Gqeberha’s distinctive coastal seeps are likely one of the reasons why the region became the global springboard for early modern humans, and 120,000 years later they have been flagged as the “canary in the coal mine” for critical groundwater resource in the area.
That is the main thrust of a Water Research Commission-funded study, undertaken by a Nelson Mandela University (NMU) team, in partnership with the SA Environmental Observation Network and the Council for Geoscience.
The study was led by oceanographer Dr Gavin Rishworth, and the fieldwork was spearheaded by Carla Dodd and Tristan O’Connell.
Rishworth said there were about 1,500 seeps or freshwater streams flowing out the dunes and rock in the 50km stretch of coast between Cape Recife and Maitland.
“We started by trying to establish where the seeps originated, and how old they were.
“To do that we analysed their chemistry and compared what we found to the groundwater in the area, and as far away as the Elands Rivier mountains, on the edge of the metro’s catchment.
“We found that the seeps were a mixture of water from both these sources and that they were between 10 and 100 years old.
“We also identified micro-pollutants including traces of chemicals typically found in sewage, fertilisers and herbicides — and also pharmaceuticals, which would have come either from pit latrines or leaching from refuse dumps.
“So now we have a good baseline, and we have used that to launch a long-term monitoring programme.
“These seeps are our canary in the coal mine and they will be particularly useful to monitor the effect of borehole extraction when the next drought hits, and any groundwater pollution as population and development expands.”
Rishworth said some coastal seeps occurred in pockets in other countries, and in SA they were also present elsewhere in the Eastern Cape, KwaZulu-Natal and the Western Cape.
“But Gqeberha is a global hotspot for them and they are one more reason Algoa Bay is such a diverse and interesting area.
“Their presence allows for a range of tiny marine critters to flourish that would otherwise not be there.”
He said it was apt that the seeps should prove as useful today as they were to our ancient forebears.
“We know that early modern man evolved right here on the southern and Eastern Cape coastline, because of their diet of shellfish — rich in Omega 3 fatty acids, that helped their brains evolve — and other environmental triggers.
“And as they moved up and down this coast, they would have drank water from these seeps.”
In an interview in 2011, after the first presentation of the landmark coastal cradle of humankind discoveries, a member of the research team, renowned NMU botanist Prof Richard Cowling, said homo sapiens had been hit by a brutal ice age.
Holed up on what is now the southern and Eastern Cape coast, they had been reduced to about 600 breeding adults and a total population of less than 3,000 people.
They ate bulbs, tubers and corms, a rich source of carbohydrates from the surrounding fynbos, as well as shellfish, giant zebra, warthog and buffalo.
They had to work out how to drain toxic tannins from some of the bulbs and how to bring down the game without injuring themselves.
They developed practically and culturally, fashioning for the first time digging sticks and fish hooks, calendars to help them forecast the low tide necessary for the best shellfish harvest, and also decorations.
The Herald
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