WILD ISLAND
Swamped with new life Fringed on the north, east and south by swamps, Straddie is home to one of the world’s premier wetlands, the 18 Mile Swamp. he 18 Mile Swamp is a great trough in the sand, lying seaward of the huge dunes of the Island’s main sand mass. Teeming with life, it is full of fresh water that seeps from the sand dunes, rather than from surface run off. A recognised RAMSAR site (the RAMSAR Convention on Wetlands of International Importance) 18 Mile Swamp is the longest wetland of its type in the world. This year it was finally given the highest form of regulatory protection available in Queensland, when it was declared part of the Naree Budjong Djara national park, to be jointly managed by Minjerribah’s traditional owners, the Quandamooka people, and the state. Extending from about 3.5 km south of
PHOTO: FOSI
T
increase in tea-tree and weeds, instead of reeds, in the southern and mid sections of the swamp. This could be caused by an increase in salt-water coming from Swan Bay, due to a slight increase in sea levels, or due to water beng extracted for drinking water and mining purposes. Within the swamp is Freshwater Creek, which is surprisingly deep where it meets seawater from the mangrove and palm swamp at the edge of Swan Bay, in the south. At the northern end are the Keyholes, clear freshwater lakes, delightful for canoeing, but now closed to the public as they are too close to the Yarraman mine and, therefore, in a prohibited mining area. The swamp is also said to contain a mystery shipwreck, described by Fred Campbell of Amity in a manuscript he handed to his-
In the late 50s, the sand mining company worked a lease covering the sand dunes on the beach. A high moving aerial ropeway, with moving hoppers, led from the beach directly across the swamp to the present sand-loading facility. Steel towers to support the pulleys were erected across the Island, including three in the swamp. Remains of these may still exist. Part of the swamp was dredged and cleared to allow access for a small motorised barge. Since 1988 the Centre for Coastal Management at the Southern Cross University has been conducting ongoing monitoring of 18 Mile Swamp for the Redland City Council. New species of invertebrates and other forms of life, not found on the mainland, have been discovered. Some life forms depend entirely on the existence of freshwater. There is insufficient information on the hydrology of 18 Mile Swamp or much of Straddie’s groundwater systems. It has not yet been determined how either groundwater extrac-
18 Mile Swamp – longest wetland of its type in the world. Point Lookout to Swan Bay, north of Jumpinpin, the swamp looks inviting from afar. Closer contact, however, reveals an environment that is challenging to humans. Mosquitoes are abundant, especially at night, in spite of fish that feed on their larvae. Disease, inherent in the anaerobic (without oxygen) bacteria that sit in the peat atop the swamp, is another deterrent to human visitors. Although it was formed about 6,500 years ago, 18 Mile Swamp is the most recent formation on the Island. And it remains relatively untouched. The peat below the swamp’s surface mat of tea-tree, reeds, gahnia (a tall razor-sharp grass) and ferns, is about 10-metres deep, consisting of four metres of fibrous peat over six metres of gellike, embryonic coal. Approximately 8,000 years ago, the sea level in this area was up to seven metres below present levels. In the past 60 years there has been a noticeable
SPRING 2011
torian Tom Welsby, before his death in 1898. Campbell positioned the wreck a few miles miles north of Swan Bay, well into the swamp. All fire-blackened remains visible above water level have disappeared since 1954. Descriptions of the ship say it was heavily built, oak-framed, sheathed in Muntz metal and containing copper and iron bolts and rivets. It has been described as 30 yards long, aligned as a beeline north south with the bow facing north. Fred Campbell learned about the wreck from the tribal elders of Moongalba and Amity and wrote that the first white men the Aborigines had ever seen were former convicts, Pamphlett and Finnegan, credited with leading explorer John Oxley to the Brisbane River. History suggests that the mystery ship was abandoned at sea by its crew and may have washed ashore onto the beach to await an intense cyclonic storm or tsunami to carry it into the swamp.
tion, or the potential subsequent saltwater intrusion, will affect the swamp ecosystem or the quality of the water in the surrounding connected ecosystems and the Island’s aquifer itself. With deep dredge mining continuing close by at Enterprise Mine, 18 Mile Swamp could still experience negative effects of mining. The risks of water extraction are also ongoing. The precautionary principle should come into play in the care of this new national park. The declaration of the 18 Mile Swamp as national park brings public attention to its natural values and puts the onus on all to tread lightly on this delicate wetland. — By Duncan McPhee and Angela McLeod, with thanks to Kathy Townsend and Emma Lewis from the UQ Marine Research Station for providing background information. This is an edited version of an article that first appeared in the FOSI newsletter.
10 YEARS OF LIVING IN SIN — STRADDIE ISLAND NEWS 11