Measuring, mapping and modelling: an integrated approach to the management of mangrove and saltmarsh in the Minnamurra River estuary, southeast Australia

Mangrove and saltmarsh ecosystems appear particularly vulnerable to the impacts of climate change, and their effective management will require forecasts of how these wetland habitats are likely to respond to sea-level rise through the twenty-first century. We describe a preliminary study of a small stand of mangrove and saltmarsh that involves measuring of elevation change and accretion, mapping of wetland communities, and modelling of their potential response to sea-level rise. The wetland occurs on the banks of the Minnamurra River estuary in southern New South Wales and has been the focus of several studies over recent decades. The research includes empirical measurements of sedimentation at sites in both mangrove and saltmarsh vegetation using the surface elevation table-marker horizon technique. This is a site at which mapping has been undertaken to delineate the extent of each vegetation community from a time-series of aerial photographs using geographical information systems; the gradual incursion of the mangrove, Avicennia marina, into more landward saltmarsh communities, observed over past decades for many systems in southeastern Australia, has continued into the twenty-first century. The observed patterns of change are compared with simulations of how this wetland system might respond to future sea-level rise, adopting several different approaches and the upper and lower bounds of Intergovernmental Panel on Climate Change sea-level rise projections. The model results show considerable variability in response depending on the parameters adopted. We advocate the need for the integration of these three approaches, measuring, mapping and modelling, as a basis for future management and adaptation. Our study demonstrates the considerable opportunities to refine the data input and model outputs as part of adaptive management, as more sophisticated technologies and data become available.