Water Wheel Jan/Feb 2025: Groundwater Sources

Abstract

Cover feature Microbialite seeps harnessed to monitor aquifer health Over the past decade, researchers in the Eastern Cape have been studying microbialite ecosystems associated with freshwater seeps along the province’s south coast. Initially, when the first few sites were identified in 2012 on the outskirts of Gqeberha (formerly Port Elizabeth), they were referred to as ‘living stromatolites’ in accordance with the first report of such structures along the South African coast in 2003, near Kei River mouth. Derived from the Greek words for ‘layer’ (stroma) and ‘rock’ (lithos), the term stromatolite is used for layered sedimentary structures that are formed by microbial organisms and that first appeared in the fossil record almost 3.5 billion years ago. Microbialite is a more all-encompassing term that includes non-layered forms. Where calcium-rich groundwater is discharged as seeps and springs onto the highest zone of the south coast’s rocky shores, mineral precipitation and/or sediment trapping by communities of cyanobacteria and algae promotes the formation of microbialites.

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