Lake Thetis
{{Short description|Lake in the Mid West of Western Australia}}
{{about|a lake in Western Australia|the lake in Victoria, British Columbia|Thetis Lake}}
{{Use Australian English |date=April 2025}}
{{Use dmy dates |date=April 2025}}
{{Infobox body of water
| name = Lake Thetis
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| image = Stromatolites at Lake Thetis - Western Australia.jpg
| image_size = 280
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| caption = View on Lake Thetis and stromatolites
| pushpin_map = Australia Western Australia
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| pushpin_label_position = top
| pushpin_map_caption = Location in Western Australia
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| location = Mid West, Western Australia
| coords = {{coord|30|30|26|S|115|04|50|E|region:AU-WA_type:waterbody|display=inline,title}}
| type = Saline
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| basin_countries = Australia
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| length = {{convert|0.42|km|abbr=on}}
| width = {{convert|0.29|km|abbr=on}}
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| depth = {{convert|2|m|abbr=on}}
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| embedded={{Infobox mapframe
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Lake Thetis is a saline coastal lake in the Mid West region of Western Australia. The lake is situated east of the small town Cervantes, {{convert|2|km}} inland from the Indian Ocean, on a Quaternary limestone pavement.{{Cite web |last=Reitner |first=Joachim |last2=Paul |first2=Josef |last3=Arp |first3=Gernot |last4=Hause-Reitner |first4=Dorothea |date=1996 |title=Lake Thetis Domal Microbialites - a Complex Framework of Calcified Biofilms and Organomicrites (Cervantes, Western Australia). |url=http://webdoc.sub.gwdg.de/pub/geo/geobiologie/2005/reitner/1996-tethis.pdf |access-date=9 April 2024 |website=www.webdoc.sub.gwdg.de}}
The lake is part of Nambung National Park.
Stromatolites, algal mats and fauna
The lake is one of only a few places in the world with living marine stromatolites. The Lake Thetis stromatolites exhibit unusual columnar branching. These narrow, closely spaced and almost parallel columns are extremely rare in modern stromatolites.{{Citation | author1=Wacey, D | author2=Urosevic, L | author3=Saunders, M | author4=George, A. D | title=Mineralisation of filamentous cyanobacteria in Lake Thetis stromatolites, Western Australia | publication-date=2018 | issn=1472-4677}}
Alongside the stromatolites, a diverse array of benthic microbial communities, such as algal mats, inhabit various layers of the lake.{{Citation | author1=Telles, Frank | title=Geochemical analysis of Holocene lake sediment from Western Australia | publication-date=2015 | publisher=Saarbrücken, Germany Lambert Academic Publishing | isbn=978-3-659-75809-6}} Some of these algal mats are associated with the stromatolites while most confine themselves to a particular area such as the high foreshore areas, splash zone or the central basin of the lake.{{Citation | author1=Grey, Kathleen | author2=Planavsky, N. J | author3=Geological Survey of Western Australia | title=Microbialites of Lake Thetis, Cervantes, Western Australia : a field guide | publication-date=2009 | publisher=Geological Survey of Western Australia | isbn=978-1-74168-256-4}}
The lake water is alkaline and nutrient poor but provides an ideal environment for bottom dwelling microbial communities. The lake contains some small fish, amphipods and a few crustacean species adapted to living in highly saline environments.{{Cite web|url=http://www.visitpinnaclescountry.com.au/pages/lake-thetis-and-stromatolites/|title = Pinnacles Visitor Centre - Lake Thetis and Stromatolites}}{{full citation needed |date=April 2025}}
The stromatolite community is threatened by nutrient enrichment and physical crushing. An interim recovery plan is currently being written which will provide direction to further protect this extremely valuable community for future generations.{{Cite journal|url=http://www.publish.csiro.au/?act=view_file&file_id=MF9900275.pdf|doi = 10.1071/mf9900275|title = Lake Thetis, Western Australia: And example of Saline Lake Sedimentation dominated by Benthic Microbial Processes|year = 1990|last1 = Grey|first1 = K.|last2 = Moore|first2 = LS|last3 = Burne|first3 = RV|last4 = Pierson|first4 = BK|last5 = Bauld|first5 = J.|journal = Marine and Freshwater Research|volume = 41|issue = 2|page = 275}}
Recent development
In March 2008, a new entry road and car park, as well as walkways on the shore of the lake were constructed. There is also a {{convert|1.5|km}} walk trail around the lake. Additionally, a disused rubbish pit on the northern side of the lake is being rehabilitated and this has eliminated threats associated with rubbish disposal.{{Cite web|url=https://www.westaustralianexplorer.com/stromatolites-at-lake-thetis/|title = Stromatolites at Lake Thetis|date = 10 February 2017}}{{full citation needed |date=April 2025}}