Effects of experimental lead exposure on physiological indices of nestling great tits Parus major: haematocrit and heterophile-to-lymphocyte ratio.

Marcin Markowski,Adam Kaliński,Jerzy Bańbura,Joanna Skwarska,Mirosława Bańbura,Jarosław Wawrzyniak,Michał Glądalski,Gary Burness

doi:10.1093/conphys/coz067

Abstract

Lead (Pb) is recognized as one of the most toxic trace elements that can induce a wide range of negative health effects in wildlife. Because the investigation of basic environment-sensitive physiological indicators is easy to perform in wild birds, they have been considered as valuable bioindicators of lead contamination. The harmfulness of lead poisoning can depend on the type of exposure, and in most studies of birds, an effect of chronic lead exposition has been considered. In this study, we investigated whether a single exposure to specific doses of lead affected such physiological indices as haematocrit and the heterophil-to-lymphocyte ratio (H/L ratio). For this purpose, we conducted an experiment based on intentional lead supplementation, with the use of two different doses, applied to randomly chosen great tit (Parus major) nestlings from randomly selected broods. A few days after the exposure (when the nestlings were 15days old), we determined haematocrit and the H/L ratio as potentially sensitive physiological indicators of lead intoxication. We found that the treatment with lead resulted in a significant decline in haematocrit level. In addition, we found that the age when lead exposure occurred can be considered as an important factor influencing haematocrit variation. A decrease in haematocrit was observed on consecutive days of nestling life. In contrast, the H/L ratio did not show any significant response to lead exposure. These results clearly show that the assessment of haematocrit level for nestling great tits can provide a simple and rapid method of indirect evaluation of physiological effects of lead intoxication caused by a single exposure.

Highlights

IntroductionHeavy metal contamination is a well-known phenomenon which notably concerns the urbanized and industrialized areas of the world
The day of exposure to lead in the middle of the postnatal period significantly affected haematocrit variation in nestling great tits
We found that the supplementation of two different amounts of lead compounds in the diet of great tit nestlings, even when in the form of one-off dose, results in a significant haematocrit decrease (Fig. 1)

Summary

Introduction

Heavy metal contamination is a well-known phenomenon which notably concerns the urbanized and industrialized areas of the world. This is related to the growth of the human population observed on a global scale since the mid-19th century and, to the ongoing intensive development of industry (Swaileh and Sansur, 2006; Markowski et al, 2014). In urbanized areas which seem to be the most exposed, the most common sources of lead are by-products of combustion processes of fossil fuels used in energy and metallurgic industry (Hoff Brait and Antoniosi Filho, 2011; Chatelain et al, 2016)

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