Tracking down Bd Taiwan- part 2!

By Jenny Shelton

Nearly a week has passed since returning from my fortnight in Taiwan and my mind is still alive with the unforgettable sights, sounds and smells of the island. Some highlights include the beautiful fireflies that emerge at dusk, a tunnel full of bats that swooped silently above our heads as we passed, my first time holding a snake, and the cacophony of noise that greets you at night when frog-hunting. I can now pick out the indignant croaking of fighting Olive frogs (Babina adenopleura), the taunting call of tree frogs (Rhacophorus moltrechti) and the entrancing trill of a Harpist frog (Babina okinavana), as well as the calls of thrushes, night jars and owls. The trip was fieldwork for my National Geographic Young Explorer’s Grant entitled “Identifying ancient associations between amphibians and chytrid fungi on the island of Taiwan”- or #Taiwan2017 if you’ve been following my exploits on Twitter @jenmgshe! In 11 days and nights of amphibian hunting, we caught and swabbed an incredible 706 tadpoles, frogs and salamanders from swamps, ponds, weirs, streams, roads and mountain paths. We were fortunate to find individuals from 3 species of Taiwan’s IUCN Endangered salamanders- Hynobius alisanensis, Hynobius formosanus and Hynobius sonani– as well as 2 species of toad and 13 species of frog, including the elusive Harpist frog.

The aims of my fieldwork trip were:

  1. Using non-invasive skin swabs to ascertain the prevalence of Batrachochytrium dendrobatidis (Bd) in Taiwan’s frog populations, as part of an ongoing study by Dirk Schmeller and colleagues. Of particular focus is the IUCN Endangered Harpist frog, which are restricted to 2 geographical areas within Taiwan and are threatened by habitat loss.
  2. To obtain isolates of Bd grown from frog toe-clips that are free from fungal or bacterial contamination, which can be sequenced to determine their lineage. Toe-clips were only taken from the most common frog species on the island; those considered of least concern by IUCN.
  3. To monitor Taiwan’s Hynobius salamander populations for the emergence of Bd’s sister pathogen Batrachochytrium salamandrivorans (Bsal), which is responsible for mass mortality events in European fire salamanders. Hynobius salamanders have a restricted distribution within the mountain regions of Taiwan and are threatened by habitat loss, and high levels of inbreeding make them susceptible to disease. Salamanders were swabbed but not toe-clipped and were returned to the exact place they were discovered.

Why Taiwan? Taiwan is an ideal location for studying Bd because it is an island, which makes it a closed system with fewer opportunities for introduction. Likely sources of Bd infection are the amphibian pet trade, frog farming for the food industry and the import of non-native species for zoo exhibits. Taiwan is also a fascinating place to study Bd because it is an island of extremes- from sea level to 4000m, daytime temperatures ranging from 4oC to 40oC, distinct rainy and dry seasons, urban versus rural- all factors that affect the behaviour and distribution of amphibians and thereby the development and distribution of Bd. Due to a high-speed rail line that stretches from Taipei in the North to Zuoying in the South and extensive road networks covering the rest of the island, all these extremes, and everything in between, are accessible within a day’s travel, which is both a blessing and a curse. A blessing because it allows researchers, like myself, to travel the length, breadth, heights and depths of the island within an achievable timeframe. A curse, however, because the quick and easy transport of people, animals, and produce around the island also facilitates the spread of pathogens, such as Bd. Despite this, several native amphibian species have maintained a limited distribution on the island, often in isolated or protected areas, which makes their Bd infection status a natural focus of interest.

Amphibian populations in Taiwan are frequently monitored by researchers from Taiwan’s Endemic Species Research Institute (TESRI) and appear healthy: no morbidity or mortality has been observed that could be attributed to chytridiomycosis. If Bd is present on the island the lack of disease could be explained by several scenarios: that the deadly Bd Global Panzootic Lineage (BdGPL) has been recently introduced and is becoming established; that Taiwanese amphibians are colonized by an endemic chytrid fungus that protects them against BdGPL; or that the island’s amphibians have evolved to co-exist with BdGPL infection. Furthermore, if Bsal is present in the geographically-restricted and protected mountain regions where Taiwan’s Hynobius salamanders dwell the likelihood of recent introduction is low, which may suggest an ancient association between Taiwanese amphibians and chytrid fungi.

Fieldwork is very rarely the work of a single individual and this trip has been no exception. There are many people that I’d like to thank as without them this trip would not have been as successful, or even possible! Thank you to Dr Dirk Schmeller of Helmholtz-Center for Environmental Research (UFZ) for inviting me along on his fieldwork in April 2016, which inspired me to pursue my own funding to return to this beautiful island and continue researching Bd. A HUGE thank you to Lin Chun-Fu (a.k.a. Spring), who is the font of all knowledge regarding Taiwanese amphibians, and his wonderful field assistants Yeh Ta-Chuan, Lin Yi-Lun (a.k.a. Fish) and Chen Sin (a.k.a. Sharon) of TESRI for their incredible hospitality. While we suffered from heat and mosquito bites in the lowlands, cold and altitude sickness in the mountains, and general jetlagged tiredness they worked tirelessly and cheerfully around the clock: transporting us around the island, collecting amphibians for us, and waiting patiently while we swabbed and toe-clipped them. We really could not have done it without you! Thank you to my boss Prof. Mat Fisher for his guidance with my grant application and unerring enthusiasm towards my research, and to cameraman Matthew Richards for his multimedia coverage of the trip; despite dropping his expensive camera in the pond on day 1! Finally, thank you to National Geographic and private donor for choosing to fund my project and for making #Taiwan2017 fieldwork possible.

Now to keep up the hard work in processing the samples, and see whether Taiwan will yield to us its chytrid secrets!

***Photos courtesy of Matthew Richards, Dirk Schmeller and Lin Chun-Fu. More to follow!***

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