Fig. 1

A Map of Australia. The area circled is part of the Recherche Archipelago (Bay of Isles) off the southern coast of Western Australia, which contains Middle Island and the study site of Lake Hillier. B Map of the study area. Each icon shows the approximate location of the sampling sites where sediment (bank and lake) and water from the top (surface) and mid-depth was collected. C Diagram showing an illustrated cross-section of Lake Hillier and an image from the day of sample collection. Each dot shows the approximate location where each sampling type was collected. D An overview of the sample collection and preservation workflow, where aliquots of the water and sediment samples were preserved in EtOH (40%), DMSO, or frozen over dry ice following collection. The samples were then processed and analyzed using shotgun metagenomics, 16S and 18S rRNA gene sequencing, and archaeal 16S (A2F) rRNA amplification