Doctoral thesis defense of Elisabeth Debusschere, March 11, 2016: “On the effects of high intensity impulsive sound on young European sea bass Dicentrarchus labrax, with special attention to pile driving during offshore wind farm construction”.
“The European guidelines concerning underwater noise as a result of human activities at sea should be revised,” concludes ILVO/Ghent University research Elisabeth Debusschere at the end of her doctoral studies. Using experiments she tested the effects of intense underwater sound bursts on young sea bass, the result of pounding windmill foundations into the sea floor. Originally, she expected to see widespread death of the young fish in the area of the pile-driving, but instead observations revealed that they survive exposure to loud sounds close to a construction site. Even though they are sensitive to intense underwater sounds due to their swim bladder, and the fish did show signs of severe stress and changed behavior, these effects were only temporary. The tests with seabass show that the effects of pile-driving noise for young fish with a pressure-sensitive swim bladder are generally milder than expected.
“In terms of damage to young fish, no stricter measures are required either in Belgium or in other Member States,” says Elisabeth Debusschere, “but additional research on other species and other stages of life, as well as research on long-term effects, are clearly needed.” In spite of the need for additional research, these results can already be used to steer the goals set out in the European Guidelines for Marine Strategy, which are currently nearly exclusively oriented to the effects on sea-dwelling mammals and measurements of standard sound characteristics.