Lake Thetis is a saline coastal lake in south-western Australia.
- Situated east of the small town Cervantes, 2 km inland from the Indian ocean.
- The lake is 300 m wide and ca. 2 m deep.
- The lake is situated on a Quaternary limestone pavement.
Stromatolites, algal mats and fauna in Lake Thetis
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.
Alongside the stromatolites, a diverse array of benthic microbial communities, such as algal mats, inhabit various layers of the lake. 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.
The lake water is alkaline and nutrient poor but provides an ideal environment for bottom dwelling microbial communities. The lake contains some small fish, amphiods and a few crustacean species adapted to living in highly saline environments.
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.
In March 2008, a new entry road and car park, as well as walkways on the shore of the lake were constructed. Additionally, a disused rubbish pit on the northern side of the lake is being rehabilitated and this has eliminated threats associated with rubbish disposal.