A window into the earliest life on Earth?
Rock formations known as stromatolites that were recently discovered near Morgan’s Bay and throughout the coastline between Port Elizabeth and Storms River, may help scientists understand conditions on our planet when life was just beginning to take hold around three-and-a-half billion years ago.
The significance of the still growing stromatolites along the Eastern Cape coast and how they compare to similar structures formed during the Achaean Eon will be the topic of this year’s Smith Memorial Lecture entitled: Extant marine stromatolites of the Eastern Cape: a window into the earliest life on Earth?
Prof Renzo Perissinotto, the SARChI Chairperson in Shallow Water Ecosystems at NMMU in Port Elizabeth will deliver the lecture dedicated to the memory of Prof JLB and Margaret Smith at SAIAB on 27 September.
Stromatolites are layered structures built up over thousands of years by mats of cyanobacteria. They vary considerably in appearance, ranging from slightly wrinkled horizontal laminations in sedimentary rocks to prominent mounds sometimes resembling large button mushrooms.
The cyanobacteria that built up the early stromatolites and formed some of the oldest fossils on Earth were also responsible, through photosynthesis, for producing our oxygen-rich atmosphere.
Stromatolites are rare today so it was remarkable that over 500 living marine stromatolites systems were discovered recently along a 200km stretch of coastline, between Cape Morgan in the east and the Storms River mouth in the west.
Perhaps the best-known examples of living stromatolites are found in Shark Bay, West- ern Australia, first identified in 1956; and in the Bahamas.
Modern stromatolites are scarce globally for two main reasons: firstly, ocean chemistry has shifted from conditions which were once rich in calcium carbonate; and secondly animals and higher-level algae have now evolved and are able to out-compete or graze upon and disrupt the stromatolite matrix.
In his lecture, Perissinotto will consider questions like why the stromatolites have been able to form along this coastline while they are completely absent from most shores around the world.
He will also discuss his most recent findings and set them in the context of current threats caused by anthropogenic activities and climatic change along this coastline.