| UNESCO World Heritage Site | |
|---|---|
 Shark Bay | |
| Location | Gascoyne region,Western Australia, Australia |
| Criteria | Natural: vii, viii, ix, x |
| Reference | 578 |
| Inscription | 1991 (15thSession) |
| Area | 2,200,902 ha (5,438,550 acres) |
| Coordinates | 25°30′S113°30′E / 25.500°S 113.500°E /-25.500; 113.500 |
  Location of Shark Bay at the most westerly point of the Australian continent | |
Shark Bay (Malgana:Gathaagudu,lit. 'two waters') is aWorld Heritage Site in theGascoyne region ofWestern Australia. The 23,000-square-kilometre (8,900 sq mi)[1] area is located approximately 800 kilometres (500 mi) north ofPerth, on the westernmost point of the Australian continent.
UNESCO's listing of Shark Bay as a World Heritage Site reads:[2]
Shark Bay's waters, islands and peninsulas....have a number of exceptional natural features, including one of the largest and most diverseseagrass beds in the world. However, it is for itsstromatolites (colonies of microbial mats that form hard, dome-shaped deposits which are said to be the oldest life forms on earth), that the property is most renowned. The property is also famous for its rich marine life including a large population ofdugongs, and provides a refuge for a number of other globally threatened species.
The bay features Australia's most abundantmarine ecosystems.[3] It is a popularfishing spot.
The record ofAustralian Aboriginal occupation of Shark Bay extends to 22,000 yearsBP. At that time most of the area was dry land, and rising sea levels flooded Shark Bay between 8,000 BP and 6,000 BP. A considerable number of Aboriginalmidden sites have been found, especially on Peron Peninsula and Dirk Hartog Island, which provide evidence of some of the foods gathered from the waters and nearby land areas.[2]
An expedition led byDirk Hartog happened upon the area in 1616, becoming the second group ofEuropeans known to have visited Australia, after the crew ofDuyfken underWillem Janszoon had visitedCape York in 1606. The area was given the name Shark Bay by the English explorerWilliam Dampier,[4] on 7 August 1699.[5] Shark Bay was also visited byLouis Aleno de St Aloüarn in 1772,Nicolas Baudin from 1801 to 1803 andLouis de Freycinet in 1818.[6] Europeans, mostly pastoralists, settled in Shark Bay during the 1860s to 1870s.[6]Pearling developed rapidly from 1870.[6]
Commercial whaling was conducted in the bay in the first half of the 20th century byNorwegian-ownedfactory ships and their catcher vessels.[7] In the late 1930s, up to 1,000humpback whales were taken per season.
The heritage-listed area had a population of fewer than 1,000 people as at the2011 census. The half-dozen small communities making up this population occupy less than 1% of the total area.
The Shark Bay Heritage Area has ahot desert climate under theKöppen Climate Classification, with hot, dry summers, and very mild, relatively wet winters.[8]
| Climate data forShark Bay Airport (25º53'S, 113º35'E, 34 m AMSL) (2004-2020 normals and extremes) | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °C (°F) | 47.3 (117.1) | 49.8 (121.6) | 47.2 (117.0) | 39.9 (103.8) | 37.0 (98.6) | 30.7 (87.3) | 30.3 (86.5) | 35.6 (96.1) | 36.7 (98.1) | 42.8 (109.0) | 44.8 (112.6) | 46.2 (115.2) | 49.8 (121.6) |
| Mean daily maximum °C (°F) | 34.1 (93.4) | 34.9 (94.8) | 34.2 (93.6) | 31.0 (87.8) | 27.5 (81.5) | 23.8 (74.8) | 22.9 (73.2) | 24.2 (75.6) | 26.1 (79.0) | 28.4 (83.1) | 30.4 (86.7) | 32.5 (90.5) | 29.2 (84.5) |
