Invasive species have long been known to have the potential to wreck havoc upon ecosystems, especially unique island ecosystems. Madagascar is no exception to that, as it boasts some of the planets richest and most threatened biodiversity which is under fire from a variety of hazards. The most recently known threat may be the most pressing as experts warn that unless immediate action is taken against it, disaster may be just around the corner.
The Asian Toad (Duttaphrynus melanostictus) is believed to have arrived in the country between 2007 and 2010, carried on freight containers travelling from South East Asian countries. Although it was only formally identified in 2014, there are thought to be more than 4 million toads now established on the island and they are spreading rapidly. As you can probably imagine from those numbers they are prolific breeders, producing 40,000 eggs a year.
This is bad news for the wildlife of Madagascar as the toads secrete a milky toxin which is poisonous to the native birds, mammals, snakes or anything that may prey on the toads. Its not just predators which may feel the impacts of the Asian Toad. Conservationists are increasingly worried about the transmission of disease between this invader and native amphibians. Nearly all the amphibian species in Madagascar are endemic so found nowhere else in the world and nearly all are threatened with extinction so any spread of disease amongst them would be apocalyptic.
Whilst the toads have the potential to impact food chains from the top to the bottom, experts are also warning that the toad may have dramatic impacts on the human population. There have been reported cases of cardiac arrest caused by the species in Laos, thus lethal impacts especially amongst the large rural population of Madagascar are a primary concern. This is combined with the potential for Asian toads to wipe out predators which would cause an increase in black rats and where there is an increase in black rats there is the potential for impacts on human health.
Moreover there will be economic impacts. Madagascar has a strong tourism economy built from its unique biodiversity which would be understandably harmed by any damage to the countries biodiversity. Biosecurity concerns may also cause restrictions on exports which would harm trade.
You might be reading this thinking it sounds grossly doom and gloom. Another nail in the coffin for Madagascar’s environment which already suffers from heavily logged rainforests, another nail in the coffin for hundreds of species of amphibians already under threat from disease and climate change, another invasive species ready to wreck havoc upon an ecosystem and be a scare story example.
Experts however are crying out that this does not need to be the case. Despite the large influx of Asian toads, they are currently restricted to the port city Toamasina an area of 110sq km. Therefore eradication experts that now is our last chance to act. With their rapid rate of expansion it is believed that if they reach the Pangalanes canal system eradication will no longer be an option.
Whilst an amphibian species has never been eradicated on this scale before, conservationists remain optimistic as small-scale eradication trials have been successful. These trials have also established which methods seem to be the most successful and which will be rolled out on a larger scale. Some of these methods include tadpole trapping, manual removal and spraying with citric acid.
Although this is an ambitious project and may cost $2m-$10m; a price Madagascar may struggle to pay with their limited resources. However experts maintain that this is a challenge which should be accepted. Chris Raxworthy, herpetologist maintains “Considering the broad range of biological and economic negative impacts that are expected from this toxic toad, future generations will be furious, should we not make an eradication effort now, while there is still a chance of success. We do not want to look back 20 years from now and wonder what Madagascar would be like if we had addressed this issue properly.”
Featured Image by James Reardon
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