Répteis e serviços ecossistêmicos: o lagarto Phyllopezus pollicaris (Spix, 1825) como bioindicador de exposição à radioatividade natural em região semiárida do Nordeste brasileiro

Abstract

The use of animals as bioindicators has proven to be relevant for assessing the effects of ionizing radiation. Among reptiles, especially Testudines and Crocodylia have stood out. Lizards, although less studied, exhibit characteristics that make them sensitive to environmental changes. In Brazil, there are large uranium reserves, particularly concentrated in regions such as the Seridó area of Rio Grande do Norte and Paraíba, where natural radiation levels are high. A study conducted with lizards in this region identified Phyllopezus periosus as a good bioindicator due to the detection of genetic damage caused by radon. Considering that reptiles play essential roles in identifying environmental damage and maintaining ecosystems, this study aimed to evaluate whether the lizard Phyllopezus pollicaris, which has greater environmental plasticity than its congener P. periosus, is also sensitive to natural radioactivity, with possible DNA alterations, as well as to identify the ecosystem services provided by lizards. In this context and perspective, the general objective of this study was to qualitatively and quantitatively analyze the genotoxic patterns and effects of contamination by radioisotopes in Phyllopezus pollicaris, while also identifying and evaluating the ecosystem services provided by lizards at a global level. To assess the sensitivity of P. pollicaris, blood smear slides from specimens collected during a previous study in three municipalities of the Seridó region of Rio Grande do Norte — Lajes Pintadas, Currais Novos, and Serra Negra do Norte — all with high levels of ionizing radiation, were analyzed. For radiation level comparisons, fieldwork was carried out in the Mata Estrela Private Natural Heritage Reserve (RPPN), in the municipality of Canguaretama/RN, which has low levels of natural radioactivity. Specimens of P. pollicaris were collected there, acclimated in the laboratory, and had their blood drawn for smear preparation. All blood smear slides from all specimens, across all study locations, were analyzed, and their erythrocytes were evaluated using the micronucleus test. To identify and categorize the ecosystem services provided by lizards globally over the last 15 years, bibliometric research was conducted using three academic databases. The results were organized and categorized according to the various ecosystem service functions reported for reptiles. The results demonstrate that P. pollicaris is sensitive to radon, but its environmental plasticity does not result in increased DNA damage, and micronucleus formation is associated with high rates of natural radiation. The main categories of ecosystem services provided by reptiles identified were Provisioning and Regulation, as well as Cultural services, due to the importance of these animals as a food resource and their cultural relevance. This study, therefore, highlights the lizard P. pollicaris as an indicator of environmental changes that directly affect human health, such as radioactivity, which is known to cause diseases like lung cancer, in addition to emphasizing the ecological importance of lizards and the relevant role they play in nature, whether as a cultural asset and/or a protein source.