engleski

No harm done: biomarker assessment in white stork nestlings' blood from differently polluted areas in Croatia

The white stork (Ciconia ciconia) is an abundant breeding species in continental Croatia, a top predator inhabiting mostly agricultural fields, wetlands, and meadows. White stork nestlings are a good bioindicator species providing information regarding the local environment. Due to environmental transformation and intensive agriculture, white storks leave their breeding areas indicating a decline in natural value. During breeding season 2021, as a part of white stork ringing scheme, blood samples (4 mL) were collected from the nestling brachial vein (n = 106) for enzyme analysis, few feathers were plucked for sex determination, and beak length was measured for determining hatching order. Study areas are in the proximity to three major rivers in Croatia: Sava, Drava and Danube, and one sampling area is located in Zagreb, landfill Jakuševec. A set of biochemical biomarkers: acetylcholinesterase (AChE), carboxylesterase (CES), and glutathione reductase (GR), as well as molecular biomarkers: glutathione (GSH) and reactive oxygen species (ROS) were analysed. By analysing a set of specific and non-specific biomarkers in two blood fractions we obtained a more complete overview of the nestlings' physiological condition. Lower AChE activity is recorded in Podunavlje, an area known for high fertiliser use and intensive agriculture, indicating the presence of chemical stressors in the environment. On the other hand, oxidative stress biomarkers show the lack of statistical difference in regard to sampling areas. Due to complex antioxidative responses, other antioxidative mechanisms may be included, thus no conclusion could be made about pollutants from the environment and/or their possible effect on the nestlings.

blood sampling ; white-stork nestlings ; biomarker analysis ; Croatia

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