They analyze the presence of 50 elements in the blood of eagle owls exposed to different scenarios of environmental contamination

    Relatively high levels of lead (Pb), arsenic (As) and thallium (Tl) in eagle owl chicks in the surroundings of the old mining district "Cartagena-La Unión" warn of the risk posed by mining contamination for the conservation of avifauna


    Some metals and metalloids, such as lead (Pb), mercury (Hg), cadmium (Cd) and arsenic (As), are well known for their high persistence, their ability to bioaccumulate and the toxic effects they cause in humans. wildlife exposed to elevated levels. However, the exposure and effects on fauna of other lesser-known trace elements, such as “rare earths”, have been scarcely explored..

    The extraction and use of many of these trace elements is intensifying as they have become critical minerals for the advancement of modern technology, which is why it is very necessary to know better what is its incidence in ecosystems and its potential impact on wildlife.

    This was the objective of a research work carried out by scientists from the University of Murcia, the University of Las Palmas de Gran Canaria, the Center for Biomedical Research in Physiopathology of Obesity and Nutrition (CIBEROBN) and the University of Turku (Finland). , with the participation of Research Group in Wildlife Toxicology of the Instituto de Investigación en Recursos Cinegéticos (IREC – CSIC, UCLM, JCCM), whose results have recently been published in the journal Environmental pollution.

    Birds of prey are considered good "sentinel species" of environmental pollution, so the scientists used as a study model the eagle owl chicks (vulture vulture) to evaluate the blood levels of a total of 50 mineral elements as a biomarker of exposure to environmental contamination by metals. In addition, in the blood plasma of the samples collected analyzed the levels of vitamin E and carotenoids as biomarkers of effect, since the physiological state of these nutritional components, which play a fundamental role in the growth and development of chickens, can be affected by exposure to toxic elements.

     

    the eagle owl (vulture vulture) is a nocturnal, resident (nonmigratory) and strongly territorial raptor. Studying chickens, in addition to being easier than capturing and sampling adult individuals, makes it possible to identify exposure to local contamination over a relatively short period of time (weeks).

    The nests sampled, located in the Region of Murcia, were located in three well-differentiated areas by land use and potential sources of contamination. Thus, one of the eagle owl populations was located in the catchment area of ​​an industrial complex dedicated to the production of plastics and whose activity is associated with the emission of various metals into the environment. A second population was located in the old metallurgical mining district "Cartagena-La Unión", which is currently abandoned and has never been restored or rehabilitated, so it continues to be a source of metal contamination. Finally, the third population studied was located on agricultural land where there are no known sources of contamination by metals, in order to be used as a reference.

    The results obtained clearly show that the local contamination by metals derived from the old mining district contributes significantly to the fact that eagle owl chicks in this area have levels of Pb, As and thallium (Tl) in their blood almost 20 times higher than those in the reference area. This increase in blood levels of Pb, As and Tl was positively associated with an increase in plasma vitamin E concentration. Vitamin E is one of the most powerful nutrients in the antioxidant system of cells, so this observation can be interpreted as a protective physiological response to alleviate the oxidative effect caused by exposure to polluting metals.

     

    The study also shows higher plasma levels of lutein (the most abundant carotenoid in birds of prey) in eagle owl chicks from the areas impacted by the old mining district and the industrial complex, which could be mainly due to differences in diet and /or availability of prey compared to the reference area.

    This work reveals the value of vitamin E as a biomarker of physiological effects associated with exposure to polluting metals in birds. Also as already shown in a previous study with nightjars, shows that contamination by metals could constitute a threat to the conservation of avifauna in old mining areas. Finally, it provides valuable ecotoxicological information by establishing the basal levels of exposure of a bird of prey to a total of 50 little-known metallic elements.

    The scientific publication of this research is available at: