Billabongs 'a biodiversity jungle'
The billabongs of the Murray-Darling Basin might be as rich in biodiversity as the waters of the Amazon jungles, according to a scientist with the Murray-Darling Freshwater Research Centre at Albury.
Dr Russell Shiel said his study of billabongs on the Murray River flood plain had found them to be teeming with life. The species in two neighbouring billabongs, sometimes only metres apart, were often utterly different.
The billabongs, filled by floodwaters every few years, could carry up to 1000 times more biodiversity than the river which flowed past them, Dr Shiel said. Flowing water provided few niches for species to live in, while still billabongs had a diverse range of areas for nesting, feeding and breeding.
"What we're finding is that billabongs might be absolutely crucial to the health of all the wildlife of the river", he said. "We think the billabongs act like genetic banks which help replenish the biology of the whole river system.
"They are natural storehouses of thousands of different species. When the river floods, these species spill out into the flood plain and breed in the shallow flood water, providing instant food for native fish.
"Many of the creatures and plants which live in billabongs can survive drying out. Soil taken from a dry billabong contains millions of eggs and other 'resting stages' of billabong species.
"How long these resting stages can survive without floods is not known, but it is certain that given enough time most of them will die. Over the past century we have dammed and regulated our rivers so much that now they don't flood nearly as often as they used to. The lack of floods is endangering this precious genetic 'seed bank'."
Dr Shiel said recent research into bottom sediments had found that individual billabongs could be 10,000 or more years old, and that they had been present on the Murray flood plain for hundreds of thousands, perhaps even millions, of years.
"There has been plenty of time for individual billabongs to evolve their own unique species", he said. "Every time people fill in, degrade or permanently drain a billabong Australia might be losing a priceless pool of unique creatures. We really have very little knowledge of what is there."