Urban trace metal contamination is negatively associated with condition and wing morphology in a common waterbird

Piotr Minias, Marcin Markowski, Mirosława Słaba, Amelia Chyb, Joanna Drzewińska-Chańko, Jan Jedlikowski, Jerzy Bańbura, Radosław Włodarczyk

Urban areas suffer from different forms of environmental pollution by light, noise, and chemicals. Pollution by heavy metals has long been associated with industrialization and urbanization processes, increasing the risk of bioaccumulation and compromising the health, condition, and fitness of urban animals. Here, we aimed to investigate the effects of urbanization on bioaccumulation of six heavy metals (Cu, Ni, Zn, Cd, Pb, and Mn) in the integumentary structures (feathers) of a non-passerine waterbird, the Eurasian coot Fulica atra. For this purpose, we quantified and compared heavy metal concentrations in feathers of 300 coots from four pairs of non-urban and urban populations associated with major agglomerations in Poland. We found that concentrations of three heavy metals (Cu, Ni, and Zn) were significantly higher in coots from the urban landscape, compared to individuals from natural or semi-natural non-urban habitats. Elevated heavy metal concentrations were negatively associated with morphology (wing length) and condition (body mass and blood haemoglobin concentration) of coots, and these associations were detected exclusively in the urban landscape. The evidence of elevated heavy metal pollution in the non-urban landscape was limited. Only one heavy metal (Pb) showed a negative association with health parameters of non-urban coots, promoting elevated physiological stress (heterophil/lymphocyte ratios). Our results suggest that heavy metal contamination may be considered an important cost of urbanization processes in wildlife. We argue that mitigation of heavy metal pollution in urban ecosystems should likely increase their sustainability and viability of urban animal populations.