Impacts of UVB Provision on Serum Vitamin D3, Pigmentation, Growth Rates and Total Body Mineral Content in Mallorcan Midwife Toad Larvae (Alytes muletensis)

Abstract. Our understanding of captve husbandry for amphibians is rapidly improving as empirical knowledge in this area grows. Early evidence indicates that UVB radiaton is an important aspect of captve husbandry for at least some species, and may be critcal in combatng nutritonal metabolic bone disease and other environmentally linked diseases. However, the limited evidence in this feld is restricted to post-metamorphic anurans, and impacts of UVB provision on larvae are even less well known. We measured the effects of ecologically appropriate levels of UVB exposure on growth rates, pigmentaton acquisiton, serum vitamin levels in the blood plasma, and whole-body mineral content in the Mallorcan midwife toad (Alytes muletensis). There were no signifcant effects of UVB exposure on any parameters measured. We were therefore unable to provide clear evidence that UVB irradiaton can be used to synthesise vitamin D3 in the skin. Our data suggest that when A. muletensis larvae have access to a diet containing vitamin D3 and under husbandry conditons currently recognised as best practce, UVB irradiaton is not required to maintain this species successfully. These results do not indicate that UVB provision is unimportant for amphibian larvae in general, however. Further research is needed to elucidate how tadpoles interact with UVB radiaton in nature and to examine how UVB
radiaton is provided in captvity, and to test for effects using a wider variety of species from a range of different habitats.