| Mean daily minimum °C (°F) | 21.6 (70.9) | 22.3 (72.1) | 21.4 (70.5) | 18.3 (64.9) | 14.5 (58.1) | 11.7 (53.1) | 10.6 (51.1) | 11.2 (52.2) | 12.8 (55.0) | 15.4 (59.7) | 17.7 (63.9) | 19.8 (67.6) | 16.4 (61.6) |
| Record low °C (°F) | 16.3 (61.3) | 16.5 (61.7) | 13.8 (56.8) | 10.0 (50.0) | 4.5 (40.1) | 3.7 (38.7) | 2.8 (37.0) | 5.0 (41.0) | 6.2 (43.2) | 7.6 (45.7) | 10.3 (50.5) | 13.2 (55.8) | 2.8 (37.0) |
| Averageprecipitation mm (inches) | 6.7 (0.26) | 24.5 (0.96) | 16.3 (0.64) | 10.3 (0.41) | 23.1 (0.91) | 42.3 (1.67) | 28.6 (1.13) | 19.3 (0.76) | 8.1 (0.32) | 4.6 (0.18) | 2.1 (0.08) | 7.1 (0.28) | 193 (7.6) |
| Average precipitation days(≥ 1.0 mm) | 0.7 | 1.2 | 0.9 | 1.1 | 2.8 | 4.3 | 4.1 | 3.1 | 2.0 | 1.2 | 0.5 | 0.3 | 22.2 |
| Averagerelative humidity (%) | 43 | 43 | 38 | 41 | 40 | 42 | 43 | 39 | 40 | 41 | 41 | 41 | 41 |
| Averagedew point °C (°F) | 16.7 (62.1) | 17.4 (63.3) | 14.6 (58.3) | 13.1 (55.6) | 10.1 (50.2) | 8.1 (46.6) | 7.7 (45.9) | 6.9 (44.4) | 8.3 (46.9) | 10.4 (50.7) | 12.3 (54.1) | 14.1 (57.4) | 11.6 (53.0) |
| Source:Bureau of Meteorology[9] | |||||||||||||
The World Heritage status of the region was created and negotiated in 1991,[10] the first such site in Western Australia.[6] The site wasgazetted on theAustralian National Heritage List on 21 May 2007[1] under theEnvironment and Heritage Legislation Amendment Act (No. 1), 2003.[11]
Declared as a World Heritage Site in 1991, the site covers an area of 23,000 square kilometres (8,900 sq mi), of which about 70 per cent are marine waters. It includes many protected areas and conservation reserves, includingShark Bay Marine Park,Francois Peron National Park,Hamelin Pool Marine Nature Reserve,Zuytdorp Nature Reserve and numerous protected islands.[2]Denham andUseless Loop both fall within the boundary of the site, yet are specifically excluded from it.
The bay itself covers an area of 1,300,000 hectares (3,200,000 acres), with an average depth of 9 metres (30 ft).[2] It is divided by shallow banks and has many peninsulas and islands. The coastline is over 1,500 kilometres (930 mi) long. There are about 300 kilometres (190 mi) oflimestone cliffs overlooking the bay.[12] One spectacular segment of cliffs is known as theZuytdorp Cliffs. The bay is located in the transition zone between three major climatic regions and between two majorbotanical provinces.
Peron Peninsula divides the bay and is the home of its largest settlements as well as aNational Park at the northern end.
Dirk Hartog Island is of historical significance due to landings upon it by early explorers. In 1616, Dirk Hartog landed at Inscription Point on the north end of the island and marked his discovery with apewter plate, inscribed with the date and nailed to a post. This plate was then replaced by Willem de Vlamingh and returned to the Netherlands. It is now kept in theRijksmuseum. The Shark Bay Discovery Centre in Denham has a replica of this plate.
Bernier andDorre islands in the north-west corner of the heritage area are among the last-remaining habitats of two varieties of Australian mammals,hare-wallabies, threatened with extinction.[13] They are used, with numerous other smaller islands throughout the marine park, to release threatened species that are being bred at Project Eden in François Peron National Park. These islands are free of feral non-native animals which might predate upon the threatened species, and so provide a safe haven in which to restore species that are threatened on the mainland.
