Effect of UV-B exposure on eggs and embryos of the Patagonian frog Pleurodema bufoninum and evidence of photoprotection

PEROTTI, M .G.; DIÉGUEZ, M.C.

CHEMOSPHERE

Elsevier

Lugar: Oxford; Año: 2006 vol. 65 p. 2063 - 2070

0045-6535

In Patagonia, enhanced levels of ultraviolet radiation (UVR) are affecting not only the southernmost territories but the northern aswell, and there is a growing body of evidence indicating effects on terrestrial and aquatic communities. Anurans occur along a wide geographicalgradient in Patagonia and are common in shallow waters, usually breeding during spring when seasonal UV-B radiation is atits highest level. In this paper we analyse the effective irradiances (I) experienced in nature by eggs and embryos of the patagonian anuransPleurodema bufoninum, Pleurodema thaul and Bufo spinulosus papillosus, considering water and egg jelly optical properties. Besides,we determine photoprotective pigments in eggs and embryos of the different species, and ontogenetic shifts in pigment concentration.Finally, we studied the effects of natural and enhanced levels of UV-B on eggs of P. bufoninum aiming to evaluate the role of the jellyenvelope in screening the damaging radiation. The evidence gathered in this work shows that natural and enhanced UV-B levels did notinduce significant changes on the survivorship but incremented the occurrence of malformations. Also, the species experiencing high levelsof exposure presented high concentrations of melanin suggesting that exposure to sunlight triggers photoprotection by pigments. Collectivelyour results suggest that the studied species bear certain levels of adaptation to cope with high ambient UVR conferred byenvironmental and biological factors.