Neonatal biometry and characterization of Amazonian Turtle nests (Podocnemis expansa)

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 datawere 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 eggshatching 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 hatchlingsin Brazil.

Neonatal biometry and characterization of Amazonian Turtle nests (Podocnemis expansa)

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 datawere 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 eggshatching 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 hatchlingsin Brazil.(AU)

Management and relocation of nests of Podocnemis expansa (Schweigger, 1812) (Testudines, Podocnemididae) on the Crixás-Açu river, Brazil

Podocnemis expansa nests in the sandbanks of the Crixás-Açu River in central Brazil during the dry season. With the return of the rainy season, the river banks are once again inundated, flooding nests and eggs and drowning hatchlings. This study evaluated relocation as an alternative to manage nests at risk of flooding. Forty P. expansa nests from four beaches of the Crixás-Açu were relocated to nurseries constructed in tanks filled with sand from the same river. Nine nests were covered with palm fronds to simulate shading conditions and to lower the incubation temperature. The base of the egg chamber was at a depth of 60 cm in all the nests. The duration of incubation varied for sunlit (49.1 ± 2.35 days) and shaded nests (51.7 ± 1.75 days), but did not change with nest position (center or edge of nurseries). Hatching success was 47.3 ± 13.6%, and did not vary significantly with sunlight/shade or nest position. The mean incubation temperature during the thermosensitivity period varied from 33 ± 1.56 °C to 34.1 ± 1.40 °C. The lowest mean temperature during the thermosensitivity period (31.9 ± 0.95 °C) and the highest proportion of males (up to 45% of hatchlings) were observed in a shaded nest. Most sunlit nests produced only females. The results suggest that relocation is a viable alternative in managing nests at risk of flooding during the rainy season in the Crixás-Açu. Moreover, artificial shading was shown to be an option to increase the proportion of males.

Durante o período de maior vazante do rio Crixás-Açu na região central do Brasil, nos meses de setembro e outubro, Podocnemis expansa (tartaruga-da-amazônia) desova nos bancos arenosos que surgem nas suas margens. Com o retorno do período chuvoso em novembro é comum que as praias deste rio sejam inundadas afogando ovos e filhotes. Este trabalho avalia a transferência como alternativa de manejo dos ninhos que seriam naturalmente alagados. Foram transferidos 40 ninhos de P. expansa oriundos de quatro praias do rio Crixás-Açu para berçários construídos em tanques de alvenaria que foram preenchidos com areia oriunda do próprio rio. Nove ninhos foram cobertos com folhas de palmeira para simular o sombreamento e diminuir a temperatura da incubação. A base da câmara de ovos de todos os ninhos situou-se a 60 cm de profundidade. A duração de incubação variou entre os ninhos ensolarados (49,1 ± 2,35 dias) e ninhos sombreados (51,7 ± 1,75 dias), mas não foi afetada pela posição do ninho, se nas bordas ou no centro dos berçários. O sucesso da eclosão foi de 47,3 ± 13,6% e não foi afetado pelo sombreamento ou pela posição do ninho nos berçários. A temperatura média de incubação durante o período termossensitivo variou de 33 ± 1,56 °C a 34,1 ± 1,40 °C. Os ninhos ensolarados produziram 100% de fêmeas em sua maioria. Os resultados mostram que a transferência é uma alternativa viável para o manejo dos ninhos que seriam alagados durante as cheias do rio Crixás-Açu e o sombreamento artificial dos ninhos é uma alternativa para aumentar a produção de machos nos berçários.

Management and relocation of nests of Podocnemis expansa (Schweigger, 1812) (Testudines, Podocnemididae) on the Crixás-Açu river, Brazil / Manejo e transferência de ninhos de Podocnemis expansa(Schweigger 1812) (Testudines, Podocnemididae) no rio Crixás-Açu, Brasil

Podocnemis expansa nests in the sandbanks of the Crixás-Açu River in central Brazil during the dry season. With the return of the rainy season, the river banks are once again inundated, flooding nests and eggs and drowning hatchlings. This study evaluated relocation as an alternative to manage nests at risk of flooding. Forty P. expansa nests from four beaches of the Crixás-Açu were relocated to nurseries constructed in tanks filled with sand from the same river. Nine nests were covered with palm fronds to simulate shading conditions and to lower the incubation temperature. The base of the egg chamber was at a depth of 60 cm in all the nests. The duration of incubation varied for sunlit (49.1 ± 2.35 days) and shaded nests (51.7 ± 1.75 days), but did not change with nest position (center or edge of nurseries). Hatching success was 47.3 ± 13.6 percent, and did not vary significantly with sunlight/shade or nest position. The mean incubation temperature during the thermosensitivity period varied from 33 ± 1.56 °C to 34.1 ± 1.40 °C. The lowest mean temperature during the thermosensitivity period (31.9 ± 0.95 °C) and the highest proportion of males (up to 45 percent of hatchlings) were observed in a shaded nest. Most sunlit nests produced only females. The results suggest that relocation is a viable alternative in managing nests at risk of flooding during the rainy season in the Crixás-Açu. Moreover, artificial shading was shown to be an option to increase the proportion of males.

