The study, conducted between December 2022 and February 2023, examined chytrid fungus levels in two frog species in Sydney's Royal National Park, downstream from the Metropolitan Mine. Lead author Shannon Kaiser, an ecotoxicologist from Macquarie University, said the wastewater could not be definitively identified as the cause, but described the association as concerning.
"However, the association is concerning and suggests pollution and wildlife disease risk may interact in freshwater ecosystems," Mr Kaiser said. He called for water quality monitoring programs to be expanded to include biological effects such as frog health and pathogen loads, rather than just pollution, temperature and oxygen.
The study period followed unlicensed discharges of coal-contaminated water from the mine into Camp Gully Creek. The NSW Environment Protection Authority subsequently fined the mine's operator, Peabody, more than $500,000 and issued clean-up orders and new regulatory conditions.
Cooper Riach from the Sutherland Shire Environment Centre, who raised concerns after witnessing the discharge in 2022, described finding an oily, thick substance in the creek. "You could put your hand into the water and just swish your hand around a bit and all this oily, thick, viscous substance would come off the base of the creek," he said.
In response, a Peabody spokesperson said any causal link between water chemistry changes and frog infection intensity was speculative. The company noted it had invested more than $1.5 million in upgrades since 2022, including expanded water storage capacity and real-time water quality data publication. Peabody also separately funds a three-year program in Royal National Park to support rehabilitation of the southern stuttering frog, a species affected by chytrid fungus.