Geological control of Podocnemis expansa and Podocnemis unifilis nesting areas in Rio Javaés, Bananal Island, Brazil

Acta Amazonica

Paulo Dias Ferreira Júnior¹  Paulo De Tarso Amorim Castro¹ 

[1] ,Universidade Federal de Ouro Preto Escola de Minas Departamento de GeologiaOuro Preto MG

关键词: Podocnemis;    turtle;    sediment;    nesting place;    incubation duration;    Podocnemis;    nidificação;    tartaruga;    sedimento;    duração da incubação;   

DOI  :  10.1590/S0044-59672003000300010

来源: SciELO

【 摘 要 】

The distribution of the nests of Podocnemis expansa (Amazon turtle) and Podocnemis unifilis (yellow-spotted side neck turtle) along the point bars of the Javaés River in Bananal Island, demonstrates a clear preference of these chelonians for differentiated geological environments, in respect to the morphology, grain size or height of the nests in relation to the level of the river. The topographical distribution and the differences in the grain size of the sediments that compose the point bars of the river, originated from the multiple sedimentary processes, and make possible the creation and separation of different nesting environments. Each turtle species takes advantage of the place that presents physiographic characteristics appropriate to the hatching success of their eggs. The superposition of the P. expansa and P. unifilis nest placement areas is rare. The P. expansa nests are concentrated on the central portion of the beaches where successive depositional sedimentary events produced sandy banks more than 3.3 m above the river water level. The P. unifilis nests are distributed preferentially in the upstream and downstream portions along the point bars where the sandy deposits rarely surpass 1.5 m at the moment of laying. P. expansa nests located on the beaches of fine to medium sized sand hatch in a mean of 68 days, while those incubated on beaches of medium to coarse sand size take a mean of 54 days to hatch.

【 授权许可】

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