Antarctic fauna at risk from human pathogenic bacteria

Human sewage disposal into the Antarctic marine environment poses a risk of introducing non-native organisms, and ‘gene pollution’ from pathogenic human bacteria, according to research published in Environmental Pollution in May.

The research*, led by Macquarie University, was part of a larger environmental impact assessment of sewage discharge at Davis research station, conducted by the Australian Antarctic Division in 2009–10 (see previous story).

Macquarie University biologist Dr Michelle Power, and her colleagues, showed that the presence of human bacteria in the marine environment, specifically Escherichia coli, could affect the diversity and evolution of native Antarctic microbial communities and the health of associated Antarctic fauna.

The team used DNA technology to identify genes commonly associated with E. coli in humans, and track what happened to these bacteria after they were released into the Antarctic environment in sewage.

Testing of E. coli isolated from Antarctic marine invertebrates, and faecal samples from seals and penguins, showed that human E. coli had established in Antarctic animals. The bacteria also contained antibiotic resistance genes within mobile genetic elements, known as integrons, which can move within and between microbial species.

“Our study confirms that the sewage disposal practice occurring at the time of this study facilitated the introduction of non-indigenous microorganisms into the Antarctic ecosystem, specifically human E. coli strains with pathogenic characteristics,” Dr Power said.

“Some of the E. coli strains that we detected in seal faeces are known to cause disease in humans and birds.

Antibiotic resistance genes were also discovered in many of the E. coli strains tested. They were not detected in penguins or seals, but were found in a filter-feeding shellfish species that is part of Antarctic food-web.

“The integrons and associated genes these E. coli are carrying are polluting the Antarctic environment and their presence may affect the evolution of endemic microbes through the transfer of novel genetic material,” Dr Power said.

In accordance with Antarctic Treaty requirements, the release of untreated sewage into the sea is allowed under certain conditions and is common practice at many coastal research stations. With most stations located on the Antarctic coastline, the research provides scientific evidence to support development of improved regulations for human waste disposal.

“With more than 30 nations operating in Antarctica, and around 4000 people living at Antarctic research stations during the summer months, the potential impact of their presence on the surrounding ecosystem cannot be underestimated,” Dr Power said.

She said further research is needed to identify a baseline for the natural distributions and genetic and physical characteristics of microbes associated with Antarctic marine life.

“Simple and rapid genetic tools can and should be used to determine the extent of gene pollution across Antarctica,” she said.

“Such approaches provide a means for measuring impacts of microbial pollution in Antarctica.”

Wendy Pyper1 and Anna Garcia-Loyola2
1Australian Antarctic Division, 2Macquarie University

*Australian Antarctic Science project 2936