Shark Bay, inscribed as a World Heritage in 1981,
is located in western Australia. The site comprises a
marine segment and a coastal segment and numerous
groups of islands. It has one of the largest banks of sea
grass in the world and a large population of sea cows.
Shark Bay is also one of the few marine areas in the
world dominated by carbonates not associated with
reef-building corals. The property has marine parks,
marine nature reserves, terrestrial nature reserves,
public land and pastoral land. The site is a meeting point
of three major climatic regions.
Shark Bay is home to a large number of endemic plant and animal species. The diversity of the avifauna, marine fauna, amphibians and reptiles of the site is amazing. The region has a very effective management plan. The human disturbance, including disturbance from recreational activities, continues to be a threat, although the numbers of visitors are still low, and this threat is appropriately managed. Climate change remains the major threat, with extreme weather events being a threat to the value of the heritage site. Risks posed by climate change and invasive species require special consideration.
Management practices adopted by the Australian Government in coordination with the indigenous people have been effective in the conservation and management of the site.
Shark Bay is located in the most westerly part
of Australia on the Indian Ocean coast (250 29' 10" S,
1130 26' 10" E). It has an extent of 2,200,902 ha. It was
inscribed as a World Heritage Site in 1981. The coastline
of the Shark Bay World Heritage Site is more than 1500
km long (Department of Environment of Australia,
2006). Marine waters with a number of exceptional
natural features make up 70% of the area. The site is
a large, divided, semi-enclosed bay behind a chain of
barrier islands (UNEP/WCMC, 2008). The three major
features of the site are its vast sea-grass beds, dugong
("sea cow") population and stromatolites (colonies of
algae that form hard dome-shaped deposits and are
among the oldest forms of life on Earth).
The property is a meeting point of three major climatic regions. The climate is semiarid to arid and is characterized by hot, dry summers and mild winters. The annual precipitation range is 200 mm to 400 mm, whereas the annual evaporation ranges between 2000 mm and 3000 mm. Shark Bay has been the home to aboriginal people for more than 40,000 years (Playford et al. 2013).
The presence of a steep gradient in salinity is one of the exceptional features of Shark Bay. This has a marked effect on the distribution and abundance of marine organisms and has created three biotic zones. Shark Bay is among the few marine areas in the world that are dominated by carbonates not associated with reefbuilding corals (UNESCO whc.unesco.org).
Because of the long isolation of its islands and the peninsular ecosystem, Shark Bay has great botanical and zoological importance. The flora of the region is adapted to the semi-arid and arid environment. Of the 26 species of endangered Australian mammal, five are found on Bernier and Dorre Islands. These are the boodie, or burrowing bettong, rufous hare wallaby, banded hare wallaby, Shark Bay mouse and the western barred bandicoot (Department of Environment of Australia 2006).
More than 4000 km2
of the marine area is dominated
by the sea-grass beds. Shark Bay is known for its living
fossil microbial communities, present mainly in Hamelin
Pool. The property is home to 26 species of threatened
Australian mammal and has a diverse marine fauna,
including 10,000 dugongs (almost 12% of the total world
population). The migratory humpback whale visits the
marine part of the park. The herpetofauna of Shark
Bay comprises around 100 species. Three hundred and
twenty-three fish species and over 80 coral species are
found in the park (Advisory body IUCN).
Vast stretches of sea grass are the main feature of the marine flora. These, the largest and richest seagrass beds, extend over an area of 4800 km2 and have contributed to the evolution of Shark Bay (UNESCO WHC 2016). Twelve species of sea grass are found in this region.
One of the superlative natural phenomena present
in this property is its stromatolites, which represent the
oldest form of life on Earth and are comparable to living
fossils. Shark Bay isalso one of the few marine areas in
the world dominated by carbonates not associated with
reef-building corals. This has led to the development of
the Wooramel Seagrass Bank within Shark Bay, one of
the largest seagrass meadows in the world with the most
seagrass species recorded from one area. These values are
supplemented by marine fauna such as dugong, dolphins,
sharks, rays, turtles and fish, which occur in great
numbers.
The hydrologic structure of Shark Bay, altered by the formation of the Faure Sill and a high evaporation, has produced a basin where marine waters are hypersaline (almost twice that of seawater) and contributed to extensive beaches consisting entirely of shells. The profusion of peninsulas, islands and bays create a diversity of landscapes and exceptional coastal scenery.
