¹1School of Biological, Earth and Environmental Sciences, University of New South Wales, Australia 2052
²Conservation and Research Department, Zoological Parks and Gardens Board, Parkville, Victoria, Australia 3052 and Department of Zoology, University of Melbourne, Parkville, Victoria, Australia 3001

^*Corresponding author, Tom R. Grant, School of Biological, Earth and Environmental Sciences, University of New South Wales, Australia 2052, fax 61-2-9527-2862, email t.grant@unsw.edu.au

Abstract

  The platypus (Ornithorhynchus anatinus) is an Australian icon. It is an integral part of the biodiversity of many eastern Australian freshwater ecosystems and is protected by legislation in all States in which it occurs. Its conservation is of considerable importance not only because of its unique features, status and niche but also because it is the only living representative of a significant lineage of platypus-like animals with a 60 million year fossil history. As a result of its specific habitat requirements it is affected by many of the widely recognised threatening processes operating in Australian limnological systems. In spite of these threatening processes, the species has continued to inhabit and reproduce in considerably degraded environments. The present overall distribution of the platypus appears to be little different from pre-European times. There are, however, now almost certainly no naturally occurring populations in South Australia, where it once occurred, and its distribution has apparently shrunk in the lower reaches of the Murray and Murrumbidgee River systems in Victoria and New South Wales. Despite being considered common throughout its current distribution its abundance is not readily measured and therefore its future conservation status is not easily predicted. Several studies have reported fragmentation of platypus distribution within individual river systems. This has been attributed to poor land management practices associated with stream bank erosion, loss of riparian vegetation and channel sedimentation. There is currently also evidence for adverse effects of river regulation and impoundments, introduced species, poor water quality, fisheries by-catch mortality and disease on platypus populations, but none of these has been well studied. Investigations of these aspects of the species' biology and interaction with human activities are research priorities, while management priorities include the development and implementation of strategies aimed at reducing the effects of these human activities on the platypus and its habitat.