Biomonitorización de contaminantes ambientales persistentes y evaluación de efectos subletales en aves silvestresuso de plumas y biomarcadores de estrés oxidativo

Abstract

Title: Biomonitoring of persistent environmental pollutants using feathers and assessment of sublethal effects using oxidative stress biomarkers in wildbirds ABSTRACT Biomonitoring programs are conducted in order to assess concentrations of environmental pollutants and to know the effects that contaminants may cause in living beings. The general objective of this thesis was to assess the organochlorine pesticides (OC) and metals exposure in wildbirds, with a focus on the use of feathers as biomonitoring tool, and the sublethal effects induced by metal exposure using oxidative stress biomarkers. OC and Hg concentrations were analyzed in internal tissues and feathers of Razorbill (Alca torda), and metals (Hg, Pb, Cd, Cu and Zn) concentrations and oxidative stress biomarkers (catalase, CAT; glutathione peroxidase, GPx; superoxide dismutase, SOD; glutathione-S-transferase, GST; total glutathione, GSH; and thiobarbituric acid reactive substances, TBARS) were analyzed in blood and feathers of Eagle owl (Bubo bubo) and Griffon vulture (Gyps fulvus). Significant correlations were found between Hg concentrations in internal tissues and feathers of both Razorbill and Eagle owl. Prediction equations of the Hg concentrations in brain and kidney for Razorbills, and in blood for Eagle owl, were provided using the Hg concentrations in feathers. Results found in this thesis confirm that the feather is an excellent tool for Hg biomonitoring. Regarding the use of feathers in OC biomonitoring, more studies are needed to evaluate the external contamination, whose influence has been proved in this thesis. Besides, few and low significant correlation coefficients were obtained between OC concentrations in feathers and internal tissues of Razorbills, most probably because of the time elapsed between the last molt of the bird and the sampling moment. Therefore, further studies are required in order to clarify the effect of this time on the correlations. In general, OC and metal concentrations found in Razorbills from Mediterranean area, Eagle owls from Murcia Region and Griffon vultures from Valencian Community are below levels known to cause adverse reproductive and behavioural effects in birds. Regarding the study of the oxidative stress parameters, correlations found between some oxidative stress biomarkers in both Eagle owl and Griffon vulture prove that the antioxidant defence operates as a balanced and coordinated system. The antioxidant enzymes GPx and CAT may function as useful biomarkers of Pb and Cd exposure and effect, while SOD seems to be a useful biomarker of Hg exposure in both owls and vultures. Besides, TBARS levels may be useful biomarkers of Pb-induced lipid peroxidation. Interspecific differences were found in the response of the antioxidant system against Cd and Pb exposure in Eagle owl and Griffon vulture. Thus, Pb concentrations lower than 20 ?g/dl in blood were able to produce an induction of TBARS levels of 28% and 11% in red blood cells of owls and vultures, respectively. Results suggest that Griffon vulture may be more resistant to Pb-induced oxidative damage than Eagle owl. Finally, results found in this thesis may help to establish no-effect reference levels for metals in different bird species. However, more studies are needed to provide new information about the effects that these metals can produce on oxidative stress biomarkers in different wildbird species. Keywords: Razorbill, Eagle owl, Griffon vulture, biomonitoring, feathers, metals, organochlorines, contaminants, toxicology, oxidative stress.