Understanding the biogeochemical influences on modern actively accreting microbialite deposits is essential for unravelling past environmental conditions, preserving current vulnerable habitats and informing future endeavours in, for example, conservation planning and sustainable development, as well as astrobiology. The South African microbialite systems are the best developed and most biogeographically widespread of those forming globally in the supratidal zone under mixed influence of ground- and seawater. Therefore, these habitats are especially useful with regard to understanding how groundwater geochemistry differs geographically and with respect to local geology at each site, with implications for the organisms that these habitats could support or that could contribute to their formation. This is important regarding general interpretation of similar habitats, both locally in South Africa and globally. Furthermore, in light of coastal urbanisation and increasing groundwater abstraction, understanding the role of the groundwater on the biogeochemistry and formation of the microbialite pools is important to their long-term conservation. In this project, we aim to (1) carry out a multi-tracer study on the origin of the groundwater feeding the supratidal microbialite pools that links precipitation (source), groundwater (channel) and microbialite seep (outflow) water bodies; (2) assess the degree of anthropogenic impact or threats to these unique habitats; and (3) compare population- and community-level genetic similarities across a network of microbialite-forming seeps to correlate spatial separation or connectedness. This will comprise the first comprehensive dedicated assessment of simultaneous geochemical and biological connectivity dynamics within supratidal spring-fed microbialite habitats.

Deutsche Forschungsgemeinschaft (DFG)

2022 – 2025

Carla Dodd