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Scientists are calling it a revolution in biology. Environmental DNA, or eDNA, is changing how we monitor waterways and rare or invasive species. It’s also opening up new areas of research.
Most people aren’t thinking about the skin cells, mucous and faeces of fish when they look at a creek or ocean. But it has become the norm for a group of researchers and citizen scientists taking eDNA samples across the Wet Tropics to find out more about fish populations and water quality.
eDNA is a new go-to for scientists. It’s being used to detect the pest fish tilapia, to monitor elusive and critically endangered largetooth sawfish, to find coral-destroying crown-of-thorns starfish at larvae stage and to assess whether polluted waterways are becoming healthier.
Scientific advances have made eDNA sampling much easier. In the Wet Tropics, CSIRO is partnering with Terrain NRM to trial a new method of sampling, using fine filter papers, to see its potential for citizen science projects and to better understand the impacts of pesticides, nutrients and sediment on freshwater and estuarine ecosystems.
Mamu Indigenous rangers, volunteers from the Cairns and Far North Environment Centre and Terrain NRM and Wet Tropics Waterways scientists are sampling at three different spots in each of the Mossman, Barron, Johnstone and Tully River catchments.
Volunteer Stacey Buchanan says the project has been an eye-opener.
“It’s a hands-on project that our kids are loving too. We’re sampling at the same location over 18 months. I’ve grown up in Redlynch and we swim in Freshwater Creek all the time. It’s great to be helping with research looking at the effects of water quality on fish species.”
CSIRO researcher Sharon Hook says eDNA is an emerging science.
“When animals are in a habitat, they normally shed some DNA. By sampling it, we can quickly and accurately determine the number of species using an area. And with newly developed devices we can sample in more places more often.
“It’s more about the presence of species than populations because we are working with variability – from different animals shedding at different rates to their sizes and the persistence of DNA. But that’s still a huge advancement. North Queensland can be a difficult place for field work with its terrain, crocodiles and the big difference between wet and dry seasons. eDNA sampling can give us answers much more quickly and safely.”
Aquatic ecologist and Wet Tropics Waterways executive officer James Donaldson says eDNA sampling could be particularly useful in estuarine areas.
“As the interface between fresh and saltwater, estuaries are the breeding and nursery habitat for many fish species. It’s hard to monitor fish communities in tropical estuaries because we often can’t use traditional sampling methods like nets and snorkelling because of crocodiles, or electrofishing because of the high conductivity of sea water, or cameras because of poor water clarity. The impact of eDNA, for this knowledge gap, is potentially massive.”
Starfish seekers
eDNA sampling is helping to reduce crown of thorns starfish outbreaks. Scientists at the Australian Institute of Marine Science can now detect the larvae of these starfish in small seawater samples. An adult crown-of-thorns starfish can eat a dinner plate-sized chunk of coral every day, so the sooner outbreaks are detected the better.
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James joined Wet Tropics Waterways as Executive Officer in 2021 and is passionate about working with stakeholders to communicate the value of our unique waterways. His role involves facilitating and coordinating our partnership program, growing our network and investment into the report card program, and science communication. James oversaw the 2022 Innovations in Waterway Health Forum, and hosted season four of the Reef and Rivers podcast.
James is an ecologist and has previously worked on wetland management in the Murray Darling basin, fish passage in Mackay, and aquatic research in the Wet Tropics.
Outside of work you’ll find him in a local waterway with a mask and snorkel, or hiking or biking around our beautiful region.
Richard has been the Science Technical Officer for Wet Tropics Waterways since 2016. His role involves producing the annual results for the waterway health assessment of the wet tropics region using data from a wide range of sources, to present as scores and grades, as well as developing new indicators to address knowledge and monitoring gaps. He works in collaboration with technical staff at other regional report cards.
Richard has a background in freshwater ecology research projects and environmental assessments with CSIRO, University of Queensland, Queensland Government and as a consultant. For a long time he’s been interested in freshwater aquaculture and continues this interest through farming freshwater crayfish, alongside other farming activities.
Greg is a career Aquatic Scientist who has worked extensively on waterways and waterway health across eastern Australia for almost 30 years, including estuarine and marine environments. He’s been living in the Wet Tropics Region since 2017 and continues to work as a consulting scientist on a range of projects for multiple clients.
Greg returns to Wet Tropics Waterways as Independent Chair, having previously managed the partnership from 2018-2021, and was involved with three report card launches, and overseeing the inaugural Urban Water Stewardship Framework implementation and the inaugural Wet Tropics Waterways forum.
Outside of his profession Greg enjoys a range of recreational pursuits that involve exploring the rivers, estuaries and coastal zones of the Wet Tropics.