MEPS 557:261-275 (2016)  -  DOI:

Harbour porpoise movement strategy affects cumulative number of animals acoustically exposed to underwater explosions

Geert Aarts1,2,*, Alexander M. von Benda-Beckmann3, Klaus Lucke1,4, H. Özkan Sertlek5, Rob van Bemmelen1, Steve C. V. Geelhoed1, Sophie Brasseur1, Meike Scheidat1, Frans-Peter A. Lam3, Hans Slabbekoorn5, Roger Kirkwood1

1Wageningen University & Research, Wageningen Marine Research, Ankerpark 27, 1781 AG Den Helder, The Netherlands
2Wageningen University & Research, Department of Aquatic Ecology & Water Quality Management (AEW), Droevendaalsesteeg 3a, Building 100, 6708 PB Wageningen, The Netherlands
3TNO Acoustics and Sonar, Oude Waalsdorperweg 63, 2597 AK, The Hague, The Netherlands
4Centre for Marine Science & Technology, Curtin University, GPO Box U1987, Perth, WA 6845, Australia
5Leiden University, Institute of Biology Leiden, Sylviusweg 72, 2333 BE Leiden, The Netherlands
*Corresponding author:

ABSTRACT: Anthropogenic sound in the marine environment can have negative consequences for marine fauna. Since most sound sources are intermittent or continuous, estimating how many individuals are exposed over time remains challenging, as this depends on the animals’ mobility. Here we explored how animal movement influences how many, and how often, animals are impacted by sound. In a dedicated study, we estimated how different movement strategies affect the number of individual harbour porpoises Phocoena phocoena receiving temporary or permanent hearing loss due to underwater detonations of recovered explosives (mostly WWII aerial bombs). Geo-statistical distribution models were fitted to data from 4 marine mammal aerial surveys and used to simulate the distribution and movement of porpoises. Based on derived dose–response thresholds for temporary (TTS) or permanent threshold shifts (PTS), we estimated the number of animals affected in a single year. When individuals were free-roaming, an estimated 1200 and 24000 unique individuals would suffer PTS and TTS, respectively. This equates to respectively 0.50 and 10% of the estimated North Sea population. In contrast, when porpoises remained in a local area, fewer animals would receive PTS and TTS (1100 [0.47%] and 15000 [6.5%], respectively), but more individuals would be subjected to repeated exposures. Because most anthropogenic sound-producing activities operate continuously or intermittently, snapshot distribution estimates alone tend to underestimate the number of individuals exposed, particularly for mobile species. Hence, an understanding of animal movement is needed to estimate the impact of underwater sound or other human disturbance.

KEY WORDS: Marine mammals · Anthropogenic sound · Individual-based model · Cumulative effects · Impact assessment · Population consequences of disturbance · Species distribution · Acoustics

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Cite this article as: Aarts G, von Benda-Beckmann AM, Lucke K, Sertlek HÖ and others (2016) Harbour porpoise movement strategy affects cumulative number of animals acoustically exposed to underwater explosions. Mar Ecol Prog Ser 557:261-275.

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