The buildings and structures that make up Australia's historic heritage were built up to 100 years ago. At the time of their construction, they were built to last only a few years (e.g. Mawson's Huts at Commonwealth Bay). It was never anticipated that they would still be standing a century later and considered a valuable part of Australia's Antarctic heritage.
The building materials are vulnerable to deterioration and the greatest threat to the integrity of the buildings and structures lies in the natural elements. Wind, weather, frost, ice and melt water all contribute to the deterioration of buildings. Corrosion, fungal growth, wind and snow loads, exposure to ultraviolet radiation, the freeze-thaw cycle and high relative humidity inside the main hut affect the conservation of structures and artefacts.182 An artefacts conservation program was instigated in 2008.214-216
The illegal removal of artefacts is also a concern. All visitors require permits if they intend to visit the island; however, the region's remoteness-which has protected its natural values-also makes it extremely difficult to control unauthorised access. For example, fishers on illegal fishing vessels operating in the area may visit and remove artefacts.
On the subantarctic islands, the maritime climate promotes corrosion of metal artefacts. Wooden items are abraded by windborne sand and salt particles. Disturbance by wildlife, land erosion and slippage is also a potential problem,186,217-218 as is erosion and exposure of artefacts. Cultural heritage on the islands may also be damaged by volcanic and seismic activities. Seismic activity has been identified as a specific threat to structures on Macquarie Island, although most of the research expedition buildings have been built to withstand tremors.182
Heard Island is a long way from Australia and caring for the components of historic heritage on the island is an enormous challenge. The cultural heritage of Heard Island is conserved through a process of managed decay. This is a pragmatic management option, which acknowledges the practical impossibility of conserving all elements of the cultural environment in a remote area where access is extremely limited.182,217 Permitted visits are highly infrequent and tend to be restricted to the short summer. The management plan states that heritage values, such as buildings, are and have been in a greatly deteriorated state for a long time and are permitted to disintegrate under the influences of weather and climate. There are several sealers' graves in the south-eastern part of the island, not far from a large king penguin colony. The vegetation cover is dense and continues to engulf and cover the old graves.
A specific risk to Heard Island is the changing coastline. For example, wooden oil barrels that were left by sealers at Oil Barrel Point have disappeared steadily over the past few decades as the barrels have eroded out of the beach cliff.219 Fewer than a quarter of those recorded in the 1980s are still in place.