Shark Bay contains, in the hypersaline Hamelin Pool, the most diverse and abundant examples of stromatolites (hard, dome-shaped structures formed by microbial mats) in the world. Analogous structures dominated marine ecosystems on Earth for more than 3,000 million years. The stromatolites of Hamelin Pool were the first modern, living examples to be recognised that have a morphological diversity and abundance comparable to those that inhabited Proterozoic seas. As such, they are one of the world's best examples of a living analogue for the study of the nature and evolution of the earth's biosphere up until the early Cambrian. The Wooramel Seagrass Bank is also of great geological interest due to the extensive deposit of limestone sands associated with the bank, formed by the precipitation of calcium carbonate from hypersaline waters.
Shark Bay provides outstanding examples of processes of biological and geomorphic evolution taking place in a largely unmodified environment. These include the evolution of the Bay's hydrological system, the hypersaline environment of Hamelin Pool and the biological processes of ongoing speciation, succession and the creation of refugia.
One of the exceptional features of Shark Bay is the steep gradient in salinities, creating three biotic zones that have a marked effect on the distribution and abundance of marine organisms. Hypersaline conditions in Hamelin Pool have led to the development of a number of significant geological and biological features including the 'living fossil' stromatolites.
The unusual features of Shark Bay have also created
the Wooramel Seagrass Bank. Covering 103,000 ha, it is
the largest structure of its type in the world. Seagrasses
are aquatic flowering plants that form meadows in nearshore brackish or marine waters in temperate and tropical
regions, producing one of the world's most productive
aquatic ecosystems. Australia has one of the highest
diversity of seagrasses globally, with 12 species occurring
in the Bay
Shark Bay is a refuge for many globally threatened species of plants and animals. The property is located at the transition zone between two of Western Australia's main botanical provinces, the arid Eremaean, dominated by Acacia species and the temperate South West, dominated by Eucalyptus species, and thus contains a mixture of two biotas, many at the limit of their southern or northern range. The property contains either the only or major populations of five globally threatened mammals, including the Burrowing Bettong (now classified as Near Threatened), Rufous Hare Wallaby, Banded Hare Wallaby, the Shark Bay Mouse and the Western Barred Bandicoot. A number of globally threatened plant and reptile species also occur in the terrestrial part of the property.
Shark Bay's sheltered coves and lush seagrass beds are a haven for marine species, including Green Turtle and Loggerhead Turtle (both Endangered, and the property provides one of Australia's most important nesting areas for this second species). Shark Bay is one of the world's most significant and secure strongholds for the protection of Dugong, with a population of around 11,000. Increasing numbers of Humpback Whales and Southern Right Whales use Shark Bay as a migratory staging post, and a famous population of Bottlenose Dolphin lives in the Bay. Large numbers of sharks and rays are readily observed, including the Manta Ray which is now considered globally threatened.
The Australian Government agency that is responsible for the management of the property is the Department of Biodiversity, Conservation. The site's advisory committee is the body that provides conservation- and management-related advice to the State and Commonwealth governments. The Australian Government and the Western Australian Government have entered into an agreement to manage as per Australia's obligations under the World Heritage Convention.
According to the IUCN World Heritage Outlook Report 2020, the conservation outlook of the site assessed "Good with some concerns". The site does not face significant threats arising from outside the boundary due to the inaccessibility and appropriateness of its boundaries (Claudino 2018). The impacts of human activities include trampling of sensitive environments, hardening of shorelines and 4WD traffic over soft sediments (IUCN world heritage outlook 2020). Potential threats such as fires (Cowell 2013) and the introduction of invasive species might affect the biodiversity of the park severely, and so proper monitoring and management are needed (Fourqurean et al. 2012).
Climate change is the major threat to the region, and it is expected to intensify in the future. Climate change can impact the complex ecosystems of the site. The region might suffer from severe impacts of climate change such as desertification and acidification, considering its semi-arid conditions.
The rising sea level can cause more erosion of the coastline. The ecological characteristics of the environment change as the hypersaline environment can increase the amount of salt. The State of the Conservation Report, 2000 recognizes that there are some potential threats in the property such as the production of salt and prospecting for and extraction of mineral and petroleum resources, which will eventually impact the values of the park. Invasive alien species pose a serious threat in the region. The pressure arising due to the fishing has been effectively managed. The sea grasses, found in abundance in this region, are extremely vulnerable to climate change. Once lost, they can regenerate only very slowly. Sea grasses hold the largest stock of organic carbon stock and their preservation becomes crucial in the global context (Arias et al. 2018).
