Effects of Pine Needle Accumulation on Tadpole Development, Oxidative Stress and Genetic Damage in Odontophrynus reigi (Anura: Odontophrynidae)

Abstract

Large extensions of the Atlantic Forest in Brazil and Argentina have been replaced by monoculture tree plantations (mainly Pinus spp.). Small changes in the chemistry of pools where leaf litter tend to accumulate can have major effects on amphibian physiology and ecology. This work studied effects of pine needles on Odontophrynus reigi tadpoles. We exposed tadpoles to different concentrations of pine needles (0, 0.5, 1.5 and 2.5 g/L). In tadpoles, we determined: 1) morphological endpoints, 2) growth rate and development stage, 3) oxidative stress parameters (catalase, glutathione-S-transferase, lipid peroxidation (LPO) and protein oxidation (PO)) and 4) genetic damage (micronucleus, erythrocytes nuclear abnormalities and mitotic index). Dissolved oxygen (DO), pH, ammonia and total phenols (TP) were determined in water. As pine needle concentration increased, DO, pH and ammonium decreased in water, and TP increased. All morphological endpoints increased as pine needle increased, except body width that decreased. Oxidative damage had opposite effects: LPO decreased 50%, and PO had a 3-fold increase at 2.5 g/L. Catalase and glutathione-S-transferase enzymatic activities did not change significantly. Mitotic index increased with pine needle concentration. These physiological responses, likely driven by changes in water chemistry, suggest a potential long-term cost for individuals inhabiting pine monocultures.