Mussels are suffering from stress as a result of underwater noise from ships, research suggests.
Scientists said that while this was not “immediately dangerous” for the creatures, it could impact on growth and may even help explain a decline in mussel banks in some areas of the UK.
Previous studies have looked at how noise affects larger marine creatures, such as whales and dolphins.
Now a team of marine scientists from Napier University and Heriot Watt University, both in Edinburgh, have looked at the impact on mussels.
Mussels don’t have ears but they can detect changing sound levels in their environment
Despite the molluscs not having ears, the researchers found they can detect changing sound levels in their environment.
The scientists collected mussels from the shore at Musselburgh, outside Edinburgh, and tested their response to noise in a lab at the St Abbs Marine Station near Eyemouth – a charity dedicated to marine science, conservation and education.
Karen Diele, from Edinburgh Napier University, the co-director of research at the marine station, said: “The blue mussel is an extremely important invertebrate in the UK: it is commercially valuable and it plays an essential ecological role as a reef builder and a filter-feeder that keeps the water clean.”
She added: “Mussels don’t have ears but they can detect changing sound levels in their environment.
“We recorded and played the sound of a ship’s motor to a sample of blue mussels in a controlled setting, and measured biochemical and behavioural changes in the mussels.
“For the first time in a marine species, we detected noise-induced changes in DNA integrity, indicating an underlying source of stress.”
Matt Wale, also from Edinburgh Napier University, told how the mussels that had been exposed to noise consumed 12% less oxygen – adding this would lead to increased energy use and potentially slower growth.
He continued: “The filtration rate, or how much algae they consume, decreased by over 80% and there was a 60% increase in valve gape, which means the mussels are spending more time vulnerable to predators.”
Another member of the team, Mark Hartl from Heriot-Watt University, stated: “Given the wide distribution of mussels in areas where they may be exposed to noise, the impact of noise does not appear to be fatal or immediately dangerous for mussels.
“However, this doesn’t mean it isn’t having a long-term effect on mussel populations in high noise areas, it could be affecting their growth, reproductivity and may help explain the decline of mussel banks in some areas of the UK.”
He added: “It’s important that we understand how noise is stressing mussels in environmental risk assessments so that we can ensure environmental policy and regulation is effective.”
The research was supported with funding from the Marine Alliance for Science and Technology for Scotland.
The team is also looking at how Norway lobsters, squid and native oysters respond to underwater noise.