Advances in the study of River Murray ecology and the legacy of Keith Forbes Walker (1946−2016)

Keith Forbes Walker (1946–2016). Photo: Jan Walker

The rivers of the Murray-Darling Basin are central to the lives of many in south-eastern Australia, through provision of water for human consumption and agriculture, through ecosystem services and by providing enormous recreational and cultural capital. The development of the River Murray as a water resource has fundamentally altered the integrity of the river’s aquatic and floodplain ecosystems. Many researchers, conservationists, managers, and policymakers have devoted their careers to a better understanding of the ecology of this river system, with the ultimate aim of rehabilitating it. A central character in River Murray ecological research was Keith Forbes Walker.

Keith was born in Aberdeen, Scotland, on 20 June 1946. In 1951, his family emigrated to Australia and lived in Melbourne. Keith completed a Bachelor of Science (Honours) at Monash University and then continued on to a PhD at Monash where his supervisor (and mentor) was WD (Bill) Williams, a pioneer in Australian limnology. After completing his PhD, he undertook Post-Doctoral studies at the University of Washington with the famous limnologist Tommy Edmundson who developed our understanding of lake eutrophication, and more importantly how to manage it. Keith returned to Australia to take up a postdoctoral position with Professor Ralph Slatyer at the Australian National University (ANU). While at ANU, Keith took part in the first ecological review of the River Murray at Albury-Wodonga with a small group of scientists who later formed the Murray-Darling Freshwater Research Centre and thus began his more than 40 years of work on the Murray. Keith continued his association with the Centre which facilitated his students and himself gaining a “whole of river” perspective from their research base in Adelaide.

In 1975, Bill Williams became Professor of Zoology at The University of Adelaide and Keith was his first appointment. Keith was an outstanding teacher and taught subjects in freshwater ecology, invertebrate biology and statistical methods. In 1986, he designed and presented Research Methods in Environmental Biology, which was based in statistics but importantly introduced students to the scientific method, the process of logical thinking, careful writing and a belief that ideas needed to be proven and developed quantitatively. These are all hallmarks of Keith’s way of science. Keith ran and developed this course until his retirement in 2007. In 1992, Keith was one of the inaugural winners of the University’s Stephen Cole the Elder Prize for Excellence in Teaching.

From his arrival at the University of Adelaide, Keith’s research focussed on the ecology of floodplain rivers, especially the River Murray. Much of his research was undertaken with the nearly 200 research students he supervised who worked on topics covering hydrology and hydraulics, geomorphology, weir pool impacts, aquatic and riparian/floodplain plants, molluscs, biofilms, trophodynamics, and fish ecology. Keith had a lifelong impact on his students, many of whom have gone on to make significant contributions of their own to aquatic ecology and management. The number of Keith’s past students who have held (and are holding) influential positions in managing water resources is noteworthy and they carry on his passion for scientific rigour in this area. Keith also worked extensively with colleagues in botany, geomorphology, hydrology and engineering. From these collaborations and those with his research students, Keith’s research provided significant advances in our knowledge of Australia’s rivers and their floodplains, their ecological communities and the ways they were affected by water abstraction and flow regulation. Low flows lead to loss of connectivity between the river and its floodplain, limiting exchange of resources between them and stranding floodplain vegetation. Keith provided an understanding of the striking ecological and physical changes to the lower River Murray caused by a series of low level weirs. These transformed a lotic lowland floodplain river into a series of heavily regulated weir pools. These weir pools have stable water levels above them and highly variable water levels below them. This leads to significant changes in the riverine, littoral and floodplain environments. Keith and his students and colleagues showed that large and rapid variation in managed water levels impacted the life histories of littoral plants with falls exposing submersed plants to desiccation and rising water limiting colonisation depth. It also changed biofilm communities which Keith and his students showed were an essential part of the Lower Murray food web. The changed habitats and trophodynamics in the river led to displacement and local extinction of some species and invasion of the channel by wetland species. Alien species have thrived in the changed environment.

Keith’s research and scholarship led him to become indisputably Australia’s most well-regarded expert on the River Murray. His expertise is captured in 37 book chapters, more than 100 refereed journal publications and a further 40 refereed reports and conference proceedings. He received the Australian Society for Limnology Medal for excellence in freshwater research in 1993 and Keith and Paul Humphries were awarded the Whitley Medal of the Royal Zoological Society (NSW) for the best book on Australian fauna in 2013 for the book “Ecology of Australian Freshwater Fishes”. Keith was editor of the Transactions of the Royal Society of South Australia from 2001 to 2002. Keith also had a vision for bringing together the fast-developing literature on the large rivers of the world. Along with Geoff Petts and others, in 1986, Keith formed a new journal focussed on research and management of large rivers, Regulated Rivers: Research and Management, later changed to River Research and Applications. This has become a world leading journal on river research. Keith was the founding co-editor and Editor for the Asia Pacific region and remained on the Editorial Board for the rest of his life. As well as his research on ecological change, Keith retained a love for the natural history and the plants and animals of the River Murray, Murrundi the native river. This was captured by his insatiable interest in freshwater mussels, another topic in which he was an internationally respected expert. Keith published his first monograph on the freshwater mussels of the system (see “Bibliography”), supported by an Australian Water Resources Council grant and his further work resulted in considerable clarification of the taxonomy and life history of the group. Keith also wrote and spoke extensively for community-based organisations, whether it was on the management of the River Murray or some aspect of natural history. He was recognised through the Unsung Hero of South Australian Science Award received from the Australian Science Communicators in 2000.

Keith was also a wise voice in river and environmental management, sitting on many advisory panels including MDBA/MDBC panels from 1986. He was a member of the “Sustainable River Audit” and other Expert Panels that published many key reports for the Murray Darling Basin Commission. As a member of the Environmental Water Advisory Board, Keith made key contributions to the recently developed Murray Darling Basin Plan that now provides increased environmental water to the Murray. In his committee roles, Keith rarely seemed to have the loudest voice in the room, but such was his influence that when he did speak everyone listened.

Keith passed away suddenly and unexpectedly in February 2016 at 69 years, far too young. He had immeasurably more love to give his wife Jan, children Jenny and Craig and his six grandchildren, and much more knowledge to contribute to the understanding and management of rivers in Australia. Since his retirement in 2007, Keith had been an Adjunct Associate Professor in the School of Biological Sciences and kept up a frantic pace of consultancies and publication.

In this special issue of the Transactions of the Royal Society of South Australia, we present a number of new articles concerning the ecology and geomorphology of the River Murray. These have been authored by Keith’s former students and colleagues, providing exemplars of his intellectual legacy. The articles cover a breadth of Keith’s research interests, including the hydrology and hydraulics of the River Murray, geomorphology, aquatic and terrestrial vegetation, fish communities and ecology. It is hoped that this compilation is useful for those with an interest in the River Murray and forms a fitting tribute to the legacy of Keith Forbes Walker.