Over 80 per cent of freshwater rivers and estuaries have received ‘good’ or ‘very good’ grades in the latest Wet Tropics Report Card.
The news is also good for inshore coral with improvements in all zones, but offshore coral has declined substantially as the effects of mass bleaching events in 2016-17 and increasing crown-of-thorn starfish outbreaks take their toll.
Released today, the 2019 Wet Tropics Report Card assesses the health of nine river catchments from the Daintree to the Herbert. It is produced annually by the Wet Tropics Waterways partnership as an initiative of the Reef 2050 Plan, an Australian and Queensland Government framework for protecting and managing the Great Barrier Reef.
Wet Tropics Waterways Chair Steve Turton said relatively dry conditions for most of the July 2017 to June 2018 reporting period appeared to have mitigated the effect of wet season floods, despite the major flood event in March 2018.
“Heavy rain and floods are obviously associated with higher run-off of sediments and pollutants,’’ Professor Turton said. “Because we had relatively dry conditions for most of this reporting period - with below-average monthly rainfall for most of the wet season - the very high localised rainfall and flooding events in March didn’t have as negative an impact on grades as they might have.”
The report card analyses scientific monitoring data from many organisations and is reviewed by an independent scientific panel made up of individuals with a range of expertise.
Professor Turton said the overall health of inshore marine seagrass had improved. He said species composition in the North zone, off Cairns and Port Douglas, was back at levels not seen since Cyclone Yasi severely impacted the Wet Tropics region, mainly in the south, in early 2011. However he said no seagrass had been found in the monitoring areas of the Moresby estuary, near Innisfail, for the first time since monitoring began in 1993.
“There is little chance of recovery in the Moresby estuary without assisted restoration,’’ he said.
For the first time, this year’s Report Card includes a fish index in two freshwater basins and there are plans to roll this index out in other river basins over time. Professor Turton said fish diversity was ‘good’ or ‘very good’ at most sites in the Mulgrave and Russell basins.
“The assessment found 42 species of native fish and only four species of pest fish, which is great news,’’ he said. “The pest fish species found with naturalised populations were Mozambique Tilapia, Spotted Tilapia, Guppy and Swordtail.
“Pest fish are an emerging issue because they prey on native fish, compete for food and degrade the natural environment. Species like tilapia can displace native species and dominate a river’s ecosystem. We are urging fishers to learn to recognise tilapia and bury or bin them if they catch them.”
Wet Tropics Waterways will highlight some of the region’s key emerging issues at a waterway health forum in November.
“While there is a focus on reducing sediment, pesticide and nutrient runoff into waterways flowing to the Great Barrier Reef, it is also important to be aware of emerging issues,’’ Professor Turton said. “These include climate change, micro-plastics and PFAS, a harmful chemical used as a flame retardant in many industries.
“We want to get on the front foot so we are inviting a number of experts to Cairns in November to help lead community discussion on ways we can mitigate these risks to our waterways.”
Professor Turton congratulated more than 50 Wet Tropics Waterways partner organisations for working together to produce the 2019 Report Card.
He said ongoing community efforts also deserved recognition with this year’s report card highlighting the culling of more than 40,000 crown-of-thorn starfish and the uptake of Best Management Practice programs on 80 per cent of the region’s banana and cane land.