Publication: Aplicaciones del estudio de la ultraestructura y composición de la cáscara de los huevos de quebrantahuesos ("Gypaetus barbatus") en la conservación de la especie
Loading...
Files
Official URL
Full text at PDC
Publication Date
2016-08-18
Authors
Advisors (or tutors)
Editors
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad Complutense de Madrid
Citations
Exportar
Abstract
El Quebrantahuesos (Gypaetus barbatus) es una especie longeva, amenazada, con una población europea de 170 territorios. La población española, con 121 territorios, es el núcleo principal en Europa y se han aplicado medidas para su conservación desde 1985. Sin embargo, en los últimos años, la población ha sufrido de bajas tasas de productividad y éxito reproductor que están afectando a la dinámica de la población y está amenazando su viabilidad a largo plazo. Evaluamos la idoneidad del estudio de la cáscara de los huevos utilizando microscopía electrónica de barrido para determinar las causas de fracaso reproductor; se han obtenido muestras de 8 cáscaras de huevos colectados antes del uso masivo de pesticidas y depositados en museos, y que nos han permitido caracterizar la ultraestructura normal de la cáscara del huevo de los Quebrantahuesos. La cáscara es trilaminar y reticular, con la porción calcificada compuesta por tres capas, como se ha descrito en otras Falconiformes, así como poros simples y careciendo de la capa cristalina superficial. Todos los parámetros ultraestructurales mostraron mayores rangos de variación de lo esperado, sugiriendo que el Quebrantahuesos tiene una alta capacidad de adaptación a diferentes condiciones ambientales. Se han estudiado 27 huevos enteros y 90 cáscaras colectadas desde 1996 hasta 2013 en los Pirineos tras el fracaso reproductor y en colaboración con las autoridades medioambientales. Se investigaron también los niveles de pesticidas organoclorados y PCBs. Los análisis toxicológicos revelaron niveles muy bajos de contaminación, por lo que la contaminación por pesticidas organoclorados no era la causa del fallo reproductor. La fertilidad en la muestra actual es también mayor de lo esperado y el fallo reproductor se producía mayoritariamente al final de la incubación o en los primeros días de vida del pollo. Se ha encontrado que los huevos fértiles tenían mas longitud, cáscaras mas gruesas y mayores valores del Índice de Ratcliffe, siendo, por tanto, de mayor calidad. Desde 2006 el espesor de la cáscara y otros parámetros ultraestructurales están disminuyendo. Esta pérdida de calidad de los huevos desde 2006 está relacionada con las políticas sanitarias de la UE que han provocado un súbito descenso en la disponibilidad de cadáveres de animales domésticos y de recursos tróficos. Los cambios temporales encontrados en la carga de pesticidas organoclorados, que también se incrementa desde 2006, indica que los Quebrantahuesos están modificando sus estrategias de alimentación y búsqueda de alimento para explotar recursos de peor calidad y aumentando el riesgo de consumo de presas contaminadas o envenenadas.
The Bearded vulture (Gypaetus barbatus) is a long-lives threatened species with a European population of only 170 territories. The Spanish population, with 121 territories, is the largest European core, and conservation measures are being applied since 1985. However, in recent years, the population has been suffering from low rates of productivity and reproductive success which, in turn, are affecting the population dynamics and threatening its long-term viability. We evaluated the suitability of the study of eggshell using scanning electron microscopy in determining causes of breeding failure; eight samples from eggs collected prior to the massive use of pesticides were obtained from museums and allow us to characterize the normal ultrastructure of the Bearded vulture eggshell. The Bearded vulture eggshell is trilaminar and reticulate, with the calcified portion composed of three layers, as already described in other Falconiformes, and single pore channels and lacking the outer crystaline layer. All eggshell parameters showed higher range of variation than expected, suggesting that the Bearded vulture has a high capability for adaptation of different environmental conditions. From 1996 to 2013, in collaboration with the environmental authorities, 27 whole eggs and 90 eggshell fragments collected after breeding failure in nest of the Pyrenean population were studied. Levels of organochlorine pesticides and PCBs in whole eggs were also investigated. Toxicological analysis revealed low levels of contamination and, thus, that contamination with organochlorine pesticides was not the cause of breeding failure. Egg fertility was higher than expected in the studied sample and breeding failure was found to be mainly produced at the end of incubation or in the first days of the chick live. Fertile eggs were found to be longer, with thicker eggshells and higher Ratcliffe Index, thus showing better quality. From 2006 onwards, eggshell thickness and other eggshell parameters were decreasing. This lost of egg quality since 2006 was related to sanitary policies in the UE that caused sudden decrease in livestock carcasses and food shortages. Temporal changes in organochlorine levels also showed an increase since 2006, suggesting that the Bearded vultures are modifying their feeding and foraging strategies to exploit other food resources of lower quality and more contaminated, increasing the risk of consuming contaminated or poisoned preys.
The Bearded vulture (Gypaetus barbatus) is a long-lives threatened species with a European population of only 170 territories. The Spanish population, with 121 territories, is the largest European core, and conservation measures are being applied since 1985. However, in recent years, the population has been suffering from low rates of productivity and reproductive success which, in turn, are affecting the population dynamics and threatening its long-term viability. We evaluated the suitability of the study of eggshell using scanning electron microscopy in determining causes of breeding failure; eight samples from eggs collected prior to the massive use of pesticides were obtained from museums and allow us to characterize the normal ultrastructure of the Bearded vulture eggshell. The Bearded vulture eggshell is trilaminar and reticulate, with the calcified portion composed of three layers, as already described in other Falconiformes, and single pore channels and lacking the outer crystaline layer. All eggshell parameters showed higher range of variation than expected, suggesting that the Bearded vulture has a high capability for adaptation of different environmental conditions. From 1996 to 2013, in collaboration with the environmental authorities, 27 whole eggs and 90 eggshell fragments collected after breeding failure in nest of the Pyrenean population were studied. Levels of organochlorine pesticides and PCBs in whole eggs were also investigated. Toxicological analysis revealed low levels of contamination and, thus, that contamination with organochlorine pesticides was not the cause of breeding failure. Egg fertility was higher than expected in the studied sample and breeding failure was found to be mainly produced at the end of incubation or in the first days of the chick live. Fertile eggs were found to be longer, with thicker eggshells and higher Ratcliffe Index, thus showing better quality. From 2006 onwards, eggshell thickness and other eggshell parameters were decreasing. This lost of egg quality since 2006 was related to sanitary policies in the UE that caused sudden decrease in livestock carcasses and food shortages. Temporal changes in organochlorine levels also showed an increase since 2006, suggesting that the Bearded vultures are modifying their feeding and foraging strategies to exploit other food resources of lower quality and more contaminated, increasing the risk of consuming contaminated or poisoned preys.
Description
Tesis inédita de la Universidad Complutense de Madrid, Facultad de Veterinaria, Departamento de Medicina y Cirugía Animal, leída el 01/02/2016