Reef Report for Friday, April 5, 2019
Control of Sediment Inputs to the Reef Creates Controversy
It’s been a very wet summer here in Queensland, with some parts of our coast receiving almost 3 meters of rain over the past few months. The good news is that the wind and clouds that come with our rainy weather have kept water temperatures low, so no significant episodes of coral bleaching have been noticed.
With all that rain there’s been erosion, and the resulting silt being transported through the catchment and into the ocean beside the Great Barrier Reef by the many rivers that we have hear. In most years, when there is less rain the sediment plumes do not extend out all the way to the reef, and the sediment settles onto the ocean bottom without reaching the reef itself. This year many rivers reached flood stages, with flows large enough to push these sediments onto the reef itself, with negative results such as stimulating algal growth, inhibits the colonization of empty spaces by coral larvae, and other impacts.
Farms and grazing properties are implicated in the measurable increase in sediment loads, as well as other measures of water quality in rivers. Overgrazing, ag chemical use, poor erosion control on farms and land clearing all have roles in lowering water quality in the rivers that drain into the Great Barrier Reef lagoon.
Recently the Queensland Government has proposed stricter regulations over land clearing and agricultural practices. The increase in land clearing rates in the Great Barrier Reef catchment over the past six years is a problem that needs to be addressed.
While conservation groups commend these efforts, farmers and graziers are not supportive of these proposed regulations, consider them burdensome and would prefer an industry sponsored incentive-based self-regulatory system.
We’ve followed the pro and con arguments for some time now. Our thoughts lie with protecting the reef in the most effective way possible, and therefore advocate increased thoughtful regulation aimed at reducing runoff from agricultural and grazing properties, and for that matter, urban areas as well.
Self-regulated incentive based best management programs for sugar cane farms have been in place for an number of years now, and while there are lots of success stories, as far as we can tell less than 25% of the 4,000 sugar cane farming operations in Queensland have adopted these practices, and the measurements of water quality in the annual Great Barrier Reef report card have not shown improvements in overall water quality that meet the annual goals set by the program.
Oddly enough, the agricultural sector does make a good point when it comes to inconsistencies in regulation of sediments on the reef, especially with regulations of the mining sector. Just this year the Great Barrier Reef Marine Park approved of the plan to dispose of millions of metric tons of sediments being dredged from a mining port, and current state regulations, while they admirably prohibit ocean disposal of dredging spoils from new ports, allow it for maintenance dredging of existing ports.
Some additional reading for you:
The most recent (2016) Great Barrier Reef Report card.
From the Brisbane Times: Threat of sediment runoff to Great Barrier Reef worse than thought.
From The Australian Broadcast Corporation: Why is land clearing bad news for the Great Barrier Reef?
From Beef Central: Reef law anger as consultation sidetracked.
From SBS News: Dumping sludge in Great Barrier Reef Marine Park given go ahead.
From The Weekly Times: Water quality outcomes with cane program.
From Smartcane: Natural Systems Management case study
The weekly reef report is written by Joel Groberg of DiveTheReef.com,
who compiles them from the many conversations he has with dive staff in the area, as well as many other local sources in the dive
Index of all reef reports.