A commentary on 'Long-term ecological trends of flow-dependent ecosystems in a major regulated river basin', by Matthew J. Colloff, Peter Caley, Neil Saintilan, Carmel A. Pollino and Neville D. Crossman

Colloff et al. in Marine and Freshwater Research (http:dx.doi.org/10.1071/MF14067) examined time-seriesdata for flow-dependent vegetation, invertebrates, fish, frogs, reptiles and waterbirds in the Murray'Darling Basin,1905'2013. They concluded that temporal patterns fluctuated, declining during droughts and recovering after floods. Theysuggested that major changes in land use in the late 19th century permanently modified these freshwater ecosystems,irretrievably degrading them before major water diversions. Restoring water to the environment might then be interpretedas not addressing biotic declines. We argue that their conclusions are inadequately supported, although data qualityremains patchy and they neglected the influence of hydrology and the timing and extent of water resource development.We are critical of the lack of adequate model specification and the omission of statistical power analyses. We show thatdeclines of native flow-dependent flora and fauna have continued through the 20th and early 21st centuries, in response tomultiple factors, including long-term changes in flow regimes. We argue that flow-regime changes have been critical, butnot in isolation. So, returning water to the environment is a prerequisite for sustained recovery but governments need toimprove monitoring and analyses to adequately determine effectiveness of management of the rivers and wetlands of theMurray'Darling Basin.