A Very Special Fish %u2013 Australian Lungfish under Threat

A Very Special Fish %u2013 Australian Lungfish under Threat

The Queensland Government%u2019s surprise decision (5 July 2006) to proceed with a very large dam on the Mary River threatens the survival of one of the most scientifically important animals on earth. Throughout most of its length for most of the year, the Mary is nothing more than a small, meandering coastal creek but it is uniquely important as habitat for several of the country%u2019s endangered species.  One of these is the Australian or Queensland lungfish, a %u2018living fossil%u2019 that has existed unchanged since the time of the dinosaurs. Of all living fish groups, the lungfish are the closest relatives of the land vertebrates %u2013 the amphibians, reptiles, birds and mammals, including ourselves. Lungfish were abundant 400 million years ago, during the Devonian (the %u201CAge of Fish%u201D) but have now dwindled to only three kinds, respectively living in South America, Africa and Australia. The South American and African forms are weirdly modified larval-looking creatures, but the Australian lungfish is still very similar to those ancient fish that gave rise to the first land vertebrates. It is thus uniquely important to scientists studying the origin of land animals.  

Fossils show that the Australian lungfish was alive as it is today already during the Cretaceous, alongside the dinosaurs.  This probably makes it the oldest living vertebrate species. At that time it was much more widespread than it is today.  Now it only occurs naturally in the Mary and Burnett rivers in SE Queensland.  Introductions into other rivers in the past have largely been unsuccessful, with the exception of the Brisbane River, but this population of lungfish is only just hanging on due to extensive damming of the river to provide water for greater Brisbane. Australian lungfish have an absolute requirement for shallow, slow-flowing, densely vegetated riffles as spawning and nursery habitat.  These environmental features are characteristic of both the Burnett and the Mary but it is exactly these features that are lost entirely by permanent flooding resulting from the construction of dam walls. Dams thus pose a mortal threat to the long-term survival of the lungfish populations.

A mega dam was completed late 2005 on the Burnett River.  When it is full, it will have permanently destroyed 42 km of lungfish spawning/nursery grounds.  Prior to construction of this dam the lungfish were listed as vulnerable on the Federal Environment Protection and Biodiversity Conservation Act.  With the destruction of their spawning/nursery habitat on the Burnett and now even greater destruction on the Mary, should this dam go ahead, that listing would need to be revised to %u2018critically endangered%u2019. The dam can still be stopped by the Federal Minister for Environment and Heritage, but he needs to be persuaded to act.

The significance of the Australian lungfish cannot be overstated.  As a %u2018living fossil%u2019 it provides the only opportunity to study the development and physiology of the aquatic predecessors of all land vertebrates, including ourselves.  Australia is the custodian of this invaluable information source for the rest of the world.  The answer to Queensland%u2019s water problem lies in education on water use and smart new technologies, not in damming a fragile coastal river system and willfully extinguishing a uniquely important animal.