Effects of ultraviolet radiation on amphibian embryonic and larval development

Effects of ultraviolet radiation on hatching success, larval survival, and induced abnormalities were tested in three threatened (Hyla arborea, Bufo c alamita, and Triturus cristatus) and two common (Rana temporaria and Bufo b ufo) amphibians of Sweden. In the laboratory, all species were exposed to a rtificial UV-radiation (intensities corresponding to midsummer conditions i n Sweden) or visible light (controls) for ten days, during which hatching o ccurred. The effects of ambient levels of UV-radiation on hatching success and survival of B. bufo, R. temporaria, and B. calamita were also determine d during outdoor conditions when exposed to three different light regimes: Full solar: radiation, UV-filtered sunlight (exposed to photo-synthetically active radiation only) or darkness. In the laboratory experiment, neither eggs nor larvae of R. temporaria, B. bufo, B. calamita, and H. arborea were negatively affected by UV-radiation. However, UV-radiation induced darker pigmentation in tadpoles of H. arbore a. Only one species, T. cristatus, showed reduced hatching frequencies and lower larval survival when exposed to UV-radiation in comparison to visible light However, since female T. cristatus wrap their eggs in macrophyte lea ves, embryos are effectively protected against solar radiation. In the outd oor experiments, there were no differences between the light treatments for any of the species. Thus, none of these species are likely to be threatene d by moderately increased levels of ultraviolet radiation.