Towards the Conservation of Declining Amphibians: A New Non-Invasive Hormone Monitoring Technique for Assessing Adrenocortical and Reproductive Activity

10 Feb 2017 National Zoological Gardens of South Africa, South Africa, Africa Amphibians

Juan Scheun

We aim to establish mucus sampling as a new non-invasive method for monitoring stress and reproductive hormone patterns in frog species worldwide. This would allow for easy, accurate and longitudinal sample collection and analysis, with minimal stress to individuals, across all species sizes in captive and free-ranging environments.

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First noticed in the 20th century, the global decline in amphibian population and species numbers, due to a range of natural and anthropogenic factors, has steadily accelerated into the 21st century. Amphibian species play an important role in the natural food chain, assisting in the efficient transfer of energy, from the primary producers to tertiary consumers, while acting as an important biomonitoring species in the natural environment. Despite their importance in the natural environment, conservation efforts have been unable to stop the recent amphibian decline. Although in situ conservation practice work relentlessly on conserving the natural habitat and population health of amphibians, very few tools exist to assist in this endeavour. Monitoring endocrine patterns in threatened animals can give a robust indication of the adrenocortical activity, indicative of stress and possible stressors present, as well as the reproductive activity and thus population viability of a population. The small size of most amphibians makes invasive techniques, such as frequent blood collection, impractical. Additionally, the collection of faeces and urine samples in the field, for non-invasive hormone monitoring, is extremely difficult and time consuming. Thus a new, easy to use and non-invasive technique for monitoring hormone patterns in amphibians, especially threatened frog species, is urgently required to assist conservation efforts of amphibians, both in and ex situ globally.

During this project we will:

(1) determine whether mucus can be used to monitor stress and reproductive hormone patterns in frogs;

(2) establish a sampling technique and sample analysis protocol for frogs, which can be shared with any institution or organization involved in frog conservation efforts;

(3) validate the most appropriate enzyme immunoassay for monitoring stress and reproductive hormone patterns in the African bullfrog. Following the validation of mucus as a robust sampling matrix for hormone monitoring in frogs we will apply the technique on free-ranging population of endangered frogs in South Africa and globally.

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