Durante o período de maior vazante do rio Crixás-Açu na região central do Brasil, nos meses de setembro e outubro, Podocnemis expansa (tartaruga-da-amazônia) desova nos bancos arenosos que surgem nas suas margens. Com o retorno do período chuvoso em novembro é comum que as praias deste rio sejam inundadas afogando ovos e filhotes. Este trabalho avalia a transferência como alternativa de manejo dos ninhos que seriam naturalmente alagados. Foram transferidos 40 ninhos de P. expansa oriundos de quatro praias do rio Crixás-Açu para berçários construídos em tanques de alvenaria que foram preenchidos com areia oriunda do próprio rio. Nove ninhos foram cobertos com folhas de palmeira para simular o sombreamento e diminuir a temperatura da incubação. A base da câmara de ovos de todos os ninhos situou-se a 60 cm de profundidade. A duração de incubação variou entre os ninhos ensolarados (49,1 ± 2,35 dias) e ninhos sombreados (51,7 ± 1,75 dias), mas não foi afetada pela posição do ninho, se nas bordas ou no centro dos berçários. O sucesso da eclosão foi de 47,3 ± 13,6 por cento e não foi afetado pelo sombreamento ou pela posição do ninho nos berçários. A temperatura média de incubação durante o período termossensitivo variou de 33 ± 1,56 °C a 34,1 ± 1,40 °C. Os ninhos ensolarados produziram 100 por cento de fêmeas em sua maioria. Os resultados mostram que a transferência é uma alternativa viável para o manejo dos ninhos que seriam alagados durante as cheias do rio Crixás-Açu e o sombreamento artificial dos ninhos é uma alternativa para aumentar a produção de machos nos berçários.

Geological characteristics of the nesting areas of the giant Amazon river turtle (Podocnemis expansa) in the Crixás-Açu river in Goiás State, Brazil

A large population of the giant Amazon river turtle (Podocnemis expansa) nests along the beaches of the Crixás-Açu River in the central western region of Brazil. In spite of the existence of several point bars in the area, only a selected group of beaches is used for nesting by P. expansa. Geological aspects, such as river width and depth, beach height above 200 cm with sandy sediments, were indispensable for the choice of these nesting sites. The relatively reduced dimensions of the point bars and the great number of turtles, which nest in the same local, contributed to the existence of a high nest concentration. The rapid rise of the Crixás-Açu River caused the flooding of the beaches and the drowning of hatchlings and embryos. It is estimated that nearly all the nests were lost. The height of the nesting place and the time of flooding related to the incubation period are decisive in embryo survivorship. The Retiro, Júnior, Assombrado and Limoeiro beaches, which are situated at heights of 183 to 310 cm, were inundated on 8 November 2000. The Barreira Branca beach, with a height of up to 380 cm was completely inundated on 13 December 2000. All of these beaches were flooded before the hatchlings emerged.

Uma das maiores populações de tartaruga-da-amazônia (Podocnemis expansa) da região Centro-Oeste do Brasil nidifica ao longo das praias do rio Crixás-Açu no estado de Goiás. Apesar de existirem inúmeras barras em pontal na área, apenas um seleto grupo de praias foi eleito como ponto de nidificação pela tartaruga-da-amazônia. Aspectos geológicos, tais como um substrato constituído por sedimentos arenosos, a presença de locais amplos e profundos no rio, e patamares elevados, acima de 200 cm foram imprescindíveis à escolha dos pontos de desova. As dimensões relativamente reduzidas das barras em pontal e o grande número de indivíduos a desovarem no mesmo local fazem com que haja uma alta concentração de ninhos. A rápida ascensão do nível do rio Crixás-Açu, a partir de 25 de outubro de 2000, provocou o alagamento das praias e o afogamento de filhotes e embriões. Estima-se que quase todas os ninhos foram perdidos por este motivo. A altura do local de desova, em relação ao nível do rio, exerceu um papel crucial sobre o momento do alagamento das praias, mas foi incapaz de assegurar a conclusão do período de incubação e saída dos filhotes dos ninhos. As praias do Retiro, Júnior, Assombrado e Limoeiro, situadas a uma altura que variou de 183 a 310 cm, foram alagadas em 8 de novembro. A praia da Barreira Branca, com altura de até 380 cm foi completamente alagada a partir de 13 de dezembro.