Titanium dioxide nanoparticles as a risk factor for the health of Neotropical tadpoles: a case study of Dendropsophus minutus (Anura: Hylidae).

The production and use of titanium dioxide (TiO2) nanoparticles are increasing worldwide. The release of this substance into the environment can induce toxic effects in aquatic invertebrates and vertebrates, although the exact nature of its impacts on Neotropical amphibians is still poorly understood. In this context, the present study evaluated the toxicity of TiO2 nanoparticles and their counterpart-dissolved titanium dioxide (TiO2)-in the tadpoles of Dendropsophus minutus. The biometric parameters, DNA damage, and behavioral changes were verified in tadpoles exposed to three different concentrations (0.1 mg·L-1, 1.0 mg·L-1, and 10 mg·L-1) of TiO2 nanoparticles and dissolved TiO2 for 7 days. We verified significant DNA damage in the D. minutus tadpoles exposed to both forms of Ti, in comparison with the control group. We also identified a reduction in total size, body length, and width, and the height of the musculature of the tail of the tadpoles exposed to all concentrations of both substances in comparison with the control. In the behavioral test, the tadpoles exposed to nanoparticles and dissolved TiO2 presented reduced mobility and a tendency to be less aggregated than normal. Here, the simultaneous use of multiple biomarkers was fundamental for the reliable assessment of the adverse effects of nanomaterials on anuran amphibians and the establishment of a systematic approach to the biomonitoring of aquatic ecosystems. The present study expands our understanding of the genotoxic, morphological, and behavioral effects of TiO2 nanoparticles and dissolved TiO2 on anuran amphibians, and contributes to the establishment of further research for the more systematic assessment of the environmental risk of nanomaterials.

Anfíbios anuros associados a corpos d'água do sudoeste do estado de Goiás, Brasil / Anuran amphibians associated to water bodies in Southwest of Goiás State (Brazil)

O Cerrado é o segundo maior bioma brasileiro e é considerado um dos mais importantes hotspots de biodiversidade. Neste bioma foram registradas cerca de 150 espécies de anuros, das quais 30 por cento são endêmicas. Entretanto, existem muitas áreas ainda não inventariadas, nas quais não se conhece quase nada sobre a diversidade de anuros. Assim, neste estudo apresentamos informações referentes a anurofauna do sudoeste do Estado de Goiás (Brasil Central), a qual vem sendo modificada principalmente pela agropecuária. Nesta região, 45 corpos d'água foram amostrados entre os meses de novembro/2007 a fevereiro/2008 e novembro/2008 a março/2009, localizados próximos a plantações de soja, cana-de-açúcar, pastagem e vegetação nativa. No total, foram registrados adultos e girinos de 36 espécies de anuros, a maioria comum de áreas abertas. As curvas de acumulação de espécies, tanto para adultos quanto para girinos, apresentaram a formação de uma assíntota, o que indica uma baixa probabilidade de registro de novas espécies mesmo com a amostragem de outros corpos d'água. Nesta área com forte influência de impactos agrícolas, a riqueza encontrada representa aproximadamente 1/4 do total de espécies conhecidas para o bioma Cerrado.

The Cerrado is the second largest biome in Brazil and is considered one of most important among the biodiversity hotspots. In this biome can be found about 150 anurans species, from which 30 percent are endemic. However, there are many Cerrado areas that have little information gathered about the anuran biodiversity. Thus, in this study we present the result of an inventory of anurans species from the southwest region of Goiás State (Central Brazil). In this region, we sampled 45 water bodies, located near soybean and sugar-cane cultures, pastures and natural vegetation, from November/2007 to February/2008 and from November/2008 to March/2009. Altogether, adults and tadpoles of 36 species were registered, with the majority of species registered in association to open areas. The rarefied curve of species richness show an asymptote formation, which indicates that the chance to add species to the inventory is low, even with additional habitats sampling. Therefore, our results reveal high species richness in the present sampled region, which represented almost one fourth of all species found in Cerrado.