Sea-level variation and the zonation of microbialites in Hamelin Pool, Shark Bay, Western Australia

Astronomical tides are not the primary driver of microbial zonation in Hamelin Pool, Shark Bay. Instead, seasonal oceanic cycles and short-term irregular variations dominate sea-level fluctuations, dictating the duration of immersion and exposure that shapes microbial community distribution. The study analyzed a 1983–1985 sea-level record using time-series analysis, revealing five key components: seasonal cycles, short-term irregularities, complex tidal systems, isolated major events, and wind-stress-induced variations. Microbial communities are stratified into three zones—Zone 3 (permanently submerged microbialite-forming mats), Zone 2 (lower littoral environments with exposed, colonized microbialites), and Zone 1 (ephemeral communities inundated only under exceptional conditions). This zonation is fundamentally controlled by seasonal cycles rather than tidal forces.

Burne, R. V., & Johnson, K. (2012). Sea-level variation and the zonation of microbialites in Hamelin Pool, Shark Bay, Western Australia. Marine and Freshwater Research, 63(11), 994–1004. https://doi.org/10.1071/mf12184