Análise do manejo de ninhos de Podocnemis expansa (Schweigger, 1822) no Parque Nacional do Jaú e implicações para a conservação

Abstract

The Amazon turtle is the largest species of the Podocnemis genus, averaging 109 cms in length and weighing up to 90 kgs. Their nests contain an average of 100 eggs in each spawning. Their habitat includes most tributaries of the Amazon River, from the eastern Andes to the Orinoco River Basin. Population declines, due to; the hunting of adult animals, the collection of eggs by humans, the destruction of their habitats, and climate change have been observed for decades in the region. Nest management studies are focued on conserving chelonians. This study was conducted in the surveillance period from October 2022 to January 2023 within the National Park Jaú, Amazonas, Brazil. The park is located between the municipalities of Novo Airão and Barcelos, in the north of the state of Amazonas. The objective of this study was to assess how the collection of eggs from beach nests, their transportation to hatcheries, and the eggs transplantation into new nests affects; hatching success, emergence time, and sex ratio. Amazon turtles create their nests during the night. In the early morning hours during the surveillance period selected beaches were monitored daily for evidence of new nests. New nests are identified by changes visible in the sand, which are consistent with nest construction. The eggs from these nests were harvested and transported to the hatchery. There the eggs were divided into three groups; T1- whole nests, T2- nests split twice and T3- nests split three times. The number of transplanted eggs was carefully noted. The hatcheries were monitored daily by visual inspection and temperature. Upon completion of the incubation process the hatchlings emerged. Each nest was analysed for; number of live hatchings, stillborn hatchlings, unfertilized eggs, undeveloped fertilized eggs, and eggs with evidence of fungal infections. Seventy-five newly hatchlings were selected for sex ratio determination using histological analyses. Sand samples were collected from the selected beaches and the hatchery. The sand was graded as “very coarse sand”. The results indicated that there was no statistical difference between undivided nests and nests divided two and three times. Hatching success was 59.3 percent, with an average emergence time of 77.6 days and an extremely unbalanced sex ratio; 74 males and one female. The techniques for managing nests on beaches and transferring them to hatcheries emphasize the importance of improving methods to increase hatching success, promote a more balanced sex ratio and with a view to the sustainability of Amazonian turtle populations.