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Marine Ecology Progress Series

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MEPS 596:213-232 (2018)  -  DOI:

Disturbance of harbour porpoises during construction of the first seven offshore wind farms in Germany

Miriam J. Brandt1,*, Anne-Cecile Dragon1, Ansgar Diederichs1, Michael A. Bellmann2, Veronika Wahl3, Werner Piper4, Jacob Nabe-Nielsen5, Georg Nehls1

1BioConsult SH GmbH&Co.KG, 25813 Husum, Germany
2Institute of Technical and Applied Physics (itap) GmbH, 26129 Oldenburg, Germany
3IBL Umweltplanung GmbH, 26122 Oldenburg, Germany
4Institute for Applied Ecosystem Research (IfAÖ) GmbH, 20357 Hamburg, Germany
5Department of Bioscience, Section for Marine Mammal Research, Aarhus University, 4000 Roskilde, Denmark
*Corresponding author:

ABSTRACT: We investigated the disturbance effects of offshore windfarm construction on harbour porpoises Phocoena phocoena using acoustic porpoise monitoring data and noise measurements during construction of the first 7 large-scale offshore wind farms in the German Bight between 2010 and 2013. At 6 wind farms, active noise mitigation systems (NMS) were applied during most piling events, and 1 was constructed without. Based on generalized additive modelling analyses, we describe a clear gradient in the decline of porpoise detections after piling, depending on noise level and distance to piling. Declines were found at sound levels exceeding 143 dB re 1 µPa2s (the sound exposure level exceeded during 5% of piling time, SEL05) and up to 17 km from piling. When only considering piling events with NMS, the maximum effect distance was 14 km. Compared to 24-48 h before piling, porpoise detections declined more strongly during unmitigated piling events at all distances: at 10-15 km declines were around 50% during piling without NMS, but only 17% when NMS were applied. Within the vicinity (up to about 2 km) of the construction site, porpoise detections declined several hours before the start of piling and were reduced for about 1-2 d after piling, while at the maximum effect distance, avoidance was only found during the hours of piling. The application of first generation NMS thus reduced the effect range of pile driving and led to a lower decline of porpoise detections over all distances. However, NMS were still under development and did not always work with equal efficiency. As NMS have further developed since, future investigations are expected to show additional reduction of disturbance effects.

KEY WORDS: Acoustic monitoring · Acoustics · Anthropogenic impact · Behaviour · Marine mammal · PAM · Phocoena phocoena · Spatial scale · Wind turbine · Pile driving

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Cite this article as: Brandt MJ, Dragon AC, Diederichs A, Bellmann MA and others (2018) Disturbance of harbour porpoises during construction of the first seven offshore wind farms in Germany. Mar Ecol Prog Ser 596:213-232.

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