EVIDENCE OF REDUCED FEEDING AND OXIDATIVE STRESS IN COMMON TREE FROGS (HYPSIBOAS PULCHELLUS) FROM AN AGROECOSYSTEM EXPERIENCING SEVERE DROUGHT

JULIE C. BRODEUR; JOSEFINA VERA CANDIOTI; SONIA SOLONESKI; MARCELO L. LARRAMENDY; ALICIA RONCO

JOURNAL OF HERPETOLOGY

SOC STUDY AMPHIBIANS REPTILES

Año: 2012 vol. 46 p. 72 - 78

0022-1511

Modern agricultural intensification may impact amphibian populations through both habitat loss and the direct and indirect effects of the pesticides it relies on.  The increased homogeneity of modern agricultural landscapes may furthermore be detrimental in times of extreme low and high temperatures brought about by climate change, as refuge abundance and habitat connectivity are decreased.  In this study, the impacts of the herbicide glyphosate and of a subsequent intense drought were evaluated in the common tree frog, Hypsiboas pulchellus, inhabiting an agricultural landscape.  Parameters examined include a series of organismic indices (stomach content index, hepatosomatic index, body fat index, gonadosomatic index, condition factor) as well as biomarkers of oxidative stress (hepatic catalase activity and reduced glutathione (GSH) content), exposure to contaminants (hepatic gluthatione-S-transferase activity) and genotoxicity (frequency of micronuclei).   No significant differences were observed in the parameters measured when comparing frogs sampled before and 2 and 15 days after glyphosate exposure.  However, anurans sampled in the same site two months later, when a drought was at its peak, presented a decrease in stomach content and hepatosomatic index, as well as an increase in hepatic catalase activity, hepatic GSH content and micronuclei frequency in peripheral circulating erythrocytes.  Taken together, these findings are suggestive of a reduction in food intake as well as the presence of oxidative stress associated to dehydration. Overall, field results obtained in this study demonstrate how surviving a period of drought is clearly challenging for an anuran species lacking specific adaptations to prevent desiccation.