Movement and habitat use of Australia's largest snake-necked turtle: implications for water management

Abstract

Hydrological regimes strongly influence ecological processes in river basins. Yet, the impacts of management regimes are unknown for many freshwater taxa in highly regulated rivers. We used radio-telemetry to monitor the movement and activity of broad-shelled river turtles Chelodina expansa to infer the impact of current water management practices on turtles in Australia's most regulated river - the Murray River. We radio-tracked C. expansa to (1) measure the range span and examine the effect of sex, size and habitat type on turtle movement, and (2) examine habitat use within the river channel and its associated backwaters. C. expansa occupied all macro habitats in the river (main channel, backwater, swamp and connecting inlets). Within these habitats, females occupied discrete home ranges, whereas males moved up to 25 km. The extensive movement of male turtles suggests that weirs and other aquatic barriers may interfere with movement and dispersal. Turtles regularly move between backwaters and the main river channel, which highlights the likely disturbance from backwater detachment, a water saving practice in the lower Murray River.