This month, we had the opportunity to catch up with Dr. Jonathan Kolby, founder of the Honduras Amphibian Rescue & Conservation Centre (HARCC) 🇭🇳🐸. On a mission to save the world, one frog at a time, Jonathan shared his insights on the global amphibian declines caused by chytrid fungi.
Con Con: What drove your interest in amphibian conservation?
Jonathan: When I was quite young I started volunteering my time doing herpetological field surveys with conservation groups, and when I was 15 years old I had an opportunity to join someone who was doing long-term biodiversity surveys in Hong Kong and China. That was my first time ever doing field work and it got me hooked ever since!
I went back with them and was their field assistant every summer and after doing that for about five years I wanted to start somewhere different. I saw a vacancy announcement for a position with Operation Wallacea who were looking for some help in Honduras. I knew absolutely nothing about Honduras and the species that live there but I thought: ‘You know what, that sounds good. I’ll try that!’
I went there for the first time in 2006 as one of the staff on their team doing a long-term biodiversity survey with the hope that our data could be used to help protect the forest which was under a lot of pressure. I was asked to come back again in 2007 and that was a critical turning point for me! While I was preparing to go back for the second season, I started doing a lot more homework than I had done the first year to really understand what were those species that we were catching. I was reading a lot of the IUCN Red List assessments for some of these frogs, many of which were already listed as Endangered or Critically Endangered, and a lot of them had been reported to be declining, some of them for enigmatic reasons.
At the exact same time, I was able to take a class about amphibian disease monitoring and that’s when I learned about chytrid. I learned how easy it was to sample for chytrid and that it was associated with unknown reasons for decline so I just thought why don’t I see if that’s in this forest as it might be why these frogs are disappearing!
Limosa Harlequin Frog (Atelopus limosus) that tested positive for chytrid (Bd) - note the lesions, skin-shedding and the frog is not attempting to 'right' itself when laying on its back. 📸 Brian Gratwicke
That was really the first time I ever designed my own research project and the results of that summer project showed me that chytrid was everywhere in this forest 🌳. It was highly prevalent in these endangered species that were declining for unknown reasons. I decided to sink my feet in Honduras and see if we could understand what was happening to these frogs. That was the beginning of my crusade to save the frogs in Honduras! 💪
📸 Simone Sbaraglia
ConCon: How does chytrid impact on amphibians and why it is threatening various frog species around the globe?
Jonathan: There are hundreds of different species of chytrid fungi. Most of them are beneficial in the environment but there are a few species that parasitised living animals. There are now two species of chytrid fungi known to attack living amphibians. Most of the focus is on the one that mostly affects frogs which is Batrachochytrium dendrobatidis, but more recently there’s been a second one discovered, Batrachochytrium salamandrivorans, which is specifically attacking salamanders.
📸 Ray Hennessy - Orange and black long-tailed salamander
The chytrid fungus is a highly aquatic pathogen and it basically latches on to an amphibian and starts to burrow under the skin until it goes a few layers down to parts of the tissue that produces keratin. That’s where it sinks its roots and feeds and feeds and reproduces. Once it reproduces, it exudes new spores into the environment that will be carried by the current and will find another tadpole and latch on to that and start the process over.
📸 Brian Gratwicke
The reason it is so bad for amphibians is that their skin structure is so important for the exchange of gases and chemicals! The growth of the fungus in the skin interferes with those processes. It doesn't actually cause much internal damage to the organs but by interfering with the skin it causes things like heart attack and electrolyte imbalance.
ConCon: How are you planning to tackle the chytrid crisis you’ve witnessed in Honduras through the Honduras Amphibian Rescue & Conservation Centre?
Jonathan: There are a handful of other rescue projects around the world that are also trying to save frogs from chytrid. What most of them have done is go to an area where they know the wave of chytrid is about to arrive or has arrived and basically collect as many frogs as they can to save them and protect them in captivity. There are simple veterinary anti-fungal medicines that are effective against chytrid in captivity but the biggest global problem is that most amphibians do not respond to re-exposure the way mammals do. They don’t learn to protect themselves after the first exposure and because of that everyone has been unsuccessful so far in creating any sorts of vaccination method. So while you can protect a species under controlled care, if you put them back in the wild to the same habitat that has chytrid and they get infected again they have no advantage from animals that you’ve never made an effort to protect.
From closely studying the three species that we are focusing on [in Honduras] for so many years across life stages, we think that we found a critical aspect of how to adaptively manage the frogs and allow them to survive in the wild. We know that in the species in Cusuco National Park most of them get exposed to chytrid as tadpoles. Because chytrid is an aquatic pathogen, it’s always in the river and we can’t get rid of it safely, but it doesn't often seem to cause negative effects on the tadpoles. It’s localised in their mouths because that’s the only place a tadpole has keratin.
📸 Jan Van Der Voort
There are some beliefs that this could affect their feeding and nutrition and it probably does to an extent but not merely to the extent it does once they start to transition into baby frogs! Then keratin starts to be produced all over their skin and suddenly it has so much more surface area. At that same time, the frog immune system suppresses itself because it starts growing the organs of an adult frog. That double whammy is the critical weakest link in the system in terms of survival. We believe that most of the frogs that already have infections as tadpoles are dying at that point or shortly after and very few survive to become adults.
The key is, though, that some do survive to become adults! It’s probably genetic but it could just be random chance, nobody has figured that out yet. Regardless of why, the point is that it happens and through radio-tracking we have found that a lot of those adult frogs are able to still live in infected habitats, get exposed and cure themselves. We’ve seen their infections go back and forth from positive to negative and they always maintain it at a very low level whereas in the baby frogs the level of chytrid is sky-high showing that it is causing diseases. So basically, we want to turn the system around. Rather than just focussing on captive breeding, we want to do something called ‘head-starting’ which is working with what nature is already providing but then identifying the weakest link and giving that link an advantage.
For us, the baby frogs and the tadpoles are the weakest links and our plan is to start taking out hundreds of those weak animals every year, bring them to our bio-secured facility where we can care for them under medical attention, cure and manage their chytrid infection, and then raise them until they become adults with their adult immune system. Eventually, we hope to reintroduce every year hundreds of adult healthy frogs right back to where they were collected so that they can rejoin the breeding population and then extract babies over and over again. Our hope is that by doing this, they will then breed more in the wild and produce many more offsprings.
📸 Franco Andreone
We’re not tinkering too much with the system but we are just playing a numbers game. We want to provide nature with a natural selection with a lot more animals to sort through to find those genetically superior animals and prevent extinction during this bottleneck. If we do this long enough, we won’t have to keep doing this forever and the animals can naturally evolve resistance because nature will select for that. Then the population will start to increase without our reintroduction effort.
ConCon: What are you the proudest of having accomplished so far as a conservationist?
Jonathan: In my second chytrid survey in Honduras in 2008, I rediscovered a frog in Cusuco National Park that was declared extinct and looking back that’s what I’m the proudest of! To be able to find a species that was thought to have gone ext