Abstract
The present study aimed to study the reproduction of the Amazon turtle (Podocnemis expansa) through the evaluation of the reproductive parameters of adult females. This study was carried out in the Crixás-Açu River, municipality of Mundo Novo, state of Goiás, Brazil. In September, the biometrics of 20 females were evaluated during the spawning period. Their nests were marked for subsequent evaluation of hatchlings, measuring the distances of each nest to the river and vegetation. The second stage consisted of the evaluation of hatchlings and characterization of nests after egg hatching. The data were tested using the Pearson Correlation to measure the degree of linear correlation between the variables analyzed, such as the parameters of females, hatchlings, nests, and eggs. Nest depth was positively correlated with the number of eggshells found. We also found a correlation between the number of eggsshells and the distance of nests to the vegetation. Although moderate, this result indicates that as the distance to the vegetation increases, the number of eggshells found in nests decreases. The spawning site for Amazon turtle breeding is crucial to determine a higher number of eggs hatching and better development of hatchlings. However, the literature is still very scarce regarding the choice of spawning grounds and the influence that vegetation may have on the development of freshwater turtle hatchlings in Brazil.
Highlights
Brazil is one of the most biodiverse countries in the world, with more than 20% of the total number of species on Earth Podocnemis expansa, popularly known as the Amazonian turtle, suffers from predatory hunting, commercialization of shells, and capture of eggs to be used as oil since the discovery of Brazil (Ribeiro & Navarro, 2020)
The females analyzed in September laid their eggs at different distances to the vegetation present on the beach of spawning in the Crixás-Açu River
We categorized these distance into two groups: far and near the vegetation
Summary
Brazil is one of the most biodiverse countries in the world, with more than 20% of the total number of species on Earth Podocnemis expansa, popularly known as the Amazonian turtle, suffers from predatory hunting, commercialization of shells, and capture of eggs to be used as oil since the discovery of Brazil (Ribeiro & Navarro, 2020).Podocnemis expansa is the largest freshwater species in South America (Rodrigues, 1992). The reproductive activity of chelonians is strongly related to climatic conditions, where rainfall indexes and water and air temperatures are determinant factors for these animals’ behavior (Souza, 2004) They are selective concerning the egg position in comparison with P. unifilis (Castro & Ferreira Júnior, 2008), where they prefer fine sandbanks with little gravel and free of vegetation. Ferreira-Júnior, Castro, Addad, Lorenzo (2003) assessed the influence of the spawning site of sea turtles on hatching success and sex ratio of hatchlings. They found that the spawning site choice directly affects the reproductive success of these chelonian species. The knowledge about this behavior is of great interest for understanding the reproduction of overall chelonians, including Podocnemis expansa
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