A plane from the United States recently arrived in Dar es Salaam, Tanzania, carrying an unusual load of passengers: 100 tiny toads. The homecoming of these toads represents the beginning of the world’s most complicated reintroduction project.
The Tanzanian government, along with the International Union for Conservation of Nature (IUCN) and the World Bank, among other organizations, are attempting to rebuild a broken environment, combat the amphibian-killing chytrid fungus in the wild, and reintroduce the Kihansi spray toads back into their natural habitat, all in one go.
No one said it would be easy.
The Kihansi toads were only just discovered in 1996. Scientists stumbled upon the toads' unique environment, the Kihansi Gorge, while conducting an assessment of the down-stream impacts of building a hydroelectric dam along the Kihansi River.
A lush Eden-like refuge, the gorge represented a hidden hot spot of biodiversity, brimming with unique creatures like the Kihansi spray toads, a species that thrives in the spray of the gorge’s giant waterfall and whose females give birth to live tadpoles, rather than laying eggs.
At the time, Tanzania had no laws requiring companies to adequately accommodate or respond to environmental pressures. So, the construction of the dam continued as scheduled.
Once opened, the dam reduced water flow to the gorge by 90 percent and devastated its delicate habitat. Tanzanian authorities installed a sprinkler system to help bring a little more water to the area. At first, the frogs rebounded.
Then came the fungus.
Chytrid fungus is to frogs as the black plague was to humans: for most, it spells swift and brutal death. The fungus hit the already crippled Kihansi toad community like a bomb. The last toads were observed in the gorge in 2004, and the IUCN officially declared them extinct in the wild in December 2009.
Fortunately for these penny-sized amphibians, there were thousands living abroad in American zoos. In 2001, a joint team of American and Tanzanian researchers spirited a small population of the toads away to the United States to prevent them from disappearing forever.
America treated them well, and by 2010 the initial population of 499 grew into 6,000 -- the Toledo and Bronx Zoos were nearly bursting with toads.
Meanwhile, back in Tanzania, change was flowing through the gorge.
In 2004, the country passed the Environmental Management Act, which mandated an environmental impact assessment for all new major developments.
“[More recently] Tanzania ratified the Biodiversity Convention, Convention on International Trade of Endangered Species (CITES) and the Ramsar Convention on Wetlands (Kihansi is a moist spray wetland),” Fadhila Hemed, a spokesperson for the Tanzanian government, told Discovery News.
“With the ratification of these conventions, Tanzania has to do something about the toad as part of biodiversity that only existed in Kihansi, Tanzania,” Hemed said.
The obvious answer: take some of the surplus toads back to Tanzania and try and reintroduce them to their restored native habitat. Apart from returning an exiled species to its rightful home, the move is also a unique attempt to study ways of fighting chytrid fungus in the wild.
Reviving a healthy population of Kihansi spray toads in the wild is a gamble, Hemed admits. The odds are against these fragile toads.
But if it's successful, Tanzania will have proven that a developing country can afford to participate in large-scale conservation projects, and that there is still hope to save the growing numbers of endangered amphibians around the world.
Image: University of Dar es Salaam
Tags: Amphibians and Reptiles, Animals, Wildlife Conservation
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