In 1999 theAustralian Wildlife Conservancy acquired the 5,816-hectare (14,370-acre)pastoral lease overFaure Island, offMonkey Mia.Sea turtles nest there seasonally and are the subject of studies conducted in conjunction with theDepartment of Biodiversity, Conservation and Attractions.[14]
Shark Bay is an area of major zoological importance. It is home to about 10,000dugongs ('sea cows'), around 12.5% of the world's population,[12] and there are manyIndo-Pacific bottlenose dolphins, particularly at Monkey Mia. The dolphins here have been particularly friendly since the 1960s.[12] The area supports 26threatened Australianmammal species, over 230 species ofbird, and nearly 150 species ofreptile. It is an important breeding and nursery ground forfish,crustaceans, andcoelenterates. There are over 323 fish species, many of themsharks andrays.
Some bottlenose dolphins in Shark Bay exhibit one of the few known cases oftool use in marine mammals (along withsea otters): they protect their nose with asponge while foraging for food in the sandy sea bottom. Humpback andsouthern right whales use the waters of the bay as migratory staging post[12] while other species such asBryde's whale come into the bay less frequently but to feed or rest. The threatenedgreen andloggerhead sea turtles nest on the bay's sandy beaches. The largest fish in the world, thewhale shark, gathers in the bay during the April and May full moons.[12]
Shark Bay has the largest known area ofseagrass, withseagrass meadows covering over 4,000 square kilometres (1,500 sq mi) of the bay.[1] It includes the 1,030-square-kilometre (400 sq mi)Wooramel Seagrass Bank, the largest seagrass bank in the world[1] and contains a 200-square-kilometre (77 sq mi)Posidonia australismeadow formed by a single plant, the largest in the world.[15]
Shark Bay also contains the largest number of seagrass species ever recorded in one place; twelve species have been found, with up to nine occurring together in some places. The seagrasses are a vital part of the complex environment of the bay. Over thousands of years, sediment and shell fragments have accumulated in the seagrasses to form vast expanses of seagrass beds. This has raised the sea floor, making the bay shallower. Seagrasses are the basis of the food chain in Shark Bay, providing home and shelter to various marine species and attracting the dugong population.
In Shark Bay's hot, dry climate, evaporation greatly exceeds the annual precipitation rate. Thus, the seawater in the shallow bays becomes very salt-concentrated, orhypersaline. Seagrasses also restrict the tidal flow of waters through the bay area, preventing the ocean tides from diluting the sea water. The water of the bay is 1.5 to 2 times more salty than the surrounding ocean waters.
Based on growth rate it is believed that about 1,000 years agocyanobacteria (blue-green algae) began building upstromatolites inHamelin Pool at theHamelin Station Reserve in the southern part of the bay.[16][17][18] Thesemicrobialites, a type ofsedimentary structure, are modern examples of some of the earliest signs of life on Earth,[19] with fossilized stromatolites being found dating from 3.5 billion years ago atNorth Pole near Marble Bar, in Western Australia, and are considered the type of fossil with the longest continuous presence in the geological record.[12] Shark Bay's modern examples were first identified in 1956 at Hamelin Pool, before that only being known in the fossil record. They may, however, be significantly different from fossilised examples, as growth rates may be up to 250 times slower than the estimated growth rates of somePrecambrian stromatolites. There is debate, however, over whether this indicates a true difference in growth rate, or if Precambrian growth estimates are instead too high.[18] Hamelin Pool contains the most diverse and abundant examples of living stromatolite forms in the world. Other occurrences are found atLake Clifton nearMandurah andLake Thetis nearCervantes.[1] It is hypothesized that some stromatolites contain a new form ofchlorophyll,chlorophyll f.[20]
Facilities around the World Heritage area, provided by theShire of Shark Bay and the Department of Biodiversity, Conservation and Attractions, include theShark Bay World Heritage Discovery Centre in Denham which provides interactive displays and comprehensive information about the features of the region.
Access to Shark Bay is by air viaShark Bay Airport, and by the World Heritage Drive, a 150-kilometre (93 mi) link road betweenDenham and theOverlander Roadhouse on theNorth West Coastal Highway.
The Shark Bay area has threebioregions within theInterim Biogeographic Regionalisation for Australia (IBRA) system: Carnarvon, Geraldton Sandplains, and Yalgoo. The bioregions are further divided into sub-bioregions:[21]
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