Biomarkers of exposure and effects of environmental contaminants on swallows nesting along the Rio Grande, Texas, USA

• Published in: Environmental toxicology and chemistry 2006-06, Vol.25 (6), p.1574-1584
• Main Authors: Mora, Miguel A., Musquiz, Daniel, Bickham, John W., Mackenzie, Duncan S., Hooper, Michael J., Szabo, Judit K., Matson, Cole W.
• Format: Article
• Language: English
• Subjects: 1,1‐Dichloro‐2,2‐bis(p‐chlorophenyl)ethylene; 1-Dichloro-2; 2-bis(p-chlorophenyl)ethylene; Animal, plant and microbial ecology; Animals; Applied ecology; Aves; Biological and medical sciences; Biomarkers; Birds; Body Weight - drug effects; Breeding seasons; Coefficient of variation; Contaminants; DDE; Deoxyribonucleic acid; DNA; DNA damage; Ecotoxicology, biological effects of pollution; Environmental effects; Environmental Exposure; Environmental health; Environmental Monitoring; Environmental Pollutants - analysis; Flow Cytometry; Fundamental and applied biological sciences. Psychology; General aspects; Inorganic elements; Metal concentrations; Nesting; Nitrous oxide; Organ Size - drug effects; Organochlorine compounds; PCB; Petrochelidon fulva; Pollution; Polychlorinated biphenyls; Radioimmunoassay; Rio Grande; Selenium; Swallows; Texas; Thyroxine - blood; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution
• ISSN: 0730-7268; 1552-8618
• DOI: 10.1897/05-447R.1

We collected adult cave swallows (Petrochelidon fulva) and cliff swallows (P. pyrrhonota) during the breeding seasons in 1999 and 2000 from eight locations along the Rio Grande from Brownsville to El Paso (unless otherwise specified, all locations are Texas, USA) and an out‐of‐basin reference location. Body mass, spleen mass, hepatosomatic index (HSI), gonadosomatic index (GSI), thyroxine (T4) in plasma, DNA damage measured as the half‐peak coefficient of variation of DNA content (HPCV) in blood cells, as well as acetylcholinesterase and butyrylcholinesterase in brain were compared with concentrations of organochlorines, metals, and metalloids in carcasses to determine potential effects of contaminants on swallows during the breeding season. Concentrations of 1,1‐dichloro‐2,2‐bis(p‐chlorophenyl)ethylene (p,p′‐DDE) were significantly greater in swallows from El Paso than in those from most locations, except for Pharr and Llano Grande. All swallows from these three locations had p,p′‐DDE concentrations of 3 μg/g wet weight or greater. Swallows from El Paso either had or shared the highest concentrations of p,p′‐DDE, polychlorinated biphenyls, and 13 inorganic elements. Swallows from El Paso exhibited greater spleen mass and HPCV values as well as lower T4 values compared with those from other locations. Thyroxine was a potential biomarker of contaminant exposure in swallows of the Rio Grande, because it was negatively correlated with p,p′‐DDE and Se. Spleen mass was positively correlated with selenium and HSI and negatively correlated with body mass, GSI, Mn, and Ni. Overall, the present study suggests that insectivorous birds living in areas of high agricultural and industrial activity along the Rio Grande bioaccumulate environmental contaminants. These contaminants, particularly p,p′‐DDE, may be among multiple factors that impact endocrine and hematopoietic function in Rio Grande swallows.