Sources of groundwater such as springs are
helping keep threatened species alive, by
providing a supply of good water.
Image: iStockphoto
Habitat change, decline in water quality and introduction of exotic fishes has had a major impact on the freshwater fish of the
South-West, according to Murdoch freshwater fish experts Drs David Morgan and Stephen Beatty.
The Centre for Fish and Fisheries Research researchers say extensive surveys in every river system in Western Australia’s South-West have shown major range reductions and loss of populations of the region’s unique freshwater fishes, a number being listed as endangered.
“Eighty per cent of our South-West species are only found here and play an important role in structuring aquatic ecosystems,” Dr Morgan said.
“The combination of habitat change, decline in water quality and introduction of exotic fishes has had a major impact on the distribution of species and led to a number being listed as endangered. “The other concern is recent work has shown genetic differences between populations so losing them results in the loss of important genetic information.” The research team surveyed more than 2000 sites in the South-West.
Dr Beatty said their findings had also shown fresh groundwater intrusions, such as spring-fed tributaries, were crucial in allowing remnant fish populations to exist.
“These areas of fresh groundwater intrusions in systems such as the Blackwood River effectively dilute the main channel and maintain permanent tributary habitats for threatened species, such as the Balston’s Pygmy Perch, and therefore it is very important to maintain this input – particularly in light of the predicted reduction in rainfall due to climatic change in the South-West,” Dr Beatty said.
“The surveys have mapped the introduction and colonisation of feral fishes such as goldfish and mosquitofish that are also having a massive impact on these fishes.
“In fact, our research has shown that there are now more species of exotic fishes than natives in these waterways, with a number of new species having being recently recorded.”
Editor's Note: Original article from Murdoch University's Explore Magazine.
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