Genetic variation vital to saving Australia’s wetland fish

The DNA of freshwater fish in the Murray-Darling Basin has given scientists clues to which species may have natural resilience against potential climate change in one of Australia’s most ecologically and economically important wetland habitats.

The golden perch, also known as yellowbelly, has been identified by Flinders University ecologists as being “genetically wired” to cope with environmental change due to the harshness and unpredictability of its native habitat.

“In many cases, the rate of environmental damage to our wetland ecosystems is exceeding evolution, however we now believe that those fish populations like the golden perch that already occupy extreme habitats have a high resilience to environmental change due to their DNA make-up,” says Dr Catherine Attard, Lecturer in Molecular Ecology at Flinders University.

“By analysing the genetic variation of golden perch populations in the Murray-Darling Basin, we have indeed been able to show that environmental variability is a driving force in genetic diversity and natural selection and may help future-proof the species in an increasingly human-modified world.”

Dr Attard said the golden perch’s ability to traverse thousands of kilometres and brood in different habitats enabled it to distribute its genetic diversity.

In contrast, the research team has shown the threatened southern pygmy perch was less likely to cope with change.

“We have seen that the southern pygmy perch and many other small native fish in the Murray-Darling are incapable of moving long distances,” said Dr Attard.

“Their populations have become fragmented and so, even if they were genetically resilient to environmental change, their diversity cannot currently spread to newly-altered habitats.”

The Murray-Darling Basin is home to 46 species of native fish that have been reduced to 10 per cent of their pre-colonisation population levels due to the loss and degradation of habitat.

Australia’s Native Fish Strategy for the Murray-Darling Basin aims to rehabilitate native fish communities back to 60 per cent of their pre-colonisation levels by 2050.

“Given that climate change is expected to increase aridity across our river systems and further alter native habitats, there has never been a better time to study the genetic resilience of our native species and use this information to fortify our aquatic wilderness,” Dr Attard said.

“We can now help pinpoint which species are particularly threatened by climate change and enact conservation strategies to save them, such as translocation or captive breeding followed by reintroduction to favourable habitats”.

The Molecular Ecology Lab at Flinders University, led by Professor Luciano Beheregaray, is undertaking research on other fish species to examine their susceptibility to environmental change.