Aggressive Vibrio bacteria have been found in parts of Sydney Harbour, including Rozelle, Parramatta Park and Olympic Park. Photo: Adam Hollingworth
An aggressive species of marine bacteria responsible for many more deaths than sharks worldwide each year has been found in Sydney Harbour, with experts predicting outbreaks in spots along the city’s waterfront as water temperatures rise with global warming.
Vibrio bacteria, which includes the species that causes cholera, can cause serious illness in humans and animals, including gastrointestinal sickness through consumption of contaminated seafood and flesh-eating infections in swimmers.
According to a new study by University of Technology Sydney scientists, two species of potentially dangerous Vibrio bacteria were detectable in particularly high concentrations when the water was warmest and in areas of mid-salinity, around Parramatta Park, Olympic Park and Rozelle.
In the report, published in Frontiers of Microbiology on Tuesday, UTS researchers detail the composition of water samples collected from Sydney Harbour between Parramatta Park and Chowder Bay.
While the cholera-causing strain of Vibrio cholerae was not found in any of the samples, a closely related strain of this species was detected in high quantities. It can cause skin infections and gastrointestinal infections if ingested or exposed to open wounds.
A second pathogen, Vibrio vulnificus, was also detected. It is responsible for 95 per cent of all seafood-related deaths in the US, and aggressive flesh-eating infections in swimmers, where it carries a mortality rate of up to 50 per cent amongst those infected, the report states.
Co-author and associate professor at UTS’ Climate Change Cluster, Justin Seymour, said the findings have serious implications for Sydney Harbour users and authorities as coastal water temperatures rise in south-east Australia, a region considered a global climate change hot spot.
“Given that these are naturally occurring marine organisms, it’s not surprising that we’re seeing them,” he said. “People don’t need to be super alarmed about their occurrence in Sydney Harbour at the moment. But what we’ve seen in other parts of the world are links between increasing seawater temperatures and the abundance of these bacteria and associated illnesses.
“I don’t think people should change the way they use their local beaches, but it is something local management authorities should be aware of. There are potentially harmful effects for humans if outbreaks of these bacteria in the environment become more severe and common.”
Peter Steinberg, director of Sydney Institute of Marine Sciences, welcomed the report which is part of a wider program attempting to understand the ecosystems and diversity of the harbour in collaboration with SIMS. He said the results warrant further study and awareness of microbial changes in Sydney Harbour.
A spokesperson for the Department of Health said swimming in water always carries the risk of infection.
“Germs, including a large range of bacteria and viruses, occur naturally and are very common in the environment. Vibrio species are commonly found in aquatic environments. Many of these bacteria and viruses are harmless to people. However some can be harmful if swallowed or if they infect wounds.”
Simple precautions include “not getting water in your mouth, keeping any wounds covered with a watertight dressing and avoiding injuries on sharp objects”.