Pink Lake (Western Australia)

Pink Lake
Pink Lake sunset
Location Goldfields-Esperance, Western Australia
Coordinates 33°50′43″S 121°49′40″E / 33.84528°S 121.82778°E / -33.84528; 121.82778Coordinates: 33°50′43″S 121°49′40″E / 33.84528°S 121.82778°E / -33.84528; 121.82778
Type Salt lake
Basin countries Australia
Max. length 4 km (2 mi)
Max. width 2 km (1 mi)
Surface area 99 ha (245 acres)[1]
Surface elevation 0 m (0 ft)
References [1]

Pink Lake (previously known as Lake Spencer) is a salt lake in the Goldfields-Esperance region of Western Australia.[2] Although historically the water in the lake was visibly pink, as of 2017 it had not been pink for over ten years.[3] Salt concentration is vital to Pink Lake's pink hue, and Pink Lake may turn pink again as conditions change. It lies about 3 kilometres (2 mi) west of Esperance and is bounded to the east by the South Coast Highway.

The dynamics of why a lake turns pink is very complex. External changes and weather conditions can affect the colour of the lake. Esperance's Pink Lake has lost its pink colour due to a number of contributing factors.

Eastern end from Observation Point

Description

The distinctive colour of the water changes as a result of green alga Dunaliella salina, halobacterium Halobacteria cutirubrum, and/or high concentration of brine prawn. Once the lake water reaches a salinity level greater than that of sea water, the temperature is high enough and adequate light conditions are provided, the alga begins to accumulate the red pigment beta carotene. The pink halobacterium grow in the salt crust at the bottom of the lake.[4]

It is believed that the construction of a highway and a rail line altered the flow of water into the lake reducing its salinity which is why (as of 2017) it no longer appears pink.[3]

Name

In 1848 explorer John Septimus Roe named the waterway Lake Spencer after Sir Richard Spencer, a Resident Magistrate in Albany who contributed to the early formation of the colony of Western Australia. Lake Warden, adjacent, is recorded as having been named after Sir Richard Spencer's wife, Lady Ann Warden Spencer.

The Lake has displayed a distinct pink hue in the past and was colloquially referred to as Pink Lake until 1966 when the Shire President, Cr W S Paterson submitted a request to the Geographic Names Committee which was successful and resulted in Lake Spencer officially becoming Pink Lake. For many years Pink Lake was a tourist attraction in the Esperance region with the surrounding area, an arterial road and local businesses adopting the name.

Misleading name

Because tourists who visit Esperance to see the Pink Lake are disappointed not to see a pink lake, there have been proposals to either change the name of the lake and the town back to Lake Spencer or to find a way to alter the salinity so that the lake appears pink once again.[3]

Confusion with Lake Hillier

Lake Hillier is located on Middle Island in the Recherche Archipelago off the coast of Cape Arid, east of Esperance. The Lake is well known for its bright pink hue that contrasts with the deep blue of the ocean. The Island is managed by the West Australian Government and accessible by boat and air.

History

Historically Pink Lake was the terminal lake in the Lake Warden wetland system, where water from the central suite of lakes (Wheatfield, Woody and Windabout) and Lake Warden would periodically flush into Pink Lake, bringing accumulated salts into the environment.

Increasing salt concentrations combined with decreasing water levels from evaporation during summer trigger the appearance of the pink hue that can be seen in lakes across the country. Pink Lake lost its connection to Lake Warden and the eastern lakes with the construction of the railway line and South Coast Highway.

Commercial salt mining, which began in 1896 and ceased in 2007 reduced salt levels in the lake. With further reductions to the lake's salt concentration being caused by freshwater entering the system through a combination of surface water inflow and increased groundwater inflow due to clearing in the catchment area associated with nearby subdivisions.

Salt Production

Prior to salt production the lake's environment was investigated in the 1980s.[5] Table salt is produced in solar ponds at the eastern end of the lake.[6] The company WA Salt Supply produce water softening salt, coarse salt and sheepskin salt at the Esperance site. The salt is kiln dried, crushed and bagged at the site before being distributed.[7]

The science behind pink lakes

The dynamics of why a lake turns pink is very complex and external changes and weather conditions can have a big impact. Esperance's Pink Lake has lost its pink colour due to a number of contributing factors. The orange/pink colour of salt lakes across the world is caused by the green alga Dunaliella salina and the archaea Halobacterium cutirubrum.

Dunaliella salina is the most salt tolerant alga known and can grow in salinities as high as 35% NaCl (in comparison to seawater, which contains approximately 3% NaCl).

At high salinities, high temperatures and in high light, this alga accumulates the red carotenoid pigment, Beta-carotene. This is the same pigment that gives carrots, which contain 0.3% of Beta-carotene, their colour. Concentrations as high as 14% of the dry weight can occur in Dunaliella salina, which is the highest in any organism. The Beta-carotene protects the alga against damage from high light, coating the green chlorophyll and giving the alga an orange/red colour.

Dunaliella salina is found in salt lakes around the world including Antarctica, Chili, US, China, Tibet, France, South Africa and more closely can be observed off the coast of Cape Arid, east of Esperance in Lake Hillier located on Middle Island. The alga was named after Michel Félix Dunal who first recognised the red colour of certain salt lakes in France was due to an organism.

The archaea Halobacterium cutirubrum is pink in colour and generally grows within the salt crust on the bottom of the lake. The exact colour of the lake depends on the balance between Dunaliella salina and Halobacterium cutirubrum with salt concentration having a direct impact.

Birds

The lake has been identified by BirdLife International as an Important Bird Area because it usually supports significant numbers of hooded plovers and sometimes over 1% of the world population of banded stilts. It has had many migrant and native birds. Between 1997 and 2006, populations of between 12 and 12,000 of the banded stilt were recorded. There was a population of between 5 and 68 of the hooded plovers from 1995 to 2005.[8]

References

  1. 1 2 "Map of Pink Lake, WA". Bonzle Digital Atlas. 2009. Retrieved 28 March 2009.
  2. ↑ Pink Lake, Esperance - the discovery of and use of the lake Esperance traveller, Summer 1990, p.34
  3. 1 2 3 de Garis, Christian (27 November 2017). "Famous Esperance Pink Lake fades, leaving tourists confused and town with an identity crisis". ABC News. Archived from the original on 21 January 2018. Retrieved 21 January 2018.
  4. ↑ "Esperance - Natural Attractions". 2007. Retrieved 28 March 2009.
  5. ↑ Pink Lake Hydrological Study Group (W.A.) (1986) The report on investigations into the hydrology & use of Pink Lake at Esperance by the Pink Lake Hydrological Study Group to the Minister for Lands & the Esperance Shire Council. Perth : W.A. Dept. of Conservation and Environment. Bulletin (Western Australia. Dept. of Conservation and Environment) ; no. 262. ISBN 0-7309-0595-0 (pbk.)
  6. ↑ "SMH Travel - Esperance". The Sydney Morning Herald. 2004-02-08. Retrieved 28 March 2009.
  7. ↑ "WA Salt Supply - Esperance Location". 2004. Retrieved 28 March 2009.
  8. ↑ "IBA: Pink Lake (Esperance)". Birdata. Birds Australia. Archived from the original on 6 July 2011. Retrieved 19 September 2011.
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