Study finds underwater noise pollution from human activity could have profound impacts on marine life
In short:
A study has found noise pollution caused by human activities in estuaries across New South Wales could have devastating impacts on marine life.
Researchers say noise from recreational boating is so loud, it has the potential to mask some marine species' ability to communicate and navigate.
What's next?
Researchers say the findings could inform policy and practice to minimise noise pollution in lakes and rivers.
The first study into underwater noise pollution in estuaries on the east coast of Australia has uncovered the potentially devastating impacts noise from human activities is having on marine life.
Led by University of Newcastle PhD candidate Brittney Valenzisi, the study involved collecting thousands of hours of underwater sound recordings to understand what noise can be heard beneath the surface in four estuaries across the state.
"We found an array of sounds, including boats, wind and wave activity, car traffic going over a bridge and underwater pump stations," Ms Valenzisi said.
Aeroplanes and even people talking could also be heard in the recordings, some from a depth of 6 metres.
Loading...Ms Valenzisi said many marine animals relied on sound for survival and anthropogenic noise pollution heard underwater was "concerning".
"Marine life use sound for communication, feeding, navigation, to detect and deter predators, and for mating cues as well," she said.
"The underwater noise pollution recorded in some areas was so loud it has the potential to mask their ability to communicate."
The research
While other studies have been done on underwater noise pollution, Ms Valenzisi said much of it had focused on noise in the ocean and its impact on larger animals such as whales and dolphins.
"But if you consider an estuary, it's much smaller in size and sound can bounce, reflect and potentially amplify in this smaller environment," she said.
"Which can have detrimental impacts on estuarine fauna."
Ms Valenzisi used a hydrophone, which is "basically an underwater microphone", to record sounds in four lakes across the Hunter, Central Coast and South Coast in New South Wales.
Hydrophones have been placed at the bottom of four estuaries, some up to 6 metres deep. (Supplied: University of Newcastle)
"It's taken me around a year to collect all of the data for these estuaries," she said.
"I think to date, across my PhD we've recorded close to around 4,000 hours of sound."
She then had to decipher the thousand hours of underwater sounds, listening out for human-made noise.
Noise from recreational boating was found to be the biggest contributor to noise pollution in the estuaries.
Ms Valenzisi then compared levels of noise pollution in estuaries in urban areas such as Tuggerah Lake and Lake Macquarie to Burrill Lake, which is surrounded by a quiet national park.
"Boats were audible in 68 per cent of sound files recorded in Lake Macquarie … while in Burrill Lake, noise pollution from boats was recorded in 30 per cent of audio recorded," she said.
What does this mean for marine life?
Ms Valenzisi said while more research was needed to understand the full extent noise pollution could have on different marine species, she had identified a range of potential impacts.
"It's species dependent, but some impacts include deafness, so it [noise pollution] can mask their ability to communicate with one another," she said.
Some of the anthropogenic noise she recorded overlapped with the frequency that fish communicate at.
Research shows underwater noise can afffect fish health. (Supplied)
"Fish can actually lose their buoyancy, it can lead to disorientation and stranding," Ms Valenzisi said.
"Studies show it can also increase cortisol levels, so their stress levels, which can impact their physiological traits as well, which can also increase their risk of illness."
Joni Pini-Fitzsimmons is a marine scientist and research fellow at Charles Darwin University.
She said the study provided important baseline information researchers could build on.
"So you expect in estuaries like where this study was conducted, that there would be a high degree of sound … but this has found what those sound levels are and sound sources are," Dr Pini-Fitzsimmons said.
"So it's a really important starting piece … for other research to then start looking at how does this impact on specific species and their movements and their interactions with each other, and start taking that up to a whole ecosystem level."
Informing policy and practice
Megan Huggett, who lectures in marine science at the University of Newcastle, supervised the PhD project.
She said the research could inspire change to lower noise pollution.
"Boats were the main contributor to those higher levels of sound," she said.
"We could restrict boating areas or reduce speed limits to reduce noise levels during breeding time or when species are most active," she said.
"Modifying propellers and hulls of boats has proven to be quieter as well."
Megan Huggett says some of the noise heard in the study recordings is "surprising". (Supplied: University of Newcastle)
Dr Huggett said as coastal communities continued to grow in NSW, estuaries were becoming more urbanised and she hoped authorities would consider the impact of noise pollution when planning for these areas.
She said ensuring the health of marine life in estuaries was important, not only for the animals themselves, but for recreational and business purposes.
"Estuaries support 87 per cent of the population of New South Wales," she said.
"They support multi-billion dollar commercial and recreational activities."
The study was published in Marine Pollution Bulletin and funded by Lake Macquarie City Council’s Environmental Research Grants Program.