Eggshell resorption, and embryonic mobilization and accumulation of calcium and metals in eggs of wild and captive Capercaillies Tetrao urogallus. (June 2019)

• Record Type: Journal Article
• Authors: Orłowski, Grzegorz; Merta, Dorota; Pokorny, Przemysław; Łukaszewicz, Ewa; Dobicki, Wojciech; Kobielski, Janusz; Kowalczyk, Artur; Rzońca, Zenon; Krzywiński, Andrzej
• Is Part Of: Environmental pollution. Volume 249(2019)
• Page Start: 152
• Page End: 162
• Publication Date: 2019-06
• Subjects: Maternal resources -- Calcium -- Trace elements -- Eggshell etching -- Rotten eggs; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2019.03.010
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Although it is fairly well known that eggshells are the major source of Ca and other micronutrients for developing avian embryos, potential anatomical and/or ecological correlates explaining the variation in embryo-induced depletion of micronutrients from eggshells remain to be addressed. Using unhatched eggs at various developmental stages and post-hatched eggshells of wild and captive-bred birds of a large precocial species, the Capercaillie Tetrao urogallus, we explored two major questions. (i) Do egg size, regional eggshell thickness as well as levels of two major micronutrients (Ca and Mg) and eight trace elements (Cr, Cu, Mn, Fe, Co, Cd, Pb and Zn) measured in egg shells and contents vary with embryonic age within and between wild and captive-bred bird eggs? (ii) How the proportions of eggshell elements become depleted during the entire process of embryogenesis? The eggshells of wild Capercaillies were thinner at the equator and the sharp pole, and contained more Mg and Ca, while in their contents there was more Cu, Cd and Pb compared with captive birds. All ten metal concentrations measured in the egg contents increased (from 15% to 285% more) with the age of embryos. The concentrations of six elements measured in eggshells (Cu, Mn, Fe, Co, Cd and Zn) decreased consistently (from 15 to 70% less) during embryogenesis. This suggests the presence of these elements in the innermost decalcified shell layer and their further mobilization into the embryos/egg contents. Our results strongly imply that most trace elements present in the egg contents/developing embryos are mobilized from the eggshells. We highlight the fact that knowledge of the magnitude of embryogenesis-related functional changes in the physical (such as shell thickness) and chemical traits of the eggs and eggshells of oviparous vertebrates is fundamental for drawing correct inferences regarding the response of an individual to variable environmental conditions. Graphical abstract: Image 1 Highlights: Eggshells in wild Capercaillies (WC) were thinner than in captive Capercaillies (CC). Egg contents of WC have higher concentrations of Cu, Cd and Pb than those of CC. Eggshell Cu, Mn, Fe, Co, Cd and Zn decreased consistently during embryogenesis. All ten metal concentrations in the egg contents increased with the age of embryos. Abstract : Capsule: Our study emphasizes the fact that linking the state of embryonic advancement with metal levels in egg shells and contents is critical to an in-depth assessment of the sources of variation in egg/eggshell quality.