Influência de diferentes sistemas de incubação sobre o sucesso reprodutivo de tartaruga-da-Amazônia (Podocnemis expansa, Schweigger, 1812) em cativeiro

Abstract

Historically, many species of chelonians around the world have significant importance in terms of food, economy, and culture. Among the Amazonian species, the Giant South American River Turtle (Podocnemis expansa) holds the greatest commercial potential due to its high performance and acceptance in the consumer market. However, the reproduction of these animals in legal commercial breeding facilities has faced challenges over the years, with low hatching rates and limited studies addressing reproductive efficiency in captivity. This study aims to evaluate the influence of different incubation systems (natural, with transfer, and artificial) on the reproductive success of the Giant South American River Turtle (P. expansa) in captivity. The study analyzed egg hatchability rates, sex ratio, and the performance of Giant South American River Turtle hatchlings incubated in natural nests, incubators, and hatcheries with temperatures set at 29°C, 30°C, and 33°C. The experiment has been ongoing since 2021 at the Bicho de Rio breeding facility in Iranduba, AM, and the Wildlife Laboratory of UFAM (LAS). In 2021 and 2023, the reproduction tank beaches were monitored, and natural nests (3) were recorded and marked each year, some of which were transferred (3) to hatcheries (enclosed artificial beach) and others to incubators with controlled temperatures (3). Incubation temperatures in all three systems were monitored using HOBO TidbiTv2© data loggers, and humidity/temperature levels were recorded with thermohygrometers. The characteristics of each nest, egg biometrics, hatching rates, and hatchling biometrics were analyzed. The average hatching rates were as follows: natural (33.1±36.7), hatchery (43.3±32.6), 29°C incubator (46.9±20.7), 30°C incubator (51.7±28.6), and 33°C incubator (31.1±34.7). However, there was no significant difference between treatments for hatching rates. There was no difference in sex ratio between treatments, but a trend was observed (R²=0.35), indicating that higher temperatures resulted in fewer male hatchlings. There is a strong correlation (R²=0.97) between temperature (°C) and incubation days; lower temperatures prolong the incubation period. There is also a trend (R²=0.13) indicating that longer incubation times lead to lower hatching rates.