|
In a bid to save endangered species, the Johannesburg Zoo has teamed
up with an international organisation on a frog-breeding programme.
Frogs are indicators of the health of an ecosystem and provide an early warning of threats to other species
ALMOST one in three types of frogs are facing extinction, according to
the Red List of Threatened Species of the World Conservation Union
(IUCN). And the Johannesburg Zoo is doing its bit to ensure these
amphibians do not go the way of the kwagga.
The zoo has embarked on a frog-breeding programme with the World
Association of Zoos and Aquariums, after it volunteered to take the
initiative in such a project. Zoo chief executive Jenny Gray explains
that the organisation has sent people "to go look for bullfrogs and
then we will breed them in captivity".
Zoo manager of animal collections Dr Stephen van der Spuy says the
Johannesburg Zoo South African Frog Project started about six months to
a year ago. Its primary focus is to have a captive propagation of
certain South African endangered frogs.
Resources and space has been made available at the zoo for the project.
According to the Red List, 1 856 out of 5 743 amphibian species, or
almost one in three, are threatened with extinction. Van der Spuy cites
the reasons for the "critical frog decline" as global warming, the
chytrid fungus and pollution.
Earlier this year IOL, the Independent Newspapers website,
reported that global warming had triggered the decline of hundreds of
species of frogs and toads by helping a deadly skin infection to spread
across the world's frog species.
One of the participants in the zoo's frog breeding programme
A study by an international team of researchers has established that
global warming is helping the spread of a type of chytrid fungus called
Batrachochytrium dendrobatidis as tropical temperatures rise.
The scientists believe that the average temperatures of many tropical
highland regions, which are rich in endemic species of frogs and toads,
have shifted to become ideal for the growth of the fungus.
And this has Van der Spuy worried. "If it kills frogs, it will eventually kill us."
He cites a report that in the 1930s this fungus was apparently
identified in South Africa. One of the reasons for this is because the
common platanna frog was used around the world for scientific research.
Theoretically, this could be how the fungus was distributed.
The website of the popular conservation programme, 50/50
reports that another factor is that most frogs are suited to life in
water in that their skins are permeable to the gases dissolved in water.
Dr Stephen van der Spuy with one of his wards
This means they can "breathe" in water. However, this permeability also
makes them vulnerable to any pollutants in the water. Thus, the use of
fertilisers, pesticides and herbicides in a river catchment area can
result in abnormalities in frogs, such as extra limbs or death.
In this way frogs are indicators of the health of an ecosystem and
provide an early warning of threats to other species, including people.
Johannesburg Zoo is working with the Pan-African Association of
Zoological Gardens, Aquaria and Botanic Gardens and the amphibian
keeper from the Henry Doorly Zoo in Omaha, Nebraska, US, Amacha Heury,
in establishing systems for the breeding programme.
Van der Spuy says bullfrogs are a problem as there is a lack of information about them and they are difficult to find.
Giant bullfrogs in their enclosure
The programme is focusing on those species it feels "comfortable"
breeding and the group has decided to concentrate initially on five
non-endangered species of frogs that have similar breeding habits as
those that are critically endangered.
These non-endangered species are the Heleophryne natalensis (painted reef frog), the Bufo Gutturalis (guttural frog), the Hyperolius marmoratus (natal ghost frog), the Breviceps adspersus (giant bullfrog), and the Cacosternum boettgeri.
"We practise with these species so that we can slow the process of them being endangered in the future," he says.
Once the zoo has perfected the breeding technique it will apply for
permits from regional nature conservation departments to attempt
breeding endangered South African frog species.
Van der Spuy says that during dry seasons frogs stay hidden in the ground; they come out during the rainy season.
And when they do come out, they are often killed as humans encroach on
their habitats. An example of this in action can be seen in Midrand,
north of Johannesburg, Van der Spuy explains.
The problem is widespread in Gauteng, especially in Johannesburg, as a
result of the amount of development taking place in the frogs' habitat.
|
