Tibby, J.Marshall, J.C.Lobegeiger, J.S.Amos, K.J.Pickering, G.Myburgh, T.Unmack, P.2023-08-212023-08-212023Marine and Freshwater Research, 2023; 74(12):1050-10701323-16501448-6059https://hdl.handle.net/2440/139219Context: In arid and semi-arid river systems, waterholes are often the only refugia for aquatic organisms during no-flow spells. Sediment accumulation in waterholes reduces their persistence. Aims: To assess this threat, we surveyed the depth of, and dated, waterhole sediments from John Tibby Geography, Environment and Population, the Moonie River, a northern tributary of Australia’s largest river system, the Murray–Darling Basin. Methods: Fine-sediment depth was determined in three of the deepest waterholes in Australia 2010 and 2011 before, and after, the largest flood in over a century. The rate of sediment build up in two waterholes was also determined. Key results: In the deepest sections (>75th percentile depth), there was between 0.7 and 2 m of fine sediment in 2010. Following flooding, sediment depth reduced by 24–54%, with the largest proportional reductions in sediment occurring in the shallowest waterhole. However, net sediment accumulation is still 1.4–2.0 cm year–1 since the 1950s. Conclusions: Sedimentation has reduced the persistence of the deepest waterholes by over 200 days, representing an up to 30% reduction. During the longest droughts known in the Moonie River, this would dry many otherwise permanent waterholes. Implications: Sedimentation is a marked threat to waterhole persistence even following large floods.en© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution Non Commercial-No Derivatives 4.0 International License (CC BY-NC-ND).catchment management; climate change; ecology; erosion; floodplains; limnology; Murray–Darling Basin; sediment processes; sedimentationJournal article10.1071/MF230162023-08-21651281Tibby, J. [0000-0002-5897-2932]Amos, K.J. [0000-0003-0306-7588]