Kelleway, J., Williams. R.J. and Allen, C.B., 2007. An assessment of the saltmarsh of the Parramatta River and Sydney Harbour. Final report to NSW Maritime Authority. NSW DPI – Fisheries Final Report Series No. 90. 100pp.

Summary

Coastal saltmarshes occur along the intertidal shore lines of estuaries and are vegetated by herbs, grasses, rushes and small shrubs. These plants provide habitat for a range of animals, including fish and crustaceans of commercial and recreational importance. Because of its rarity, coastal saltmarsh is listed in NSW as an ‘Endangered Ecological Community’ under the Threatened Species Conservation Act 1995.

The first map of the cover of saltmarsh along the estuarine foreshore of the Parramatta River was produced in the early 1980s from aerial photographs, and a map prepared in the early 2000s suggested there had been little change in distribution, with a total area of about nine hectares. However, anecdotal reports indicated that there may be many more small patches of saltmarsh than could be defined with aerial photography.

For this study, aerial photography was supplemented by a pedestrian survey to locate saltmarsh on the foreshore of the estuary, including Sydney Harbour, Middle Harbour, Lane Cove River and Duck River. Over 750 patches were found, having a combined area of 37 ha. The location, species composition and condition of each patch were recorded. Large-scale maps were prepared to represent locations where saltmarsh occurs, and electronic imagery is available for fine-scale analysis by stakeholders.

The distribution of saltmarsh is uneven, with most patches located in the upper and middle portions of the estuary. Some species of saltmarsh occur only rarely and these, as well as some exotic species, are also restricted in their distribution to the upper estuary. The majority of patches of saltmarsh were considered to be in a poor condition.

The threats facing these saltmarshes, including incursion by mangroves, rise of sea-level, unauthorised access, weed invasion and pollution and dumping are considered. It is clear that without fine-scale assessments there is no way of knowing if subtle changes have occurred in distribution and abundance of saltmarsh, or which natural and/or human influences might be implicated in bringing change about.

Management considerations arising from this study are: the need to protect saltmarsh within conservation reserves, the need to conserve species considered by their rarity to be “sensitive”, as well as the need to remove the invasive species Juncus acutus. It is important that future planning for the estuary and foreshore of the Parramatta River and Sydney Harbour minimises the threats to, and protects the conservation value of, saltmarsh.