- Full (HTML) - Full (PDF) - Related EHP Articles - PubMed:Related Articles - PubMed:Citation - Cited in PMC - Purchase This Issue

Raquel Baos,¹ Julio Blas,² Gary R. Bortolotti,² Tracy A. Marchant,² and Fernando Hiraldo¹

¹Department of Applied Biology, Estación Biológica de Doñana, Sevilla, Spain; ²Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada

Abstract
Background/Objective: Endocrine parameters have proven useful in the detection of early or low-level responses to pollutants. Although most of the studies on endocrine modulation have been focused on processes involving gonadal steroids, contaminants may target other parts of the endocrine system as well. In this study we examined the adrenocortical stress response and thyroid hormone status in free-living nestling white storks (Ciconia ciconia) in relation to heavy metals (zinc, lead, copper, cadmium) and arsenic levels in blood.

Methods: Fieldwork was conducted in an area polluted by the Aznalcóllar mine accident (southwestern Spain) and in a reference site. We used a standardized capture, handling, and restraint protocol to determine both baseline and maximum plasma corticosterone. Circulating levels of thyroxine (T₄) and triiodothyronine (T₃) were also measured.

Results: No effects of metals or As were found on baseline corticosterone, but maximum levels of corticosterone were positively related to Pb in both locations. This relationship was stronger in single nestlings than in birds from multiple-chick broods, which suggests a greater impact of Pb on more stressed individuals. Metal pollution did not affect plasma T₄ or T₃ levels, although thyroid status differed with location.

Conclusions: Because a compromised hypothalamus–pituitary–adrenal (HPA) function can have far-reaching consequences in terms of altered behavioral and metabolic processes necessary for survival, our results suggest that birds exposed to sublethal Pb levels may be at risk through an altered adrenocortical stress response, and further support the idea that HPA axis-related end points might be useful indicators of metal exposure and potential toxicity in wild animals.

Key words: Aznalcóllar, corticosterone, free-living birds, handling-restraint protocol, lead, metal pollution, stress response, thyroxine, triiodothyronine, white stork. Environ Health Perspect 114: 1497–1501 (2006) . doi:10.1289/ehp.9099 available via http://dx.doi.org/ [Online 11 July 2006]

Address correspondence to R. Baos, Department of Applied Biology, Estación Biológica de Doñana (CSIC) , Avda Mª Luisa s/n Pabellón del Perú, Apdo 1056, E-41013 Sevilla, Spain. Telephone: (34) 95 423 23 40. Fax: (34) 95 462 11 25. E-mail: raquel@ebd.csic.es

We thank A. Román, A. Tamayo, J. Ramírez, M.C. Quintero, J.L. Arroyo, B. Jiménez, R. Tobar, C. Alonso, C. Sánchez, R. Álvarez, R. Rodríguez, G. García, and N. Pastor for assistance during fieldwork ; J.C. Núñez, J.L. Tella, and S. Cabezas for providing logistic support and access to the breeding colonies ; V. Benito for analyzing metals ; and R. Jovani for providing valuable comments on earlier drafts of the manuscript.

This work was supported by Empresesa de Gestion Medioambiental, S.A., the European Union (i3P) , and the Isabel María López Martínez Memorial Scholarship in a grant to J.B. ; the Spanish Ministerio de Educación y Cultura in a postdoctoral fellowship to J.B. and a predoctoral F.P.U fellowship to R.B., and a Natural Sciences and Engineering Research Council of Canada grant to G.R.B. The Junta de Andalucía also provided funds to support this research.

The authors declare they have no competing financial interests.

Received 14 February 2006 ; accepted 11 July 2006.