Scientists are to measure the effect on the marine environment and wildlife of devices that harness tide and wave energy using sonar technology that has, for the first time, been successfully deployed on the seabed.

Researchers from the Universities of Bath and Aberdeen, together with the expert acoustic and technical teams at Marine Scotland Science, have combined two sonar systems on a seabed frame placed within 25-metres of a tidal turbine. This monitors fish and diving seabirds that pass through or feed within the location; in particular, the study is assessing how fish and seabirds interact with the installation.

This is the first time these sonars – which are normally mounted on a ship as separate units looking down at the seabed – have been adapted to operate autonomously in combination for several weeks, while facing upwards. Collecting the data in this way allows imaging of a full ‘acoustic curtain’ along the tidal flow and around the turbine in a highly challenging environment.

A marine radar has also monitored activity on and above the sea surface, mapping the currents and waves at the site and tracking the behaviour of birds and marine mammals in the immediate area. Along with all the high tech instrumentation, a skilled birder, University of Aberdeen PhD, James Waggitt, made observations on high ground nearby which identified the times and types of seabirds diving for food within the site.

Dr Philippe Blondel, Senior Lecturer in Physics and Deputy Director of the Centre for Space, Atmosphere and Ocean Science at the University of Bath, said: “Using waves and tides as a renewable energy source is more predictable than solar or wind energy, and of course there isn’t the same visual impact. Tidal energy devices alter the local water flow and this project aims to measure and assess whether this has an effect on the wildlife around it.

“We’ll be sharing the knowledge gained with other users and providing data as an open resource for environmental scientists at the end of the project. Our presentation of the first results at the European Conference in Underwater Acoustics, a few days after recovery, has been extremely well received by operators and researchers working with marine renewable energies.”

Dr Beth Scott, Senior Lecturer in Marine Ecology at the University of Aberdeen, said: “After detailed analysis these data will determine how mobile animals, such as seabirds and their fish prey, behave around marine renewable devices over an entire fortnightly tidal cycle – as the instruments successfully ‘pinged’ away and collected data for every second of that two-week period. This research will help to determine the actual risk of collision between marine animals and turbines and will allow governmental marine spatial planners a step change in the level of certainty about where to allow renewable developments. ”

Further reading:
National Oceanography Centre