We have overloaded nature’s washing machine, scientists warn
Wetlands — hacked, polluted and channelled by machines, yet teeming with life — are officially the most threatened ecosystem in SA.
A hour or two in the wetlands at the Nahoon Estuary Nature Reserve, itself struggling to survive a daily assault of sewage and other hazardous pollutants, will reveal a plethora of birds, animals, fish, insects.
Wetlands are one place where many of the last 30% of wildlife left on Earth congregate, drink, wash and feed.
But they have another amazing function: They are nature’s 24/7 scrubbers and filters of human pollutants.
But their battle is being lost. Kevin Cole, principal natural scientist at the East London museum, said the 2011 National Biodiversity Assessment identiefd wetlands “as the most threatened ecosystem type in SA”.
“SA has a very low extent of wetland coverage — only 2.4 % of the country comprising about 2.9-million hectares.
“This is largely attributable to climatic conditions which do not allow the persistence of surface water.
“The annual average evaporation potential over most of SA far exceeds rainfall.”
However, when the impact of human activity is factored into the situation, Cole said 65% of SA wetland types were under threat — of which 48% was critically endangered, 12% endangered and 5% vulnerable.
Most of the remaining wetlands have no protection.
“Only 11% of wetland ecosystem types are well protected, with 71% not protected at all,” he said.
This degradation confounds East London’s nationally respected scientist, who says: “Wetlands provide cleaner water, enhance biodiversity, sustain base-flows in rivers, and reduce the impact of flooding.
“They improve water quality by intercepting runoff from surfaces prior to reaching open water, and remove pollutants through physical, chemical and biological processes.”
There is clearly a lack of comprehension in the mind of the public about the natural power of wetlands to launder and preserve all life.
Cole says, politely: “I think there could be a better understanding of our wetlands in the regional and local context with regard to how BCM has already shown an increased vulnerability to natural disasters such as flooding.
“And with the climate predicted to change rainfall patterns, the protection and rehabilitation of wetlands will play a more important role than ever in reducing the impacts of floods.
“The most obvious example in BCM where a wetland is being protected is the Gonubie Wetland Reserve, demonstrating the importance of the role this reserve plays in flood abatement, habitat enhancement, recreation (bird hide and pathways), and previously it was visited by schools for educational purposes.”
It appears the city needs more information on the perilous state of its wetlands.
Cole, who walks in and works deep in the metro’s amazing but impacted forests and rivers, said: “A wetland audit across the metro will reveal other areas that need protection and that hold a similar potential to be rehabilitated by building gabion and concrete structures to arrest erosion to trap sediment to re-saturate previously drained wetland localities.
“Plugging artificial drainage channels, removing invasive alien plants and revegetating with indigenous plants will also assist in the rehabilitation process.
“The recreational, educational and tourism value of a wetland can also be enhanced by building boardwalks, bird hides and interpretive signboards.
“The Nahoon Estuary Nature Reserve is an example of this.”
“Areas in the metro identified for wetland rehabilitation can be turned into community projects — reclaiming spots which now are overgrown with alien plant species and utilised for illegal dumping reverting back to open spaces providing safer havens for recreation and improved ecosystem function.
“Presently wetland ecosystems in the metro and the province face the threat of dam construction, stream channelisation, the discharge of municipal sewage and industrial wastes (point source pollution) and runoff from urban and agricultural areas (non-point source pollution).
In the midst of this decline, there is, ironically, a legal shield and sword in place to fight for the wetlands, and keep urban and commercial developments from “affecting or altering the natural state of wetlands”.
He listed Nema, the National Environmental Management Act 107 of 1998, the National Water Act 36 of 1998 (NWA), and the environmental provisions of the Mineral and Petroleum Resources Development Act 28 of 2002 (MPRDA).
But the truth is that “compliance with this legislation is sometimes debatable”.
He urged the public to fill days like the Wetlands Day with local content and action.
He urged people to “recognise the value of these important ecosystems in flood abatement, erosion control, improved water quality, habitat enhancement, education, recreation and eco-tourism”.
Marine biologist Siani Tinley said: “A lot of people do appreciate the role and importance of wetlands, and the negative impact we can have if we are not careful.
“But there are always those people that don’t — is it education or lack of appreciation?
“There is definitely a big gap in how much we say about wetlands and their importance.
“Our human behaviour on a daily basis, what we chose to buy, and use how we chose to dispose of it, our general behaviour, is where we have lost and affected our wetlands (and coastal forests) negatively.”
Yes, she said, reintroducing wetlands, or any other ecological system, “can reverse some of the effects of humans are having on the planet”.
But this will not work until humans eliminate the cause, such as sewage spills into the environment.
“Ecology-based systems can work but must be managed in the same way as physical extraction systems and human behaviour management systems.
“Anything that is done in this ecological way would improve the situation but the outcome will be based on the cause being eliminated.”
Cole said 65% of SA wetland types were under threat of which 48% — was critically endangered