Interactions between heavy metal exposure and blood biochemistry in an urban population of the black swan (Cygnus atratus) in Australia

This research was published in the journal Archives of Environmental Contamination and Toxicology by Damien Nzabanita, Raoul A Mulder, Damian C Lettoof, Stephen Grist, Jordan O Hampton, Jasmin Hufschmid, Dayanthi Nugegoda

Black swans are one of the most common waterbird species found in Australian wetlands, rivers, and urban parks. They are one of Australia’s largest waterbirds, with an average mass of 7.0 kg for males and 5.6 kg for females.

Our study species, the black swan (Cygnus atratus), and urban study site, Albert Park Lake, Melbourne, Australia (a) hand-capture method (b) and blood collection technique from the brachial (wing) vein (c). Photos by Damien Nzabanita

We caught 15 swans in 2021 and (a) measured heavy metal concentrations in feather samples, (b) measured plasma biochemical values in the same birds, and (c) explored correlations between the two sets of variables.

Results for heavy metal levels and blood plasma biochemistry values are shown in the Tables below.

Concentrations (mean ± SE, mg/kg) of heavy metals in feathers of 15 black swans (Cygnus atratus) captured at Albert Park Lake, Melbourne, Australia, in 2021.

Concentrations of plasma biochemical markers (mean ± SE) in different age and sex classes from 15 wild black swans (Cygnus atratus) captured at Albert Park Lake, Melbourne, Australia in 2021. Sample sizes vary for each biochemical marker due to assay reliability.

There was only a significant association found between feather-heavy metals and plasma analytes. This was a negative relationship between cholesterol and zinc.

None of the heavy metals examined in feathers were markedly elevated. Generally, the concentrations of heavy metals we report in these black swans are lower than in other swan species (table below), except for zinc and mercury.

The concentration of heavy metals (mg/kg dry weight: mean ± SE) in feathers of swans (Cygnus spp.) from different global regions as reported in the published literature. NR = not reported.

This study provides unique knowledge on the growing awareness of environmental impacts facing Australian bird species by examining chemical threats to an urban bird population, and the effects of contaminant exposure on avian physiology.

The full article can be found here