14 March, 2019
Experts pinpoint eight unique lakes in SA
Free-flowing rivers are rare features in our landscape and an
important part of our natural
heritage. Opportunities for conserving
free-flowing rivers are fast disappearing with the
growing demand for
development of water resources.
Eight South African lakes with unique
characteristics have been identified in the course of the National Biodiversity
Assessment 2018. Experts emphasise the need to protect these wetlands from
environmental and other pressures that threaten to degrade them.
have singled out eight South African lakes for their unique characteristics.
"These are the only depressions or pans in South Africa - that we know of -
which are more than two metres deep, making them unique," says CSIR senior
researcher, Dr Heidi van Deventer. She adds that a 100% biodiversity target has
been set on these lakes. The biodiversity target
is the minimum proportion of an ecosystem type that needs to be kept in a
natural or near-natural state, in the long term, to maintain viable
representative samples of all ecosystem types and the majority of species
associated with those ecosystems.
in general, are impacted in several ways, including water abstraction, deteriorating
water quality, invasive species, land degradation and fragmentation, climate
change and a collapsing capacity of expertise to monitor and minimise the
impacts. "This tends to change the condition and threat status of the ecosystems,"
she says. "The 2018 National Biodiversity Assessment (NBA 2018), due to be
released in 2019, will model the condition of wetlands on a national scale."
eight unique lakes were distinguished from other water bodies from a literature
review, including CSIR reports, websites and journal papers, conducted for the NBA
2018, during which the first South African Inventory of Inland Aquatic
Ecosystems was established. The inventory offers a collection of data layers
pertaining to the aquatic ecosystem types and pressures for both rivers and
inland wetlands. According to the inventory, South Africa boasts a total of
158 407 wetlands of which 147 044 are inland wetlands and the rest are
rivers and estuaries.
The National Biodiversity
NBA is a national collaborative effort led by the South African National
Biodiversity Institute (SANBI). Van Deventer leads the inland aquatic component
of the NBA 2018, which contains a rivers subcomponent led by CSIR senior
researcher, Dr Lindie Smith-Adao. CSIR senior researcher, Dr Lara van Niekerk
leads the estuarine component of the assessment. The assessment also contains a
terrestrial and marine component, which is led by SANBI.
assessment evaluates the state of South Africa's ecosystems based on best
available evidence and is used to understand trends over time and inform policy
and decision-making across a range of sectors, including mining, fisheries and
agriculture. It informs South Africa's Outlook reports on the Sustainable
Development Goals to the United Nations Environmental Programme and the
Convention on Biological Diversity.
2018 NBA: Estuarine component
estuary is a body of water containing freshwater from rivers and saltwater from
the sea, forming a transitional zone between the river and maritime
environments. The major pressures on estuaries include pollution, flow
modification, overfishing, habitat modification and emerging pressures from
alien species and desalination. "These pressures are increasing and it is
challenging to track the condition every five years because aquatic systems do
not change that fast," says Van Niekerk. More than half of South Africa's
estuaries are in good health, but over 60% of estuarine areas have been
modified significantly, placing a strain on important ecological functions,
such as nursery functions and fisheries production.
2018 NBA: Rivers subcomponent
Africa boasts a total of 200 955 km of rivers, measured in length. A key
finding of the NBA 2018 points to only 33% of South African rivers being in
good condition. Smith-Adao warns that the country's rivers are impacted severely
by flow alteration, resulting from damming or over-abstraction, habitat
destruction, invasive alien plants and pollution of water. Hence, free-flowing
rivers are rare features in our landscape. A free-flowing river is a long
stretch of a relatively large river that has not been dammed or does not
experience major flow alteration. The NBA 2011 identified 19 flagship
free-flowing rivers which are an important part of our natural heritage. Examples
include the Doring, Elands and Mtentu Rivers. These rivers should be protected
to maintain their free-flowing character.
Eight unique lakes
The eight unique lakes cover just over 13 000 hectares. They are Barberspan, Chrissiesmeer, De Hoop, Groenvlei, Lake Banagher, Lake Fundzudzi, Lake Sibaya and Tevredenpan. Lake Sibaya is the largest freshwater lake, making up more than 8 000 hectares or 63% of all of the lakes. It provides freshwater to the communities surrounding it.
Chrissiesmeer during the dry season. This is one of the eight unique lakes
South Africa that hold a 100% biodiversity target.