Little do most people know but today on 30th November, an annual event is taking place. Today marks Remembrance for Lost Species Day – as an amphibian biologist this is an extremely pressing and relevant day. Currently 41% of amphibian species are threatened with extinction, making amphibians the most threatened group of vertebrates. Threats facing amphibians such as habitat loss, pollution and disease have lead to drastic declines in species globally. One of the diseases the amphibian chytrid fungus (Batrachochytrium dendrobatidis) has been implemented in amphibian declines all over the world, especially in Australia and Central/South America. It is this disease that I wish to highlight as the causative agent for the extinction of up to 200 frog species.
On 26th September 2016, the last individual of a relatively unknown species took its final breath. This individual was the last known remaining Rabbs’ fringe-limbed treefrog (Ecnomiohyla rabborum), named Toughie and housed at the Atlanta Botanical Garden. Toughie’s life wasn’t an easy one – I apologise if I’m anthropomorphising too much here.
Toughie was part of a group of individuals collected in an effort to start a captive breeding program to help safeguard the species in 2006. Toughie sired tadpoles with a female whilst housed in captivity but unfortunately but none survived. After the female died in 2009, the only other known individual was a male, leaving the species no other options of reproducing. At this time the species had become functionally extinc. A few years later in 2012, the other male, who lived at Zoo Atlanta, was euthanized due to health concerns. This left Toughie as the sole remaining individual of his species. On December 15, 2014, Toughie was recorded calling for a mate again. Unfortunately for him, his calls would never be answered.
The Rabbs’ fringe-limbed treefrog is one of many species whom we have lost due to the effects of the chytrid fungus. The gastric brooding frogs (Rheobatrachus silus & R. vitellinus) are two unique species lost from Australia in the mid-1980s. These frogs were the only known species which incubated their larvae in the stomach of the mother (hence their name). Unfortunately the range of both species was extremely small making them susceptible to disease and habitat loss. They were only known for a decade before disappearing, fortunately their party trick was discovered before this time. The last species I want to talk about briefly is the golden toad (Incilius periglenes). Again a victim of the chytrid fungus, the last sighting of a single male golden toad was on 15 May 1989. Since then extensive efforts have failed to locate any remaining.
These are depressing stories I know but we can’t let it stop us from working to save other species. It may cause upset but we use that as power and drive to ensure that other species don’t have to suffer the same fate. Also these descriptions are no where near complete, I ask you on this day to go forth and research the three species I have mentioned as their fate, ecology and life histories are all fascinating beyond belief. When Toughie passed away, I was in Malaysia and the news sank me like a boat – the loss of an iconic individual within the amphibian community which has gone largely unnoticed.
It’s been 18 years since we first discovered the chytrid fungus, in 2013 a new species (Batrachochytrium salamandrivorans) that exclusively effects salamanders. Huge declines have already been seen in European fire salamanders (Salamandra salamandra), so who knows which species we may lose because of this new player in town. Novel amphibian disease are constantly being discovered, we need to act fast and work together if we are to safeguard these colourful and important members of the biosphere.
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