UNDERWATER sound linked to human activity could alter the behaviour of seabed creatures which play a vital role in marine ecosystems, according to new research.

The study found exposure to sounds that resemble shipping traffic and offshore construction results in behavioural responses in certain invertebrate species which live in the marine sediment.

These species make a crucial contribution to the seabed ecosystem as their burrowing and bioirrigation activities (how much the organism moves water in and out of the sediment by its actions) are vital in nutrient recycling and carbon storage.

The study, from the University of Southampton and reported in the journal Scientific Reports published by Nature, showed that some man-made sounds can cause certain species to reduce irrigation and sediment turnover.

Such reductions can lead to the formation of compacted sediments that suffer reduced oxygen, potentially becoming anoxic (depleted or dissolved oxygen and a more severe condition of hypoxia), which may have an impact on seabed productivity, sediment biodiversity and also fisheries production.

Lead author Martin Solan, professor in marine ecology, said: "Coastal and shelf environments support high levels of biodiversity that are vital in mediating ecosystem processes, but they are also subject to noise associated with increasing levels of offshore human activity.

"Previous work has almost exclusively focused on direct physiological or behavioural responses in marine mammals and fish, and has not previously addressed the indirect impacts of sound on ecosystem properties.

"Our study provides evidence that exposing coastal environments to anthropogenic sound fields is likely to have much wider ecosystem consequences than are presently understood."

Tim Leighton, professor of ultrasonics and underwater acoustics and study co-author, said: "There has been much discussion over the last decade of the extent to which whales, dolphins and fish stocks, might be disturbed by the sounds from shipping, wind farms and their construction, seismic exploration etc.

"However, one set of ocean denizens has until now been ignored, and unlike these other classes, they cannot easily move away from loud man-made sound sources.

"These are the bottom feeders, such as crabs, shellfish and invertebrates similar to the ones in our study, which are crucial to healthy and commercially successful oceans because they form the bottom of the food chain."