European settlement in Australia has always been concentrated along or close to the coast. As a consequence, saltmarshes, mangroves and other coastal marshes have experienced a long history of modification and destruction. Depletion statistics are available for many coastal marshes in the Northern Hemisphere and, in Australia, for parts of New South Wales and Queensland. There are no equivalent state-wide data for Victoria.

Using a suite of historical information, including extensive use of early surveyors’ maps, In this collaborative project staff from Victoria University of Technology and other institutions we aimed to provide a consistent view of the change in the extent of coastal marshes since European colonization in Victoria (i.e. the mid-19th century). Notwithstanding the difficulties of interpretation, we estimated that prior to European colonisation Victoria supported approximately 346–421 km2 of coastal marsh, of which approximately 80–95% remains. Although a simplistic interpretation suggests a net loss of 5–20% in wetland area over this time period, it is clear that some parts of the coast have experienced relatively little change since the mid 19th century whereas others have been severely depleted and, in a few sectors, there may have been an expansion of coastal marsh.

The situation with the Gippsland Lakes is complex. According to the method used to interpret the original data sources there has either been a substantial increase or a loss of up to 35% in wetland area around Lake Wellington. The largest absolute losses have probably been of EVC 140 Mangrove Shrubland and of coastal saltmarsh dominated by Tecticornia spp. Parts of the coast where significant losses have occurred include the Lonsdale Lakes, western shore of Port Phillip Bay, Anderson Inlet, Shallow Inlet, Powlett / Kilcunda, Corner Inlet and Nooramunga, and possibly Lake Wellington. With the exception of the Lonsdale Lakes, all these areas are situated along the Gippsland coast.

Changes to coastal marshes have not stopped and are unlikely to cease in the near future. The destruction of coastal marshes for industrial development remains an ongoing threat in many regions (e.g. in Western Port) and is likely to be compounded by climate change and, in particular, sea-level rise.  Further details of the results of this project can be found in this publication.