Over the last two decades the level of activity in the seas and oceans across the world has drastically increased. Today there is an ever growing number of offshore oil rigs, wind and wave farms, alongside extensive shipping, dredging and industrial harbour development. But very little is known about what impact man-made noise has on the marine environment, what safe levels are and how you can mitigate it. Judy Wing went to meet underwater acoustics expert Dr Paul Lepper from the University’s Department of Electronic, Electrical and Systems Engineering, who is hoping to answer these questions.
For more than 20 years Dr Paul Lepper and his colleagues have carried out extensive research on noise levels in the waters surrounding the UK and across the world. They work with a number of high profile national and international universities, businesses and organisations, including the National Physical Laboratory (NPL), to try and better understand the impact underwater noise has on the marine environment.
Today there is growing pressure across the world for marine industries and developers to monitor and attempt to reduce the noise pollution their activities create. However despite this, in the UK and many other countries formal regulation regarding aquatic noise levels is relatively new and still evolving. One key reason for this is that it is still not known what a safe or acceptable level of noise is for marine life.
“The main barrier to effective regulation of underwater noise is lack of information,” Dr Lepper added. “We have found ourselves in a situation where scientific research is playing catch up with the demand for facts. So much work still needs to be done in this area and we are involved in several projects to try and fill in the gaps.”
A key step forward in this field of research was the discovery of the Temporary Threshold Shift (TTS) – the point at which noise has a temporary detrimental effect on hearing – for harbour porpoises. Dr Lepper worked with experts in Germany to establish for the first time the TTS for this species in relation to seismic airguns and construction of offshore wind farms. This was an important breakthrough that now enables scientists to better predict what noise levels would cause porpoises and similar marine mammals harm.