Studying amphibian decline due to chytrid in the Costa Rican forests

The forests of Costa Rica offer ideal living conditions for many different species of amphibians. Climatic zones range from wetland jungles to dry, high altitude forests. This variable climate supports a variety of species adapted to different conditions making Costa Rica a rich environment to study amphibians. But Costa Rican frogs are under attack from disease that has caused some species to become extinct in the past few decades. This disease, Chytridmycosis, is a significant issue for conservationists as it is affecting amphibians in wet areas throughout the world. However, a few species appear to be coming back from the brink of extinction. For example, those in the forests of Guanacaste where the majority of affected species already have been significantly reduced.

Lecturer and researcher Robert Puschendorf, based out of the School of Biological Sciences at Plymouth University, UK, is conducting a behavioural study of amphibian life in Guanacaste national park, Costa Rica, to gain an understanding of chytrid mycosis and determine why certain species of frogs appear to be resistant to the disease.

To conduct this study, Dr Puschendorf must collect samples from a range of different frog species and test them to determine if they carry the chytrid fungus. This involves catching the frog, taking the sample (either a toe clipping or a skin swab), performing a PCR test on the sample and then returning the frog to its habitat. Issues arise with this method of testing when a behavioural study is the underlying aim of the research. If frogs are held in captivity for more than five minutes, their behaviour and responses to stimuli are altered. To ensure that behavioural observations aren’t adversely affected, the entire sampling process must be completed within a five minute window for each frog. This means ideally the frog should be swabbed as quickly as possible.

Another issue confronting Dr Puschendorf is Latin American biosecurity laws, particularly in Costa Rica. In the past samples were PCR tested back in the UK lab, something that used to be relatively easy to do. This is becoming increasingly more difficult. Tightening of biosecurity laws in Latin America makes it almost impossible to send the samples overseas. This jeopardises the whole study as the PCR results establish if, or which frogs are carrying chytrid fungus.

Dr Puschendorf has recognised the need for mobile molecular testing as it would solve both major issues he is facing with his research. Immediate identification of frogs carrying chytrid fungus while he and his team are still in the field would remove the need to send samples out of Costa Rica for testing.  

Better understanding of amphibian decline and the emergence of resistant populations would potentially point to ways of protecting other threatened populations of amphibians around the world. With large tracks of forestry in Australia, Europe and other parts of Northern and Central America facing similar threats to their amphibian populations, this study has the potential to provide tools to save more amphibians from extinction.

Ubiquitome is running a grants program for research groups who would benefit from a mobile qPCR device. Robert Puschendorf has been chosen as one of the finalists. To find out more about the program and view the other finalists, visit the website here.