Effects of Water Level Fluctuations on Spawning Habitat of an Endangered Species, the Australian Lungfish (Neoceratodus Forsteri)

Abstract

AbstractThe Australian lungfish Neoceratodus forsteri is an endangered native fish species currently protected under federal and international agreements. The impoundment of riverine habitats by water storages has substantially decreased the availability of dense beds of macrophyte (e.g. Vallisneria nana) in shallow water, the preferred spawning habitat of Australian lungfish. Storage management, such as storage drawdown and maintaining storages at specific levels, may impede establishment and development of dense macrophyte beds, although the effects of storage operation on macrophytes are poorly understood. Storage bathymetry and modelled stream data were used to examine the impact of water level changes (frequency and magnitude) on V. nana habitat within storages and associated riverine areas. Three storages located within the natural range of the Australian lungfish in the Burnett River (Ben Anderson Barrage, Ned Churchward Weir and Paradise Dam) were found to provide limited potential for V. nana habitat when at the full supply level. Furthermore, water storages within the distribution of Australian lungfish fluctuate by ±1 m more frequently in comparison to associated riverine environments. These frequent water level fluctuations challenge the establishment of dense macrophyte beds required for lungfish spawning. Since aquatic macrophytes and streamflow play an integral role in lungfish spawning, management of water storages should focus on releases to the downstream reaches. These releases should mimic natural flow and water temperature regimes to allow establishment and growth of V. nana beds in synchrony with the timing of Australian lungfish spawning. Riverine reaches downstream of storages have the greatest potential for restoration of macrophyte beds. © 2014 Queensland Government, Department of Natural Resources and Mines. River Research and Applications © 2014 John Wiley & Sons, Ltd.