Evidence based ex situ husbandry for captive amphibians

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Abstract

Amphibians are declining worldwide in response to pressures that are too numerous, difficult and rapid to ameliorate in the wild before some taxa become extinct. Ex situ conservation, whereby animals are maintained in captivity until threats in the wild have been resolved, is the only means of saving up to five hundred amphibian species. Amongst political, financial and practical hurdles, the most fundamental problem for these programmes is lack of knowledge about how to maintain species successfully in captivity. Captive populations have failed to survive or reproduce and, furthermore, captive husbandry may produce animals unsuitable for reintroduction through intra or inter-generational changes. These problems entirely undermine initiatives and if ex situ programs are to succeed, evidence based captive husbandry is needed to support captive breeding programs. In this thesis, I quantify our ignorance of amphibian requirements in captivity. Furthermore, I present investigations into fundamental areas ofamphibian husbandry, about which we currently know very little. I investigate the relationship between amphibians and Ultraviolet B (UVB) radiation and examine the relationship between UVB provision and calcium provision and evaluate routes of dietary calcium supplementation. I also present data on the effects of enrichment and rearing environment on the growth, fitness, behaviour and dermal bacterial communities of captive amphibians. These results, from a range of areas of amphibian husbandry, together demonstrate the power of the captive environment to influence the phenotype and therefore the fitness of amphibians, even within single generations. Additionally, I provide some of the first data addressing key areas of amphibian husbandry that until now have been led mostly or entirely by anecdote and hearsay.

Layman's Abstract

Amphibians are threatened around the world and in many cases, the threats causing declines and extinctions are impossible to address before species become extinct in the wild. Therefore, captive breeding programmes, which aim to safeguard species in captivity and to breed them for future reintroductions, have become a prominent part of amphibian conservation. However, amphibian captive requirements are complex, variable and highly specific and for most species, captive husbandry protocols do not exist. This lack of knowledge has led to the failure or partial failure of a number of otherwise well-resourced captive breeding programmes and threatens the viability of this sort of conservation. The problems in captivity are often underpinned by a lack of evidence-based knowledge of broad, overarching themes affecting amphibians and their captive care. In this thesis, I quantify the level of ignorance and empirically address, sometimes for the first time, aspects of captive husbandry including environmental enrichment, diet and dietary supplementation, ultraviolet B radiation exposure and varying methods of raising juvenile amphibians. My research demonstrates that fundamental parts of amphibian husbandry can have important effects on a variety of characteristics in amphibians that are likely to influence the success of captive breeding programmes.

Keyword(s)

Amphibian; UVB radiation; calcium supplementation; conservation breeding; environmental enrichment; ex-situ conservation

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