Alometria reprodutiva de Podocnemis unifilis Troschel,1848 (Testudines: Podocnemididae) no rio Andirá, Barreirinha, Amazonas, Brasil

Abstract

The Brazilian Amazon is one of the regions with the greatest wealth of chelonians, housing around 21 species, of which 4 belong to the genus Podocnemis, namely: Amazon turtle (Podocnemis expansa), tracajá (Podocnemis unifilis), iaçá or pitiú (Podocnemis sextuberculata) and irapuca (Podocnemis erythrocephala). The body size of organisms represents an important parameter, which can have consequences for reproductive activities, evolution and development. The objective of this work was to carry out a study of the reproductive allometry of the species Podocnemis unifilis TROSCHEL, 1848, popularly known as tracajá, belonging to the Podocnemididae family, on the Andirá river, in the municipality of Barreirinha, Amazonas, Brazil. The research was carried out on beaches located on the banks of the Andirá River. The females found nesting were captured, marked, weighed and measured, totaling 12 female individuals of P. unifilis. Both measurements of body size (carapace length) and body mass of females were used to establish relationships between clutch variables and eggs. P. unifilis females had an average weight of 4,917.67±1,353.67 g, carapace length of 34.98±2.48 cm and plastron length of 30.44±2.30. The eggs analyzed were 39.95±2.60 mm long, 27.6±1.94 mm wide and average weight 19.77±2.49 g. We found a strong relationship between female size and aspects of the clutch and eggs (clutch size, number of eggs per nest, clutch mass and egg mass) of Podocnemis unifilis. Therefore, the larger body size of females produces a greater number of eggs with greater mass than smaller females. A strong relationship was also found between the mass of the female tracajá (P. unifilis) and the aspects of the clutch and eggs (quantity of eggs, clutch mass and egg mass). Therefore, we can say that the heavier the female is, she tends to have a greater number of eggs, a greater clutch mass and has heavier eggs. We found no significant relationships between female mass and egg width. These studies can contribute to future research, to better understand the reproductive ecology of these species, being useful in the management and conservation of P. unifilis populations.