42) WETLANDS
There is clear water up to your ankles and a dragonfly zips past
your head as you watch some ducks fly off the water - welcome to
the soggy world of the wetland!
Wetlands are difficult to define because of their great variation
in size and location. The most important features of wetlands
are: Waterlogged soils or soils covered with a shallow layer of
water (permanently or seasonally), unique types of soil, and
distinctive plants adapted to water-saturated soils. Marshes,
bogs, swamps, vleis and sponges are examples of wetlands.
WHY ARE WETLANDS IMPORTANT?
* Flood busters:
Wetlands associated with streams and rivers slow floodwaters by
acting as giant, shallow bowls. Water flowing into these bowls
loses speed and spreads out. Plants in the wetland play an
important role in holding back the water. The wetland acts as a
sponge as much of the flood water is then stored in the wetland
and is slowly released to downstream areas, instead of it all
rushing to the sea within a few days. This greatly reduces flood
damage, particularly erosion, and ensures a more steady supply
of water throughout the year.
* Filters:
Wetlands improve water quality as they are very good natural
filters, trapping sediments, nutrients (e.g. nitrogen and
phosphorus), and even pathogenic (disease-causing) bacteria. In
addition, pollutants such as heavy metals (e.g. mercury, lead)
and pesticides, may be trapped by chemical and biological
processes. In other words, the water leaving the wetland is
cleaner than the water entering it.
* Wetlands and wildlife:
Wetlands are filters where sediments and nutrients accumulate,
so many plants grow there, e.g. bulrushes, grasses, reeds,
waterlilies, sedges and trees. The plants, in turn, provide food
and a place for attachment and shelter for many creatures. There
is more life, hectare for hectare, in a healthy wetland than in
almost any other habitat. These productive places support huge
numbers of insects, fish, birds and other animals. Some animals
are completely dependant on wetlands, whilst others use wetlands
for only part of their lives. The wattled crane, for example, is
dependant on wetlands for breeding. The rich diversity of
waterbirds in southern Africa (totalling 130 species) is possible
because of the many wetlands spread across the sub-continent. The
wetlands of southern Africa are of international importance as
they are the southern destination for many migratory wading
birds.
* People and wetlands:
Wetlands have been used for centuries as grazing for domestic
stock, and as a source of reeds used for thatching, hut
construction and basket weaving. They are provide fishing,
hunting and the opportunity to observe wildlife, especially
birds. Wetlands are appreciated for their beauty as open spaces
and also for their educational value.
WETLANDS IN TROUBLE
To most people words such as "marsh, swamp, bog and vlei",
conjure up little more than the "four D's" - dampness, disease,
difficulty and danger. Because of this wetlands have been seen
as wastelands to be converted to alternative uses such as
cropland, dams, plantations of exotic trees, waste disposal sites
and pastures. Many wetlands have been "reclaimed" for industry
and the construction of airports, harbours and sewage treatment
plants. Historically wetlands have been drained in attempts to
control malaria.
All wetlands in southern Africa are threatened. Botswana's
magnificent Okavango Delta is threatened by the possible
canalization of the Boro river to supply water for both domestic
and industrial use. In KwaZulu/Natal, debate rages over the
mining of the dunes on the eastern shores of St. Lucia because
of the unknown consequences to the water table in the area.
St. Lucia is a Ramsar recognised site. The Ramsar Convention on
Wetlands of International Importance recognises such wetlands and
works to conserve them. South Africa has 12 sites recognised by
the Ramsar Convention, including Langebaan on the west coast,
Barberspan in Gauteng and De Hoop vlei in the Cape.
WHAT YOU CAN DO
* The Department of Environment Affairs and Tourism runs a
wetland
conservation programme and all interested people are invited to
participate.
* Get to know the wetlands in your area and list the plants and
animals growing there. Draw a map of the wetland's position,
size and usage. Take photographs of the wetlands from fixed
vantage points and at different seasons of the year to compare
the changes between seasons and from year to year.
* Report the abuse of wetlands to your local nature
conservation, agricultural extension officer or Department of
Environment Affairs. Always make your report in writing to ensure
that the officer concerned has to investigate.
* Read "The Biology and Conservation of South Africa's Vanishing
Waters" (see below) which has a very useful chapter titled "What
you can do".
DID YOU KNOW?
* In KwaZulu/Natal, 58% of the wetlands associated with the
Mfolozi River catchment have disappeared as a result of siltation
caused by erosion of overgrazed lands.
FURTHER READING
SOUTH AFRICAN WETLANDS.
Newsletter on the activities relating to the Ramsar Convention
in South Africa. Department of Environment Affairs.
THE WETLANDS OF NATAL (PARTS 1-4).
Natal Town and Regional Planning Commission. Private Bag 9038,
Pietermaritzburg, 3200.
ECOLOGY AND CONSERVATION OF WETLANDS IN SOUTH AFRICA.
CSIR occasional report no.56. CSIR 1982. Waterlogged Wealth. E.
Maltby, Earthscan,1986.
WETLANDS.
C. Gaigher. Dept. Environment and Cultural Affairs (previously
Cape Nature Conservation).
THE BIOLOGY AND CONSERVATION OF SOUTH AFRICA'S VANISHING WATERS.
B.R. Davies and J.A.Day. CEMS, University of Cape Town and The
Wildlife Society of Southern Africa, Cape Town, 1986.
Enviro Facts: River Catchments.
USEFUL ADDRESSES
The Department of Environment Affairs and Tourism.
Private Bag X447, Pretoria 0001. Tel. 012-310 3425.
All provincial nature conservation authorities.
Universities of Cape Town, Orange Free State, KwaZulu/Natal,
Witwatersrand and Rhodes.
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