Identifying Major Stressors: The Essential Precursor to Restoring Cultural Ecosystem Services in a Degraded Estuary Jenny Davis & Ian M. Kidd Received: 13 November 2011 / Revised: 5 March 2012 / Accepted: 16 March 2012 / Published online: 3 April 2012 # Coastal and Estuarine Research Federation 2012 Abstract Worldwide estuaries have been subject to multiple and escalating anthropogenic impacts which have resulted in the loss of many ecosystem goods and services including: commercial activities, navigation and marine transportation, recreational and landscape values, and flood control and biodi- versity support. An example of these losses is provided in an urban-industrial region of an estuary in northern Tasmania, Australia, where excessive silt deposition has resulted in almost complete loss of the channel at low tide. The causes of siltation have long been attributed to poor watershed management and high concentrations of flocculated and suspended sediments transported upstream by asymmetrical tides. However, histori- cal analysis of anthropogenic changes in estuarine and riverine processes revealed different stressors. These included the de- crease in the tidal prism and hence regime equilibrium, brought about by channel infilling and draining of tidal wetlands to create dry land for urban and agricultural uses, and the reduc- tion and redirection of freshwater inflows for the generation of hydroelectricity. Watershed sediment loads exerted a relatively minor role in the estuarine equilibrium, which is solely depen- dent on tidal flows and river discharges for maintenance of stable cross-sectional areas. Sustainable remediation measures include increasing the tidal prism through the restoration of dynamic river flows and reconnection and restoration of tidal wetlands. However, the former will not be achievable without changes in major provisioning services, particularly the use of water to generate hydroelectricity. This study emphasises the importance of identifying stressors as the basis for examining the potential to reduce the trade-offs between the multiple ecosystem services provided by an estuary and its tributaries, particularly between provisioning and cultural ecosystem serv- ices, within a rehabilitation context. Keywords Tidal prism . Dynamic flow regime . Tidal wetlands . Hydroelectricity Introduction Globally, estuaries are not only focal areas for much human activity but also represent the most anthropogenically degraded habitats on earth, being subject to multiple and escalating impacts (Baird 2005; Lotze et al. 2006). In Australia, as elsewhere, estuaries were the principal sites of European set- tlement due to multiple benefits, including the ease of shipping access, availability of freshwater and presence of productive alluvial lands for agriculture (Edgar et al. 2000). The Tamar River estuary, in northern Tasmania (Fig. 1), was one of the earliest sites of European settlement in Australia, with initial settlement in the lower reaches at Yorktown in 1804, followed by establishment further upstream of the nation’ s third town, Launceston, in 1806, which now supports a regional popula- tion of 90,000 (Launceston City Council 2011). A management plan was developed in 2000 in recognition of the considerable pressure placed on the natural values of the estuary through intensive use and development within the watershed (NRM North 2011). Continuing community con- cern about the poor state of the Tamar River estuary and Esk Rivers resulted in the establishment of a Tasmanian parliamen- tary committee to investigate the issues, particularly sedimen- tation and flooding. It recommended the establishment of a J. Davis (*) School of Biological Sciences, Monash University, Clayton, Victoria, Australia 3800 e-mail: Jenny.Davis@monash.edu I. M. Kidd Aquatic Ecosystems Research Group, 14 Wyett Street, West Launceston, Tasmania, Australia 7250 Estuaries and Coasts (2012) 35:1007–1017 DOI 10.1007/s12237-012-9498-7