Lake Eyre Basin Rivers 58 Waterloo billabong on Noonbah Station). They were observed walking just in front of a flood on the floodplain of South Galway Station, near Windorah, far from the nearest permanent waterhole (Sandy Kidd, pers. comm.). The turtles probably know the landscape well, and use the floods to move between waterholes and floodplains where there is plentiful food. The food source then concentrates as the boom period ends and floodplains dry out and fish, crustaceans and insects concentrate in the waterholes where the only water remains. Cooper Creek turtles are giants of the turtle world in Australia (Fig. 5.1). They reach sizes up to 37 cm in shell length (White 2002). It could be that their size reflects these periods of considerable plenty, punctuating the relatively extensive periods of scarcity. Food resources are partitioned between maintaining essential body functions (cellular maintenance and sustenance), body growth and reproduction (Bowden et al. 2011). When food is limiting, turtles allocate their resources more tightly. For example, Emydura macquarii nigra on Fraser Island partition food resources for maintenance and growth until Fig. 5.3. Waterholes along Cooper Creek are deep and critically important aquatic habitat for turtles, which need to survive through prolonged dry periods. They form along the main channel during dry times. These waterholes are vulnerable to reductions in flows resulting from future water resource development (photo, R. T. Kingsford).