Deakin University Research Fellow Dr Jake Martin, based at the Marine Science and Innovation Centre in Queenscliff, is a co-author on a major new study showing that pharmaceutical pollution can disrupt the river-to-sea migration of Atlantic salmon.
Led by the Swedish University of Agricultural Sciences (SLU) and published in Science, the study is the largest of its kind to investigate how commonly detected medications - such as those used for anxiety or pain relief - alter fish behaviour in real ecosystems.
Dr Martin was a key researcher on the international team while based at SLU.
Now at Deakin, he plans to continue this critical work, investing how freshwater and marine wildlife are impacted by pharmaceutical contaminants in Australia.
'I plan to continue this research by investigating how animals interact with these drugs in their environment and adjust their movement patterns,' Dr Martin said.
'We're particularly interested in how these drugs influence the way animals use space, and whether certain behavioural or physiological traits make some individuals or species more vulnerable.
Understanding these patterns, can help us better predict which populations or ecosystems are most at risk.'
The original study used acoustic telemetry and newly developed slow-release implants to track how juvenile Atlantic salmon (Salmo salar) in Sweden's River Dal responded to exposure to clobazam, a medication used to treat sleep disorders, and tramadol, an opioid painkiller.
Researchers found that fish exposed to clobazam were more likely to reach the sea and passed through two hydropower dams more quickly than unexposed fish. Additional lab work suggested the drug may alter social behaviours and risk-taking, which could have broader implications for survival in the wild.
'Pharmaceutical pollution is an emerging and underestimated threat to wildlife and ecosystems,' said Dr Jack Brand, lead author of the study. 'This is one of the first real-world studies to show how these substances can impact key behaviours like migration.'
'While previous studies have shown that pharmaceuticals can alter wildlife behaviour, most of this research has taken place in controlled laboratory settings,' Dr Martin added.
'These conditions can't fully capture the complex; real-world interactions animals face in the wild.
By using acoustic telemetry, we were able to glimpse the hidden lives of fish-tracking their movements and behaviours as they embarked on their remarkable migration from river to sea.'
Atlantic salmon are ecologically, culturally and economically significant, but populations across parts of Europe are now listed as endangered by the IUCN. Migration is a critical life stage for salmon, and the study raises concerns that environmental pharmaceuticals may pose a previously overlooked threat to their survival.
The research team notes that pharmaceutical residues are now commonly detected in rivers and lakes on every continent -including Antarctica - and that standard wastewater treatment systems often fail to remove them entirely.
Dr Martin is also a co-author on a recent Deakin-led publication, alongside Professor Timothy Clark and Associate Professor Damien Callahan, examining how pharmaceutical contaminants affect animal physiology and behaviour in more naturalistic settings (Deakin publication).
'I'm excited to build on these findings and develop new approaches to understanding how pharmaceuticals affect native Australian species and ecosystems,' he said.
The researchers advocate for investment in improved wastewater treatment, as well as green chemistry innovations-designing drugs that degrade more readily in the environment-to limit long-term ecological harm (Nature Sustainability article).
Photo credit: Jorgen Wiklund
