Marine and Freshwater Research Marine and Freshwater Research Society
Advances in the aquatic sciences

Response of estuarine wetlands to reinstatement of tidal flows

Alice J. Howe A , José F. Rodríguez A D , Jennifer Spencer B , Geoff R. MacFarlane C and Neil Saintilan B

A School of Engineering, University of Newcastle, Callaghan, NSW 2308, Australia.

B NSW Department of Environment, Climate Change and Water, Sydney South, NSW 1232, Australia.

C School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia.

D Corresponding author. Email:

Marine and Freshwater Research 61(6) 702-713
Submitted: 8 July 2009  Accepted: 15 December 2009   Published: 25 June 2010


The importance of estuarine wetlands to ecosystem services such as primary productivity and flood attenuation, as well as their function as habitat for threatened species has prompted efforts to restore tidal flows to degraded wetlands. We tracked the response of estuarine vegetation to tidal-flow reinstatement over 12 years (1995–2007) in a wetland of the Hunter estuary, Australia. This site provides important habitat for migratory shorebird species, which favour shallow tidal pools and saltmarsh over mangrove forest. Increased tidal flows following culvert removal reduced shorebird roost habitat by 17% because of mangrove encroachment on saltmarsh and shallow tidal pools. Saltmarsh occurred in areas with a spring tidal range <0.3 m, hydroperiod <1.0 and elevation >0.4 above the Australian height datum (mAHD), whereas mangrove occupied areas with spring tidal range >0.3 m, hydroperiod <0.45 and elevation <0.4 mAHD. By using these parameters, it is possible to exclude mangrove from saltmarsh areas and to establish saltmarsh at lower elevations in the tidal frame than would occur under natural conditions, effectively expanding saltmarsh area. These measures can be useful where landward migration of estuarine communities is restricted by infrastructure; however, they should not be considered a substitute for conservation of remnant saltmarsh or establishment of landward buffer zones.

Additional keywords: Hunter estuary, mangrove, migratory shorebirds, saltmarsh, south-eastern Australia, wetland rehabilitation.


The authors gratefully acknowledge the support of the Australian Research Council through Grant LP0348539, the University of Newcastle, the Australian Catholic University, Hunter–Central Rivers Catchment Management Authority’s Kooragang Wetland Rehabilitation Project, Energy Australia and the Hunter Bird Observers Club. NSW Fisheries (No. P04/0057) and NSW National Parks and Wildlife Service (No. 11263/11265) permits were obtained to conduct the research. Tracey MacDonald and Richard Kingsford kindly gave permission for reproduction of data to generate Figs 5 and 8, respectively. Comments from Dr Scott Johnston and two anonymous referees improved the manuscript substantially, and are also gratefully acknowledged.


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