN).
She said that 45 per cent of the DIN from the Mary catchment comes from sugarcane.
As for sediment testing, the results can be diverse depending where tests were taken.
“Some reef areas will be more susceptible to influence than others,” she said.
“That’s why local assessments and monitoring are so important.”
The Scientific Consensus Statement has had 48 authors including Ms Waterhouse, and 14 organisations involved in the study, and seven additional organisations that reviewed the work.
It provides the evidence for the Reef 2050 Water Quality Improvement Plan.
But local farmers have urged the state government to pause its controversial reef management laws until further independent testing was completed, as it could hurt the sugarcane industry.
Dr Ridd, who recently spoke in Bundaberg while supported by Canegrowers, questioned the science that dictated political policy.
He said that peer review work is good enough for public policy decisions.
“The 2019 GBR outlook report has around 1500 references that were peer reviewed, but only a tiny percentage of these are of any great importance,” Dr Ridd said.
“I have analysed most of these and believe that there are flaws in all of them but, more importantly, they have not been subject to rigorous and antagonistic scrutiny.”
Dr Ridd said different organisations were peer reviewed each others’ work, which meant that they were following the status quo.
He said that an independent organisations had to be tasked with scrutinising the science.