Parâmetros populacionais e aspectos da conservação de Podocnemis expansa(Testudines, Podocnemididae), nas regiões do médio Araguaia e baixo Xingu, Brasil

Abstract

Anthropic pressure on Amazonian turtles has intensified. Factors such as water pollution, the expansion of agricultural activities, fires, deforestation of the floodplains and riparian forests, water bodies, and illegal hunting are contributing to the decline of these reptile populations in the Amazon region. The recovery and maintenance of the population indexes of Amazonian turtles at desirable levels are conditioned to the continuity, improvement and expansion of the work of protection, management and research with these animals. In this sense, the present study intends to verify which hydroclimatic variables better explain the variations in the population parameters of Podocnemis expansa, in a stretch of the Formoso River located in the municipality of Lagoa da Confusão/TO. To evaluate the perceptions of residents of the lower Xingu River about aspects related to the conservation of turtles. To verify if changes in knowledge and attitudes about chelonian occur among elementary school students, after participating in environmental education actions. In Rio Formoso, as a result of 205 hours of sampling over the years 2016, 2017 and 2018, 466 individuals of P. expansa were captured and tagged, including 47 adult males, 76 adult females and 343 juveniles - revealing themselves to be a population predominantly composed of juveniles (73.60%) and with functional sex ratio deviated to females (0.62: 1). The increase in relative abundance, the reduction in the number of individuals in the classes of larger sizes and better body conditions were associated, respectively, with lower average rainfall in the reproductive period, higher average flow of the river in the dry season and with an increase in flow in the period rainy. Future long-term studies should seek to deepen the knowledge about how hydroclimatic factors and agricultural activities developed in the region affect the demographics of the species. In the lower Xingu region, the majority of the 55 residents interviewed consider that the turtles have great cultural, social and environmental importance; highlights customs and lack of financial resources as the main reasons for the use of turtles in the region; recognizes that the conservation initiatives developed are effective, however, affirms that natural stocks have decreased or are decreasing due to anthropic action; I would voluntarily participate in actions to conserve turtles, but I would not encourage family and friends not to consume these reptiles. Knowledge and attitudes about turtles were related to the interviewees' socioeconomic characteristics. The results suggest that due to cultural use as food and illegal trade, turtles suffer intense hunting pressure, as well as highlight the relevance of cultural and socioeconomic aspects, effective community involvement, generation of income alternatives and continuous educational efforts for recovery and maintenance of species of turtles in the region. The Environmental Education (EE) activities contributed to increase students' knowledge about the social and ecological importance of Amazonian turtles, as well as to reveal their perception regarding the main threats and what to do to conserve these animals. Conservation and research programs that include turtles need to be planned in such a way as to make it possible to periodically evaluate the effectiveness of the EE actions carried out, thereby making possible any corrections and optimizing scarce financial resources.