Impacts of UVB provision on serum vitamin D3, pigmentation, growth rates and total body mineral content in Mallorcan midwife toad larvae (Alytes muletensis)

Abstract

The health of amphibians in captive breeding programmes can be compromised by nutritional metabolic bone disease and secondary hyperparathyroidism, which is a result of poor calcium metabolism or an inverse calcium:phosphorus ratio in the blood. UVB provision allows for cutaneous photobiosynthesis of vitamin D_3, which is needed for adequate absorption of calcium from the diet, and so many post-metamorphic anurans are routinely provided with UVB radiation in captivity; however, tadpoles are not. This is the first study of its kind to investigate the effect of UVB radiation provision for anuran larvae from a captive husbandry perspective. This study examines the effects of ecologically appropriate levels of UVB exposure on growth rates, pigmentation acquisition, serum vitamin levels in the blood plasma, and whole-body mineral content in the Mallorcan midwife toad (Alytes muletensis). There were no significant effects of UVB exposure on any parameters measured. This may be because UVB radiation is simply not required by the larvae of this species, or because the provision of UVB radiation alone is not sufficient for its use in calcium metabolism. Further research is needed to elucidate how tadpoles interact with UVB radiation in nature and to examine how UVB radiation is provided in captivity and test for effects using a wider variety of species from a range of different habitats.