Aspectos químicos e morfológicos e efeitos da parationa metílica em cascas de ovos de Podocnemis expansa (testudines, podocnemididae) incubados artificialmente

Abstract

CHAPTER II: The chemical and morphological composition of reptile eggshell varies according the species and the environmental conditions in which the eggs are incubated. Besides increasing knowledge on reproductive characteristics of each species, the description of structural features of these shells can be quite useful to evaluate the effects of xenobiotcs launched to the environment, that may cause reduction of the population of various animals. In this context, it was aimed to quantify and qualify the chemical properties of Podocnemis expansa eggshells. For this, sixty eggs were used, collected from two nests (A and B) in Araguaia River beaches (GO), and incubated artificially.After hatching, eggshells were submitted chemical analysis (mineral matter, calcium, phosphorus, ether extract, crude protein and nitrogen). And the thickness of the eggshell was 179 ± 18 μm in the nest A and 188 ± 12 μm in the nest B, indicating that eggs of p. expansa have flexible shells. The chemical composition varied from one nest to another, being: 8.13 ± 0.093% nitrogen and 7.83 ± 0.103% crude protein, 50.83 0.571% ± and 48.98% 0.640 ± 0.07 ± 0.008% ether extract and 0.07 ± 0.008%, mineral matter 17.90 ± 0.417% and ± 22.70 0.836%, calcium 11.48 0.368% and 15.26 ± ± 0.739% and 0.17 ± 0.008% phosphorus and 0.18 ± 0.016% to eggshells of nest A and nest B, respectively. The physical and chemical components of eggs of p. expansa differed between nests, this may be for environmental, nutritional, physiological factors, among others. CHAPTER III: Knowing that substances released in the environment, such as pesticides, can alter the shape, size and composition of eggshells, this study aimed to understand how methyl parathion, insecticide widely in use in Brazil, interferes on the chemical and morphological characteristics of Podcnemis expansa eggshells, during the artificial incubation. For this, 264 eggshells of this specie were utilized, all they came from protected areas of Araguaia River. The eggs were incubated artificially in sand substrate from the river beaches with a layer of vermiculite, and divided in four experimental groups, that received different concentrations of methyl parathion technical product (control, 35, 350 e 3500 ppb). To the control group was added distilled water. The eggshells were collected in intervals of three days, beginning on the third day and ending on the 63rd day of l incubation, and submitted to thickness measurement, chemical analysis, histology in light microscopy and scanning electronic microscopy. It was observed that the exposure of eggs to pesticides caused increase of phosphorus levels and reduction of ether extract levels in the shells during the incubation.