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29 February 2008
Plight of Frogs in South Africa
The status of amphibians in
South Africa according to the Atlas and Red Data Book of the
Frogs of South Africa, Lesotho and Swaziland which was published
in 2004, indicates
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Four species
of amphibians as critically endangered,
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Eight as
endangered,
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Eight as
vulnerable,
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Five as near
threatened and
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Eight data
deficient.
The four critically endangered
species are:
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Hewitt’s
Ghost Frog( Heleophryne hewitti) This frog is endemic to
Southern Africa and is found in areas with high –rainfall in
the mountainous regions.
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Table
Mountain Ghost Frog (Heleophryne rosei) this frog has a
small area that it is endemic to.
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The Mistbelt
Moss Frogs (Arthroleptllea ngongoniensis) is found
along the eastern escarpment in Kwa- Zulu Natal and they like
to breed on Steep slopes and
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The Micro
frog (Microbatrachella capensis) this frog is found in
the Western Cape. It is restricted to certain wetlands and is
Southern Africa’s most threatened low- land amphibian.
The threats that are facing
amphibian in South Africa are habitat loss, in the form of
agricultural development and urban development. In a way the
contraction of dams may seem to be increasing the habitat space
for some amphibian species, but in the same way it impacts on
the down stream flow and can stop the natural cycle of the river
or stream thus affecting other species of amphibians.
Afforestation is a huge threat
as this has been cited as one of the main threats to Mistbelt
Moss Frogs (Arthroleptllea ngongoniensis).
Pollution
affecting the water systems decreases the quality of water. This
is further influenced by the agricultural pesticides, which have
a huge influence on the amphibian decline. It has to be kept in
mind that when looking at habitats for amphibians the life cycle
of the animals have to be considered. Different phases of their
life cycle have different requirements, for example tadpoles are
extremely sensitive to changes in their environment such as
water quality.
Seasonal burning of some areas
do influence the habitat of amphibians and can increase the
number of exotic plants in that particular biome and can be a
cause of afforestation
The other issue facing frogs is
road mortalities and can cause the deaths of thousands of frogs
when they cross roads for breeding purposes and finding suitable
habitats. In the Greater Johannesburg area the Giant bull frogs
(Pyxicephalus adpsersus ) breeding grounds are right next
or just off main roads in the city and each year thousands of
these frogs are killed whilst trying to cross these roads.
Climate change also has a
negative impact on the amphibian population.
Another focus point on the
decline of amphibians’ worldwide is diseases like
chytridiomycosis, which has affected many species of amphibians’
worldwide. In South Africa this has been document in species
such as the Common Platanna( Xenopus laevi.)
Johannesburg Zoo response:
In response to the for call for
action from the World Association of Zoos and Aquariums to
respond to the amphibian extinction crises, the Johannesburg Zoo
has established the Johannesburg Zoo Amphibian Conservation
Centre for the captive propagation of South African endangered
amphibians
Thus the
Johannesburg Zoo selected non-threatened species to be used as
models for the development of husbandry and breeding protocols
for endangered amphibians with similar breeding habits.
The
following species were chosen:
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Hyperolius marmoratus taeniatus
(Painted Reed Frog)
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Amietophrynus gutturali
(Guttural Toads)
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Heleophryne natalensis
(Natal Ghost Frogs)
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Breviceps adspersus
(Bushveld Rain Frogs)
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Cacosternum boettgeri
(Common Caco)
The goals of the
project include
1.
Design and construct habitats at the Johannesburg Zoo for
long-term maintenance of the selected species.
2.
Data collection and publication
3.
Establish and implement a frog collection protocol with
special emphasis on the prevention of pathogen transmission
between wild populations.
4.
Develop Species Specific Action Plans for South African
threatened amphibians.
5.
Establish satellite populations in other institutions
participating in the program.
6.
Develop an South
African amphibian educational programmes.
The project
has been well supported by the Mpumalanga Parks Board who
allowed the Johannesburg Zoo to collect the species needed from
the Province. In November 2007 the team will also be going to
Limpopo province to collect
Cacosternum boettgeri
and Breviceps adspersus
Through this the Johannesburg
Zoo now has the capability of
maintaining assurance populations in captivity and is able to
assist with a “rapid response” in case of an amphibian
emergency. Ongoing data collection and research will be used to
assist in the greater understanding of the amphibian crises.
Althea
Guinsberg
Manager Alpha Section
Johannesburg Zoo
011 646-2000 ext 268
althea@jhbzoo.org.za
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