Trace Metal Concentrations in Black Swan (Cygnus atratus) Eggshells from Urban and Coastal Wetlands in Southeastern Australia

Abstract

Urban wetlands are increasingly exposed to anthropogenic contaminants, including trace metals that may accumulate within aquatic food webs and pose risks to wildlife. This study quantified trace metal concentrations in post-hatched black swan (Cygnus atratus) eggshells collected from an urban wetland (Albert Park Lake, Melbourne; n = 17) and a coastal wetland (Pelican Island, Gippsland Lakes; n = 20) in southeastern Australia. Eggshells were analysed for arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), nickel (Ni), selenium (Se), and zinc (Zn) using inductively coupled plasma mass spectrometry (ICP-MS/MS). Significant spatial differences were detected for several elements, with Mn, Zn, and Pb concentrations significantly higher in eggshells collected from the urban wetland. In contrast, As, Cr, Fe, Ni, and Cu did not differ significantly between wetlands. Elevated metal concentrations in urban eggshells were consistent with anthropogenic contaminant inputs associated with urban runoff and sediment contamination. The findings demonstrate that black swan eggshells effectively reflect local environmental trace metal exposure and provide a practical non-invasive biomonitoring matrix for assessing contamination in wetland ecosystems.