Tropical testing sharpened
A team of James Cook University researchers have been working on how to better use a revolutionary DNA technique in the tropics, so scientists can more effectively identify invasive, elusive and rare species.
JCU PhD candidate Madalyn Cooper led a study examining how the collection of environmental DNA (eDNA) differed under tropical conditions.
“It’s no exaggeration to say that eDNA sampling is a revolutionary technology, it’s completely opened up the field of biology and is a massive boost to those working in biodiversity conservation,” she said.
The technique involves taking a sample (usually filtering water from a stream, river or the sea) and analysing it for trace elements of the DNA shed by living creatures. Scientists are able to accurately tell, from a single sample, which fish live in a waterhole or which terrestrial animals have visited it.
“There are some special challenges to using eDNA analysis in the tropics and we wanted to explain what they were and suggest ways to overcome them,” said Ms Cooper.
She said tropical scientists faced logistic challenges in tropical and remote locations, including high heat, UV levels and humidity, high microbial activity, and the impacts of monsoonal events.
“All of this has a detrimental effect on the use of eDNA techniques. What we have done is lay the groundwork for how this might be overcome,” she said.
JCU researcher Dr Cecilia Villacorta Rath said there was still a place for traditional detection methods.
“The eDNA samples generally do not capture data for age, size, and reproductive status, so if we want this information we still need to use traditional visual assessment methods.”
Dr Villacorta Rath said one of the crucial uses of the technology was in combatting the spread of invasive species.
“Detection programs are only successful when detection is early. Environmental DNA is a great tool, but it has to be used properly. Early detection of invasive species still requires constant monitoring and rigorous surveillance over large areas,” she said.
Ms Cooper said biodiversity research and conservation management would be transformed in the tropics if eDNA methods and traditional biodiversity field studies were successfully blended.
Main recommendations of the research:
Improved understanding of how the complex set of environmental conditions unique to the tropics influence eDNA dispersal, degradation, and detection.
Concerted effort to expand sequence databases, not only by haphazard submission of sequences, but a targeted effort to increase sequencing information for tropical species.
Established best practice eDNA protocols appropriate for field work conducted under tropical conditions and subsequent laboratory methods that ensure the reliability of the obtained results.
Ms Madalyn Cooper
Dr Cecilia Villacorta Rath