One of the two remaining natural populations of the Australian lungfish (Neoceratodus forsteri) is under threat from a proposed dam, according to a paper to be published in the journal Environmental Biology of Fishes by Angela Arthington.
Natural populations of the Australian lungfish are restricted to the Burnett and the adjacent Mary river drainages in southeast Queensland, Australia (although other populations of lungfishes exist in Australia, these are the results of translocations), and the species is considered Vulnerable under Australian legislation.
The proposed Traveston Crossing Dam on the free-flowing main channel of the upper Mary River could seriously threaten the lungfish, according to the author. Construction of the dam is thought to adversely impact the lungfish population in several ways:
1. Loss of habitat " Adult lungfishes typically inhabit stream and river reaches with overhanging riparian vegetation along the banks, woody debris in the water and dense macrophyte beds.
The construction of the dam would not only inundate the preferred main channel and tributary habitat for lungfish but will also spill out of the main channel to flood surrounding low lying terrain.
2. Loss of spawning sites " Previous studies have shown that lungfish prefer to spawn in areas with intermediate flow velocities, low turbidity, a broad range of temperatures, high dissolved oxygen levels, depths of 40"60 cm and moderate to high densities of aquatic macrophytes 16"35 cm in height. The inundation of the river channels caused by the dam would wipe out many such areas.
3. Reduced juvenile recruitment " "Dense beds and banks of vegetation provide suitable microhabitat for developing lungfish embryos and newly hatched lungfish, where they feed on small invertebrates such as microcrustaceans, molluscs and worms.
Impoundments with steep profiles and fluctuating water levels typically do not provide suitable nursery habitat and food resources for very young fish and juveniles (