Inscribed as a World Heritage Site in the year
1997, the Heard and McDonald Islands are volcanic
islands located in the Southern Ocean, in western
Australia. These islands are approximately 1700 km from
Antarctica and cover a total area of 658,903 hectares.
Heard Island recorded the last volcanic activity in the
1980s and the McDonald Islands in the 1990s. Heard
Island is dominated by snow and glaciers. Both these
islands are dominated by large volcanic mountains.
The islands are low in species diversity. Due to their
geographical remoteness, the number of visitors here is
very low, and hence the islands do not face any threats
caused by anthropogenic activities and non-native alien
species. Climate change serves as the major threat to
the site. It is responsible for the retreat of the glaciers,
increasing the chances for the invasive species to thrive.
The Heard and McDonald Islands are located
in the Southern Ocean, 4100 km southwest of Perth,
western Australia, and approximately 1700 km from
Antarctica. These islands are home to Australia's only
active volcanoes. The site covers a total area of 658,903
hectares of which about 37,000 hectares is terrestrial.
The McDonald Islands are located 43 km west of Heard
Island. The last volcanic activity occurred during the mid1980s in Heard Island and in the 1990s in the McDonald
Islands. The size of the McDonald Islands doubled with
an increase in elevation by about 100 m, due to the
volcanic activity. These volcanic islands 'open a window
into the earth', and provide an opportunity to observe
ongoing geomorphic processes and glacial dynamics
(whc.unesco.org).
The islands are a typical example of a sub-Antarctic island group with low species diversity but with huge populations of certain species (Dasett 1990). These islands has pristine ecosystems in the world, with complete absence of alien animal and vegetal species and with minimal impact from human activities. The site provides a crucial habitat for large populations of marine birds and mammals. The ongoing evolutionary process is demonstrated by the endemic species in the region.
According to Woehler et al. (1982), the seabird and seal communities on the islands account for a total of 27,893 tons of biomass, of which 70% is attributable to 15 breeding species of seabirds. The site is an important habitat for a number of resident breeding and transitory populations of seabirds, seals and the distributionrestricted black-faced sheathbill (IUCN World Heritage Outlook Report 2020.
The overall biodiversity of Heard Island is contributed mostly by non-vascular plants: there are 62 recorded species of bryophytes and 71 recorded species of lichen. It is a significant site for the study of plant colonization due to the isolation of plant communities combined with the increasing growth of habitat resulting from glacial retreat (Ryan and Scott 2004).
The islands contain outstanding examples of
significant on-going geological processes occurring in an
essentially undisturbed environment, particularly physical
processes which provide an understanding of the role
of crustal plates in the formation of ocean basins and
continents, and of atmospheric and oceanic warming.
The islands are distinctive among oceanic islands in being
founded upon a major submarine plateau which in this
case deflects Antarctic circumpolar waters northwards,
with striking consequences for geomorphological
processes. They also offer an active example of plume
volcanism, providing direct geological evidence of the
action of the longest operational plume system known
in the world. This includes information about plume
interaction with overlying crustal plates, as well as insights
into mantle plume composition due to the widest range of
isotopic compositions of strontium, neodymium, lead and
helium known from any oceanic island volcano system. Big
Ben on Heard Island is the only known continuously active
volcano on a sub-Antarctic island, whereas the volcano
on MacDonald Island recently became active again after a
75,000 year period of dormancy, increasing significantly
in size since inscription. Heard Island’s relatively shallow
and fast-flowing glaciers respond quickly to climate
change, faster than any glaciers elsewhere, making them
particularly important in monitoring climate change.
They have fluctuated dramatically in recent decades and
have retreated significantly
Heard Island and McDonald Islands are outstanding examples representing significant on-going ecological, biological, and evolutionary processes. As the only subAntarctic islands virtually free of introduced species and with negligible modification by humans, they are a classic example of a sub-Antarctic island group with large populations of marine birds and mammals numbering in the millions, but low species diversity. These intact ecosystems provide opportunities for ecological research investigating population dynamics and interactions of plant and animal species, as well as monitoring the health and stability of the larger southern oceans ecosystem. Areas of newly deglaciated land as well as areas isolated from each other by glaciers provide unparalleled opportunities for the study of the dispersal and establishment of plants and animals. The islands also furnish crucial, alien-free habitat for large populations of marine birds and mammals, including major breeding populations of seals, petrels, albatrosses and penguins. Endemic species demonstrating ongoing evolutionary processes include the Heard Island cormorant, the endemic subspecies of the Heard Island sheathbill, and a number of endemic invertebrates (some endemic to Heard and McDonald Islands, and some endemic to the Heard and McDonald Islands-Kerguelen region).
The property is managed as a strict nature reserve
by the Australian Antarctic Division through Australian
Government's Heard Island and McDonald Islands
Marine Reserve Management Plan primarily for scientific
research and environmental monitoring (whc.unesco.
org). Strict measures have been incorporated by the
management authorities to minimize the introduction
of non-native species in order to conserve the native
species of plants and animals and also prevent the
adverse impacts of waste and pollution (McIvor 2007).
According to the IUCN World Heritage Outlook Report
(2020), climate change is the biggest threat in the area
resulting in the colonization by the flora and fauna (IUCN
World Heritage Outlook Report 2020; Bergstrom et al.
2015) and also in ocean acidification (Kawaguchi et al.
2013).
It is responsible for the accelerating retreat of glaciers, causing the alien grass species Poa annua to displace the native vegetation in deglaciated regions on Heard Island. Visitors serve as the major factor responsible for bringing the alien species to the islands (IUCN Consultation 2020). Poa annua is expanding at an alarming rate leading to competition among the native vegetation, thus causing a disturbance in the ecosystem (Meyere et al. 2000). If visits to this site occur without proper biosecurity measures, it might have serious environmental consequences (IUCN Consultation 2020).
Threats like accumulation of solid waste in the marine area cause deterioration in the conditions of the marine life. Issues like wildlife entanglement, ingestion of plastic by the marine animals and oiling of seabirds are harming the whole ecosystem (Auman et al. 2014). Plastics and microplastics have been found in the Southern Ocean and are regularly washed up on the Heard Island beaches.
The extreme geographical remoteness of the site limits the Australian Government's ability to undertake regular onsite management operations. The site has no native or permanent residents, and hence it faces no threats due to significant anthropogenic activities in the region (IUCN Consultation 2020). The threat of fishing is low, but there are chances of some illegal and unregulated fishing within the foraging range of albatrosses, penguins, petrels etc. (Crawford et al. 2017).
