Dear Colleagues,

Those of you interested in the effects of underwater noise on aquatic life may 
be interested in our recent Open Access publication in Scientific Reports:

Underwater noise levels in UK waters (2016)
Nathan D. Merchant, Kate L. Brookes, Rebecca C. Faulkner, Anthony W. J. 
Bicknell, Brendan J. Godley & Matthew J. Witt
Scientific Reports 6, Article number: 36942

Abstract: Underwater noise from human activities appears to be rising, with 
ramifications for acoustically sensitive marine organisms and the functioning 
of marine ecosystems. Policymakers are beginning to address the risk of 
ecological impact, but are constrained by a lack of data on current and 
historic noise levels. Here, we present the first nationally coordinated effort 
to quantify underwater noise levels, in support of UK policy objectives under 
the EU Marine Strategy Framework Directive (MSFD). Field measurements were made 
during 2013–2014 at twelve sites around the UK. Median noise levels ranged from 
81.5–95.5 dB re 1 μPa for one-third octave bands from 63–500 Hz. Noise exposure 
varied considerably, with little anthropogenic influence at the Celtic Sea 
site, to several North Sea sites with persistent vessel noise. Comparison of 
acoustic metrics found that the RMS level (conventionally used to represent the 
mean) was highly skewed by outliers, exceeding the 97th percentile at some 
frequencies. We conclude that environmental indicators of anthropogenic noise 
should instead use percentiles, to ensure statistical robustness. Power 
analysis indicated that at least three decades of continuous monitoring would 
be required to detect trends of similar magnitude to historic rises in noise 
levels observed in the Northeast Pacific.

Kind regards,


Dr Nathan Merchant
Principal Scientist, Noise & Bioacoustics Team
Pakefield Road, Lowestoft, Suffolk, NR33 0HT, UK
Tel: +44(0) 1502 527780 | Mob: +44 (0) 7789 651086
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