This study explored the movement of four metals (iron, zinc, aluminium and barium) across trophic levels; water, sediment, aquatic invertebrates and platypus. Two metals are essential for mammalian function (Fe and Zn), two are not essential (Al and Ba). There are currently no published studies that examine metal load and platypus health. Studies have examined other aquatic apex predators, including river otters, suggesting fur as a threshold excretory method for metal contaminants. This research aimed to determine if similar trends are found for platypus.
Samples of water, sediment, macroinvertebrates and platypus fur were collected from four sites across the Sydney basin, in the Hawkesbury-Nepean catchment, two creeks, (Fitzgerald Creek, (Warrimoo) and Mulgoa Creek (Mulgoa) and one river Bargo River (Tahmoor). Prior to analysis macroinvertebrates were freeze-dried and platypus fur samples were cleaned. All samples were then analysed at a NATA-accredited facility for analysis.
All metals moved through the environment and accumulated in platypus fur. The essential metals, iron and zinc were more readily accumulated into the fur of platypus in greater concentrations than the non-essential metals, barium and aluminium (399mg/kg, 173mg/kg, 20mg/kg and 45mg/kg respectively).
Platypuses, while not considered endangered in NSW, are under threat from increased urbanisation and continued water pollution. Current aquatic regulatory frameworks do not consider broader-scale ecosystems and higher-order trophic levels when determining pollutant limits in Environmental Protection Licences. This study aims to consider the end point of metal pollutants and provide recommendations to regulators, stakeholders and community groups.