Abrupt historical change in the nature of a Ramsar Wetland: Seaford Swamp, greater Melbourne, Australia

Peter A. Gell; Emmy Frost; Cameron Gell; Rebekah Kurpiel

doi:10.1071/MF25095

RESEARCH ARTICLE (Open Access)

Previous Contents Vol 76(12)

Abrupt historical change in the nature of a Ramsar Wetland: Seaford Swamp, greater Melbourne, Australia

Peter A. Gell

^A ^B ^C ^* , Emmy Frost

^D , Cameron Gell ^A and Rebekah Kurpiel

^D

+ Author Affiliations

- Author Affiliations

^A Diatoma, 7 Gear Avenue, Mount Helen, Vic., Australia.

^B Cluster for Paleolimnology, Diponegoro University, Semarang, Indonesia.

^C Future Regions Research Centre, Federation University, Mount Helen, Vic., Australia.

^D Department of Archaeology and History, LaTrobe University, Bundoora, Vic., Australia.

^* Correspondence to: p.gell@federation.edu.au

Handling Editor: Michelle Casanova

Marine and Freshwater Research 76, MF25095 https://doi.org/10.1071/MF25095

Submitted: 29 April 2025 Accepted: 25 July 2025 Published: 21 August 2025

© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Context

Seaford Swamp is a back-of-dune wetland on the eastern side of Port Phillip Bay in greater urban Melbourne. It is a fresh marsh dominated by the reed Phragmites australis that is expanding into open water.

Aims

Three sediment cores were collected to determine the ecological history of the wetland.

Methods

The cores were analysed for diatoms and pollen and dated using ¹⁴C and ²¹⁰Pb.

Key results

The longest core showed an abrupt change from marine–brackish to saline and ultimately the present fresh condition. Saltmarsh declined and was replaced by reed, sedge and rush species. Cores from the centre and south of the wetland showed a similar history, albeit more variable in the south, yet still reflecting a sustained change from marine–estuarine conditions to fresh–brackish. The 7000-year record showed considerable stability despite known climatic and sea-level changes.

Conclusion

The abrupt change in condition appeared to correspond with hydrological engineering of the site from 1870 for agricultural and urban development. Increased catchment runoff, including from urban areas, are likely to have sustained the freshwater state.

Implications

The marine–estuarine state represents an alternate condition of the swamp that may broaden options for management under future sea-level rise.

Keywords: diatoms, palaeoenvironmental reconstruction, Phragmites australis, Ramsar Wetland, saltmarsh, Seaford Swamp, urban runoff, wetland change.

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