Underwater noise levels in UK waters.
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 97thpercentile 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.
Centre for Environment, Fisheries &Aquaculture Science (Cefas), Lowestoft, UK.
Nathan D
ND
Merchant
Marine Scotland Science, Aberdeen, UK.
Kate L
KL
Brookes
Centre for Environment, Fisheries &Aquaculture Science (Cefas), Lowestoft, UK.
Rebecca C
RC
Faulkner
Environment and Sustainability Institute, University of Exeter, Penryn, UK.|Centre for Ecology and Conservation, University of Exeter, Penryn, UK.
Anthony W J
AW
Bicknell
Environment and Sustainability Institute, University of Exeter, Penryn, UK.|Centre for Ecology and Conservation, University of Exeter, Penryn, UK.
Brendan J
BJ
Godley
Environment and Sustainability Institute, University of Exeter, Penryn, UK.
Matthew J
MJ
Witt